Sudden Vehicle Battery Drain

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Bibbers

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Oct 12, 2021
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Swift Bolero 2013
Hi
Out of the blue today the vehicle battery on my Swift Bolero was pretty much flat for no apparent reason. We have been relying on our solar panel for the last 4 days as we are on a non electric site and it has never happened before. Our leisure battery is fine and fully charged.
We have been traveling around Europe for the last month doing well over 2000 miles, on and off grid with no issues at all.
Any help would be much appreciated
Cheers
 
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How old is the battery as it may just be at the end of it's life.
Did it recharge OK, if not it could be an OC cell.
 
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Bibbers said:
Hi
Out of the blue today the vehicle battery on my Swift Bolero was pretty much flat for no apparent reason. We have been relying on our solar panel for the last 4 days as we are on a non electric site and it has never happened before. Our leisure battery is fine and fully charged.
We have been traveling around Europe for the last month doing well over 2000 miles, on and off grid with no issues at all.
Any help would be much appreciated
Cheers
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We had something similar at home a couple of weeks ago- alerted by CO alarm going off. The vehicle battery appeared to charge from EHU, but wouldn’t hold a charge at all and wouldn’t turn the engine over. Our vehicle battery had been totally reliable until then.

How old is the battery? Does it feel warm? I’m not remotely technical, but it could be your battery is knackered? Sorry to be bringer of possibly bad news. I’m sure someone will be along with more helpful suggestions soon.
 
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Lenny HB said:
How old is the battery as it may just be at the end of it's life.
Did it recharge OK, if not it could be an OC cell.
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The battery is only about 2 years old so it should still be ok yet. I started the engine with one of the little starter packs (life savers) and got the revs going for a good while. Showing 12.2 volts this morning and it started no problem. Just have to see how it goes later this week and hope it was a one off.

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GeoffnDee said:
Is it flat or could it be a poor connection ?
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It was just low voltage on the vehicle battery and not the leisure one for some reason. Not sure what drained some charge out of it.
Like I said to Lenny HB I'm just going to hope it was a one off. If not I will have to dig deeper.
 
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sounds like you have inadvertently switched the power source to the vehicle battery and not the leisure battery. And 12.2v on the engine battery is near enough flat still. A full battery at rest should read 12.8v fully charged. If you have allowed the vehicle battery to drop so low a few times, it prematurely ages the battery and it dies suddenly
 
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David and Sally said:
Is something like a radio draining it if you are not on ehu?
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That did cross my mind but I'm sure it shuts off after a set time for that reason. I was wondering if one of the grandkids may have knocked the interior light on or something like that.
It hasn't been an issue since the new battery was fitted a couple of years ago.

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Any chance you could have been running the habitation side off the vehicle battery?

Jev88 beat me to it
 
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TheBig1 said:
sounds like you have inadvertently switched the power source to the vehicle battery and not the leisure battery. And 12.2v on the engine battery is near enough flat still. A full battery at rest should read 12.8v fully charged. If you have allowed the vehicle battery to drop so low a few times, it prematurely ages the battery and it dies suddenly
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I have a solar panel fitted and was under the impression it looked after both batteries. I have a quick check now and again the voltage screen on the Sergeant box and again and both batteries always seem well charged.
That's why I was puzzled as we do non electric quite a bit.
 
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Bibbers said:
I have a solar panel fitted and was under the impression it looked after both batteries. I have a quick check now and again the voltage screen on the Sergeant box and again and both batteries always seem well charged.
That's why I was puzzled as we do non electric quite a bit.
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If you inadvertently switch to using the vehicle battery, combined with starting the solar is unlikely to keep up. Generally the vehicle only gets trickle charged at about 10% of the solar output. The rest goes to the leisure battery

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TheBig1 said:
If you inadvertently switch to using the vehicle battery, combined with starting the solar is unlikely to keep up. Generally the vehicle only gets trickle charged at about 10% of the solar output. The rest goes to the leisure battery
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Would this be done on the control panel. Despite having the van 5 years this is all new to me ??
 
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TheBig1 said:
It is usually a switch on the control panel
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Would me pressing the 'vehicle battery' symbol for example transfer the solar input to the vehicle battery ?

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Bibbers said:
It was steady at 12.7 yesterday after I reved the engine for a while and turned it off
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That is not the state of charge, that is the charging voltage, which should be over 13 volts, usually 13.8. Then when you switch off, the battery settles down to it's state of charge after 10 or more minutes
 
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Bibbers said:
Would me pressing the 'vehicle battery' symbol for example transfer the solar input to the vehicle battery ?
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No but everything in the back will be run of the engine battery
 
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Forgot to say, on some older systems the mains charger can be switched to charge the engine battery and using that battery when plugged in
 
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Bibbers said:
It was steady at 12.7 yesterday after I reved the engine for a while and turned it off
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You need to get it fully charged to see its real state, at that state of charge it would take several hours driving to fully charge it.
 
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TheBig1 said:
That is not the state of charge, that is the charging voltage, which should be over 13 volts, usually 13.8. Then when you switch off, the battery settles down to it's state of charge after 10 or more minutes
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I did check when the engine was running and it was as you say 13.8 but it settled down to 12.7 but was 12.2 this morning.
I'm a retired gas engineer, never was great with electrics as you can obviously see

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Your battery needs a full charge on mains, 24 hours or more ideally
 
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Lenny HB said:
You need to get it fully charged to see its real state, at that state of charge it would take several hours driving to fully charge it.
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I've just driven to Switzerland and back, that should have been far enough 😂.
We were on non electric on 8 or 9 stops with no issues. It's wired how it's just started now 🤔
 
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Bibbers said:
I've just driven to Switzerland and back, that should have been far enough 😂.
We were on non electric on 8 or 9 stops with no issues. It's wired how it's just started now 🤔
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Wired not wired obviously 🙄
 
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The way an alternator charges a battery is slightly confusing as it will push 40 amps soon after you start up then reduce the charge current minutes later. So although you top up the starting charge taken, if you have a constant draw it wont keep up. This is why car batteries often struggle in winter/bad weather and at night due to other loads not taken care of fully by the alternator. If the regulator on the alternator is aging or failing it will produce even less
 
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