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etrim avatar image
etrim asked

Multiplus 12v/3000/120v putting out 80v


Need help trying to figure out multi setup. This is my first install of a battery bank with a inverter/charger. There is much to be learned , so thank you in advance. I installed my multiplus 12v/3000/120v with 2 chins 300AH batteries and have a BMV 712 and Ve Bus dongle to read info. First night testing it was running in inverter mode and did not appear to be charging batteries, but seemed to be letting passthrough power through. I check it in morning and it was flashing low battery ( not sure why it was using battery when shorepower is passing though). So when I switch off battery cutoff multi will have a solid low battery light and no passthrough power is present. I test voltage and get 120v on ac in and 80v on the ac out. I am not even sure where to begin.


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voltagelow battery warning
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3 Answers
Paul B avatar image
Paul B answered ·

you seem to be measuring the AC2 out .

the standard install is to connect to AC1 out

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1 comment
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You also need to check the battery voltage at the multiplus and check this when under load and inverting and when shore power is connected and it charging
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etrim avatar image
etrim answered ·

Thank you @Paul B I double checked, It is the AC1 out.Ok couple of things have changed since I posted. After the overnight event I shut everything down for a while to explore what to do. The multiplus must have gone through a hard reset or something. I turn it back on and charger kicks on for the first time ever and starts going through the bulk phase and into the absorption phase. Shore power had been hooked up the enitire time btw.When I test now it reads 124 everywhere. Once in a while the AC 1 leg in the app wont show but will list the wattage in the app, is this just a fluke in the app showing and not showing. Also BMV shows a max voltage of 14.8, that is not right correct. I had to turn off the charger once the batteries showed 13.7 on my multimeter. Im trying to get all the settings right. I just bought the interface MK3-USB but will not have it in hand for a week. Should I not turn back on anything until I can connect directly to the multiplus to program? Thank you


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Paul B avatar image
Paul B answered ·

max voltage reading could have occurred a long time ago basically when the BMV was installed or fully reset. re the app I dont use this all the time so cant comment, I would think that if the multi is set to lithium then the Bulk/absorption voltage will be 14.2 volts it would hold this for one hr then the voltage would drop to float voltage of about 13.7

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Also I would recomend that you get a Cerbo GX and then you can monitor everything and even do all your updates WITHOUT a MK3 unit via the VRM
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