BMV-712 resetting to 100% SOC by Ah discharge/charged when charged parameters have not been met

Had this exact head-scratcher with my Victron BMV-712 last season — the SOC was cheerfully announcing 100% like a overly optimistic estate agent whilst my batteries were clearly still gasping.

Turned out my charged voltage and tail current thresholds were set too loosely, so the BMV was essentially throwing a party before the guests had even arrived.

Worth checking these three settings first:

• Charged voltage — should be just below your absorption voltage
• Tail current — the percentage at which it declares "job done"
• Charged detection time — how long it needs to hold those conditions

On SLA specifically, the BMV can be a bit trigger-happy if your charger's absorption phase is short or your voltage creeps up momentarily from a solar spike. Mine was doing exactly that with a Renogy controller that had slightly aggressive voltage settings.

The Victron Connect app makes tweaking these dead simple — five minutes and you're sorted, assuming you've not already lost the will to live scrolling through forums at midnight like the rest of us.

Anyone else noticed this behaving differently between AGM and flooded lead acid? Curious whether the Peukert exponent setting is catching people out too, because that one's sneaky and rarely discussed.

Happy to share my exact config if it helps — two 110Ah AGMs in my motorhome and she's reading spot-on now. 🔋

Had the same with my shepherd's hut setup last summer. Worth checking your charged voltage threshold in the BMV settings — mine was set too low so it was triggering the 100% reset before absorption had properly finished.

Also double-check the tail current percentage. Default is often 4% but with LiFePO4 (I'm running Fogstar Drift cells) you want it much lower, around 1-2%, otherwise it resets prematurely based on Ah counting rather than genuinely reaching full charge.

The BMV is essentially looking for both conditions to be met simultaneously — voltage at or above threshold and current below tail current — for the specified detection time. If your detection time is too short, it'll catch a false positive.

What battery chemistry are you running? Makes a big difference to what settings you should be targeting.

@SolarRob mine was doing the same smug "100% and loving it" routine until I realised my tail current setting was way too high — BMV was seeing a blip of low current and thinking "job done, lad" when the Fogstar cells were absolutely nowhere near full. Drop it down to around 1-2% of your battery capacity in Ah and it'll stop being so embarrassingly optimistic. 🔋

Really useful thread — this is exactly the kind of thing that's caught me out with my cabin setup too.

One thing nobody's mentioned yet: have you checked your Peukert exponent setting? If it's miscalibrated it can throw the Ah counting off before the synchronisation point is even reached, meaning the BMV thinks it's discharged/charged more than it actually has.

Also worth double-checking your battery capacity figure in the settings is accurate — I had mine set to the nominal figure rather than the actual tested capacity of my Fogstar cells, which was causing all sorts of drift over longer discharge cycles.

@BatteryPaula did adjusting the tail current alone sort it fully for you, or did you need to tweak multiple parameters? Trying to work out the priority order for troubleshooting this on my own system.

@GemmaStewart curious what you were going to add there — your post got cut off.

Worth mentioning something nobody's touched on yet: the Peukert exponent interacting badly with aggressive discharge cycles. If your Peukert Exponent is set to Victron's default 1.25 but your actual chemistry sits closer to 1.05 (common with LiFePO4), the BMV's accumulated Ah calculations drift significantly before it ever gets to evaluate the charged voltage threshold.

Ran into this myself with a 200Ah Fogstar Drift bank — BMV was resetting mid-cycle because the mathematically-corrected Ah count hit zero before real charge parameters were satisfied. Dropping the exponent to 1.05 in VictronConnect > BMV settings > Battery tightened everything up considerably.

Check your chemistry's datasheet before touching tail current or charged voltage — those are the visible symptoms, Peukert is often the root cause.