BMV 712 Amp-Hours reset to 0?

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pgrogan5326 asked Jan 11, '22

BMV 712 Amp-Hours reset to 0?

We are attempting to assess the ability of our solar panels to recharge (“refill”) our batteries and are confused by the Amp-Hours being reset to 0. Example: over last night the Amp-Hours consumed were 21.6 (-21.6 showing in the app). When sun hit the solar panels the current and power moved to positive values and the Amp-Hour reading started slowly moving back to 0- exactly what we were expecting to see. Later the Amp-Hours displays as 0 while the current and power are both still positive. No where near enough charging had happened to fully recharge the batteries. What is going on? It would seem the Amp-Hour display should show cumulative totals until fully charged again, but obviously not. Help please?

BMV Battery Monitor

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Answer 1 · 2022-01-11T23:15:57Z

klim8skeptic answered · Jan 11, 2022 at 11:15 PM

Have you set up your BMV properly?

BMV Youtube tutorial.

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Answer 2 · 2022-01-12T00:31:13Z

pgrogan5326 answered · Jan 12, 2022 at 12:31 AM

After watching the suggested youtube video several times I’ve changed the Charged Voltage setting, the Tail Current setting and the Charge efficiency factor setting. I think (???) this should help. Thank you for your direction.

My batteries are 2 - 12v AGM in parallel with both outside power source charging and solar charging. If you have any other resources I should learn from to best set up our system, I would greatly appreciate your direction.

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Matthias Lange - DE ♦ commented · Jan 12, 2022 at 04:56 AM

As always more information about your system would be great.

What components do you have exactly? Make make some screenshots of the settings of the BMV.

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Answer 3 · 2022-01-12T18:52:59Z

pgrogan5326 answered · Jan 12, 2022 at 06:52 PM

We have 2- 12v AGM batteries in parallel in our camper. Normally the batteries are charged through our converter which is connected to an outside power source. We also have 2-90 watt solar panels. Per the YouTube BMV video we changed: Charge Efficiency Factor from 95% to 80%, Charged Voltage from 13.2v to 14v, Tail Current from 4.00% to 5.00%. Batteries have 80 amp hour capacity @ 20 hour rate, bulk charge 14.2v to 14.4v, float charge 13.2v to 13.4v. Do our BMV 712 settings look correct for our application?

bmv-712-settings.jpeg (367.5 KiB)

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klim8skeptic ♦ commented · Jan 13, 2022 at 12:22 AM

I would probably leave the charge efficiency at 95% for a few days to see if you can get the BMV to synchronize. Maybe tinker with the tail current?

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bmv-sync-a.png (166.7 KiB)

Answer 4 · 2022-01-12T19:03:23Z

pgrogan5326 answered · Jan 12, 2022 at 07:03 PM

Here are the battery details.

agm-battery-details.jpeg (494.1 KiB)

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