Idiot guide to battery monitoring required!

[roadtripper]

Just spoke with the converter and he said the Dometic fridge is wired to the leisure battery and permanently on. I can turn the switch off inside the fridge and it will turn off the compressor but the light stays on unless I pull the fuse on PMS3. The habitation lights work with the charger off and switched to ‘van’
Yes, I have a water pump which again works with charger off but switch set to ‘van’

So I would just leave the battery switch on "van" and leave the charger on. That way all your 12v habitation is coming from the leisure battery and when you have EHU most of it will be coming from the PMS3.

Your biggest load is the fridge so get in the habit of turning that off when not actively camping now you know where the switch is.

 

[Garyf123]

So I would just leave the battery switch on "van" and leave the charger on. That way all your 12v habitation is coming from the leisure battery and when you have EHU most of it will be coming from the PMS3.

Your biggest load is the fridge so get in the habit of turning that off when not actively camping now you know where the switch is.

Thank you for taking the time and effort to look into this for me, I really appreciate it! Not sure how much the BM6 will help me now knowing that with all the ‘clever electrics’ involved with smart alternators etc makes them produce incorrect readings!

 

[roadtripper]

Which battery do you have the BM6 on?

 

[Garyf123]

Which battery do you have the BM6 on?

The starter battery

 

[roadtripper]

If you have the start stop system then the van will try and hold the battery at about 80%, this allows it to rapid charge the battery during braking, essentially recovering energy. You can see higher than normal voltages at these points.

You'll probably find the battery is an AGM type to deal with this charging style so if there are settings in the BM6 for type of battery try that.

I expect the BM6 will settle down over a few days. If it does keep showing low charge or draining charge then you might want to investigate if the battery selector switch is correct but I wouldn't panic now, just try and get a good couple of drives in.

 

[Garyf123]

If you have the start stop system then the van will try and hold the battery at about 80%, this allows it to rapid charge the battery during braking, essentially recovering energy. You can see higher than normal voltages at these points.

You'll probably find the battery is an AGM type to deal with this charging style so if there are settings in the BM6 for type of battery try that.

I expect the BM6 will settle down over a few days. If it does keep showing low charge or draining charge then you might want to investigate if the battery selector switch is correct but I wouldn't panic now, just try and get a good couple of drives in.

Ok, thank you!

 

[Stay Frosty]

Despite being an ex electrician I find the "KISS" method works here with a Renogy shunt and display showing what's actually going into the leisure battery and what's going out.
It can be disappointing when there's only a few amps shown going in from the solar on the roof but that's on top of what the Waeco fridge is drawing and by the same token it's then great to see that the battery has gone back to full charge while you've left it parked for the day when out.
A constant blizzard of information confuses the longer term general trend of charging performance, well in my case it does.

 

[Farnorthsurfer]

Despite being an ex electrician I find the "KISS" method works here with a Renogy shunt and display showing what's actually going into the leisure battery and what's going out.
It can be disappointing when there's only a few amps shown going in from the solar on the roof but that's on top of what the Waeco fridge is drawing and by the same token it's then great to see that the battery has gone back to full charge while you've left it parked for the day when out.
A constant blizzard of information confuses the longer term general trend of charging performance, well in my case it does.

Couldn't agree more. Lots of people choose to have switch panels and gauges that wouldn't disgrace the space shuttle but in fact a simple voltmeter gives most of the information required, especially if its an AGM leisure battery. I have the Victron Smartshunt which I read through the phone app. However I mostly just check out the voltmeter day to day.

 

[Sim60]

And this!

View attachment 210691

What battery type do you have the BM set for - I wouldn’t expect it to read 32% SOC at 12.44V On an AGM battery.

( the BM6 is only ‘guessing’ the SOC directly from the voltage it reads - there is no actual measurement of charge stored in the battery like there is with a shunt)

Simon