Split Charge Relay Size

[bdastu]

I have bought a leisure battery which I intend to fit to my Mk 7 Transit as part of my camper van conversion.
I can find plenty kits on line but they seem to vary from 30amp to over 200 amps.
My leisure battery is 110a so do I need a kit that is rated at over 110 amps, maybe a 140amp kit?
I would appreciate any advice.

[Kedishen]

Size of your battery is irrelevant in this case. To replace 1 aH of battery power, will require a sustained current of 1amp for 1 hour... so a 30amp relay can replenish 30amps in 1 hour if at full current...

If the relays are electronic, then any size will do. Its unlikely that the charge will reach more than 30 amps unless you significantly discharge your leisure battery (which you shouldn't do). I'd go for a 60amp myself, never good to run something at full capacity.

But before you buy anything, you may want to look more into split charging a mk7. I believe they need summit a bit more fancy than your normal SCR, or at least the way they are wired up?

[Croftylad]

I have a split charge relay on my mk7. It was originally a network rail crewvan . When I bought it the leisure batteries had been removed but the feed wires from the van battery had been left. They seem to be connected straight to the battery. When I pulled out the electrics there was a large relay amongst all the stuff . I used this as a relay that operates when the ignition is turned on (via a small feed wire from the fuses under the glovebox). This feed charges two 110 amp batteries. Works great and charges at 14v with the engine running.
Antony

[bdastu]

Thanks for the replys.
I've been looking on the forum to get an idea of how the split charging system works and I haven't seen anyone mentioning any special issues with the Mk 7.
I thought I just needed to take a supply direct from the existing battery through a split charge relay like Croftylad seems to have, although without the supply from the ignition.
Looks like a bit more research is needed......

[Kedishen]

I am not certain of any special requirements, but I am sure I read things in past about problems doing this with mk6 & 7... may have imagined it.

[ake]

The Mk 7 has a spare wire which is switched when the engine runs, use this to control the split charge relay.

Location of the wire can be found in the BEMM manual which can be downloaded at www.etis.ford.com

[sc_BK]

This is the relay I used

http://www.caravantechnology.com/12V-Vo ... -P125.aspx


Just connect it up to each battery with heavy leads, and it does the rest for you, job done!