joycarlaina avatar image
joycarlaina asked

BMV 712 SOC reads "--", Inverter reads "lo", No BMV history

I'm converting a Ford Transit 250 into a camper and just finished setting up my electric system last week.


BMV 712 Smart Battery Monitor

MPPT 100v 30A Solar Charge Controller

(3) 100Ah LiFePO4 Battle Born batteries

Giandel 2200W Pure Sine Wave Inverter

Sterling 60A B2B Charger

Progressive Dynamics 60A 12v LiFEPO4 Battery Converter/Charger

I've been reading forums and doing a lot of research and can't figure out why the Battery Monitor state of charge just shows 2 dashes (--), and there's no history (Deepest discharge - 0Ah, Discharged Energy 0.0kWh, etc.). It's been this way for about a week now.

Also, when I turn my inverter on, it beeps continuously and says "Lo", indicating low voltage protection. Yet my 12v system runs and works fine (water pump, lights, fan, etc.). But when I turn the inverter on to use my GFCI outlets, they don't work. And again, I can't tell what my SOC is.

I've gone through the battery settings in the Victron app and changed everything to the recommended specs (see attachment).

Could anyone please point me in the right direction?

Thank you!


BMV Battery MonitorMPPT SmartSolarLithium BatterySOC
2 |3000

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1 Answer
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

You have to make a full charge cycle to synchronize the BMV to 100%.

BTW 14.4V "charged voltage" seem a bit high to for me.

0V battery voltage everyday at the MPPT often indicates a bad connection to the battery (blown gut or open main switch).

2 |3000

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joycarlaina avatar image joycarlaina commented ·


Thanks for your answer! What would you recommend I switch the charged voltage to? I believe Battle Born recommended 14.4.

How has it not had a chance to make a full charge cycle in 1 week, when the batteries come charged, per Battle Born?

I will look into whether or not the MPPT has a bad connection or if my main 300A fuse attached to my battery from the master disconnect switch is blown.

Again, I appreciate your help very much!

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joycarlaina avatar image joycarlaina joycarlaina commented ·

Also, the MPPT appears to have been working 2 days ago, per the attached screenshot. I’m not sure if it’s helpful, but I attached a picture of the MPPT showing the green light on “float”.


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dazey77 avatar image dazey77 joycarlaina commented ·

Listen to the man! It will still show float with no battery attached, it just pins the output at 14.4v. Your seeing max 14.4 and min 0 because there is no battery attached (due to cable issue, something blown, whatever)

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joycarlaina avatar image joycarlaina dazey77 commented ·

@dazey77 and @Matthias Lange - DE You guys are correct, I just took out the 300A fuse that I had attached to my battery via a fuse block terminal, where circled in green in the attachment. It is definitely blown (see other attachment). Does anyone have any insights on why I might have blown this? I wouldn't want to replace it and just blow it again. I followed the diagram that I attached here. Should I try a different size or type or way to wire it?

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fuse-location.jpg (872.5 KiB)
diagram.png (481.8 KiB)
joycarlaina avatar image joycarlaina joycarlaina commented ·

Also, I've had my main switch open at least once everyday, as I was wiring more components in. That could be the reason why 0v is showing every day for the MPPT min? I am unclear on whether or not my 300A fuse is blown. (See photo above) Any other insights?

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dazey77 avatar image dazey77 joycarlaina commented ·

Really just buy yourself a cheap multimeter to be able to test the fuse and battery output. It will pay for itself.

I will say that it sounds like the fuse is gone and the reason your inverter doesn't work is that the solar MPPT is running your 12v circuits by itself with no battery attached. This would tally to the low voltage warnings.

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joycarlaina avatar image joycarlaina dazey77 commented ·

@dazey77 That makes absolute sense. I'll have to figure out why I blew the fuse so when I replace it I don't do it again. I will go get a multimeter though, so I can start to troubleshoot that. I really appreciate you chiming in!

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Justin Cook avatar image Justin Cook ♦♦ joycarlaina commented ·

Hi @joycarlaina, I'll add one thing in here, which is that your batteries did not come fully charged, as it is illegal to ship fully charged LFP batteries in the US.

The installation manual for Battle Born batteries may be of some assistance to you as well, which I am attaching.


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joycarlaina avatar image joycarlaina Justin Cook ♦♦ commented ·

Good to know! Thanks for the response. I watched this YouTube video straight from Battle Born's YouTube channel ( and they say that they come charged unless they're shipped over seas. This must be old? Although it was posted in 2021. Hmm.

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