# New Bosch vehicle battery fitted, battery now flat again.



## delboy0127 (Mar 3, 2009)

Hi everyone

Motorhome kept in storage
Had a problem over winter visited Motorhome approx every 2 weeks to run engine through winter last year, each time battery was almost flat. Charged battery would last approx 2 weeks then flat again.

Mercedes vehicle battery just 3 years old. had my doubts but decided to bite the bullet and buy and fit a new Bosch battery from Halfords at a cost of £129.

Yes you have guessed correct new battery now going flat, after just 2 weeks standing. So something is draining it.

I have towing plugs fitted including a grey plug fitted with relay that is used to charge the trailer battery the Smart Car trailer has a mover fitted.

Other than that I have checked the light to the glove compartment that goes off okay, no alarm fitted other than the standard Mercedes alarm fitted to the Sprinter chassis.

Any suggestions please I have a meter not to certain how to use to test if anything is draining the battery

Take care

Delboy


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## zulurita (May 9, 2005)

Modern vehicles have too much on board that drain the vehicle battery eg Fiat has Canbus, radio etc.

The only solution is to hook up to electric or if that isn't possible to have a solar panel fitted which charges the leisure battery and a battery master that enables a trickle charge to the vehicle battery.

I have found mine to be ok with this set up through winter aor not used for 4 or 5 weeks.

My car has the same problem as on our first trip away we came back to find the car wouldn't start. Never had this problem with my old car!

Chap at Honda suggested a motorcycle trickle charger as this is low amp etc and stops charging when the battery is fully charged. I have yet to use this but obviously you would need electric for this.

There are other battery to battery chargers C-tek being one of the good ones I believe.


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## javea (Jun 8, 2007)

There must be something draining the battery. My Fiat base is stored under cover and does not have any external charging whilst it is there.

Go to it about every 5/6 weeks and whilst the leisure batteries might be down a bit the vehicle battery is always fine. It has a Strikeback alarm fitted which is activated.

Suggest an auto-electrician who will be able to attach diagnostics to it and find out where the problem lies.


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## inkey-2008 (May 24, 2008)

If you don't have an alarm remove the earth clamp from the battery. I do this on my car over winter always started first time when i recnnect.

Andy


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## Stanner (Aug 17, 2006)

Regardless of whether you have anything draining it or not, just going to visit and running the engine for a while will not charge the battery enough to put back in what starting up has taken out it.

I've read somewhere that around a hour of running is needed to recharge fully after a cold start. If the battery was well down before the start, even longer is needed.


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## lufc (Jun 24, 2007)

I had a similar problem with my FIAT Ducato based van, allegedly it ws a faulty key which was continually sending signal to the van, so they said anyway.


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## raynipper (Aug 4, 2008)

This problem crops up about twice a month on this forum. Do a search and you will find so many others have the same problem.

It's either find the 'drain' which is likely to be the radio or alarm.
Disconnect the battery when in store.
Fit some charging equipment or solar.

Ray.


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## spatz1 (May 19, 2011)

you say you have a meter....

set it on amps and swap the test probes to appropriate contacts on the meter.... simply disconect a terminal off the battery and put one probe on the battery and one on the lead you ve taken off...

the display should read nothing if there s no drain and if it reads anything else you need to start looking for what is drawing the current....


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## delboy0127 (Mar 3, 2009)

*Battery Drain*

Hi everyone

Just an update.

I removed negative lead and used a multimeter to test for drain between lead and battery terminal, I found a reading of .86 so it appears something is draining the battery. I do not know how significant this reading is.

I have now took the vehicle into Mercedes commercial who have said they will put it on their Star System. have left vehicle with them they will do it a.s.a.p.

So hopefully they may have an answer in a day or to.

Thanks for all advice

Delboy


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## ched999uk (Jan 31, 2011)

I am guessing 0.86 is 0.86 amps. If so that's almost an amp, which is quite a bit. If you think that your starter battery is about 80-100amphr. Then you battery would be flat in about 5 days!!!!. 

I am sure that the main dealers will work it out. Normally after you identify that you have something drawing current. You pull fuses 1 by 1 and see when the current draw stops. When it stops you have found the fuse that the current draw is coming from. Then you find out what is connected to the fuse and look at each device and hope to find the faulty one.

Good luck and let us know what the fault was in case any other people get the same issue.


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