# A123 AMP20M1HD-A Operating Voltage Range



## Ziggythewiz (May 16, 2010)

Very interesting. So what was the amount of capacity loss?

It would be interesting to see how they would perform under the specs recommended for prismatics using just 3-3.4V


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## marc02228 (Jan 15, 2011)

Total capacity loss of setup 2 was ~210 mAh


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## Roy Von Rogers (Mar 21, 2009)

With operating voltage do you mean static, or with the load on it. When the cells are fully charged and under operating load, voltage has no meaning. If your wanting to know when the battery is going empty, you need to downcount the amp hours.

Under heavy load the voltage can sag below 2v, and it doesnt hurt the cell, under no load I would never go below 2.5 2.7 per cell (if you bottom balance), there just is no value there.

If you top balance, you better count the amp hours, or the odds are you will eat a cell.

Roy


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## Ziggythewiz (May 16, 2010)

Roy Von Rogers said:


> If you top balance, you better count the amp hours, or the odds are you will eat a cell.


I'm pretty sure single cells come top and bottom balanced from the factory.


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## Batterypoweredtoad (Feb 5, 2008)

Ziggythewiz said:


> I'm pretty sure single cells come top and bottom balanced from the factory.


 Sure nice of the factory to do that for us.


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## Roy Von Rogers (Mar 21, 2009)

He said he was testing 20ah pouch CELLS....

That S means more than one.

Roy


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## marc02228 (Jan 15, 2011)

I tested two cells on two chargers simultaneously. One with setup 1, the other cell with setup 2.

I will use a BMS (EMUS), so I am looking for the top balance voltage and the low cutoff voltage.

Right now I am leaning towards:
Top balance voltage: 3.6V
Low Cutoff: 2.8V

Maybe I'll balance at 3.5V since the voltage rises very fast at above 3.4V

Any suggestions or experiences?


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## Roy Von Rogers (Mar 21, 2009)

marc02228 said:


> I tested two cells on two chargers simultaneously. One with setup 1, the other cell with setup 2.
> 
> I will use a BMS (EMUS), so I am looking for the top balance voltage and the low cutoff voltage.
> 
> ...


Look, bottom balance the cells, figure them to be 18ah cells, and charge to 3.5 per cell, use a JLD404 for amp counting, and also use it for backing up the charger, and set the JLD to cut off the charger in case the cells go to 3.6 per cell.

Roy
Deutscher Fachmann


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## rwaudio (May 22, 2008)

marc02228 said:


> I did some "long time" tests with the 20Ah pouch cells.
> 
> Tested two cells two weeks doing infinite cycles (around 320) with the PL6 to find the best operating voltage in the car.
> 
> ...


In real world driving I don't go below 3v (static voltage) on my A123's typically I'm charging at 3.15-3.2v per cell. There is just no need to go lower Than 3.0v for the every day and if you have to your pack is too small. If you are measuring capacity and grouping the cells and top balancing I wouldn't go below 2.5v (average) or you will have some cells below 2.0v.

For the odd day I need to push my pack I don't think 1 cycle down to 2.3v or even 2.0v would make a significant difference. If you did that every day you have proved it makes a difference.


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