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Proof testing my 21P4S LFP battery

JohnJayMack

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Dec 22, 2020
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I have built a 21P4S LFP battery using 32650 6000mAh cells from Battery Hookup. This build calculates out to be a 126ah battery with a maximum continuous current of 378 amps. Since I intend this battery to be part of a house battery group in an RV, I chose to design for 120 Amps continuous output.

I just did a capacity test on this battery. The measured capacity was 134ah which is above the calculated value. These are new cells.

For the test, I used a 1500 watt pure sign wave inverter and initially I used a ceramic heater, set to low, which gave me a load current of 106-110 amps. At that level of current, the system ran for about 45 minutes before the inverter began to have trouble with the lower input voltage. I reduced the load down to around 10 amps and finished the test. I chose 10 amps because that is load option I already had.

When the heater runs at high, the current draw on the system is about 140 to 150 amps. The BMS shut itself off in that situation. Now to my question.

Does anyone know if the 120A BMS would be damaged if I changed the discharge over current to 155000 mA for a test? I am looking to see if my battery build has any hot spots at the higher current level. I calculated my design to handle between 140 and 175 amps without excessive heating. I would like to run the battery/BMS at the higher output for about 15 minutes to check for hot spots, etc. Would the Discharge over temperature setting provide enough protection for the BMS in this test? Any other thoughts and suggestions from anyone are greatly appreciated.

Thanks,

Jay
 
Buy another bms and use it parallel?

I would skip the BMS if you watching the discharge and use a cell monitor to watch the cell votages,
I bought a few bluetooth BMS to use the cell monitoring feature when in USE,

For bench I would use a cell monitor, I just bought one I will find the link and post it if that helps.

Post some pic, I am very interested in your build, this was my initial plan but I scarped it for EVE 280AH cells.

I am going to use these cells as a learning project and bench test my equipment.
 
I have built a 21P4S LFP battery using 32650 6000mAh cells from Battery Hookup. This build calculates out to be a 126ah battery with a maximum continuous current of 378 amps. Since I intend this battery to be part of a house battery group in an RV, I chose to design for 120 Amps continuous output.

I just did a capacity test on this battery. The measured capacity was 134ah which is above the calculated value. These are new cells.

For the test, I used a 1500 watt pure sign wave inverter and initially I used a ceramic heater, set to low, which gave me a load current of 106-110 amps. At that level of current, the system ran for about 45 minutes before the inverter began to have trouble with the lower input voltage. I reduced the load down to around 10 amps and finished the test. I chose 10 amps because that is load option I already had.

When the heater runs at high, the current draw on the system is about 140 to 150 amps. The BMS shut itself off in that situation. Now to my question.

Does anyone know if the 120A BMS would be damaged if I changed the discharge over current to 155000 mA for a test? I am looking to see if my battery build has any hot spots at the higher current level. I calculated my design to handle between 140 and 175 amps without excessive heating. I would like to run the battery/BMS at the higher output for about 15 minutes to check for hot spots, etc. Would the Discharge over temperature setting provide enough protection for the BMS in this test? Any other thoughts and suggestions from anyone are greatly appreciated.

Thanks,

Jay
I would love to see some pictures of that set up
 
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