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BlueNova 8KWh battery odd temperature/charging behavior


Ian
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Hi All

My neighbour has a Victron/Bluenova offgrid setup, which has been installed for a few years at his house. He's a Dutch resident, so only here occasionally.

The system is set up so that the battery controls the charging cycle. As there is very little consumption, the battery cycles daily between 90 and 100%

In the past the charge voltage has risen to 56.2 (max voltage set by battery) in the morning, and then immediately dropped to 55.5. There is a corresponding spike in the battery temp when the voltage gets to 56, and then it drops to ambient as the voltage drops to 55.5. Battery current is 0A at this stage.  Speaking to a BN tech, the cell boards will dump/balance when the cell voltage is above 3.5, so that explains the battery temperature rise.

Lately however, the voltage is kept at 56.2V all day, until the sun goes down, with the battery temperature sitting at 45-50C.

I called BN, gave them access to the VRM etc, and while first saying all is ok and the temp behavior is fine, when pressed, said he should send the battery in to be checked by them. No other diagnostics suggested.

It's obviously a big pain to send the battery in, and arrange a temporary replacement. The system needs to stay up to run the security system and cctv.

Anyone have any experience with similar BN battery issues?

I'd also like to know if it's possible to reconfigure the system to give the user more remote control of the charging arrangement. At the moment there's no way to set the battery charging behavior, as it's all up to the battery. Be nice to keep it at 70-80%(rather than 90-100%), and occasionally take it down to 20% etc, via VRM.

Cheers

Ian

PS, I can post temp/V/SOC graphs if necessary

 

 

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