Building Lithium Ion battery packs

[collins class]

I purchased a number of cheap Polystor Lithium Ion Prismatic 340948 3.7v 1300mAh batteries (spec sheet available) from Electronic Goldmine thinking I could put together some small battery packs of 2 and 3 cells to power small subs and vehicles. I have a Triton DC Computer charger which will cope with charging etc but now I have the batteries and am looking to put them in packs the instructions indicate this is in fact very dangerous to do. And there are also no solder tabs on these batteries and the instructions state no soldering should be carried out on the cell.

So has anyone put together packs based on these batteries? If so how? Or should I send the batteries to a professional to put the packs together? Is that possible?

I really think these batteries should be a great, cheap power supply for model sub apps if there is someone or someway to build packs safely.

Any assistance greatly appreciated...

Byron

[jsl]

Hmm...

I think you got yourself

Hmm...

I think you got yourself into something of challenge.

Lithium is an "half-metal" or alkali-metal, if I can translate it right. It is a metal very similar to sodium, which means that it reacts very violently with just about anything. This is why so much care must be taken when working with lithium cells.

If I recall correctly, a small saftey curcuit board is build into all lithium packs. It works as an electronic watchdog, and makes sure none of the restrictions stated in the battery datasheet is exceeded. This safety circuit board is an absolute necessity, or you'll probably experience the full awe of a lithium fire, if you make a little wrong move somewhere and does not have that little curcuit board build into your pack.

In my humble oppinion, you have only one option. Get it to a proffesional and let him find and install that little safety circuit board and spotweld the cells into a pack.

The nasty temper of lithium cells is exactly what keeps me to using the old NiCd and NiMh cells. You only start fires with those of you short circuit the packs.

But besides all of the above, lithium packs are great.

Jacob

[steve nuttall]

http://www.amondotech.com/

read this sites info on

http://www.amondotech.com/

read this sites info on those packs

[bigdave]

Hi Byron,
I have used

Hi Byron,
I have used those batteries in my micro-WTC's for over a year now. They are great! Make sure you charge the batteries seperately before you connect them in a pack. (The first time) I use three cell packs in my Kilo and my Turtle, and two cell in my V11c and Seawolf. The older cells had solder tabs but the new ones do not. You can solder to the minus end, but the plus end is stainless steel. I use a pressure connect to connect them together. Take the wire and put a solder ball on the end. Then file a flat on the solder ball. I use elec-tape and stretch it over the connection. This has worked fine, and I have had no problems. It is kind of like a battery box. They did this in the microflight hobby before the Lithium-Poly batteries had solder tabs. Steve has done the same thing with no problems. These new cells are also safety vented. But they should be treated with respect and handled properly. If done so they are a great cheap source of power for subs. Dave.



Edited By Bigdave on 1111534353

[scalefan]

Hey Dave, (or Steve)
A couple

Hey Dave, (or Steve)
A couple of pictures of the assembly of your packs would really help. I didn't understand why you couldn't solder to the positive end of these cells until your comment above. So if you get a chance.....

Paul

[bigdave]

Here is a photo of

Here is a photo of one of my packs for the Seawolf. Dave.

[anonymous]

Dave is right. They work

Dave is right. They work just great. Very long run times. Easy to charge and to build the pack. Dave showed me how he did it and I did the same although with a little variation.

I just used the brass strips for battery connectors that came with a Lineberg Destroyer I have. It was a motorized kit and I used my own nicads so I didn't need them.

I'm sure most of you have motorized kits you plan to RC and those connectors are made just perfect for this application.

I soldered to them first then placed them on the terminals and rapped the electrical tape around tight. Last I used shrink rap to seal the deal. Easy as pie!

Steve

[bigdave]

I like your twist Steve.

I like your twist Steve. Good Idea!

[anonymous]

Dave,

Quick question....
You mentioned charging them

Dave,

Quick question....
You mentioned charging them separate, then connecting them? So you need to rebuild the pack each time (doesn't seem like a big deal..)? How do you charge without the connector? Or have I totally missed the point....?
OK... so that's more than one quick question...

[bigdave]

I am sorry Chris. I

I am sorry Chris. I should have said the first time you connect them in a pack. You can leave them connected after that. That was a valid question. MY BAD! Dave.

[anonymous]

I just put the tabs

I just put the tabs on with the soldered on wires, wrapped them with tape a charged them each the first time. As Dave says after that you make up the pack and charge them for then on as a pack.

I charged them at 400 maH the first time and 1 amp from there on out. Haven't had a single problem with them.

Steve

[anonymous]

Thanks Steve/Dave!

Always had this

Thanks Steve/Dave!

Always had this problem with electrons and such. Typical mechanical engineer...

[collins class]

Thanks for the responses. Like

Thanks for the responses. Like your ideas Dave and Steve. Interestingly in my travels I found some interesting battery pack building articles for NiMh (http://www.dream-models.com/eco/LipoPack.html). I kind of thought the suggestions regarding the LiPo pack would apply to LiIo as well, such as balancing the charges etc. Might be a little difficult with no tabs though....

These are pretty good articles I think.

And I will give you suggestions a try thanks guys.

Byron