Another leisure battery type query

[SimonM]

Following on from a short while ago when I fitted a new MPPT and a solar controller and new batteries and now also a VSR (thanks for the advice Wildebus) I now have a slight voltage gauge question

All this lovely sunny weather and the solar panels are doing their job keeping the batteries topped up, and the extra volts are being crammed into the starter battery as well.

My NASA BM2 shows the leisure and the starter batteries at a regular 13.5v a completely separate voltmeter shows the starter at 13.5v, putting a voltmeter across the leisure batts shows 13.5v

The internal Burstner water and volts gauge shows the starter battery at 13.5v........

But it only shows the leisure batteries at 12v. .?????? I’d like an idea why? It has only started to do this in the past couple of days, it always showed the same as the solar previously.

Incidentally, if I turn the engine on all of the gauges show 14.4v as I’d expect, including the one which was previously showing 12v. It uses a Schaudt Elektroblok internal charger setup that the gauges take their info from. Suggestions please.

 

[wildebus]

Sounds weird that it shows all matching voltages to the NASA when engine running and non-matching on the leisure when engine off.
I doubt this is the problem but I will throw it in as a comment ... the smaller the fuse size, the larger the voltage drop, so you *could* see if there is a fuse that can be increased in size (within reason of course!).
For example, some people report that their Victron BMV Battery Monitor is underreading the voltage and correct it by replacing the 100mA rated fuse with a 1A fuse.

 

[Admin]

If I am reading this correctly you are saying that the NASA is correct but the Burstner control panel is wrong?

If it has worked fine before then I doubt it is calibration of the Elektroblok.
I suspect there is a higher resistance on the cables feeding the Elektroblok (positive or negative). This could be a loose connector or fuse.

 

[SimonM]

If I am reading this correctly you are saying that the NASA is correct but the Burstner control panel is wrong?

If it has worked fine before then I doubt it is calibration of the Elektroblok.
I suspect there is a higher resistance on the cables feeding the Elektroblok (positive or negative). This could be a loose connector or fuse.

Yes. It has worked fine for the last 7 years.

Up until I removed all of the wiring a couple of days ago to check if there was anything taking power when everything’s switched off. There isn’t.

Maybe I have a loose connection??? Er, forget I mentioned any of this. I’ll go look in the morning. OK, move along nothing to see here ?

 

[SimonM]

All checked out, it’s nowt to do with anything I’ve done/undone or whatever.

As suggested above I looked at the main habitation supply fuses, there’s a biggy at 50a and by its side a 2amp.

I pulled the 2amp, looked at it, it’s fine, pondered a bit and scraped the blades with a penknife to make them shine. I replaced it and the gauge is showing 13+ volts as it always used to. So it appears 1.5v we’re being lost to the corrosion.

It’s something to bear in mind if voltages seem a bit low

 

[SimonM]

I’ll post this as a continuation albeit 4 months later As I have another similar issue

we’ve been away for a month wilding in the mountains of Switzerland and Italy with no problems, so this isn’t as a need to cure something. We have moved almost every day and so solar has been backed up with the engines alternator output.

my battery monitor consistently will be showing 105% after travelling, or a full days sunshine from the 2 solar panels. Then, as we use power in the evening, TV and LED lights, so the amount of charge left the next morning is obviously lower 80/85% being quite common. I’m happy with that for my 4x90ah batteries. Then if we drive away or simply leave it in the sun the monitor will soon be showing full once again.

All’s OK it would seem, until I got home again and left it unattended outside the house. I’ve been doing some work inside after our time away getting it all shipshape and tidying up other odds and ends prior to doing a full service on engine and brakes next week.

I’ve noticed The battery monitor regularly shows a discharge when there’s no sun e.g. at night, which is offset during the day when the sun is doing its stuff. It’s generally shows 0.4a discharge.

there is nothing switched on though. I have actually unwired everything and then circuit by circuit I have checked for any drop using my circuit tester. No circuit is giving any use at all bar one. I’ve also eliminated the solar panels from any back drain.

The only possible circuit with any use is where the habitation batteries power the radio - maybe it also powers the alarm, but I’d thought that won’t be active until its actually working? Can a passive radio draw that much power, I assumed it would be milliamps?

If I didn’t look at the monitor then I would never have seen a ‘problem’, maybe I don’t actually have one

any thoughts?

 

[Admin]

I’ll post this as a continuation albeit 4 months later As I have another similar issue

we’ve been away for a month wilding in the mountains of Switzerland and Italy with no problems, so this isn’t as a need to cure something. We have moved almost every day and so solar has been backed up with the engines alternator output.

my battery monitor consistently will be showing 105% after travelling, or a full days sunshine from the 2 solar panels. Then, as we use power in the evening, TV and LED lights, so the amount of charge left the next morning is obviously lower 80/85% being quite common. I’m happy with that for my 4x90ah batteries. Then if we drive away or simply leave it in the sun the monitor will soon be showing full once again.

All’s OK it would seem, until I got home again and left it unattended outside the house. I’ve been doing some work inside after our time away getting it all shipshape and tidying up other odds and ends prior to doing a full service on engine and brakes next week.

I’ve noticed The battery monitor regularly shows a discharge when there’s no sun e.g. at night, which is offset during the day when the sun is doing its stuff. It’s generally shows 0.4a discharge.

there is nothing switched on though. I have actually unwired everything and then circuit by circuit I have checked for any drop using my circuit tester. No circuit is giving any use at all bar one. I’ve also eliminated the solar panels from any back drain.

The only possible circuit with any use is where the habitation batteries power the radio - maybe it also powers the alarm, but I’d thought that won’t be active until its actually working? Can a passive radio draw that much power, I assumed it would be milliamps?

If I didn’t look at the monitor then I would never have seen a ‘problem’, maybe I don’t actually have one

any thoughts?

I would disconnect the negative cables from the shunt (not the battery side) and make sure that the monitor reads zero.
If it does then you can reconnect and start to remove each habitation fuse until you work out which circuit is taking the power.
Leave that fuse out and then work out what is no longer powered in the van.

Phil