Voltage drop. (1 Viewer)

Ukbandit

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Just a quick one, a friend with Moho is having problems with the leisure voltage dropping while driving, he’s running his fridge on 12v whilst travelling, he’s been told that’s normal and he should travel with fridge on gas, which seems strange to me
So this morning his battery was showing 13.5v before setting for a 2 hour run, when he got to his destination the battery was showing 12.7v, surely not right.
Any thoughts guy’s.
 
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DBK

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Running the fridge on 12v is normal when driving as the power will be coming from the alternator.

It sounds as if the charging system is not working. I suspect the MH has solar power which explains the 13.2v at the start of the journey.

If you can give a few more details, such as make and year of the MH it would help. :)
 
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Ukbandit

Ukbandit

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Running the fridge on 12v is normal when driving as the power will be coming from the alternator.

It sounds as if the charging system is not working. I suspect the MH has solar power which explains the 13.2v at the start of the journey.

If you can give a few more details, such as make and year of the MH it would help. :)
It’s a 2018 Dethleffs trend with a solar panel
 
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Sep 3, 2012
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I thought that the 12.7 voltage was normal and that the 13.2 is only showing when on charge, ie solar panel charging etc.
I would be more concerned if it had dropped below 12.7v when a destination had been reached. Assuming he has not got a b2b alternator
Wil check ours out after we reach the Yorkshire meet tomorrow currently on ehu, fully charged on the drive but we will be running with fridge on battery for the journey, approx 2 hrs or so, traffic permitting. Lol
 

TheBig1

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I have seen that happen when the fuse to the split charge and fridge relay fails. the relays energise allowing the fridge to draw charge from the leisure battery and not the alternator/van battery

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Ukbandit

Ukbandit

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I thought that the 12.7 voltage was normal and that the 13.2 is only showing when on charge, ie solar panel charging etc.
I would be more concerned if it had dropped below 12.7v when a destination had been reached. Assuming he has not got a b2b alternator
Wil check ours out after we reach the Yorkshire meet tomorrow currently on ehu, fully charged on the drive but we will be running with fridge on battery for the journey, approx 2 hrs or so, traffic permitting. Lol
Thanks Jim
 
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I have seen that happen when the fuse to the split charge and fridge relay fails. the relays energise allowing the fridge to draw charge from the leisure battery and not the alternator/van battery
I have also had this happen to me. In my case a loose connection rather than a fuse but result the same, relay closes but no output from the alternator so it just runs from the leisure battery.
 

pappajohn

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I have seen that happen when the fuse to the split charge and fridge relay fails. the relays energise allowing the fridge to draw charge from the leisure battery and not the alternator/van battery

I have also had this happen to me. In my case a loose connection rather than a fuse but result the same, relay closes but no output from the alternator so it just runs from the leisure battery.

Is this some modern witchcraft?

Every van I've own has had two completely separate relays... One for the fridge and one for the split charge.
The only common connection is the connection at the engine battery and if a fuse blows even that connection is broken.
 
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TheBig1

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Is this some modern witchcraft?

Every van I've own has had two completely separate relays... One for the fridge and one for the split charge.
The only common connection is the connection at the engine battery and if a fuse blows even that connection is broken.
Not if you think about it John. with both relays energised and if as is standard the converter takes one fused line from the engine battery to power both relays. the leisure battery feeds through the charging relay and back through the fridge relay if the fuse fails or a wire fault. many vans also have a single 2 pole relay to charge battery and power fridge, fed by a single feed wire

modern witchcraft? no physics
 
Sep 3, 2012
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Checked out our battery voltage, when we set off after fully charged on who,it was 13.5v,driving for 2 plus hrs with fridge on battery ,when we parked up was actually 13.6v ,so alternator keeping up with fridge being on.
Looks like your friend ,@Ukbandit, does have an issue. Running a fridge on gas whilst driving is not recommended though and doesn't solve his problem.
 
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On 3rd van so not a total newbie....
The fridge should be running off the cab battery not the hab battery surely?
 

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