Flat Batteries on my Motorhome

centerman

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Hi All I made a mistake and left my refrigerator on 12volt when I moved it of the drive were it is normally hooked up to mains whilst work on our drive and kitchen was being undertaken . All work now completed but when went to start it was all dead all batteries now showing only 6.5. This is probably caused with fridge.

But as I have a good battery bank with 3 x 135AH + Cab battery and there is 2 x 85 solar panels on roof I thought these would be enough to keep up the batteries charge with fridge on, was I badly wrong. 3 batteries are showing 6.5 only and engine one is also flat will these be dead now they were replaced 8month ago expensive mistake if they are.

Brian
 

trevskoda

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If only a day or so try and recharge, but may now be well past their best if lucky, your solar set up is very small for 3 batts, should be more like 400w
 

Robmac

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I would put them on a smart charger if you have one and see how it goes.

It's never good to fully discharge batteries but I have had them recover before now. Good luck.
 

centerman

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If only a day or so try and recharge, but may now be well past their best if lucky, your solar set up is very small for 3 batts, should be more like 400w
Thanks for that did not know the solar panels would be too small. also reading the AGM batteries may mean my charger is incorrect type won't fully charge so will contact Sargent who supply there charger on my Swift Kontika 645 as standard. Bur do you recon it was the fridge that has caused main problem?Cheers
 

centerman

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I would put them on a smart charger if you have one and see how it goes.

It's never good to fully discharge batteries but I have had them recover before now. Good luck.
Thanks have one on charge to see how it goes do you recon it was fridge that flattened it all?
 

Robmac

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Thanks for that did not know the solar panels would be too small. also reading the AGM batteries may mean my charger is incorrect type won't fully charge so will contact Sargent who supply there charger on my Swift Kontika 645 as standard. Bur do you recon it was the fridge that has caused main problem?Cheers

How long was the fridge left on for?
 

trevskoda

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May be an alarm or something else like the brain if it has one, I have seen vans that will run 12v without the donkey running.
Make sure you use a smart pulse charger.
 

wildebus

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The Dometic three-way fridge freezer in my van can be operated on 12v even without the engine running.
is that due to some setup with solar/battery level to use otherwise wasted energy? With most vans it is not down to the fridge itself but the way the motorhome was wired I would say. i.e. with my Autotrail, the 12V supply will only ever be live when the engine is running as goes through a D+ controlled relay. Wouldn't matter what fridge was at the other end.
 

Phantom

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The fridge shouldn't be drawing from the starter battery except via the engine running. Hopefully all batteries will charge back up then check that solar is charging LB and SB okay. Check how fridge is wired as it should have triggered a low voltage cut off.
 

Admin

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is that due to some setup with solar/battery level to use otherwise wasted energy? With most vans it is not down to the fridge itself but the way the motorhome was wired I would say. i.e. with my Autotrail, the 12V supply will only ever be live when the engine is running as goes through a D+ controlled relay. Wouldn't matter what fridge was at the other end.
You can choose Auto, 240V, Gas, 12V. On Auto it auto switches.
 

wildebus

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You can choose Auto, 240V, Gas, 12V. On Auto it auto switches.
but if 12V is not active (such as when the engine is not running, which is the case in the majority of motorhomes surely), the Auto will never find 12V to switch TO, and will switch FROM 12V once engine stopped?
Your Hymer must be wired different from the norm (may be normal for Hymer though, of course :) )
 

colinm

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The fridge shouldn't be drawing from the starter battery except via the engine running. Hopefully all batteries will charge back up then check that solar is charging LB and SB okay. Check how fridge is wired as it should have triggered a low voltage cut off.
As this, the starter battery should be separate from the leisure batteries.
When we had a 12v fridge we had a low volt cut off which would trigger if the solar couldn't keep up.
 

Admin

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but if 12V is not active (such as when the engine is not running, which is the case in the majority of motorhomes surely), the Auto will never find 12V to switch TO, and will switch FROM 12V once engine stopped?
Your Hymer must be wired different from the norm (may be normal for Hymer though, of course :) )

AES (auto switching fridges) have a permanent 12v supply otherwise they could not work.
Most modern motorhomes fitted with an EBL and Dometic Fridge will do the same thing. If they are manually switched to 12v they will use the leisure battery to power them. If they are on Auto mode they will not switch without a D+ signal.
 

wildebus

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AES (auto switching fridges) have a permanent 12v supply otherwise they could not work.
Most modern motorhomes fitted with an EBL and Dometic Fridge will do the same thing. If they are manually switched to 12v they will use the leisure battery to power them. If they are on Auto mode they will not switch without a D+ signal.
I think we are not talking about the same thing. Obviously AES fridges have a 12V permenant supply for the electronics. that is a completely different circuit to the 12V circuit for cooling. My Thetford was an AES type fridge so did indeed have a permanent 12V, but the 12V supply for 12V running was only live with the engine. wouldn't matter what you did with the manual overrides. Selected 12V manually and you would get an error if the engine was off.

An EBL is a branded product used by certain makes of Motorhome. you will not find one in a British Motorhome.
Sorry, Phil, I just don't agree with how you are describing how the fridge typically works on 12V when using Auto or Direct 12V selection (the permanent 12V bit is a red herring).
Maybe on Hymers, but maybe not on other brands - if the 12V "cooling supply" is only present by the fridge when the engine is running, then it doesn't matter if the fridge can 'override' the D+ by manually selecting 12V, the supply will still not be there to be used. (I am pretty sure the Sargent systems commonly found on British Motorhomes still operate this way).
 

Admin

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Sorry, Phil, I just don't agree with how you are describing how the fridge typically works on 12V when using Auto or Direct 12V selection (the permanent 12V bit is a red herring).

I replied to this quote that states "Assuming it's a three way fridge it will only operate on 12 volts whilst the engine is running."

Assuming it's a three way fridge it will only operate on 12 volts whilst the engine is running.

If that's the case your problem lies elsewhere...

This is incorrect as my Hymer will operate the fridge on 12v whilst the engine is not running. This is the standard Hymer wiring.

I stated you will find that other vehicles with an EBL and Dometic fridge will do the same. I never mentioned British motorhomes and I never mentioned Sargent control units.

On an Electrobloc installation, the D+ and 20A feed from the starter battery are connected to the EBL unit not directly to the fridge. The EBL then sends D+ 12v+ and 12v- to the fridge. The EBL has an internal relay that when the D+ is off the 20A feed is supplied by the leisure batteries and is only switched to the starter battery (by the EBL) when the D+ is on. The fridge has 20A always. The Dometic fridge freezer that I have (and is fitted to many post-2012 motorhomes) can be wired so that it can be AUTO or forced into 12v, 240v or GAS.

I am going to bow out of this debate now.
 

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