Technical Battery Compartment Fuses

[Toolbox]

In my 2007 X250 battery compartment there are two fuses mounted to the forward wall. One is the really big type and the other a standard 20 amp yellow one. When I try to jump start the 20 amp fuse blows and then the battery voltage reading drops to around 6.5 amps. Any ideas why or what this fuse us for?

 

[rayc]

If the battery voltage is only 6 volts when the fuse is blown it suggests that the voltage that is being measured when the fuse is ok is coming from somewhere else via the fuse.
The fuse could be blowing because the starter is trying to operate via the fuse and not the starter battery. When the fuse is blown what voltage are you measuring on each contact of the fuse holder?

 

[Toolbox]

Actually I haven't measured that. I was wondering what this particular fuse protected as I couldn't find it in the manual.

 

[T14086]

worth checking with nearest dealer if your van has had battery fuse recall,

 

[Toolbox]

Thanks for the heads up, I hadn't realised there was such a recall and certainly haven't heard anything even though I've had the van from new. Do you by any chance have any further information about cause/effects etc?Thanks again.

 

[T14086]

If you have had vehicle from new then likely it doesn't effect your vehicle, recall was to change a fuse which could cause a non-start situation however I seem to recall (excuse the pun) something about a cable as well but don't quote me on that.

 

[Toolbox]

Thanks. Do you know what the pair of fuses located in the battery compartment? One is the really big type, the other a standard 20 amp version. This blows as soon as I try to jump start the van and the battery voltage reading halves.

 

[Crossingkeeper]

Is your van a camper or motorhome with a leisure battery?

If so perhaps the 20 amp fuse is protects the link to the leisure battery for charging from the alternator (& is blowing when the starter draws current from the leisure battery rather than the flat van battery)

If not, I read somewhere that transit vans now have two batteries fitted, starter & auxiliary; perhaps Fiat now also do this?