BQ40Z60: How DODEOC works?

Hendra Kusdarwanto

Part Number: BQ40Z60
Other Parts Discussed in Thread: BQSTUDIO

Hi,

Could you explain more how the DODEOC ( DOD at EOC) work?, is the VCT the only prerequisite to making the DODEOC updated?. We were trying to cycle the pack from 20% - 80% repeatedly without REST, so the VCT should never be triggered, but we saw DODEOC was updated (increasing) at every start of the charge. I think it makes the FCC reduce gradually in our experiment because of the reduction of Q start

Thanks

- Hendra

10 months ago

0 Wyatt Keller 10 months ago

TI__Guru* 89400 points

Hello Hendra,

VCT will still be triggered even if you do not rest the battery, just because there is no rest doesn't mean VCT won't occur. VCT happens during charge taper so you should still be getting valid updates if you are doing charge tapering.

Sincerely,

Wyatt Keller

0 Hendra Kusdarwanto 10 months ago in reply to Wyatt Keller

Prodigy 190 points

Hi Wyatt,

Yes, I agree that VCT happens during charge taper and no need for REST

Something I don't understand that why in my testing, the DODEOC was updated even though the VCT is not triggered, is there other conditions to make the DODEOC updated besides VCT?

Thanks

- Hendra

0 Wyatt Keller 10 months ago in reply to Hendra Kusdarwanto

TI__Guru* 89400 points

Hello Hendra,

Can you share the logs so we can see the conditions when the update occurs?

The VCT is not the only time the DOD at EOC will update, the DOD at EOC is based on the temperature, voltage, and current so it will be adjusted similar to the FCC value.

Sincerely,

Wyatt Keller

0 Hendra Kusdarwanto 10 months ago in reply to Wyatt Keller

Prodigy 190 points

Hi Wyatt,

The log is attached, we are using our own logger, it is not from bqstudio, so the registers may not be as complete as bqstudio

2022-07-14_06.24.38-QMAX_Docking_21_Batt_0x8b.csv

Thanks

- Hendra

0 Wyatt Keller 10 months ago in reply to Hendra Kusdarwanto

TI__Guru* 89400 points

Hello Hendra,

Your DOD at EOC updates less than 100 points out of 2^14, this is most likely just the gauge adjusting since it enters charge mode. The DOD at EOC has a current value linked with it, so the temperature and internal resistance impacts the DOD at EOC and that's why it does some small corrections at the start of charge.

Sincerely,

Wyatt Keller

0 Hendra Kusdarwanto 10 months ago in reply to Wyatt Keller

Prodigy 190 points

Thanks Wyatt,

We tested the battery pack inside a quite high and unstable temperature environment. If the discharge temperature is higher than the charge temperature, could this condition make the DODEOC adjusted?

Thanks

- Hendra

0 Wyatt Keller 10 months ago in reply to Hendra Kusdarwanto

TI__Guru* 89400 points

Hello Hendra,

Any temperature change during mode transitions (relax to charge, relax to discharge, etc) could cause the DOD at EOC to adjust for the change.

Sincerely,

Wyatt Keller

0 Hendra Kusdarwanto 10 months ago in reply to Wyatt Keller

Prodigy 190 points

Oke, got it, thanks

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BQ40Z60: How DODEOC works?