Overhead Control Panel Volt Meter

Haves1979 · Apr 10, 2023

How accurate is the overhead control panel volt meter and do you need to do anything to reset it? Currently it is showing 12.4v, however my Victron Smartsolar app is showing 13.69v and on float?

WelshGas · Apr 10, 2023

Haves1979 said:
How accurate is the overhead control panel volt meter and do you need to do anything to reset it? Currently it is showing 12.4v, however my Victron Smartsolar app is showing 13.69v and on float?

The Control Panel voltmeter is accurate.
Which vehicle do you have?
I presume your solar panel is wired to the rear Leisure Battery?

Haves1979 · Apr 10, 2023

Its a T5.1 SE, with a victron controller straight the batteries using an app.

WelshGas · Apr 10, 2023

Haves1979 said:
Its a T5.1 SE, with a victron controller straight the batteries using an app.

There is a very high probability that the Cube fuse on the +tve pole of the rear Leisure Battery has failed. This fuse, originally 50amp since upgraded to 75amp, connects the 2 Leisure Batteries together.
If it fails your Solar panel is charging the rear battery but you are using the front Leisure Battery only, hence the 2 different voltage readings.
Check the rear Cube fuse and replace BUT ensure both batteries are fully charged or you might blow the new fuse. The solar panel will fully charge the rear battery and if you plug into EHU for 24 hrs the on board charger will fully charge the front Leisure battery.

Haves1979 · Apr 10, 2023

Thanks I'll check this when we get home.

Cheers

WelshGas · Apr 10, 2023

Haves1979 said:
Thanks I'll check this when we get home.

Cheers

Please let the Forum know the outcome.

Haves1979 · Apr 10, 2023

Yep no probs. Cheers

Haves1979 · May 18, 2023

To follow up on this, the cube fuse was OK, or at least it looked OK. I have replaced anyway just in case.

Now we are getting some warmer/sunnier weather I'm seeing much better voltages. The batteries are definely both linked the rear battery voltage drops when in use.

What I'm seeing is that my volt meter matches the vw display exactly. However, the solar app, shows about 0.3-0.4v too high. Not sure of the cause but it is definitely charging the battery so a minor issue really.

Thanks for the pointers.

Steve1 · May 18, 2023

Haves1979 said:
To follow up on this, the cube fuse was OK, or at least it looked OK. I have replaced anyway just in case.

Now we are getting some warmer/sunnier weather I'm seeing much better voltages. The batteries are definely both linked the rear battery voltage drops when in use.

What I'm seeing is that my volt meter matches the vw display exactly. However, the solar app, shows about 0.3-0.4v too high. Not sure of the cause but it is definitely charging the battery so a minor issue really.

Thanks for the pointers.

I would say, either your solar charger voltmeter is very inaccurate, or you have some corroded or undersized wiring between the charger and battery and the voltage is dropping across that.

Haves1979 · May 18, 2023

Steve1 said:
I would say, either your solar charger voltmeter is very inaccurate, or you have some corroded or undersized wiring between the charger and battery and the voltage is dropping across that.

All the solar kit is the standard stuff from solar camper solutions. Charger is a Victron, which I believe are decent.

Steve1 · May 18, 2023

Haves1979 said:
All the solar kit is the standard stuff from solar camper solutions. Charger is a Victron, which I believe are decent.

Have you used your multimeter at rear battery, black probe to chassis or -ve battery terminal. Red probe first to top of cube fuse, second to bottom of cube fuse. Do readings exactly match ?

Haves1979 · May 18, 2023

I did indeed, same reading at both points.

Steve1 · May 18, 2023

Haves1979 said:
I did indeed, same reading at both points.

And is it that reading that's the same both sides that matches the control panel ? If so the. I would try to measure the voltage at the output of the charge controller. You really need to find out if it's an inaccurate controller or voltage drop in the charging wiring, if it's drop in wiring then it could potentially get hot and cause you a problem. If it's inaccuracy in the control voltage reading then less of a problem, but it does mean it probably won't fully charge your battery because if it's over reading it will think it's full before it is

yossarian · May 18, 2023

Yeah, as Steve said a good idea to get to the bottom of it.

You need to test when the charge current is reasonably high. If it's zero even duff wires will give you the same voltage everywhere.