Two batteries in an 07 Transit diesel

It's not uncommon to have a leisure battery set up for something that might be used occasionally for camping, also for certain trades where there may be a requirement for "static" power, such as farriers.

williamwright laid this down on his screen :

Possibly an 'occupation battery'. Charged when ever the engine is running via a voltage operated charge relay, but otherwise isolated from the the main starter battery road lights etc., just used of internal lights and equipment whilst engine is off. It avoids flattening the main battery. Common in ambulances, caravans and leisure vehicles.

I had one for a while and I understood they were in parallel for starting but the ancillaries ran on one when the ignition was off.

Because I never had a battery problem I never got around to understanding how they were used.

williamwright snipped-for-privacy@f2s.com wrote in news:i496saFquegU1 @mid.individual.net:

The girl on the switchboard at Ford says she is fed up with you asking!

Fredxx formulated the question :

That is very unlikely, it would need a very large relay/contactor to sustain the cranking load.

That is probably correct.

It's called a starter solenoid, but can be utilised to couple/decouple extra power when required.

jon formulated on Monday :

A starter solenoid is only designed for very intermitant use of a few seconds, whilst cranking. Powered for longer, then they can overheat and burn out.

Wouldn't it be easier to simply go to 24v?

Does seem quite odd, though. The Transit hardly has a large engine in the scheme of things. Plenty cars with bigger diesels.

Reading forums it seems one is an auxilliary batter and the other used for starting where both are charged when the engine is running.

Why would a van need this more than a car?

Unless a mobile home, etc.

That's my provisional understanding.

Bill

I have no idea, ask Ford. They are both modestly sized batteries too, and the engine uses a geared starter.