Mice in the Campervan and flat batteries - a connection?

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Full Member
Sep 27, 2005
Oxfordshire and Pyrenees-Orientales, France
Lack of use over Covid lockdowns has resulted in flat batteries in the campervan. I successfully trickle charged the main battery a few times but it only held a charge for a few days at a time. Last week, when I left the van at our friendly local garage overnight so they could make an early start on its MOT, they commented on the flat battery they had to charge before they could test it. Given the old age of the battery and the damage done by leaving it flat, it was decided that a new one might be in order. So I bought new main and leisure batteries. Not cheap!

Then we finished readying the camping bit of the campervan for the coming season, and discovered that a mouse had used the van for its winter quarters. We cleaned up and replaced as necessary and finished the business of readying the van and looked forward to a shakedown trip in the near future.

This morning the brand new battery was flat. Our garage man came and was as mystified as us and we have arranged for him to take the van in next week to run a series of tests. Visions of £££s floating away to join those spent on MOT, batteries, and replacement of mouse chewed kit!

Then Madame pulled her, " I'm only an elderly lady who knows nothing about cars" routine but remembering that a friend had had his hi-fi wrecked by an escaped hamster chewing through the wires, wondered whether the mouse and the flat battery could be connected. I suppressed my initial instinct to scoff and began to wonder - could she be onto something?


Bushcrafter (boy, I've got a lot to say!)
Apr 15, 2005
Connect a multimeter to the battery and pull various fuses to see which one causes the voltage to rise when its pulled.
Then you know which circuit has the issue.
You'll likely have to ignore the one that the alarm is on cos that will be connected when the engines off.
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Full Member
Apr 16, 2009
Hope it’s something more simple. Our leisure has been going flat because one of the led lights in the bed area has shorted and been on all the time. It’s not really bright enough to notice in the daytime while we’ve been tinkering about with the water systems and cleaning, but I noticed it after the battery had gone so flat the central locking didn’t work and I had to open the van on the key and crawl in the back door.

Our main battery is just the same as yours, just hasn’t been cycled enough and despite the van being taken out for a good hour or so run a couple of weeks ago is once again very sluggish.

Sincerely hope it isn’t mouse chewing, I think that would tend to cause a fault or blow a fuse rather than a slow discharge, but I’m no expert on these things.
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Full Member
Jan 18, 2009
Mid Wales
It's possible. As you probably know, mice (especially house-mice) make very wet latrine areas and if they did that over exposed terminals you can get current flow without blowing a fuse. Chewed through shorted wires would blow a fuse.

However, I once had a problem on the Landy split charge - the split charge unit itself had failed and was allowing a leak from the leisure battery. That doesn't happen if your split charge unit has an isolation relay (which mine does now).

It could have been worse! Mice completely ruined the seats in my Westfield by chewing them up and nesting in them. I couldn't get them re-covered for a sensible price so ended up replacing them at great expense. They also chewed through the fuel supply pipe on the Kioti and then, when I fixed that, chewed through a brake pipe - I didn't find that until I was going down a steep bank in the wood. Luckily, I was going slowly and managed to stop it on the hand brake.
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Nov 16, 2019
Vantaa, Finland
It sounds like you should keep ferrets in your vans. :) Just don't try beech martens as they are apparently eating vehicles on the continent.


Bushcrafter (boy, I've got a lot to say!)
Mar 5, 2018
What do you expect if you kidnap a French mouse?
Of course she calls home every night!

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