C rating of a cell in a battery

[WorldwideDave]

Now that I know what kind of cells are in my 200Ah 12v CHINS battery:
GFB 3.2 V
320Wh
100Ah
48173125
OALCBA3510000D
A search online reveals the C rating
Looks like it is .5 C per cell.
There are 8 cells total making it 2 series 4 parallel I think.
Because it is a 200 Ah battery, if it were 1C it could discharge 200 amps in one hour if BMS would support it I believe.

If it were 2C rated cells it could consume 200 amps in 30 minutes I believe.

Therefore - and please correct me if I’m wrong - the .5 C rating of these cells should mean a discharge rate of no more than 100 amps per hour. Is that correct? Or I could drain it no faster than 100 amps over a two hour period from full to empty.

Does this sound right, or does having cells in series play a factor?

Honestly I didn’t know what to expect when opening it. I thought there would be 4 big batteries not 8.

 

[WorldwideDave]

I should note that I also upgraded the BMS to support 150 amps. Existing one didn’t like anything over 50 amps continuous. Wondering if cells have something to do with that and not BMS.

 

[1234enough]

You sound correct, apart from cells are arranged 2P4S.
Be aware of other limits such as min / max voltage / charge rates ect.

 

[1234enough]

Also check if existing battery connections/ bus bars ect are capable of discharge / charge you intend if this is above what data sheet indicates.
As the designer / modifier it's down to you to ensure all is correct, ah the fun of responsibility

 

[hwy17]

I think:

If you take 4x 25Ah .5 C cells and put them in parallel they become a 100Ah .5 C cell.

25Ah @ .5 C =12.5A

100Ah @ .5 C =50A

It still take 2 hours to discharge at .5C. A .5C rated cell cannot be discharged within 1 hour within it's rated spec.

 

[fnnwizard]

The spec sheet says 1C continuous and up to 3C for 1 min.
So 1C * 100Ahr = 100A * 2(p) = 200A continuous.

The limiting factor is your BMS.

 

[WorldwideDave]

You sound correct, apart from cells are arranged 2P4S.
Be aware of other limits such as min / max voltage / charge rates ect.

Isn’t the charge rate .5C or 100 amps for my 200Ah battery? BMS supports 150A.

 

[WorldwideDave]

Also check if existing battery connections/ bus bars ect are capable of discharge / charge you intend if this is above what data sheet indicates.
As the designer / modifier it's down to you to ensure all is correct, ah the fun of responsibility

The other equipment has been verified by folks on these forums. T class fuses and bus bars and conductor sizing and lugs etc all good.

 

[WorldwideDave]

I think:

If you take 4x 25Ah .5 C cells and put them in parallel they become a 100Ah .5 C cell.

25Ah @ .5 C =12.5A

100Ah @ .5 C =50A

It still take 2 hours to discharge at .5C. A .5C rated cell cannot be discharged within 1 hour within it's rated spec.

But they are 100Ah cells, not 25Ah.

 

[WorldwideDave]

The spec sheet says 1C continuous and up to 3C for 1 min.
So 1C * 100Ahr = 100A * 2(p) = 200A continuous.

The limiting factor is your BMS.

The spec sheet for the 100 Ah cells I attached says 1C continuous? Saw .5 continuous.

Oh, you are saying discharge is 1C. That is good to know. I was talking about charging. I’m sorry. Continuous looks like it is .5 C.

With that information, you believe I can do 100 amp discharge and 50 charge continuous, or are you saying 200 amp discharge and 100 amp charge is what the batteries can Support?

I realize the BMS is only for 150 amp discharge. The current BMS is only for 50 A current and 100 max.

I run a pool pump and pool heater that is about 95 A continuous for several hours.

I am hoping the issue was the BMS and not the cells.

 

[fnnwizard]

Both charge and discharge at the single cell level is to 1C continuous. You have 2 in parallel so you can charge and discharge at 1C of 2x100 = 200A.

95A continuous for your battery would be = to .5C discharge.

Keep in mind though that most EOL ratings are at .5c or less so you may lose some cycles at higher C rates..

 

[WorldwideDave]

I have overlord cut off for charge and discharge set to 160 now. Is that good? I think I said it for two seconds before shutting down.

 

[Supervstech]

Please note that saying "per hour" is superflous.

Charge and discharge ratings have a time spec to them.

Per hour implies you are discussing storage or usage capacity or quantity.

And it is covered by the Ah spec, or the Wh/kWh spec...

Never a reason to say "per hour" unless you are discussing what your loads are...

 

[fnnwizard]

I have overlord cut off for charge and discharge set to 160 now. Is that good? I think I said it for two seconds before shutting down.

what are you powering?

 

[WorldwideDave]

A pool pump and a pool heater. It is happening by the way of an inverter. I have 5600 W and Solar, three different solar charge controllers, three different arrays, and have max current dialed way down.

 

[WorldwideDave]

Yes, I know I need more batteries. I am switching the inverter to 48 V soon which I already have. I just don’t have a 48 V battery yet. Quattro 48V 5000 already owned. Big MPPTs already.