Battery characterization test for modules

[Jonndeka]

Hi dear friends,

So far we had battery characterization test for a single cell. I would like to know how can we test the module (series and parallel multiple cells) using HPPC test?

I look forward to hearing your feedback.

Best regards,
Jonndeka

 

[Jonndeka]

eMark,

I checked the link which you shared the other post. Also I found out few HPPC test procedure. I'm so confused!
Which procedure is standard for HPPC test? and all above, How can I do this test for module?
Is the value of C-rate and the resting time is the same as cell testing?

 

[eMark]

I checked the link which you shared the other post. Also I found out few HPPC test procedure. I'm so confused!
Which procedure is standard for HPPC test? and all above, How can I do this test for module?

It's really not neccesary (IMO) for you to setup your own lab to perform such critical HPPC tests of your LFP modules.

The HPPC capacity test is carried out by discharging the cell at a constant current, at a user-selected Crate (normally ranged from 0.5 to 2), until the cell reaches its upper voltage limit. Then, the cell is discharged at a constant voltage (the upper limit), until the current reaches a relatively small value, close to 0. An hour of resting period is standard between each 10% SOC interval. The HPPC test is run within the range of voltage limits specified by the cell manufacturer. ...

Hybrid Pulse Power Characterization (HPPC) test profile

IMO, the critical accuracy of such accountable testing is for providing datasheet verification by lithium (LFP) manufacturers. All you really need to do with your used or new LFP 14S6P modules is to balance any "Gross Imbalance" variances among the 14 parallel groups. At least no more than 100mV (0.100V) variance between the 14 parallel groups. If possible no more than 50mV or as close as possible (time permitting) after 12-16 'balancing' hours.

Using an active equaliziing BMS Balance Board either after a partial discharge cycle before charging again and/or again after top charging. Need to first let the battery module rest for at least 1 hour before connecting to a stand alone active equalizing 14S BMS Balance Board.

Is the value of C-rate and the resting time is the same as the cell testing?

It's part of the process of determining the capcity of a cell or parallel group of cells. Even though i'm retired i don't have the patience or time to do laborious capacity testing that really isn't necessary. Suppose it's more important to track capacity with lithium powerwall batteries. Even so one gets a good enuf idea of the diminishing capacity of battery modules cycle after discharge cycle and tracking amount of any "Gross Imbalance" among 14 parallel groups.

The best one can do whether with your used or new LFP modules is to keep the voltage variance between the 14S parallel groups as small as possible for as long as possible via BMS balancing before the discharge cycle.