BBox SOC making large jumps with little load/charge

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sinbad asked Feb 5, '20

BBox SOC making large jumps with little load/charge

Hi all

The SOC on my B-Box 10.25kw battery stack jumps by around 25% at certain points in the charge/discharge cycle.

This became a problem this morning as I was expecting a 4 hour power outage. I had the SOC at 50% overnight, in preparation. The SOC dropped from 45% to 20% in a few seconds during the outage - power draw was in the region of 1kw at the time.

Then when recharging, it bounced up 25% again almost instantly.

I looked at the batteries this morning and noticed that one of the units does not have flashing lights on it. Am I looking at a failure here?

Video:

https://photos.app.goo.gl/dS7SDPUmvgg8yRRs5

SOC BYD

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sinbad answered · Mar 29, 2020 at 07:55 AM

Hi all

So after some troubleshooting with the South African BYD distributors, it was determined that the battery unit was faulty (Cells were not balancing, resulting in both overvolt and undervolt errors). The battery was replaced under warranty.

Two thumbs up to BYD for their service and support! :)

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Modifications Space

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Answer 1 · 2020-02-05T08:13:55Z

ejrossouw answered · Feb 05, 2020 at 08:13 AM

@Sinbad Firstly, start with analysing any error code on the battery. Secondly, it could be a poor/bad connection that shows up under load, so I'd check all of those too. If you are comfortable, it may also be worth removing the suspect battery and see if you can still replicate the problem. Then it will be a case for you and the supplier if the battery is actually at fault.

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sinbad commented · Feb 05, 2020 at 08:41 AM

Hi, thanks for the response.

I am not sure how to check for error codes on the battery. There are no alarm lights, just the RUN and SOC lights on steadily. On the other batteries, the RUN and SOC lights flash.

According to the CCGX, battery health is 100%. There are no alarms.

I don't believe it's load related - but I will check the connections anyway.

I am not comfortable removing the battery though... would that just be a matter of turning it off, disconnecting the power cables and moving a canbus cable? Would I need to shut the system down to do this?

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ejrossouw sinbad commented · Feb 05, 2020 at 12:45 PM

Hi Sinbad. Please do not work with any power cables unless the system is shut down and batteries properly isolated. You need to verify this with a multimeter prior to proceeding. Also only do it if you are totally comfortable with it and know what you are doing. I can see there is no light movement on the 2nd from top battery, but cannot personally comment on the BYD setup or what it's state means. Maybe the BYD form has some answers? If it is still under warranty please get the dealer to advise you further as you could jeopardise it otherwise.

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sinbad ejrossouw commented · Feb 05, 2020 at 01:10 PM

Thanks, my installer has gone AWOL.

I would expect it to be under warranty though. Hopefully the BYD rep on this site can shed some light on possible issues, and either propose a solution or recommend an agent here in RSA that can help with the warranty.

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Answer 2 · 2020-02-05T14:30:56Z

Guy Stewart (Victron Community Manager) answered · Feb 05, 2020 at 02:30 PM

The first thing I would do is fully charge the batteries to 100% (56.5V) and try to keep them there at 100% for as long as possible. It might be that module is slightly out of balance with the others for some reason.

@BYD_service may have some other ideas.

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matthew commented · Feb 05, 2020 at 02:44 PM

Make sure the CCL goes to 0 in the colour control when 100%

I would also take a video of the lights on the batteries.

Matt

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sinbad commented · Feb 05, 2020 at 03:13 PM

Hi Guy.

Thanks for your response - had a full charge the day before yesterday. I have also maintained a full charge for a couple of days in the recent past, but the behaviour predates that and has not changed.

I also allowed a full discharge to 0 and then recharge to 100.

Matthew there is a video linked in the original question :)

I have set the batteries to charge now, and will check CCL - where do I find this in the menu structure please?

Thanks!

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sinbad sinbad commented · Feb 05, 2020 at 04:51 PM

CCL indeed goes to 0 when charger goes into absorption mode.

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Answer 3 · 2020-02-05T14:48:25Z

byd-service answered · Feb 05, 2020 at 02:48 PM

@Sinbad the LED behavior is indeed unusual and it might be too much of a coincidence that the jump of SOC corresponds to 25% of the capacity. Could you register the system in our service portal support.eft-systems.de and email me the system ID? a.garcia@eft-systems.de

Thank you

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