Li-Ion/Polymer 3.6v batteries... your experiences?

[sithlordfaust]

the problem with the belt charger idea is that the Li-ions need to charge at a certain rate for safety. like 500 mah i think. I doubt a protected pack would work this way. I think as soon as you plugged the belt charger in, the protective circuit woul kick the battery pack off and it wouldnt opperate until it was plugged into a proper charger. you could do a pack without the protective circuit but then youd lose those benefits and potentially gain safety hazards.

it is a good Idea. but unil a vendor comes out with one that has the proper protective output, I think its not in our interest to temp fate

[Jay-gon Jinn]

I've seen emergency chargers for cell phones that use two AA's to recharge a Li-ion cell phone battery....not sure if it would work well as a saber re-charger though.

[Kant Lavar]

I don't know how effective that would be, given the voltage and amperage difference between, say, two AAs and two 14500s, for example. Although, I wonder what would happen if you took one and soldered in, say, an 18650 pack on a quick disconnect (for recharging) as the power supply. (My gut says "magic smoke" but if it didn't do that, there could be... possibilities.)

[cardcollector]

I have found that there are lots of different sizes of Li-ion batteries...

What size do you guys prefer? The larger cell with more Mah, or the smallerones with less mah?

[Rhyen Skytracker]

It depends on the application. You usually want the most mAh (at the correct voltage you need) that will fit in the hilt with the rest of the electronics.

[Novastar]

Card--I don't want to be harsh (again?) but this is something you can determine on your own with very little thought and logic.

When you get right down to it--EVERYONE would like a cell setup with 83273278mAh... heck... how about 83273278Ah???

But as with everything in life--capacity is limited, and physical space usually governs that limit.

Just like with a container of water: a 9 gallon tank/bottle... is far easier to fit into a fridge than a 2 gallon one. Thing is... well... DUHHH, the 9 gallon container will prevent thirst a LOT longer, hahah.

I suppose a good set of comments I could make would be:

* Li-Ion is among the most lightweight of all cells (Lithium is the lightest metal on the periodic table of elements)
* Li-Ion cells have a very high "energy density". This relates to how much power is packed into each square mm or whatever. More bang for your buck.
* ~3.7v per cell vs. 1.2 or 1.5v per cell of equivalent size can be a no-brainer: with the right driver... excess voltage can be "converted" into current.
* Flatter discharge curve. Li-Ions tend to maintain voltage and current output until they are literally "about to die" (for one discharge cycle). Other mainstream cells are very unlike this.
* HOWEVER... Li-Ions have some limitations on MAXIMUM current output. For example, most Li-Ions aren't ideal for >4A of output. However, Ni-Mh can output MUCH more than this (10A, no problem... 20A--maybe too!). I learned this from Eandori about the Ni-Mh, btw.

Although some of the above is in my initial post... all of the information can be used to understand that even battery chemistry can play into what battery solution you should use.

An example. You will be using your saber basically 24-7. Very often. You'll have it on constantly. Alkaline (1.5v) cells might be your best option, since you'll want to replace them the moment the saber shows signs of "dying".

Another example. Your saber is really crazy unique. It needs "spikes" of 4A, sometimes 5A fairly often, since you're using some bizarre and insane lighting system, and a 2" wide blade. Voltage requirements are high too... but you also want the cells to be smallform with decent runtimes. Ni-Mh may be the best choice, using AA-sized or even AAA-sized cells. Edwin (Eandori) once used 21 AAA cells (yes, that's right: twenty-one) to power one of his CF sabers. It fit in a length of 6" and a width of ~1.35". The voltage was ~13v... which Edwin stepped down to ~11v so that CF could handle it.

Another example. Your saber is SMALL. You BARELY have anyroom left. Yet... you want a simple solution. Not many connections/wires... and you have a VERY tight overall outer diameter--like 1.25" or less. A single Li-Ion cell may be your best bet.

So... ultimately, the decision comes down to planning, making educated decisions... and weighing advantages/disadvantages. No cell is "perfect". Some are close, IMHO (lol)... but none are the end-all, be-all of power solutions.

[cardcollector]

That's OK Nova, I didn't take any of your posts helping me as harsh. (though maybe I should have)

That's what I really wanted to know- If there was a cell for any hilt, any time, any where. Obviously now I see there isn't.

I'm also starting to realize that you can't make a " general list" for every saber you make because of the LED differences, hilt size, design, etc.
I've only built three "real" sabers, (two of which are broken right now) so I'm still just trying to figure out the art and difficulty of electronics.

So, I'll try to start thinking on my own more. But I also like to know what the "veterans" do and how they do it, so as to save me (and others) from making costly mistakes.

[Rhyen Skytracker]

the problem with the belt charger idea is that the Li-ions need to charge at a certain rate for safety. like 500 mah i think. I doubt a protected pack would work this way. I think as soon as you plugged the belt charger in, the protective circuit woul kick the battery pack off and it wouldnt opperate until it was plugged into a proper charger. you could do a pack without the protective circuit but then youd lose those benefits and potentially gain safety hazards.

it is a good Idea. but unil a vendor comes out with one that has the proper protective output, I think its not in our interest to temp fate

It would not be just hooking one set of batteries to another. We could need a power regulating circuit with a zener diode in it. The zener diode circuit would restrict the amount of current flowing to the receiving batteries too. So as long as the source batteries are above a certain voltage (the battery pack PCB would cut the batteries off below a certain voltage) then the regulated current passing through the zener circuit would charge the receiving batteries.

[Kant Lavar]

That's one of the reasons I liked Jay's idea about the cell phone charger. Most if not all cell phone batteries are li-ion cells, so I would imagine that a cell phone charger would want to pump its power at that 500 mA target. The big question in my mind, since cell phone batteries are 3.7 volt cells, is will the voltage be an issue in recharging, say, a 7.4v pack?

Well, that, and would the charger's electronics survive replacing the power supply with another 7.4v pack, but again, I see no real way to test that short of plugging a battery into it and seeing what happens.

[Novastar]

I'm still going to advise against trying experiments with this unless you absolutely know what you're doing... but let's see:

* Yes, many cell phones are on Li-Ion... they have been for years!
* Li-Ion generally only work with PCBs controlling over-current, over-discharge, low voltage, etc. So, they WOULD have a form of regulation circuit
* The zener diode would be very important
* Yes... using a 7.2v pack to "charge" a 3.6v pack would likely be trouble... even despite the PCB protections and a zener diode. I don't know this for a fact, so I'm erring on the side of caution.

We don't want to encourage any n00bz to try things like this without EXPLICIT knowledge. Also--it will go back to giving Li-Ions "a bad name" with people. I've seen too many abusive vids where people show how they explode... and we also have some laptop fiascos in the past (due to PCB circuits failing or outright being wired improperly/not included).

Just to be clear: ANY battery cell can be made to explode (for the mostpart). Abuse of a cell type doesn't count as "it's dangerous" to me.

If I set my house on fire... it is likely to become a hazard. DUUUUHHHHH. lol