lorettaboy avatar image
lorettaboy asked

Batteries not being fully charged.

Hello all. I have a Victron MPPT and BMV712 hooked up to 600w of solar and 2 6v Trojan T105 batteries.

The batteries never reach 100% and the MPPT is shutting down around 86%. I've taken a few screenshots of my system settings. Looking for advice on which settings I need to change to get my Batts fully charged. First 2 screens are from the BMV, last 2 are from the MPPT.


MPPT SmartSolar
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3 Answers
Ulrich avatar image
Ulrich answered ·


I saw in the data sheet for the batteries that a 6V battery must be charged with 7.4V. If there are two in series, this is 14.8V.

Select the appropriate battery in the settings, then the values will be set automatically.

I hope I was able to help, if you have any questions, I'm looking forward to it.



1617128525254.png (35.5 KiB)
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lorettaboy avatar image lorettaboy commented ·

Thank you Ulrich. The exact charging instruction for my batteries are below. I have the same values inputted into my MPPT, and its still shutting down around 83% capacity.

I noticed that on the BMV there is an option to manually adjust the current state-of-charge. Perhaps i should set this to 100% and be done with it?


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t105.jpg (171.5 KiB)
kennethknashaug avatar image
kennethknashaug answered ·

Hi. What is your c20 rating on the batteries, are they 200Ah? Second I would change "charged voltage" so that it is 0,24V lower than your "absorption". If you have good conditions for solar charge all year, and not like my situation in Norway I believe "tail current" should be set somewhere between 5-6%. I would also suggest that you change your "charged detection time" to 5 min.

So to fine tune the drift I would suggest that you change your "charge efficiency factor" to 80-85%. Value for Peukert should probably also be changed, but this value needs some trial to get correct and depends very much on how you use your batteries. (slow/fast discharge). I would probably recommend to start with 1.24 and observe if your values are drifting when SOC is being synchronized. Then I would adjust this value and also the charge efficiency factor until you see little jump in the charts when synchronizing SOC.

Hope this helps!

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Ulrich avatar image
Ulrich answered ·

Sorry for my late reply, I was out of the office.

After the battery is fully charged, the current flow decreases. A wet battery is around 80% at this point. Then the absorption phase has to charge the last 20%. It can take a long time. After this phase, the SOC can be manually set to 100%.

Have you set up VE.Smart Networking? Then the Smart Solar Charge Controller receives the exact voltage from the shunt and can thus compensate for the line losses and can recognize that other consumers are consuming the charging current.

100% SOC is reached when the current falls below a certain value for a period of time. This must be set in the BMV.

I have had very good experiences with these settings and can clearly see that the MPPT readjusts for the consumer.


Here you can see that the solar charge controller first charges the battery (bulk), then comes the absorption, then float. The current flow is adapted to the consumption so that the battery is charged correctly.

I hope that was understandable. I use google translate because my English is not that good. Sorry for translation errors.


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