question

hairyhaggis avatar image
hairyhaggis asked

Bmv 712 readings out of whack

screenshot-20201226-202726.jpgHi guys, so I'm scratching my head at the moment for a few things that have been showing on my bmv-712.


1) tonight when I checked via Bluetooth on my battery, it was showing 63% soc, but 11.9V. It is a lead acid battery, 75ah, under bonnet. I double checked voltage, as 11.9V is 40%,not 63%. It was 11.9V. The only thing running is my fridge, and the car was taken out today for a run, which was about 30 mins drive total (2 x 15mins trips) yesterday it wasn't run, and fridge was off. I now have that battery on trickle charge to top it up.

2) when I'm driving I monitor the battery, and the most the bcdc1225d is putting in, even when low voltage is 5A. I've not seen anything above 5A. It goes from say 73% straight to 100%.

3) battery is a century 75ah deep cycle lead, prob 4 months old.


My questions are, should the bcdc be putting in more than 5a when discharged down to say 70%? How do I realign the bmv and battery soc?

System has been wired properly, only battery on battery side of shunt, everything else on load side. Has been running fine for a while, now just seems out of whack.


BMV Battery MonitorSOC
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2 Answers
Alexandra avatar image
Alexandra answered ·

@Hairyhaggis

The first thing is the charge efficiency of the battery, what is that set to?

There are a few articles and videos on synchronisation of SOC

https://www.google.com/url?q=https://m.youtube.com/watch%3Fv%3D4ReljfO3k6M&sa=U&ved=2ahUKEwif0fbDz_PtAhXJiFwKHYYdBdkQtwIwA3oECAQQAQ&usg=AOvVaw2Nh14kjgockmbid1X4SBSH


https://www.google.com/url?q=https://m.youtube.com/watch%3Fv%3D4ReljfO3k6M%26list%3DPLnKCJA0l3E6aKHn32k9oRC7gsvRbgC803%26index%3D4%26t%3D0s&sa=U&ved=2ahUKEwif0fbDz_PtAhXJiFwKHYYdBdkQtwIwBHoECAUQAQ&usg=AOvVaw0z0Tg9AmfNS94bJmP71ILe


It is also possible the battery has had an event. Or from not fully going through absorption phase of charging sulphation builds up and sometimes then sheds and shorts out plates in the battery or messes with the battery chemistry. Is everything physically ok with the battery? No bulging off gassing etc

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michelg avatar image
michelg answered ·

Hi ! Try setting the Peukert value at 1.20-125, then set a value of 75Ah into the BMV, tail current 2%.

Also verify that the connexion to the BMV is correctly done and cables mounted the right way.

Michel

PS: also try charging the battery at 100% with an external charger, so you are sure everything is ok. May be it is also sulfated. The victron chargers are great, I was able to save several batteries using them.

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Related Resources

Victron BMV battery monitors product page

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