Button cells

[twizm]

im sure this has come up before, but i couldnt find it 🙁

how many button cells can you cram into a BCG? and are the effects desirable?

can they be charged with sufficient current? such as 4 AAs?

i want to blast the doors off my BCG, the 4.2 with FETS seems slow now 😛

[merc-blue]

get the smallest possible and stack them you can ft a fair few and yes the effects are reasonbly desirable.. u can get tons of voltage although i think u cant go over 6v ish or you will blow the PCB secondly it will be a strugle to find recharageble button cells and your run time will suck

[twizm]

so its not safe to charge normal batteries? i always thought it was, but the company told you not to because it would stop people buying them…

[merc-blue]

buttons arent alkalines there lithiums

[HACHI-RYOKU]

Actually, the only ones I’ve seen are nimh, and they’re finicky to charge. If you want an amazing battery, then try a “kokam” 145mah li-poly. You have to buy a special charger for it, but it’s relatively cheap. The batts are pretty cheap too. I recently perfected a car with a 145mah li-poly, and it’s definately the fastest car I have. I Will post digital speed checks soon. Anyways, the kokam 145mah li-poly bat is 3.7volts and can put out 1 amp. That’s 1000ma!, wich is way more than the car needs. So no more slowing down while turning. I’ll give some more in depth news on it soon. I just got it running today. Make sure you study up on the li-poly cells before you use them. They are wonderfull batteries, but have special needs. You’ll definately need to install an on-off switch for one.

[HACHI-RYOKU]

To answer your question, I’ve seen as many as six crammed in a bit. The effects are not that great because the batts don’t put out as much current as other batts. 6 will put out more current, but it weighs way more. I’ve spent some time with these batts. I consider them useless. I put 4 in a bit and put it to the test. I raced it with a dual cell I had. The dual cell was using regular stock tomy batteries. The dual cell absolutely smoked the button cells. Puting in one button cell barely powers the car. Puting in two button cells is ok. Puting in three button cells makes it faster than a stock bit. But interestingly enough, puting in 4 button cells isn’t much different than puting in three. From what others have concluded with similar tests, it sounds like puting more cells in, after the third cell, really doesn’t give you that much gain. I think it just gets too heavy.

[merc-blue]

yeh li polys are great but they dont take pressure or impacts or heat veey well. ive seen a heli catch fire casue he was over drawing it and it heated and wen

[HACHI-RYOKU]

Yeah, but a bit isn’t going to pull that much current. The kokam 145mah batts can put out up to 1 amp safely. They can put out 1.3 amps in shorts bursts safely. That’s way more than you need. Also, I’m not going to be hitting it with a hammer any time soon.

[HACHI-RYOKU]

Sorry, not trying to be negative, but they are safe as long as you know what you’re doing. I also wrapped the battery with electrical tape and positioned the pcb in a manner that would shield it from heat.

Still, merc-blue has got a point. If you do use lithium batteries, then it’s very important that you read about them first. People have literally burnt their house down and accidently killed people with improper use.

Not a joke. One guy in Virginia tried to charge one with a nicad recharger. Not a smart thing to do. He burnt down his house and got himself and his family killed. When one of these batts catches on fire, it burns like white Phosphorous. You can’t put it out with water too. In fact I think water makes it burn more. Not sure on that tid-bit though. Some people even recharge them in a metal container just to be safe.

Basically, this is one of those things where you need to read the instructions and warnings. They are not dangerous with proper use. In fact, just about every new electronic device these days uses them. Cell phones, digital cameras, lap-tops, flashlights. In fact I recently went to a third world country, and they even had cheaply made cell phone with lithium batteries in them.

[merc-blue]

hachi were did you get ur li-pol cells from???

[HACHI-RYOKU]

I will give every one the proper run-down of the tools and supplies used sometime tonight on the other posting about these batteries. Just look for the post on “Li-poly batteries in a bit/pht2 or ma please look”. Or you can do a search on the net for kokam 145mah batteries. I’ve also seen people use kokam 135mah batteries. They are almost the same but the 145’s can put out more juice. I am gonna pick up some 135’s though because they fit in a bit much much better. I had to make alot of extra space, with a dremmel, to fit the 145’s. They don’t sit flat for me either. I would like them to be as low as I can get them. The 135’s may put out enough juice. I haven’t really figured out how much juice a bit needs for the whole thing to run at top speed. I just know that the kokam batteries put out more than enough. The reason I say this is because there is a point where the motor just wont take any more current. This maximum current, added to the steerings maximum current would be the total current needed. Might add 10~15% on top of that because all circuits have resistance that may be unaccounted for. Especially cheap pcb’s like these.

I’ll also list the super cool cheap charger I got for the job. I deffinately recomend this charger. It’s very small and it’s one of the cheaper ones I’ve found. You don’t need an expensive recharger to recharge these tiny cells.

[betty.k]

from what i’ve learned about batteries, i look at them like this:

nicad = a grouse aussie v8, lotsa balls, take a licking, low maintenance and faily reliable.

nimh = a finely tuned aussie v8, excellent power output, relatively hardy but need some tlc to keep them running true.

lipol/lion = an f1 racer, total performance, high power output, but must be properly maitnained:8ball:

[jamiekulhanek]

hmmmm nimh need less maintainence than nicad

[HACHI-RYOKU]

Well, there are two sides to the maintenance of nicad and nimh. Nicads shouldn’t be charged half way and stored that way. The stock charger and most other chargers only charge the battery a certain percentage. It’s almost always never fully charged. This creates a problem when it comes to the batteries memory. A nicad remembers the half charge and may only charge half way for the rest of it’s life. Thankfully, the bit cars will drain the battery even when not in use so the battery never stays charged. So that cancels out the memory problem somewhat.

On the other side of the spectrum, this would be bad for a nimh battery, because if it’s stored with no charge it will screw up the chemicals in the battery and basically depreciate it slowly. Even with an on/off switch on a bit a nimh looses a little bit of charge every day, so unless you use it every now and then it still may loose it’s charge. The fact that most bits don’t have an on/off switch makes this more of a problem for nimh.

So, the statement that nicads are less maintenance for bits is true, but it’s most likely opposite for other electronics. UNLESS you install an on/off switch, or the bit comes with one already (some do).

It’s true. My cars with nimh have slowed down significantly after about 6 months of use. In fact I won’t even use nimh in my cars anymore unless it has an on/off switch. My nicads are still going strong.

Another side note, my soldered nimh batteries also start to rust from the solder paste if I don’t clean the paste off after I’m done soldering them. It’s hard to clean it all off on the positive end because of the little grooves the heated paste will go into. My nicads haven’t been doing this.

[HACHI-RYOKU]

Forgot something. Nimh actually do have a memory problem also, but it’s not even close to the nicads memory problem. It takes alot more to make a nimh battery remember it’s last charge and only charge to that much again.

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