Li-Ion Battery Packs

[Azmaria Dei]

Lithium Ion Battery Packs
How to make them and use them safely

For basic soldering to batteries, please see this thread (http://forums.thecustomsabershop.com/showthread.php?6985-Battery-Pack-Making). The same principals for soldering NiMH cells applies to Li-Ion cells, it's just a little more violent when you mess them up bad as Lithium is combustible with air and water. Fortunately, cells these days are made with a tough casing that takes a lot to puncture, as well as being vented on the positive end so that the lithium has a little room to expand. If, however, you somehow make the vented cells squirt out some of the dielectric inside, wrap it up, seal it, wash your hands and scour any surfaces thoroughly, and take the cell to a disposal facility ASAP. That stuff burns and will eat through a lot of things - i've seen it melt the PVC heat shrink on a cell before so it's nothing to play with. If you ever wondered why you can't send cells through airmail normally, this is why - the air pressure drops in a cargo jet and pulls the gel out, potentially letting the lithium come into contact with air that gets sucked back in when the jet lands.

Now that you're sufficiently scared of what can happen if you mess up badly, here's why you want to use Li-Ions. They output 3x as much voltage as most other cells on the market right now while having slightly lower capacities. Their outputs are also rather high due to the really low internal resistance. What does this all mean? That a single AA sized cell will put out a nominal voltage of 3.7V. This is only the common voltage of them though. an actual Li-Ion will vary the voltage from 4.2V at full charge to 2.7V for a completely dead cell. The voltage CAN drop lower, but the risk of damaging the internal materials of the cells rises dramatically. On that note, I've revived and reused Laptop cells that had dropped to .8V and I use them in several sabers now.

Unlike other cells, Li-Ion cells need a PCB (normally this stands for Printed Circuit Board, but in the battery communities it's normally Protection Circuit Board) to prevent it from do ing several things that can either damage the cells, the items powered by them, or potentially the user/operator. This is like a life preserver for the cell. A smart charger has similar circuitry built into them so you can charge unprotected cells with them before you make a pack yourself. There are several standard markings on Li-Ion PCBs and they are thus. B+/B- - these are the terminals you solder the positive and negative battery terminals to. P+/P- - these are the leads for the pack as a whole and go to your device/electronics being powered. BM/B1/B2/etc... - these are the Battery Middle pads where you hook the interconnecting joints between the cells in a multi-cell pack that goes over 3.7V - I'll talk more on these later, but these are basically so that the PCB can power balance the cells (minor adjustments only) and keep them at the same charge level/capacity.

Li-Ion cell sizes are labeled a little differently from other cells as well - normally in a 5 digit code. The first pair of digits are the diameter, the second pair are the length, and the last position is cell type - 0 meaning round. Some standard sizes are 18650 (18mm diameter, 65mm long, and cylindrical cell), 18500, 14500, and 18350.

If you see a Li-Ion cell that says 3.6V instead of 3.7, then that's likely a camera battery and not worth your time. The PCBs in those NORMALLY limit the cell to something like 600-800mA outputs and clip the output voltage at 3.6V so you can't get the full potential out of them. Regular lithium batteries are Li-MnO2 (heat treated Lithium Manganese Dioxide) and these are NOT rechargeable, though they are 80% of the Lithium market. These are normally 3V button cells. Energizer lithium batteries are Li-FeS2 - Lithium Iron Disulfide, and are 1.5V AA or AAA batteries - these are normally not rechargable, but if it's marked as Li/Fe, that's actually lithium iron sulfide. Lithium Polymer batteries are reportedly still too unstable and prone to destroying themselves or other things, so stay away from them as well.

And now we'll look at how to make a battery pack. We're going to do a 7.4V pack, since that's one of the two most common setups in sabers as well as the more complex of the two.

Here we have 2 18500 cells and a 7.4V figure-8 PCB normally made for the end of battery packs. Since I’m making a stick pack, but prefer these PCBs because of the 13A output cutoff, I won't be doing that. Instead I'll be wiring it a little separate from the cells and adding it into the chassis that this pack is intended for. You'll notice that these cells have tabs on them. I like the tabs as it's a little easier to solder to the tabs at times. These are also all recycled tabs from defunct devices like camcorders and laptops.
https://lh5.googleusercontent.com/_k8Kp4lNYp8g/TboWZ_5DynI/AAAAAAAAC_w/DySQhqvsJtQ/s800/IMG_4150.JPG

Like in the other tutorial, file the ends of the cells (or the tabs) so the solder has something to stick to, and tin them as you would any other connection. Once you do that, you can solder the wires all together the first battery (left in the picture) goes from the positive (indicated by the ring in the casing) to the B+ terminal on the PCB. The negative end of battery 1 gets wired to 2 places - the BM pad on the PCB and the positive end on battery 2. This is the control and multi-cell monitoring lead that I mentioned earlier. Then wire the negative side of battery 2 to the B- pad on the PCB.
https://lh5.googleusercontent.com/_k8Kp4lNYp8g/TboWaUrd1sI/AAAAAAAAC_M/kumwRFEbCkA/s800/IMG_4155.JPG

That's it for the battery side of the cells. You can now heat shrink them with your favorite PVC battery heat shrink. For most packs I use 37-42mm heat shrink.
https://lh3.googleusercontent.com/_k8Kp4lNYp8g/TboWap02bUI/AAAAAAAAC_Q/7Se0SAosFWU/s800/IMG_4156.JPG

And here's the final setup for this battery pack. It will eventualy be secured to the chassis and the power leads for the recharge/kill port soldered to the P+ and P- pads on the PCB.
https://lh3.googleusercontent.com/_k8Kp4lNYp8g/TboWbBMU_vI/AAAAAAAAC_U/hXthekFMpXk/s800/IMG_4158.JPG

Here's a look at a 2 cell 3.7V Li-Ion pack. both cells are wired in parallel for twice the capacity, but base voltage. This one is using a small rectangular 3.7V PCB good for packs like this.
https://lh5.googleusercontent.com/_k8Kp4lNYp8g/TboWbaHlOII/AAAAAAAAC_Y/4d47t88xOlE/s800/IMG_4159.JPG

Notice how each end has the same polarities soldered to each other.
https://lh3.googleusercontent.com/_k8Kp4lNYp8g/TboWbxlBKxI/AAAAAAAAC_c/YeoRrftH11o/s800/IMG_4160.JPG

Here's the same PCB on a single cell setup. notice that the same pad is used for B+ and P+.
https://lh4.googleusercontent.com/_k8Kp4lNYp8g/TboWdfAM1mI/AAAAAAAADAA/Q3jeUiCTMAI/s800/IMG_4165.JPG

This is a single cell pack made with an old 18650 cell and a small round PCB.
https://lh4.googleusercontent.com/_k8Kp4lNYp8g/TboWcGjNkXI/AAAAAAAAC_0/OZtkgxatw3M/s800/IMG_4161.JPG

It's an older pack, and the wiring sucks because my iron tip was dying, but the principal is the same. It goes on the negative end and I've folded the negative tab over and soldered it in place to the B- pad. The B+ pad is wired to the positive end. Finally, the P+ and P- pads are wired to a JST connector.
https://lh5.googleusercontent.com/_k8Kp4lNYp8g/TboWcjVoZNI/AAAAAAAAC_k/-CYebKpr6UY/s800/IMG_4162.JPG

And here's that same laptop cell rebuilt and ready for use in a saber.
https://lh3.googleusercontent.com/_k8Kp4lNYp8g/TboWdLxo6YI/AAAAAAAAC_8/h5QNAzhmeTQ/s800/IMG_4164.JPG

Upcoming FAQ will have more info.

Az

[Azmaria Dei]

Lithium Ion Battery Packs
Addendum

-=::FAQ::=-

Can I use protected cells in a pack?
yes, however there are some stipulations to this. 1 - do NOT use a second PCB - they will fight each other and can cause damage to one or both cells. 2 - over time charge levels will become uneven. worst case scenario, you cause cell damage to the one that charges slower when the faster charging one cuts off and the slow cell gets the full voltage. if you have identical cells and they're manufactured close to each other with the same batch of lithium used, there may be no issues what so ever for a year or three. Either way, I do not recommend this - do this at your own risk.

Can I charge an unprotected cell with a smart charger?
Yes. Smart chargers have more advanced versions of the PCB used, but designed for charging. For actual use, you still need to protect your cells, but this is good for initial charging and battery testing.

My PCB has an 8 Amp cutoff. Is that too high?
No, the amperage cutoff is there to prevent shorts. The PCB voltage cutoff circuit will detect voltage fluctuations from the cells being overdrawn and/or heating up and will cut output. Being overdrawn = internal heat = higher internal resistance = sudden voltage drop = PCB cuts you off.

What's the difference between unprotected and protected cells?
Protected cells have a 3.7V PCB built in. Unprotected cells do not and are commonly used for building battery packs. i normally only use unprotected cells and when I get protected cells myself, I strip off the built in PCB (dangerous in and of itself - easy to short the cell during this procedure) and wire it up for whatever pack I need. I also prefer to use cells with tabs, which make it a little easier as you have less metal to heat up to solder to.

I test 9V batteries by licking them... Can I do that with these?
Um... No... That's a good way to fry your tongue and damage your cells (both in your tongue and your batteries). Please do not do this.

Because of (reason), I have to use 2 protected cells in my pack. How can I mitigate the effects that you describe above?
There are a few things you can do. A nice rubberized heat shrink to keep them insulated from varying weather will help control temperature damage between them. Make sure you fully charge your cells (at close to the same time) before you even start soldering. And the most important part - use the same brand from the same package - that's the most likely to be from the same batch of lithium (weather and pressure differences can vary the quality from batch to batch), and that can cause minute variances in charge levels now, which can turn into clefts of difference a year later. If you MUST do this, and you follow these precautions, your batteries will last you for years to come.

Do I have to charge my cells before I make a pack?
For the pack I described, no. The PCB will handle the initial power balancing fairly well if both cells are within about a volt of each other. However, if you use the methods described in the previous question, yes - THAT is critical since the charger can't power balance the cells. If you're wiring multiple cells in parallel, you need to charge those as well, as those can't be power balanced by most hobby PCBs either - though by common power flow theory, it's not too critical. That has to do with varying voltage acceptance and internal resistances, and a subject for another day.

Ok, I soldered everything up and everything looks good, but I'm not getting power out of it! What did I do wrong?
Calm down and keep breathing. PCBs come in a protected state so you don't damage anything wiring them up. Just plug it into a charger and it'll reset.

Thanks to a particular Forgetful Jedi Knight, here's a good clear picture of the 7.4V PCB that Tim sells all wired up.
http://i1115.photobucket.com/albums/k543/forgetfuljediknight/DSC00326.jpg

Az

[Knighthammer]

Looks great so far Az - thanks a ton for this!

[cannibal869]

Most excellent work AZ!! I think it goes without saying that this should be stickied :)

[Azmaria Dei]

Most excellent work AZ!! I think it goes without saying that this should be stickied :)

it already has been. ^_^ thanks though.

[Skottsaber]

Thanks so much for the tutorial, Az!

[Silver Serpent]

Great tutorial Az! I now have another link to send to people with saber-building questions. :)

[Takanis]

I had a request from Azmaria to post a pic of the PCB that is sold in the store. Here it is!

http://i806.photobucket.com/albums/yy348/SimpiGon/Petit%20Crouton%20Project/th_014.jpg (http://s806.photobucket.com/albums/yy348/SimpiGon/Petit%20Crouton%20Project/?action=view&current=014.jpg)

[(null).exe]

Fantastic work!

Packed with information, without being too hard to digest for noobs like me, just like a good tutorial should be!

[Loachri MacTalabh]

Good Job Az, It will come in handy when I am ready to start making protected packs.

[Jedi-Loreen]

Most excellent work AZ!! I think it goes without saying that this should be stickied :)


it already has been. ^_^ thanks though.
Yep, I Stickied it not long after she posted the initial post. ;)

I guess I should see about adding it to the Thread Index.

[jin starkiller]

really good tutorial Az ....lots of useful information on how to make battery packs

[Skottsaber]

The Complete Spoonfeed from start to finish on making a battery pack
By Skottsaber :wink:

I will be demonstrating how to construct a 14500 7.4v pack.

To start of with, you are going to need some basic tools. On the left is what you need 100%, and on the right are recommended extras.
http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0077_800x600.jpg

On the left we have heatshrink, our cells (tabbed) and a protection PCB. You will also need a hot air gun or hairdryer for heatshrinking.
On the right is flux (makes the solder flow, there is some in your solder already but sometimes it helps to have more), sandpaper for filing the cells (don't worry if you have tabbed cells) and a glue gun for protecting the connections at the end of the cells (also useful for extra stability.)

Also, you can just see my benchtop mini vise that I'll be using to hold the PCB and batteries during soldering.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0078_800x600.jpg

Here is the protection PCB, you can skip this step if you want but I always do it. See that white connector? You don't need it at all, so we're going to take it off. It is a surface mount device so you will need to have a bit of skill and a small iron tip.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0079_800x600.jpg

First, add solder to all the points on the connector, bridging the back 2 pins.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0081_800x600.jpg

Then heat up those joints while pulling on the connector and once they are all molten (you may have to hit them a few times) the connector will pull right off. :cool:

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0086_800x600.jpg

Then just clean off the extra solder by wicking it off (recommended) or using a solder sucker.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0089_800x600.jpg

You should end up with something looking a bit like this comparison shot. And this is what you should have so far:

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0090_800x600.jpg

Now we get to the actual soldering of the cells, I'm going to show you in a comic strip style and then explain.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0091_800x600_400x300.jpghttp://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0092_800x600_400x300.jpghttp://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0094_800x600_400x300.jpghttp://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0095_800x600_400x300.jpghttp://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0096_800x600_400x300.jpg

(NOTE: This is how I do my tabs, and not any "definitive way", follow my advice at your own risk [of being awesome 8-)])

On the side of the pack where you join the 2 cells (BM pad), fold one tab over the other cell. Measure where it needs to stop and cut it (you want it to fold all the way over the front of the cell). Next, Tin the top of the non-folded tab. After that, fold the tab back over and solder in place. Then tin the middle of the folded tab, and fold the (as of yet) non folded tab over and solder in place.Then solder it down on top of the cell.
Keep up? Good.

This is what you should have now:

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0097_800x600.jpg

Now you need to measure and cut all your wires. Make sure that the wires coming from P+ and P- are not the same length, one needs to be longer so that they come out of the pack the same length (if you're interested in neatness like me ;) ) Your wires are ALWAYS going to be shorter than you thought they were, so add some extra when cutting (you can always take away, but never add ;) )
Strip, twist, and tin all of these wires.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0099_800x600.jpg

Solder the BM wire (having added some more solder to the final joint you made). Pull it to test the strength of the join between the cells.

Next, trim and tin the positive and negative terminals of the pack.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0100_800x600.jpg

And solder the wires in.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0101_800x600.jpg

You should end up with this:

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0102_800x600.jpg

Now tin all the pads on the PCB.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0104_800x600.jpg

Solder on the P- and P+ wires (you don't want to do any extra soldering on top of the battery pack, it is probably safer and it will also be less crowded).

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0105_800x600.jpg

And then solder in the wires coming from the cells themselves.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0106_800x600.jpg

OK that's it for tonight, I'll post the rest when I finish the pack. :wink:
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
OKIDAY now for the final part!

So after you have your PCB soldered up you'll want to quickly plug it into the charger and make sure it goes red. This also activates the PCB. Don't leave it there for too long, you don't want enough power in there to arc the wires when you continue building it.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0107_800x600.jpg

DO NOT SKIP THIS STEP! If you find once you've got it all heatshrunk that it doesn't charge or give power, you're going to have a much harder time fixing it than if it wasn't heatshrunk.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0108_800x600.jpg

Next, measure out your heatshrink. I leave a decent lip over mine that will prevent anything touching the ends of the cells, but not such a lip that will stick out of the pack more than it needs to. If you can, slide your cells into the long piece of heatshrink to "stretch it", this will help in a while.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0109_800x600.jpg

Cut the shrink to size, just using ordinary scissors.

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0111_800x600.jpg

Push your pack into the heatshrink and position any wires (for instance the pack positive and negative) that need to be placed. Having "stretched" the shrink beforehand makes this step easier.
The bit of heatshrink I have on the positive wire in this picture is just to prevent accidental shorts happening while I manipulate the pack. Take it off before you shrink the pack.

Now all you need to do is apply hot air! A heat gun / hairdryer works well. Use high heat and low air, and at first rotate the pack around, warming up the heatshrink, and then go slowly around. Once you've finished, check for any spots where you can still push the heatshrink and go over those bits again.
You should end up with this:

http://i1137.photobucket.com/albums/n520/Skottsaber/Li-Ion%20Tutorial/SANY0113_800x600.jpg

Then just stick it in the charger again and make sure it charges. If it does you're good to go! 8-)

[tachikoma1]

Great tutorial. It helped. I just picked up some of the de-soldering braid and it works wonders at mopping up solder blobs that got away from me. I'm rapidly being humbled at the art of "cram fu" on my first saber. Although I picked a 13.5 inch long hilt roughly based on the ObiWan ROTS, you run out of room surprisingly fast. I started out wanting to use a pair of 18650s. Nope. Too fat to fit side-by-side. Too long to fit anywhere as a stick. So I tried 18500s. Just short enough to fit lengthwise, but now too fat with my heatshrink to fit where I wanted. Jeeze man! So now I've conceded that I have to use "AA" size 14500s. They should fit side-by-side nicely with a little wiggle room and no pinched wires. What's the average battery life for a 7.4v 14500 pack on a Petit Crouton saber with everything except a rumble motor activated? Assuming I'm running a Luxeon Rebel Star blue at 1000mA.

[Sunrider]

If you are willing to put fourth the effort 18650s side by side with the protection pcb, and a PC, and more, can be done.

eg. http://forums.thecustomsabershop.com/showthread.php?12976-Sunrider-s-Praxis-Saber

[Darth Xusia]

Great tutorial. It helped. I just picked up some of the de-soldering braid and it works wonders at mopping up solder blobs that got away from me. I'm rapidly being humbled at the art of "cram fu" on my first saber. Although I picked a 13.5 inch long hilt roughly based on the ObiWan ROTS, you run out of room surprisingly fast. I started out wanting to use a pair of 18650s. Nope. Too fat to fit side-by-side. Too long to fit anywhere as a stick. So I tried 18500s. Just short enough to fit lengthwise, but now too fat with my heatshrink to fit where I wanted. Jeeze man! So now I've conceded that I have to use "AA" size 14500s. They should fit side-by-side nicely with a little wiggle room and no pinched wires. What's the average battery life for a 7.4v 14500 pack on a Petit Crouton saber with everything except a rumble motor activated? Assuming I'm running a Luxeon Rebel Star blue at 1000mA.

With alot of Cram-Fu you can fit 2 18650's in an MHS Obi Wan build.
http://www.fx-sabers.com/forum/index.php?topic=25662.0
I still don't have pics of the internals but I am am getting ready to update this saber and I'll take some
new pics to show how I fit everything in there. Darth Real-Life is kicking my butt at the moment.

[tachikoma1]

Two 18650s side by side measure 1.45", the largest inside diameter in my hilt is 1.25". I'd be very interested in learning how this can be done. Specifically, I have a DF4GR (4-inch grooved with "Mara Jade" screw holes) piece followed by a ribbed/choke combo piece. In the back I have a pommel style 10 with a MHS Gear piece. My PC chassis/sled goes in the rear half of the main body. an AV, aux switch and charge port take up the front half of that piece. So my battery pack has to fit entirely in the ribbed/choke combo. The 18mm batts can barely fit in the narrow choke piece, but with the wires from the Luxeon combined with wires and heat shrink on the battery pack, it don't work. So an end-to-end battery "stick" is not going to fit. I see the "praxis" saber somehow has 2 18650s side by side in the same DF4GR piece. But it looks like he reamed out some material inside to make it fit. I'm afraid that is beyond my skills at this time.

Edit: I do have the option of using 30 gauge wire for the Luxeon and battery pack. If I do that it "might" fit. But I was concerned with the amount of current going through those tiny (single strand) wires. Any input on this idea?

[Loachri MacTalabh]

It takes some grinding and sanding. Look at the links that others have presented to you.

[Azmaria Dei]

i don't recommend using solid wire - always use stranded for the better current handling ability.

[tachikoma1]

i don't recommend using solid wire - always use stranded for the better current handling ability.

My thoughts exactly. The "official" max current for 30 gauge wire for "wiring chassis" is 860mA. I'm planning on driving my LED to 1000mA or higher. That's how model rocket igniters work. A small gauge wire with a 1 or 2 amp current gets red hot. Hot enough to flare a bit of phosphorous material and ignite your solid rocket motor. I don't think I want that right next to Li-ion batteries in my hand. I think I'll stick to my 14500 battery pack idea. Grinding and sanding to make batteries fit, I think is too ambitious for me right now. I don't have the tools nor the skills to do that without ruining the piece. I''ve already ruined one DF4GR trying to figure out my internal chassis and waiting (impatiently) for a replacement from Tim.

[Azmaria Dei]

i somehow got a hold of a bunch of 28GA pure copper braid that seems to handle 5A with ease at work. not to brag or anything... but it's really great powerline wire.

[Jacen Solo]

When I get protected cells myself, I strip off the built in PCB (dangerous in and of itself - easy to short the cell during this procedure) and wire it up for whatever pack I need.



Do you have a tutorial or know of a tutorial for doing this?

Cheers

[Sunrider]

Quality 30 guage stranded wire can handle 1.5 amps easy with lengths of less than a foot.

[Azmaria Dei]

it's fairly simple - carefully strip the heatshrink off, do not let ANYTHING metal touch it, and pay extreme care to a thin metal strip running down the side with tape under it. THAT is the pos and can NOT touch the metal casing or it'll arc and you get explodeys shortly after. cut that strip FAST and CAREFULLY and pull it away from the body. after that, desolder the PCB from the negative end and you're done. easy as nitroglycerin pie topped with napalm and candles. ^_^

[Skottsaber]

OK update added to my tutorial post, enjoy ;)

[Azmaria Dei]

a quick tip - i use a cuticle cutter (the V grooved tip ones) to slice through heatshrink with ease if you do need to remove that heatshrink for any reason.

[tachikoma1]

Quality 30 guage stranded wire can handle 1.5 amps easy with lengths of less than a foot.

I couldn't find stranded 30 AWG. The only stuff I could find was solid core "wrapping wire" at Radio Shack. I had an idea to use this with little terminal posts and actually do a wire wrap setup for the neatness and to save room. But that was only for accent LEDs and switches.

[psab keel]

I figured that this would likely be the best place to post this without creating a whole new thread. I followed the tutorial exactly as shown here, and now my pack is built. I triple checked all my wiring and everything is as it should be. Only problem is that I when I plug my pack into the charger I have a constant green light. It's supposed to turn red when it's charging right?

I built a 7.4 Li-Ion Pack (14500 AA Sized pack) and have a Tenergy Li-Ion Smart charger set to the 7.4 charge setting.

Any help would be most appreciated!

Thanks, Psab

[Sunrider]

Double check proper wiring and connections.;)

[Skottsaber]

And make sure you have polarity correct on the jack/recharge port, and check the connections on your cells.

[psab keel]

I had another set to work with and started from scratch. I got it to work! Red charge light lit up. Turns out that I'd accidentally torn a trace off the PCB when I installed it. No big deal, like I said, I'd purchased extras just for this very reason.

Thanks for your help everyone!

: )

[nikk777]

Would a battery for a Nintendo ds lite be protected or raw? Here's a link to what I bought.... http://cgi.ebay.com/Rechargeable-Battery-Tool-Nintendo-DS-NDS-Lite-NDSL-/220831142922?pt=Video_Games_Accessories&hash=item336a8fd40a
I soldered 5 together in parallel to create a 3.7v 18,000mah pack for use on a cell phone used for gps tracking. I used a pcb protection board (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170665840436&ssPageName=STRK:MEWNX:IT) but after reading this, I'm wondering if I shouldn't have as they might already be protected.

Also, do cell phones have protection circuitry in them so the pack doesn't need it? or do they not? If the cell phone has the protection and the charger is a smart charger with the protection, the battery packs could be raw....correct?

What kind of charger would be best for my pack mentioned above? or a pack made up of 5-10 18650's in parallel? or one of these... http://cgi.ebay.com/One-3-7V-10000mAh-5C-Lipo-Rechargeable-Battery-Cell-/380360808130?pt=US_Batteries&hash=item588f4556c2 ?

when in parallel, do they have to be balance charged or is that only for battery packs in series?

I'm sorry for the newb questions but I've been reading a ton and think I understand but nothing has directly answered my questions and your post has come the closest to what I'm looking for. I appreciate any help.

Background: I've been the victim of several thefts and have investigated different methods of tracking devices as the cops could care less about locating thiefs. An effective and low cost method uses older motorola phones on the boost network but the phone batteries do not last very long so I'm trying to build larger battery packs to give myself several weeks worth of charge vs. a couple of days. there is a motion activated system that I have bought but can't afford to buy several of them at $250 each so larger battery capacity seemed the lowest cost option.

[Sunrider]

Batteries in parallel don't need the single PCB. I would guess those have a PCB in them but idk. Open one and look. The only 3.7v smart chargers Ive seen are 1-2 amps and would take more than a day to charge that monster pack.

[Skottsaber]

I'm 80% sure that to get that capacity with that size cell (single cells are 1600mah right?) they aren't Li-Ion cells. Probably something like Li-Po or similar.

[Azmaria Dei]

cell phone batteries are generally a different type of low output, high life Lithium formula that doesn't need a PCB. if it does, it has one built in.

[Marco]

1. Is it correct to assume that the less gauge a wire has, for example 18 gauge wire, has a better current capacity or current-carrying capacity than thinner, for example 28 gauge wire?

2. Moreover that the thicker the wire is like the lower the gauge value the less heat it will produce?

I just want to check because if Im going to build a pack I want to make sure to get the best wire for it...

Thanks in advance,

Marco (:

[Sunrider]

2 seconds on google.

http://www.firecommunications.com/dcamps.html

Spoon is in the dishwasher now.

[Marco]

haha nice thanks :D

[nikk777]

So neither the ds lite batteries nor the 18650's perrformed as expected... Basically I'm only getting power from a single cell it would seem. I have all the positives connected and going to the positive wire, then all the negative's connected and going to the negative wire. To charge the packs, is a balance charger setup required? I have the charger, just no plugs yet...

I have 4 3k mah 18650's wired together for 12k mah total and then to a pcb for 3.7v batteries. I charged it with a charger that is used for another large 4000mah pack I have and it has the LED indicator to show charging vs. charged.(red/green led) In the phone the pack lasted for about as long as what I get out of the stock 1500mah cell phone battery.

thoughts? errors I made possibly? Oversights? dumb screw-ups? I'm new to this so help me learn please.

[Sunrider]

How does 1 batt compare to 4? do they read 4.2v after charge? What kind of batteries are they?

[nikk777]

They all read 4.18v or something close to that. they are 18650 3000mah batteries. I have resoldered them to see if the joints were not connecting well. Also considering battery holders vs. soldering together....

[beavis4ever]

Has anyone made packs with 14500s with 4 cells? I would like to make 2 parallel packs and then wire them in series. I'm sure it is possible but wanted people's opinions and experiences. Thanks!

[Sunrider]

If you mean 4 cells for 7.4v than yes. Many use these.

[beavis4ever]

If you mean 4 cells for 7.4v than yes. Many use these.

Yes. That is what I meant. I didn't see any setups like that in this thread so I wasn't sure. Wasn't really sure what to search for either. I tried 2P2S but found nothing. Thanks!

[Marco]

I noticed in the tut on the second page he wired the negative lead to the bm of the pcb but the pdf file for the 7.4 v pcb from the tcss shop says this:

Terminal explanations

1、B+： Connected to the second battery’s positive terminal
2、BM/COM： Connected to the first battery’s positive terminal
3、B-： Connected to the first battery’s negative terminal
4、P+： Connected to the battery’s output or the charger’s positive terminal
5、P-： Connected to the battery’s output or the charger’s negative terminal

So you should wire the positve to the bm?

Can you check my diagram? --> 5765

[Skottsaber]

The positive and negative are connected together, so it would make no difference where on the connection to add the BM wire. I just soldered it in the most convenient place for wire routing. ;)

[Marco]

So the diagram is correct?

[Skottsaber]

Yep :mrgreen:

[Marco]

awesome do you have and dos and donts for wiring a pack up? I really dont want to blow my face of... :D Like only applying heat from the soldering iron for 5 secs max. or something like that? :D (is it actually possible to wire batteries without tabs?)

[Jay-gon Jinn]

awesome do you have and dos and donts for wiring a pack up? I really dont want to blow my face of... :D Like only applying heat from the soldering iron for 5 secs max. or something like that? :D (is it actually possible to wire batteries without tabs?)It is possible to wire batteries together that do not have tabs on them, but it is a bit more difficult to do. You'll need some solder flux, some medium grit sandpaper, and a nice hot iron.

[Skottsaber]

Jay, while I have to admit you've made many many more packs than I have, I was warned by Erv' not to use flux when soldering cells, as it's job is of course to take heat away from the surface, making soldering the cells even harder.
I don't know what results you've had with flux, so I can't say for sure though...

[Jedi-Loreen]

Really? In my experience, flux's job isn't to take heat away, it's to clean the parts you're soldering (it's slightly acidic) and to make the solder flow more easily.

But maybe an EE knows better than I do.

[Boj-Vaati Mau]

*nods* What Lori said. If you're using rosin core solder it flows on with minimal application of the iron, just a few seconds. As long as the chrome is scraped off it really doesn't take much to get the ends tinned and the wires on.

[Sunrider]

Really? In my experience, flux's job isn't to take heat away, it's to clean the parts you're soldering (it's slightly acidic) and to make the solder flow more easily.

But maybe an EE knows better than I do.

Yep, Flux or rosin is to clean the surface for proper bonding.

[Skottsaber]

But maybe an EE knows better than I do.

I wouldn't argue with a professional solderer :mrgreen: Yeah, the flux is to clean the surface of impurities and residue and help the solder "stick".
But consider that you have the flux boiling off, which is absorbing the energy and taking it away from the surface you're trying to heat, and that soldering a pad on a board requires much less heat than the tab of a metal cell. So while you might be able to get away with the extra flux on a pad, it might be detrimental on a cell.

But I don't know for sure.

[Jay-gon Jinn]

Jay, while I have to admit you've made many many more packs than I have, I was warned by Erv' not to use flux when soldering cells, as it's job is of course to take heat away from the surface, making soldering the cells even harder.
I don't know what results you've had with flux, so I can't say for sure though...well, it actually made the solder stick to the cell, where without it, the solder would simply ball up and roll off.

[FenderBender]

Which is why I scratch the surface of the cells with a file first:

http://i136.photobucket.com/albums/q169/AJFenderBender/VV%20R%20and%20D/Starkiller%20Build%20Log/Battery%20Packs/013.jpg

Makes it easier to solder to, and the solder flows quicker.

[Jay-gon Jinn]

did that...didn't help much for me. I usually avoid the issue anyway, and get cells with tabs.

[Wong Yoon Wei]

QFT for cells with tabs. They are so easy to solder to you can practically do them with your eyes closed.

[IndustrialAction]

LOL, soldering with your eyes close! Love it! :lol:

[Marco]

one more little confirmation...

Will this work --> 5896

Thanks in advance...

:)

[Silver Serpent]

Looks right to me.

[Marco]

thanks for the check :)

[Marco]

Did it thanks to all :D

[scotticus]

Okay, not a total newb, but i am to these protected circuits. Can i use two 3.7v protected cells and the 7.4v PCB? or do i have to use the unprotected cells?

[Skottsaber]

One or the other.
Either you use the 2 protected cells and no protection, or 2 unprotected cells and the protection circuit (recommended for making packs).

[scotticus]

so all i see on TCSS is protected cells sold in packs of two. I was planning on getting a PC w/ two of these cells wired in series with 2.1mm jack for recharging. if i solder two of the protected cells together, they don't need any kind of PCB? i can just hook them into the PC and recharge port?

[Skottsaber]

Yes, that will work. But you will notice after some usage that the pack will have less runtime and seem to discharge quicker. This is because each cell's protection circuit is going to be slightly off balance to the other. This will eventually lead to one cutting off before the other and your pack will start to have shorter runtimes.
I highly recommend getting unprotected cells and a PCB.

[scotticus]

okay that's what i thought. i only see protected cells on TCSS, where do you guys usually get unprotected cells?

[KuroChou]

My current supply is out of old laptops. :D

[thejedilestat]

okay that's what i thought. i only see protected cells on TCSS, where do you guys usually get unprotected cells?

http://www.thecustomsabershop.com/Li-Ion-14500-Rechargeable-AA-size-37V-800mAh-P480.aspx :)

[scotticus]

ah, yes, those don't say protected. :) how long would those last in series? i was thinking of using 2 x 18650's since they would probably last longer.

[Skottsaber]

Your battery life really depends on what you have running off of it.
What LED? Do you have a soundboard? Accent LEDs?

[Sunrider]

ah, yes, those don't say protected. :) how long would those last in series? i was thinking of using 2 x 18650's since they would probably last longer.

Whatever the setup, 2 18650s would run 4 times longer than 2 14500s. ;)

[psab keel]

I just finished up my saber using 2 Qty. Li-Ion 18650 cells in series to make 7.4 volts. Everything works fine, but I find that when the battery runs low, it simply turns off rather than dims. This is normal for this kind of set up right? Also, how long does it usually take to charge?

[psab keel]

And now for some reason I'm getting a green light on my charger when I plug my saber in to charge it. But when I turn the saber on (while plugged in to the charger) the light turns red. I know I wire it up correctly and shouldn't all power be cut from the saber when the kill key or charger is plugged in? It cut the power and was working fine for an hour or two before this. Really confused right now.

[Sunrider]

The protection pcbs turn the pack off when batteries get low. It sounds like your kill key port is not wired right.

[nuanpi1]

Hello,
I am trying to solder two Li-Ion 14500 Rechargeable AA size 3.7V 800mAh. The negative side gets solder perfectly but the positive side repels the solder wire. I am trying to look why this happen but I am not able to find any information. I would appreciate any help
thanks

[Skottsaber]

I have also tried soldering them to no avail - but I did get a handy tip from Erv'. Rub the cells with your iron to spread the heat around - and make sure to tin your iron while you solder.
Or just use tabbed cells ;)

[Silver Serpent]

Also, you can try lightly sanding the battery where you're going to solder. Use sandpaper or a file, just enough to rough up the surface.

Or just use tabbed cells. ;)

[Darth Magnus.]

besides roughing up the ends of the battery and tinning my soldering iron, I usually run my iron a little hotter (around 370-380degrees c)(wouldn't go above 400c)
helps get the heat in quickly so you dont end up heating the whole battery.

[RattleHornet]

Is this correct?
6357

4 x 14500 with no pcb
2 parallels to series

I want to make a 7.4v 1800mAh battery pack.

[Sunrider]

Looks right.

[RattleHornet]

I am uncertain but I heard it said that rechargeable battery should not connect in parallel because they charge each other and exhaust(or explode).

Is it true?:(

[Sunrider]

No. Study more you must.

[Darth Vapour]

Sorry if this is a stupid question,but can you use battery holders in making a pack to avoid needing to solder to the batteries?

[Silver Serpent]

The battery holders have a tendency to lose connection briefly when you have an impact. This can cause your saber to reboot everytime you strike another saber with yours. If you're not comfortable soldering your own packs, the store now sells a wide variety of preassembled battery packs.

[afrojedi]

Sorry Az but you indicated that you use 32-44 mm heatshrink in this tutorial and I wanted to know which heatshrink is that? All the sizing is in fractional inches.

[Silver Serpent]

1 inch = 25.4 mm. The heatshrink you'll need to build your own battery pack is not available at TCSS. You'll have to search elsewhere online for it. Specialty battery suppliers often carry the stuff you want.

[afrojedi]

1 inch = 25.4 mm. The heatshrink you'll need to build your own battery pack is not available at TCSS. You'll have to search elsewhere online for it. Specialty battery suppliers often carry the stuff you want.

Thanks Silver Serpent, you have been an amazing help. I really appreciate all the help. Now I'm off to read the plecter labs PC v3 manual.

I had to redo the list cause I accidently cleared it. the great bit about that is that it forces me to remember it over and over again.

[jamesfuss]

will these batteries be okay to do this with and work properly on a petit crouton V3.%?
http://www.jaycar.com.au/productView.asp?ID=SB2403

[Forgetful Jedi Knight]

will these batteries be okay to do this with and work properly on a petit crouton V3.%?
http://www.jaycar.com.au/productView.asp?ID=SB2403

You would need a 7.4V pack, unless you are doing the 3.7V hack on the PC.

[jamesfuss]

I mean to use two of those batteries connected to a pcb to get the 7.4v, just wondering if those batteries are okay to do so with

[Forgetful Jedi Knight]

As long as they are unprotected (no PCB built into the individual cell) cells they are.

[TheMCP]

Hello, greetings from Austria!

I have a question:
When i build a 3,7V pack with two parallel 18650, i should only use one pcb.
If i buy two 3,7V 3400mAh Panasonic with PCB build in, can i use one of the build in PCB's? (remove PCB's, wire the two unprotected cells together in parallel on one of the removed PCB).
Or do i need a special PCB?

Tom

[Madcow]

Hello, greetings from Austria!

I have a question:
When i build a 3,7V pack with two parallel 18650, i should only use one pcb.
If i buy two 3,7V 3400mAh Panasonic with PCB build in, can i use one of the build in PCB's? (remove PCB's, wire the two unprotected cells together in parallel on one of the removed PCB).
Or do i need a special PCB?

Tom

No sure why you would want to put them in parallel... You want a pack that has 3.7 volts and almost 7000 mAh? I would simply use one protected cell - done.
If you really want to wire in two cells parallel, you would need a special PCB I think.

[iainm]

Your 7.4V packs range between 800 and 1400 mAh. When buying a 7.4V pack how should I choose which mAh value to use? Does it all depend on what else is going into the saber apart from the LED? More stuff requires a higher mAh value perhaps? Thanks.

[Generic Jedi]

You want the most mAh possible in a battery pack that will fit in your saber. The more mAh, the longer your saber will run.

[MandoPyrate]

I have a question about the PCB use. Could you use an external DC power source to recharge your Li-ion batteries with the recharging/protecting circuit managing the charge? Say, with an external battery pack to recharge an internal battery pack in a saber.

[Remulos]

So am I to take this as 2 protected cells (same batch, full charge, etc) in series requires nothing more than:

[Recharge Port -] to [+battery 1 -] to [+ battery 2 -] to [Recharge Port +] ??

[Silver Serpent]

Flip both of those batteries over. You want the negative of the first battery connecting to the negative on the recharge port, and the positive of the second battery connecting to the positive on the recharge port.

[Remulos]

Thanks silver serpent! I don't know why I put them that way round ... I'm ashamed of myself.

With this setup, is the heatshrink enough to keep the two batteries together or should I solder something between them? I won't be doing any heavy dueling or anything.

[girot]

#bookmark

[jamiemp]

Sorry, noob question...can I charge a 3.7v battery with a 8.4v charger?

[NanoRex]

Sorry, noob question...can I charge a 3.7v battery with a 8.4v charger?

No you cannot.

[jamiemp]

No you cannot.
So ONLY a 3.7v charger would work?

[Jay-gon Jinn]

So ONLY a 3.7v charger would work?
Yes...if you try the 8.4v charger, the pcb on your battery will shut down and not charge the battery.

[NanoRex]

Could someone with more expertise help me out here: Are IMR (LiMn) cells appropriate for use in saber battery packs (For example AW's IMR cells)? They seem to have the same kind of specifications, and are said to be interchangeable with li-ions, but I'd like if someone could verify this for me.

EDIT: Read some posts on FX and it looks like they are. Good to know. For those who don't know, IMR cells are slightly different from the typical Li-ions, usually having lower capacities but much higher discharge rates.