charge larger than 6 cell A123 (Full Version)

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incarus -> charge larger than 6 cell A123 (11/26/2007 4:02:14 PM)

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.



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

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.



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

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.



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

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.



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

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



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

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 [:D] Tex.



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

Thx Tex, what a great smart power supply.
I rather have a charger to save all these hassle.



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

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



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

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.



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

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...........



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

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.



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

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



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