BMV displaying incorrect values

DIY
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1

Hello,
I wonder if anyone can
shed some light in the issue I’m having.

I have a small setup in my self built camper van consisting of:

  • 1x Easysolar 1600 12v smart mppt 100/50
  • 3x Victron 175w mono panels
  • 1x 30A Orion smart non-isolated 12v/12v
  • 1x BMV 712 smart
  • 1x VE.Bus BMS V2
  • 1x 330ah Victron LIFEPO4

I have only recently added the BMS and the Lithium battery. Previously it was running an AGM. But i dont actually think this issue has been happening the whole time since…

The issue i am having is that the van is sat in a barn, on a mains hookup (correct voltages etc) the whole time we are not off using it. However, i went into the van to check all was well and the BMV was showing a charge percentage of around 60%. I checked the mains hookup was still on, the easy solar is still flashing an orange light to show it is charging… I then logged into the Victron APP to see it also reflected the same 60% and next to no charge current flowing.
I flicked the switch on the easysolar between OFF and charge only to see if this changed anything - after a few seconds the charger started to operate at around 45A for a very short period, then it tailed off gradually down to nothing again (over a minute or two) but the percentage stayed the same.
Then, all of a sudden, the charge percentage changed to 100%, from around 60%, in just a few seconds.

I thought perhaps it was just a glitch, so left it. I then popped back into the van this week to check and the exact same thing happened. (Though around 80% charge this time).

I managed to get some screenshots to show the transitions.

Is there anything I should look for specifically?

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2

It is likely the shunt is not been set up correctly.

Have a read of this guide.

2 Likes
3

Thanks very much. I did think I set things up correctly, following the correct procedure etc… but will try again.

Is there any relevance with the fact all of the scenarios listed in that advise link are for the SOC being reported as HIGH - as mine is doing the opposite?

Thanks again!

4

As the author of the guide, the most common problem is the sync to 100% occurring too early. It could also occur too late but the recommendations apply regardless.

There are other settings that are different for AGM and lithium, Peukert for lithium should be 1.05 and charge efficiency 0.99, these both affect the SOC calculation.

Another reason for under reading is a zero error so it is measuring a phantom load, do a zero current calibration, the procedure is in the manual.

Finally, the wiring may be at fault, see this additional FAQ, but if so you would have had issues with lead acid also.