James35

iTrader: (1)

Acording to A123's web site, the spec sheet says they should be charged at 3.6V @ 3-10amps.


I'm picking up a 2 cell 2300mah 6.6V A123 pack.
The Team Checkpoint 1030 and ICE doesn't allow us to customize the voltage . Here is the closest settings I can get:
LiPo, 7.4V, 4600mAh
Charge Current: 9.2 amps
Max Capacity: 50%

If I defined the battery at 2300mAh, the hardest I can charge it is 4.6amps.
By setting it to 4600mAh with a max capacity of 50%, I can charge up to 9.2 amps.

What do you think? Will that cause problems? How do you use your Team Checkpoint/ICE to charge A123 batteries?

joe of loath

iTrader: (1)

well you COULD but the overvoltage would be very dangerous, and although the cells will take it, one day, maybe not. find a charger with adjustable voltage, and try that.

James35

iTrader: (1)

If I am reading the spec sheet correctly, I'm assuming charging would be 3.6V per cell, right? So in my case, charging two A123 cells = 7.2V. The charger would be doing 7.4V instead of 7.2V. That's not too bad is it?

joe of loath

iTrader: (1)

i thought the cells were 3.3, but there you go... hmm 7.2 to 7.4... should be ok... just check with a few other people first.

kuzo

iTrader: (11)

If you charge at the 7.4V setting on a lipo charger, it will not terminate the charge until the pack hits 8.4V. There are A123 capable chargers on the market - why not invest the money on something made to correctly charge the pack rather than winging it and crossing your fingers?

James35

iTrader: (1)

Yes, I will most likely do that, but I've read many posts where people are successfully using their ICE/Team Checkpoint chargers. Since I'm not sure that the A123 will be a good practice solution for me, I don't want to buy an A123 compatible charger just yet. I want to try the A123 pack first.

kuzo

iTrader: (11)

Not meaning to come off as harsh but I've never been one to use a charger for anything but what it is designed for. Particularly with the price we pay for these packs, whether a123 or lipo.

Edit:
After a quick google search, the only info I was able to find on this was don't do it. I'd like to know how others were successful if at all.

linger

iTrader: (1)

James,
The A123 cells will tolerate an overcharge fairly well. Set your checkpoint/ICE for Li-Ion mode, this way it only charges to 4.1V/cell which is less of an overcharge than LiPo mode 4.2V/cell. You're killing the cycle life of the A123 cell by overcharging it, but I don't think it's a safety issue.

Team Ash

iTrader: (22)

You are right they are 3.3v/cell charging at 7.4 might be too much but good luck.

gacjr0

iTrader: (15)

Sit nearby and watch your charger.
You're never supposed to leave any battery/charger alone anyway.
Pull it when it's done.

I've been charging lipos with a 15min charger for months while getting the ICE fixed. I do not know why I held off sending it (postage 12.50, charger got back in 1.5 weeks- no addtional charge, THANKS DURATRAX!)

Then get the right charger for it, it's only a matter of time till you get screwed by the wrong charge profile, or forget, or get distracted.

glassdoctor

iTrader: (4)

There are some who have made up an adapter to step down the voltage using diodes. This tricks the charger, so when it reads 8.4v... the battery is actually getting 7.2-7.4v

I don't recall exactly how they made this.. or what values of diodes are used, etc... but search and you can probably find out if you want. Check out rcgroups.com forums under battery/chargers

K.Copeland

iTrader: (96)

these batteries aren't lipoly, they're li-ion. I'm not too sure the Ice is compatible with these cells and would contact A123 Systems before you commit to the charger or cells.

The batteries dont have the punch of nimh's or lipo's, but they're light, can withstand some abuse, and take only 15 minutes to charge a 2s pack.

joe of loath

iTrader: (1)

on the subject of charging, my LHS sells li-ion chargers for about £20... i don't know if thay are A123 compatible, but i'll ask.

Marcos.J

iTrader: (239)

just get this
http://www.a123racing.com/html/starterkits.html

or just the charger
http://www.a123racing.com/html/soniccharge.html

James35

iTrader: (1)

I don't see how that is possible. The discharge rate is better than any other battery type. I'm assuming you are comparing an A123 6.6V pack to a 7.2V battery.