charging chevy volt/spark batteries.

E

ejonesss

10 kW
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Aug 31, 2008
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i got a chevy volt/spark battery module 12s 48 volt.

if i charge it at 2 separate batteries 8s and then 4 s each time the hobby charger (unfortunately hobbyking is not responding properly).

it cuts off ok but when i then go back to charge the cells 1 at a time to get them balanced the cells wants to continue charging past 4.2 volts no matter the current settings.

does anyone know what chemistry the volt/spark uses?

and is gm using lihv or is hobby chargers not able to handle the LiMn2O4/LiNiO2 that according to as individual cells very well

http://hybridautocenter.com/HAC4/index.php?option=com_hikashop&ctrl=product&task=show&cid=79&name=2kw-h-lithium-battery-pack-chevrolet-volt-45v-45ah-12-cells&Itemid=605 is the chemistry.

i have to treat as 2 batteries because the above charger does not do more than 8 cells and a charger that does is $250.
 
Hillhater said:
48v chargers dont have to cost $250.
you can get one for as little a $10 !
Click to expand...


does the $10 charger have balance connections and able to charge at 1000+ watts and be able to charge variable amount of cells and have a display like hobby chargers do?
 
another thing


you do realize that a chevy volt/spark battery module is 40 to 50 amp our rated and charging a 50 amp hour battery with a $10 charger that is probably no more that 3 amps will take 16 hours or more to charge?

that is why i was asking about the chemistry.
 
You were not very specific about the requirements for a 48v charger , other than the price...
.....so i responded accordingly !
...and you are not currently balance charging initially anyway, you could still individually balance cells if required.
....BUT..i get what you are trying to do, and sure , high power, 12s balance chargers are not cheap , which is why most people in this position (including GM !) use a non balancing bulk charger and a BMS to cover the balancing and various other functions.
I would suggest a simple 48v (adjustable) Meanwell , or similar, with bat Medics for balancing if you dont want a BMS.
 
fechter said:
As far as I know, the Volt batteries are Li-ion, so charge to 4.2v per cell.
Click to expand...


what i find odd is why if i charge each cell as 1s at a time the charger does not taper down the charge and stop once it reaches 4.2 volts.

i suspect maybe the volt cells are so proprietary that they use a custom chemistry that the hobby chargers do not detect properly.
 
I don't think the chemistry is your problem. Leave the charger going for a really long time and see what happens. It should eventually taper down. The cells are just 10x larger in capacity than the charger is designed for.
 
the problem is then it will charge beyond the 4.2 volts.
 
I agree with Fechter.
Leave it on a while longer. Larger batteries will still be accepting charge near finish voltage.
"charge stop" is triggered by current dropping to a point determined by charger.
It might be a few hundred ma for small battery, several amps for a large battery/charger.
For example, my 10a 4.2v chargers are set to finish at .5 amps.
If charger finish voltage is near 4.2, current must taper down. Unless charge current is smaller that self discharge rate.
 
ejonesss said:
the problem is then it will charge beyond the 4.2 volts.
Click to expand...

If that happens, then something is wrong with the charger. You can measure the charger output with no battery connected and see what you get.
 
modern hobby chargers are smart enough to detect a battery connected.

i think it may be that the internal resistance of the individual cells or s is lower than that of a normal lipo cell so maybe individually it cant do much but when you add up the cells there is enough resistance to make the charging normal.
 
Your first mistake is charging to 4.2V. In the interest of long life charge only to 4.1 or 4.15V/cell. Those batteries are so over-engineered that if they're drifting more than +/- 0.01V cell then there's something wrong. I have a number of those 12s modules in service for over 2 years, and none of them has required balancing. Either you're discharging them too deeply, another no-no, or they were worn out to begin with.

Don't call it a 48V battery, because it's not. It's a 44V battery. For charging it's a mistake to rely on Hobbyking chargers to run that kind of load for such long durations regularly. Instead pick up a couple of reasonably priced 12s 6A chargers with a cutoff set at 49.5V or so, and run them in parallel. As extra protection run the chargers through a cutoff timer, and have a fan blowing on the chargers.
 
the hobby charger is set to charge at 40 amp charges in a couple hours.

is that safe?


also where do i get 12s 6A chargers at?
 
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