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Mr Roboto avatar image

75/15 Battery Voltage Difference vs Actual Battery Voltage

Actual battery voltage 11.2 at terminals on Victron, software reads as 14.1. New firmware installed, did not have this issue before. Optima Yellow top, temp comp off. Any way to calibrate this?

charging batteryvoltagesoftware
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3 Answers
lemon avatar image
lemon answered ·

Hi,


I've installed right now my new SmartSolar 75/15 and it is connected to the solar panel and the battery only, no cable on the load outputs.

As you can see in the picture the MPPT is showing me a battery voltage of 13.79V but when I measure directly on the battery I have only 13.0V!

The MPPT is connected with a 50cm AWG12 cable to the battery, so it can't be a long or thin cable problem.

Any hint?


Thank you very much!


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Check the fuses.
There is one directly at the MPPT on the left of the connection terminals.

lemon avatar image lemon Matthias Lange - DE ·

Hi Matthias,

I've checked the fuses and you know what? I noticed only then that the positive ring terminal on the battery lost its connection to the wire. The ring was held to the wire only because of the isolation!

I crimped a new ring and problem has gone.


Thank you very much


Andreas

Mark avatar image
Mark answered ·

That delta is significant, so I believe that you have developed a poor/loose connection somewhere.

You should check each and every connection - clamped, bolted or crimped. Also check any fuses and fuse holders that are in line.

You can also measure the resistance terminal to terminal using a multimeter to identify the issue. Just best to disconnect the opposite cable first.

Alternatively the MPPT may have developed an error, but I doubt that.

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Mark,

Thank you. The readings were taken directly at the battery terminals on the Victron with a DVM, it is the same as on the battery.

Ahh sorry, now I understand the issue. In that case the problem is probably internal within the MPPT.

But also check with another multimeter first, in case your meter is faulty.

It may also be worth trying to re-secure both battery cables into the MPPT terminals, depending on the MPPT screw terminal design there could also be a poor connection leading to the screw head that you are probing.

Also, I am using the bluetooth dongle/Victron app to get the internal readings.

Stuart avatar image
Stuart answered ·

A smart battery sense would be the only answer to this one. If your solar charge controller does not have bluetooth you can add a bluetooth dongle. The smart battery sense will send back the voltage at the terminals and battery temperature.


Check in your manual and on the smart battery sense compatibility list first. I believe some of the smart solar range is not ve. smart network compatible yet.


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Thanks for the help Stuart. Our property is remote, I will be able to try your suggestions in a couple of weeks when we go back out.