# Flat Cab Battery



## swanny65 (Sep 12, 2014)

Hi
I have forgotten to switch my motorhome's charger to charge the cab battery when on my electric hook up at home. I noticed this when I went to open the motorhome at the weekend. On checking the control panel the cab battery was read 5.2v. On checking with a multimeter it read 5.4v. 

I last charged the cab battery when I had ran the engine for 20 minutes when i drained down the motorhome in mid / late November - last used the motorhome for October half term having bought the motorhome Sept this year. 

I had to disconnect the battery's earth lead as the alarm was blipping when I tried to smart charge the battery with the earth connected. I have had the smart charger on the battery for 48 hours. The battery now reads 8.2v. The smart charger had automatically switched to 2A for charging. 

Has the battery died? Should i continue to smart charge (was 48 hours long enough) it or jump start and see if the battery holds a charge when i charge via the electric hook up at home.

Any advice appreciated


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## 747 (Oct 2, 2009)

Some smart chargers have a 'Pulse charge' function which is claimed to resurrect batteries. It might work but it looks like you might need a new battery. Don't give up just yet though.


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## Sideways86 (Feb 25, 2009)

as the OP has said my Ctek would take 72hrs in auto mode to recover a dead battery


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## swanny65 (Sep 12, 2014)

Update after approx 96hrs on charge the cab battery read 10.3v on my multimeter. 

When I briefly connected the battery's earth the reading dropped to 8.8v (7.5 on the motorhome control panel). 

It appears to be charging but slowly.


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## 747 (Oct 2, 2009)

Aldi are selling a charger this week for about £14. They are a decent little charger and have multi functions, including pules charging.


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## listerdiesel (Aug 3, 2012)

Battery is dead, give a decent burial and buy a new one.

Very few batteries will come back from less than 6volts, and to get any charge through a sulphated battery you need high voltage and constant current charging, none of which you will get with any commercial chargers.

Read the Last Rites anf flash the plastic.

Fit a low battery cutoff.

Peter


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## Zebedee (Oct 3, 2007)

Agree with Peter.

Say thanks for the advice you didn't want to hear and prise open the wallet. Your battery is well and truly stuffed.  

Dave


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## blackbirdbiker (Mar 12, 2007)

And don't forget to take your old battery to the local scrap dealer...you may get £10 + for it...
KeithðŸ˜‰


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## swanny65 (Sep 12, 2014)

Thanks for the advice. 

Will replace shortly, if nothing else for piece of mind as we intend to have 3 weeks in France this summer with at least 10 days using Aire's. 

From now on i will keep both batteries on charge all the time.


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## nicholsong (May 26, 2009)

swanny65 said:


> From now on i will keep both batteries on charge all the time.


Very wise. I would never run a charging system in a mode that did not charge the vehicle battery - after all if the domestic batteries are the vehicle battery is the one that you need for the solution(charging/new batteries or whatever) for the others.

Geoff


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## Zebedee (Oct 3, 2007)

> nicholsong said:- Very wise. I would never run a charging system in a mode that did not charge the vehicle battery.


Agreed in principle Geoff. If you can't start the van you could be deep in the mire!

There is an easy alternative (_which I use_) if you don't have a system which will charge both batteries at once.

Mine will chage "_either/or_" but not both at the same time, so I set it to charge the vehicle battery for most of the time. Every couple of weeks I switch over for a few days to keep the habitation battery topped up, then switch back to the vehicle battery again.

This seems to work fine, as the hab battery hardly loses any charge when not in use, whereas the vehicle battery has to keep the alarm running, plus various other components which place a continual drain upon it.

Hope this helps Swanny to avoid future discharges of the wallet!! 

Dave


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## nicholsong (May 26, 2009)

Dave

I am surprised that there are systems which have to manually be selected from one battery to another.

For my education, is there a reason for this and some advantage in that system?

I have an Elektroblok which charges both sets of batteries, a Sterling B2B which really pumps into the hab batteries from the alternator and a solar panel which is controlled to give priority to the vehicle battery for when we are static - we wild camp. Then EHU at home because the solar is undercover.

This way I feel I have got most charging covered, but especially the vehicle battery as priority. I actually cannot find out how old it is but I have had it for 5 years and it still holds up at 12.5v, hours after coming off charge, so seems OK, but maybe that is because I have always carefully monitored it.

I reckon that ensuring that one has water, gas and electricity all topped-up gives onr the freedom to go just where you want and to park-up when you feel like it without having to search for somewhere - CRY FREEDOM!( acknowledgement to Donald Woods)

Geoff


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## Zebedee (Oct 3, 2007)

> nicholsong said:- I am surprised that there are systems which have to manually be selected from one battery to another.
> For my education, is there a reason for this and some advantage in that system?


Pass! :roll:

We have a Sargent EC325 charger in our van. Very common in British made vans, and seems very reliable, but it charges only one battery at a time when on hookup.

If there is a specific reason for this, I would guess it is so you can select which battery you want to use in the hab area. Not that I would ever choose to use the vehicle battery for hab functions, but the option is there for emergencies.

Download the User Instructions from >> here << if you are interested. They are very comprehensive.

Dave


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## cabby (May 14, 2005)

I have set up mine so that the alternator charges both, the hook up also charges both, but I have a manual switch for the solar input to vehicle or habitation.

cabby


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## rosalan (Aug 24, 2009)

As the last few suggest, there could be a problem or a simple solution to your battery issue.
Your model may have a built in facility for charging all of the batteries at the same time, which is worth checking, if not there are several devices on the market to make it so. Battery Master from Van Bitz is a well known solution. Its three wires are connected up and from there on you can more or less forget the van battery when on Hook-up, for it will be looked after.
Many people take on the next step and acquire a solar panel that eliminates the need for a hook-up for most of the year.
Finally, I am curious as to what equipment has been running to flatten your battery. Radios, security and Trackers can all help drain the van battery, a situation that may not be relieved by buying a new battery if there is no link to keep it charged.

Alan


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## listerdiesel (Aug 3, 2012)

We've fitted a separate charger for the van electrics on the Mercedes, mainly as we have nothing to start with and it's 24V.

24V 10A power supply on ebay for under £30, completely independent of everything else and we can run the mains side from the hab inverter if we need to charge the 24V side.

12V 26A PSU's are about the same money, set them for 13.60V and forget them.

Peter


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## swanny65 (Sep 12, 2014)

Thank you all very much for your help and advice. As an ex-caravanner I thought I had most of the likely problems covered!!! 

Good news, rang the dealer today to tell them the battery was dead. Without even asking was told to get it to them asap and they will do a like for like swap free of charge. 

Great result. Excellent service.

In the short term I will probably use my home EHU to charge the leisure battery and smart charge the cab battery off a 240v socket in the vehicle. I just need to work out how to run the cables to the cab battery. 

Thank you all again


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## cabby (May 14, 2005)

How long have you had the van and did the battery come with it, or did you buy a battery from the dealer.
If a case of just good after service then we should be told of such a responsible dealer for our delectation. :? :? 
OK we just need to know who it is with such a good response to your problem. we like using them as well.they deserve it.


cabby


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## swanny65 (Sep 12, 2014)

The battery was on the motorhome when we bought it 3 months ago.

Dealer is - Simpsons Motorhomes of Gt Yarmouth

Not our first little problem. On first trip away water pump failed and they drove to the site to fit a replacement.


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## cabby (May 14, 2005)

Well they will have to go on the dealer awards list for 2015 then.

cabby


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