by hectors-tranny » Sun Mar 19, 2017 5:33 pm
I thought about this before I bought my Transit. In the end I decided not to, and to install my own leisure battery myself. A few thoughts:
If you did want to consider using the purchased second battery for your motorhome electrics, you would need to find out whether it is a proper deep discharge leisure type battery, or just a second normal starter battery, in which case it would not be suitable. Also worth finding out its capacity to make sure it's enough for your needs. (Remember you need at least TWICE what you work out you need, as a leisure battery shouldn't really be discharged more that 50%. Batteries also lose about 20% capacity after a few charging cycles. Hence if you reckon you need 50Ah - you actually need 120 Ah.)
I've heard (not sure though) that for Ford double battery setups, one is used for starter, one for other electrics. That means that your conversion electrics would be sharing the battery with these. You also need to find out whether the assumption that the second battery is isolated by a split charge relay is correct! They might just be a battery bank.
One more point to note, space under the driver's seat where the starter battery (and second if ordered) are sited is extremely tight. Much more so obviously if there's two batteries in there.
Would running motorhome electrics from a manufacturer purchased battery invalidate your warranty? Fitting my own leisure battery means that I don't have to mess around with the van's own electrical system, which for me was desirable.
Hope that helps.