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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> A123Racing Support >> charge larger than 6 cell A123
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charge larger than 6 cell A123 - 11/26/2007 4:02:14 PM   
incarus


 

Posts: 55
Joined: 7/30/2005
From: , OH, USA
Status: offline 		can someone help me .

I have a hyperion 6s ac/dc charger that can hande upto 6 cell A123 so I am limited to making 6 cell packs. I need to make bigger packs(9 cell,10 cell)so I am forced to make several 6 cell and smaller packs.

is there any cheap charger or wiring set up I can make/buy to handle this requirement.

my charger only has one charge port so I cant do more than 1 bat pack at a time.

Can I use the original dewalt charger to charge these less than 10 cell packs . since the "module" is removed I assume this is not possible.

I think I am forced to buy another charger....dont want to do that if I can avoid it.
       Post #: 1

RE: charge larger than 6 cell A123 - 12/6/2007 10:36:00 PM   
Tex Gehman


 

Posts: 46
Joined: 5/9/2007
From: Winnipeg, MB, CANADA
Status: offline 		Quite a bit of discussion in RCGroups about using adjustable Constant Voltage power supplys. Set the voltage at (#of cells x 3.6) the desired amount and adjust the Amps and let the machine do the rest. A unit with 50v capability and "up to" 50Amps should do the trick for most of us flying the high cell count packs. I intend to persue this avenue rather than buying yet another charger. As far as balancing, I use SPTs and dismantle and balance the cells mechanically about once a month. Tex.

(in reply to incarus)
       Post #: 2

RE: charge larger than 6 cell A123 - 12/6/2007 11:20:16 PM   
richard2046


 

Posts: 36
Joined: 9/25/2007
From: Vancouver, BC, CANADA
Status: offline 		A123 can be charge at very high C rating, in other word, high Amp. If you set the charge to 36V (for 10 cells) and if your charger has only 50W power, you can only charge the pack at 1.3A (50W/36V) which takes you 3 hours to charge a 4000 mAH pack. If you go on with 9~10 cells A123, the best bet is to get a high power charger (at least 150W) that support 10 cells.

(in reply to Tex Gehman)
       Post #: 3

RE: charge larger than 6 cell A123 - 12/7/2007 12:26:08 AM   
Tex Gehman


 

Posts: 46
Joined: 5/9/2007
From: Winnipeg, MB, CANADA
Status: offline 		http://shop.vendio.com/Evan2002/item/770247163/index.html

In parallel mode its up to 10A. I suspect it has more capacity than any hobby charger on the market. But I'd like to know otherwise. Tex.

(in reply to richard2046)
       Post #: 4

RE: charge larger than 6 cell A123 - 12/7/2007 8:02:12 AM   
richard2046


 

Posts: 36
Joined: 9/25/2007
From: Vancouver, BC, CANADA
Status: offline 		This is expensive. I think this is a powerful AC~DC power supply and not a charger.

(in reply to Tex Gehman)
       Post #: 5

RE: charge larger than 6 cell A123 - 12/7/2007 1:16:13 PM   
Tex Gehman


 

Posts: 46
Joined: 5/9/2007
From: Winnipeg, MB, CANADA
Status: offline
quote:

This is expensive. I think this is a powerful AC~DC power supply and not a charger.]

It's not expensive in comparison to hobby chargers of this kind of power. Yes, it's a power supply. That's what chargers are, but with some sort of limiting circuitry [except for your "wall wart" which is just a fixed voltage power supply]. This unit needs to have its parameters set by the user. ie: if you charge 10 cells, you set 36 volts and the current will cease when the pack reaches 36 volts. Many people are using them for charging the A123s. Of course you need a 120 volt source, either a converter from your deep cycle battery, car battery/generator or like many of who are serious about the hobby, a small generator like the Honda 1000 Tex.


< Message edited by Tex Gehman -- 12/7/2007 7:38:20 PM >

(in reply to richard2046)
       Post #: 6

RE: charge larger than 6 cell A123 - 12/8/2007 7:12:45 AM   
richard2046


 

Posts: 36
Joined: 9/25/2007
From: Vancouver, BC, CANADA
Status: offline 		Thx Tex, what a great smart power supply.
I rather have a charger to save all these hassle.

(in reply to Tex Gehman)
       Post #: 7

RE: charge larger than 6 cell A123 - 12/10/2007 1:21:14 AM   
firemedic305


 

Posts: 104
Joined: 9/5/2002
From: Rockmart, GA, USA
Status: offline 		Well if you use 10 cell pack you could rig up a Dewalt 36 volt drill charger. but would not be good for other size packs

(in reply to richard2046)
       Post #: 8

RE: charge larger than 6 cell A123 - 12/19/2007 1:54:15 AM   
cwharper


 

Posts: 219
Joined: 2/18/2007
From: Ocilla, GA, USA
Status: offline 		I have a 50v 20amp fully variable power supply and it works great. I really like it. One important thing to do with this power supply is use a diode in between the output and battery. Also use a wattmeter so you can see how much you put back and the actual voltage at the battery after the diode.

_____________________________

When you see the mushroom cloud, you will know then that I have finally achieved fusion.

(in reply to firemedic305)
       Post #: 9

RE: charge larger than 6 cell A123 - 12/20/2007 4:27:19 AM   
pfatz



Posts: 111
Joined: 8/5/2007
From: Mena, AR, USA
Status: offline 		I have an xtrema charger / wattmeter. It also logs/analyses battery info. It will charge 10 cells, up to 8A with timer and thermo probe. It will chg all types of Lipos including A123 LiMn. Read up on it at xtrema.com (I think), Free upgrades over the net. 3 yr warranty. Made in the USA. Coming in Jan. '08 are xtrema 6 cell balancers to run 2 at a time or more from the charger.

Being new to this, I don't understand how many volts it takes to charge the A123 packs and how long it may take with my charger for example.

I will have to stick with it for now I think.

My question is, how to balance 10 or 12 cell packs? Will I have to build 4, 5 or 6 cells to use in series if I want the Volts to work out. Any better ideas? Suggestions? Educational comments.


Now to find out what I can run with my Trex 600/ 600xl motor and end up with @ 1800 rpm head speed...........

(in reply to incarus)
       Post #: 10

RE: charge larger than 6 cell A123 - 1/6/2008 3:34:27 AM   
ct420


 

Posts: 1177
Joined: 3/26/2006
From: mansfield, TX, USA
Status: offline 		I am currently researching A123 for a new project. It seems to me that for charging HV A123 (8s+), the cc/cv power supply really is the simplest and best answer. Check this out:

http://www.youtube.com/watch?v=q-1fb9_V2II


Also, no need to balance A123 cells. Much like Nicd batteries, A123 cells are very 'forgiving' about over-charge. Therefore, if the pack is a bit out of balance, the 'higher' cells will simply get slightly overcharged while the 'lower' cells 'catch up' during a full charge.

It seems most people who have been running A123 for a while stop balancing completely, as it's just not necessary. Most recommend a slow charge every so often is all that is needed to keep the pack balanced.

(in reply to pfatz)
       Post #: 11

RE: charge larger than 6 cell A123 - 1/6/2008 1:47:37 PM   
everydayflyer



Posts: 893
Joined: 8/21/2005
From: Buchanan, GA, USA
Status: offline
quote:

It seems most people who have been running A123 for a while stop balancing completely, as it's just not necessary. Most recommend a slow charge every so often is all that is needed to keep the pack balanced.


Most is hard to qualify however as one with a great deal of real A123 experience I feel that balancing is not mandatory but should be done anyway.


Myself and others have had non balanced packs dump anywhere between 25% and 50% sooner than normal.

It appears that charging at a high rate ( 10> and slightly(?) overcharging (3.8-4.0) helps maintaine balance but not enough users really keep detailed records such as I do.


Charles

(in reply to ct420)
       Post #: 12

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