A123 fast charge

6 posts / 0 new
Last post
amp_head
amp_head's picture
Offline
Last seen: 11 years 2 months ago
Joined: Saturday, May 26, 2007 - 22:41
Points: 135
A123 fast charge

Need some help charging A123 cells in a hurry.

Packs will consist of 10 series and 10 parallel cells per pack for 23ah at 31.5 volts nominal. Most lithium polymer chargers I find will only pump 10amps into the cells, which is gong to be a slow charge at best. I would like to charge them in 10min. Does anyone have any ideas on how to charge them that fast and how many amps I would have to stick to them to get them charged up that quick? Is the 30c the maximum I can pump into them safely?

Matt :jawdrop:

Fechter
Fechter's picture
Offline
Last seen: 11 years 10 months ago
Joined: Friday, November 17, 2006 - 07:01
Points: 199
Re: A123 fast charge

Even if they can only handle 10C, that would be 230 amps! Yikes!
I'm not sure what their maximum charging current is. A 10C charge would do them in abuot 6 minutes, but I think that might be pretty hard on them. Finding a source for even 100 amps at 35v is going to take a big plug.

One way I've seen is to get a bank of LARGE lead-acid batteries and use them as a souce for charging. This is called dump charging.
The lead acid batteries can be charged at a much lower rate, supplied by 120vac. I'm not sure if 36v worth of lead acids would be enough to get 100 amps into your pack. You might use 6v batteries and make something around 42v. Large 6v lead batteries are common in forklifts and golf cars. You might need to go to 48v to get the amps, but in either case, you will need to watch the voltage closely and have a way to terminate the charge before the A123's blow up.

amp_head
amp_head's picture
Offline
Last seen: 11 years 2 months ago
Joined: Saturday, May 26, 2007 - 22:41
Points: 135
Re: A123 fast charge

Thanks Fetcher for the reply. What is the formula to calculate how much time it would take to charge the cells to full capacity?

I guess my safest option would be to get a CC CV adjustable voltage charger that pumps out 40amps at 36 volts but does something like this even exist?
Blowing up expensive A123 cells does not sound like my idea of a good time. : )

Matt

amp_head
amp_head's picture
Offline
Last seen: 11 years 2 months ago
Joined: Saturday, May 26, 2007 - 22:41
Points: 135
Re: A123 fast charge

Might have found a solution. I could split the pack up into two groups of 5s and 10p and use one of these http://www.tmenet.com/xtrema.htm
When charging do I have to worry about the cells in parallel?

Matt

Fechter
Fechter's picture
Offline
Last seen: 11 years 10 months ago
Joined: Friday, November 17, 2006 - 07:01
Points: 199
Re: A123 fast charge

That looks like it should work. Lithium batteries behave nicely when paralleled.

Another option would be to look for surplus power supplies. Some of them have slightly adjustable output voltages and current limiting. If you watch the charging current, you can tell when the batteries are done. For the power, these may be the least expensive. Somewhere on the forum here is a list of surplus electronics stores.

magudaman
Offline
Last seen: 12 years 3 months ago
Joined: Wednesday, March 14, 2007 - 10:00
Points: 61
Re: A123 fast charge

The charger you pointed out will not charger your batteries that quickly. If I am not mistaken that charger will peg out at about 150 watts output so if your doing 10 cells about 4 amps. I think fechers idea of getting a power supply could work really well. They have some expensive ($1600) benchtop 36v 80a on ebay that would work perfect. This would charge your whole battery set quite quickly and dim your entire street's light at the same time ;-). So is this a dream set up or have you already set this up on something?

Log in or register to post comments


Who's online

There are currently 0 users online.

Who's new

  • F177
  • ecosavesolar
  • ghome121
  • Alt_rides
  • mourad96

Customize This