Fiat battery query

[BusyBuilder]

Our Hymer has new Fogstar/Victron and 250w solar set up and battery master. I've not used the van for about 8 weeks and been to check all is okay this morning.

the Fogstar shows 308amp but the Fiat battery is down at 12.2v but I thought the battery master kept the Fiat battery topped up ?

 

[carolyn]

The experts will want to know the voltage of your Fogstar battery plus all sorts of other info. The battery master needs a 0.5v difference to drip charge your engine battery.

We gave ourselves a nervous breakdown when we started seeing voltages of 12.2v on our engine battery via the moving intelligence app last month but with a multi meter it was more like 12.5 .

We are off to Offgrid Power Solutions tomorrow to enable us to monitor our stuff accurately and remotely.
People like Lenny HB Raul will hopefully help you

 

[fishplug]

My understanding with the Battery Master is that it will charge the leisure batteries first and once they're full then any excess charge will get diverted to the vehicle battery.

So, (yes carolyn was right ) How many Ah is your Fogstar? Where are you getting the 308A reading (Fogstar app, Victron shunt, Mystic Meg?) Also what is your MPPT (presumably the Victron in this equation) saying about Bulk/Absorbtion/Float?

Finally, do you have any other loads permanently on and is the vehicle parked somewhere where it might get some of the ten minutes of available solar in a UK winter (and are the panels covered in snow, ice, dust, squirrels. or fruit pastilles?)

 

[headlight]

My understanding with the Battery Master is that it will charge the leisure batteries first and once they're full then any excess charge will get diverted to the vehicle battery.

So, (yes carolyn was right ) How many Ah is your Fogstar? Where are you getting the 308A reading (Fogstar app, Victron shunt, Mystic Meg?) Also what is your MPPT (presumably the Victron in this equation) saying about Bulk/Absorbtion/Float?

Finally, do you have any other loads permanently on and is the vehicle parked somewhere where it might get some of the ten minutes of available solar in a UK winter (and are the panels covered in snow, ice, dust, squirrels. or fruit pastilles?)

The Battery Master does not charge the leisure batteries at all.
It trickle charges the starter battery from the leisure battery at 1 amp when it senses that the starter battery voltage is 0.75v lower than the leisure battery voltage.

 

[fishplug]

I've never had one, so thank you for the clarification.

Bottom line is that there are certain voltage criteria that need to be met between the two battery banks before charging will occur.

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[TrudeandDall]

Our Hymer has new Fogstar/Victron and 250w solar set up and battery master. I've not used the van for about 8 weeks and been to check all is okay this morning.

the Fogstar shows 308amp but the Fiat battery is down at 12.2v but I thought the battery master kept the Fiat battery topped up ?

You are a long way north for the solar to deliver much over the last 8 weeks - even in good sunlight my 280w solar in Cumbria, managed 1.5 amps at best. Most of the time it was "nowt".
12.2v for a AGM starter battery is approx 60% SOC, so you are still in the safe zone. Its best to check the starter voltage by Bluetooth before you open the doors, or wait for a while after opening the door, as using door unlocking will reduce the starter battery for a short while.
As already mentioned it is the voltage of the leisure battery that is important and do not expect the stater battery to be any higher than 0.75v less than the leisure battery when using the battery master or similar kit....

 

[Raul]

As already mentioned the battery master works on voltage, based on the leisure battery. Some ppl switched to abelmail for this reason. When you have low solar harvest the leisure battery does not have high enough voltage to charge the starter. The abelmail is programable, and you can choose a different value for it to kick in. Battery master is fixed, and for some reason I thought it was 0.6v the difference, to kick in. But, I could be wrong.
If its a smart alternator involved, the 12.2v for the starter its quite ok.

 

[carolyn]

As already mentioned the battery master works on voltage, based on the leisure battery. Some ppl switched to abelmail for this reason. When you have low solar harvest the leisure battery does not have high enough voltage to charge the starter. The abelmail is programable, and you can choose a different value for it to kick in. Battery master is fixed, and for some reason I thought it was 0.6v the difference, to kick in. But, I could be wrong.
If its a smart alternator involved, the 12.2v for the starter its quite ok.

According to the Offgrid website it’s 0.5v. I will ask tomorrow!

 

[BusyBuilder]

Thanks, I got the wife to start the van, it went on third attempt, my Fogstar is 280amp but shows 308amp. I'll check again tomorrow to see the voltages. I'll put it on EHU for a while. Can't see us using the Hymer for a while as we have had bronchitis and not on top form atm. Then we're off cruising in the far east mid March. So could be another 12 weeks yet.