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

[Jacen_Aurion]

I play airsoft a ton, and with my first gun (fortunately it was only 50 bucks and my new better gun would come in the next day) i didn't even drop it, but the NiMh battery inside was charged for 24 hours as opposed to 4 by a very good friend of mine (who is still a very good friend) and as a result the battery broke. I'm very fortunate to have not had the battery blow up in my hands. He is now much more careful with charging batteries. If you're going to use Li-Po batteries or NiMh batteries then i strongly suggest you set a timer for however long you need to charge them and then sit by them and do something while you have them charge. If you get a smart charger from any of the big airsoft places (i'm assuming you could use the same kind of battery for a lightsaber) then it will stop charging your batteries when the charge is full. Good luck with the rest of bop nova, and I have no doubt you of all people is extremely careful.

[Novastar]

There will be NO charging Li-Ions without smart chargers...

That's why I bought like 6 of them.

[Ganoran]

Okay, I'm a total newb to the pieces of batteries. What's PCB stand for and what does it do?

[Novastar]

It just means printed circuit board.

In a nutshell, Li-Ions need to be "controlled" in order to prevent several issues that would be natural to the design materials:

* Overcharge ( >4.2V )
* Overdischarge ( < 2.5 V )
* Over drain ( > 3 Amp -- depending on the battery set )
* Short circuits

That is for a 3.6v battery.

So in other words--a Lithium Ion battery is "smart" in the sense that it takes care of itself as best as possible.

This does NOT mean that they are immune to having problems. Although... I've not run into any myself.

So far, it sounds like people HAVE had issues with Lithium POLYMER... which is a different technology vs. Lithium Ion (or Lithium Primary for that matter).

[Ganoran]

Thanks for clearing that up.

[Novastar]

Old topic but just wanted to say again--these Li-Ions are GREAT...

I've been trying a Luxeon III "light side" (blue, green, white, royal b, cyan, etc.) with *NO* resistor on the circuit--just to find out what would be going on.

NOTE: I DO NOT RECOMMEND THIS TO ANYONE, I am trying it as an experiment, considering the fwd voltage of the LED being pretty close to the Li-Ion's voltage, and the fact that I've considered the possibility of the LED getting "killed" by drawing too much. It's worth $8 to $12 for the experiment (or whatever a Lux III costs, I forget).

So far... no problems other than the hilt getting pretty darn hot over some time!!

[xwingband]

That setup should be fine Nova... flashlight people do it all the time. It's what Ultra was doing in his stunts, etc...

Not the best but it works.

[Onli-Won Kanomi]

These 3.6V Lithium Ion batteries sound great...I really hope they are coming to the store soon and though I do see a Li-Ion charger available in the store I only see NIMHs listed in the rechargeable packs, which are out of stock anyways so I had to order a battery holder for alkalines instead...oh well it seems theres always another great product coming to look forward to ordering here

One hopefully not TOO dumb question I do have is about using those battery holders with these new Li-Ion batteries whenever they become available here: most battery holders I've seen in sizes like AA or AAA have marked on them that they are rated for 1.5v batteries [presumably normal alkalines?] ...will they be safe to use higher voltage Li-ions in and deliver their full power or will we need new higher-rated battery holders to put them in too??

[xwingband]

That's a great question... I think for rechargeables the best answer is to solder together your own pack and heatshrink it up.

I did once use the raw batteries in a a regular holder... the spring tension caused them to leak over time. Also they weren't button tops which was also a pain too, but that more related to the specific ones I bought.

Really with rechargeables the ideal is to have a port or quick disconnect so the idea of a holder is to be able to pull them out individually? That's very counter-productive and unless your charger works that way it's rather pointless as all I see are detractions.

[Eandori]

There is no clearcut answer, because it depends on a lot of factors. But here's some facts on the different cell types.

Lithium Polymer (Li-Po): Very high storage capacity, Very non-standard cell types, requires cell regulation circuitry, Highly dangerous if misused, best for low current applications. LiPo does not suffer the "memory effect."

Lithium Ion (LiIon): Very high storage capacity, Very non-standard cell types, requires cell regulation circuitry, less dangerous if misused then Li-Po, best for low current applications. LiIon does not suffer the "memory effect."

Nickel Metal Hydride (NiMH): Storage capacity varies greatly with cell quality as higher capacity NiMH can have up to 4x the capacity of another NiMH of the same size/shape. The highest capacity NiMH cells approach LiIon, while the lowest capacity NiMH cells are closer to NiCad. No cell regulation circuitry required. NiMH has very standard cell sizes. NiMH provides the highest available current supply of all the cell types i.e. extremly low internal resistance. NiMH are best for high capacity, high current applications or in places where cells are exposed to environmental abuse. NiMH does not suffer the "memory effect."

Nickel Cadmium (NiCad): NiCad is the lowest storage capacity of all the cell types, yet the 2nd best for providing large current supply with low internal resistance. NiCad's are the cheapest of the rechargable cells and require no regulation circuitry. NiCad's are best in low cost situations but unfortunately suffer from memory effect which requires an occasional full discharge.

=================================

-If your usage requires huge capacity, not much current draw, cell regulation circuitry is ok, and low cell abuse, then go with LiIon. That's the exact situation of a cell phone or laptop.

-If your usage requires a low cost solution, use NiCad.

-If your usage requires large capacity, and large current draw, use NiMH. This is the exact case for RC Cars where I can tell you from experience that some 7.2v packs provide upwards of 120 Amps of current in bursts and average out between 15-40 Amps of continuous draw. That's an order of magnitude higher then what a lightsaber will draw.

-If your usage requires large capacity, but inexperienced users will be building custom hardware, and the cell will be put through abuse, I would reccomend NiCad or NiMH. Putting your cells inside a sometimes novice made metal tube, with novice solder jobs, and smashing it into other devices with high impact, I would say stick with NiMH and NiCad. Sure, cell phones use LiIon, but they are built by professionals and don't smash into each other.

Having said that...

If you are very experienced with construction, and patient enough to do things right... go ahead and use LiIon in your lightsaber and take the proper precautions using them. That means...
- Use the right chargers
- Make sure the cells are insulated from sharp edges to avoid damage
- Make sure your on board regulation circuit can survive a few hard whacks.
- Make sure your on board regulation circuit cuts off from cell voltage AND temperature. Or at least install a quick remove features to get those cells out of your saber and into a bucket of SALT WATER if a runaway condition occurs.

I'm personally using 8xAA at 9.6v (base rating) with 2500mAh of capacity for my saber. I will switch to LiIon at some point, just have not yet. Since the capacity is high, it's great for me. Since I use a Luxeon V I need the large supply voltage to keep my LED running at 1 amp.

Just a quick note on what mAh (Milliamp/hour) means, since I see people constantly butchering that. It means how many milliamps your cell will provide for 1 hour of time. So a 4000mAh cell will provide 4 amps (4000 milliamps) for 1 hour. If you pull 500mA out of that same cell, expect it to last around 8 hours. mAh is a rating of cell energy capacity. Period. The voltage of a cell, and how much current it can provide with extreme load are two different things independant of the cell capacity.

Hope that helps guys, keep up the good work!!