blue sea dual battery setup

[windrover]

just bought a Blue Sea automatic charge relay (ACR) for a dual battery setup.

I am a bit confused by the schematic...the connection of the starter to the battery switch I understand, but the connection from the alternator to the start battery +ve is not clear to me. is this in addition to the connection of battery to alternator via existing harness? Thanks for any input, Ken

sorry wrong schematic... here's the correct one

Edited November 16, 2008 by western

[steve_d]

just bought a Blue Sea automatic charge relay (ACR) for a dual battery setup.

I am a bit confused by the schematic...the connection of the starter to the battery switch I understand, but the connection from the alternator to the start battery +ve is not clear to me. is this in addition to the connection of battery to alternator via existing harness? Thanks for any input, Ken

Don't see any reason why it would be in addition to your loom.

Steve

[western]

looking at the 2nd diagram, one item is marked as 'house distribution panel' looks like it could be meant for a camper van or caravan. can't see why it shouldn't work, a alternative is the X-eng split charge unit

the start wires run to starter soleniod & other to the alternator [most likely the B+ terminal] the instructions should state which terminals to connect too.

[imspanners]

Looking at it, it's very similar to the one fitted to my van.

The idea, in the event of the either starter or auxiliary battery being flat, during cranking, it closes the circuit to allow the other battery to start the vehicle. (effectively a self controlled jump start system)

[simonr]

Not the best diagram in the world.

If you ignore the terminal on the split charge which connects to the LED indicator - it's exactly the same (wiring wise) as ours.

The two big stud terminals on the split charge just connect the battery +ve's together.

The left small hand terminal connects to vehicle earth.

Middle small terminal connects to sense wire on alternator (the wire that connects to the charge light on your dash).

If you have a 300tdi, Td5 or Puma - this will not work as they use a slightly different type of alternator.

In this case connect the middle terminal to the ignition live feed for your car radio. It is live with the engine running, but not while it is cranking - and it's easy to find in the dash.

Si

[windrover]

looking at the 2nd diagram, one item is marked as 'house distribution panel' looks like it could be meant for a camper van or caravan. can't see why it shouldn't work, a alternative is the X-eng split charge unit

the start wires run to starter soleniod & other to the alternator [most likely the B+ terminal] the instructions should state which terminals to connect too.

unfortunately there are no instructions regarding the connection of the start battery to the alternator...I assume the B+ terminal connection would make the most sense.

bit of a dumb question I suppose, but in the factory setup (single battery), why is the alternator wired to the battery +ve via the starter motor (i.e. brown wire from Alternator B+ terminal to Starter then to battery +ve) and not as a second separate line? is it because it is a redundant connection?

I liked the X-eng setup, but I purchased the blue sea setup because it was at a shop next door. thanks for your input, Ken

[windrover]

Not the best diagram in the world.

If you ignore the terminal on the split charge which connects to the LED indicator - it's exactly the same (wiring wise) as ours.

The two big stud terminals on the split charge just connect the battery +ve's together.

The left small hand terminal connects to vehicle earth.

Middle small terminal connects to sense wire on alternator (the wire that connects to the charge light on your dash).

If you have a 300tdi, Td5 or Puma - this will not work as they use a slightly different type of alternator.

In this case connect the middle terminal to the ignition live feed for your car radio. It is live with the engine running, but not while it is cranking - and it's easy to find in the dash.

Si

Yeah Simonr, their diagram is quite poor, and their instructions even more vague. I appreciate your comments... could the middle small terminal SI connect (starting isolation) go to the red/white (trigger) wire on the starter? if i understand correctly, the middle connector is to temporarily isolate the accessory battery during cranking, when the battery switch is set to "combined batteries".

[simonr]

Yes and no.

It isolates the two batteries while cranking, but also when the ignition is off - that's the point of a split charge relay.

If you leave improperly matched batteries connected together - they shag one another.

You need a connection to live which ideally is only live while the engine is running and the alternator charging. The charge light output on the alternator fulfills this nicely - but as mentioned does not work on certain types of alternator.

The +ve ignition feed to the radio will work on all vehicles and only suffers from the problem that it only detects the ignition being on (but not cranking) - not that the alternator is ACTUALLY charging - but it's close enough.

Also, the wire to the starter goes live while you are cranking - where you want it dead while cranking - so would only connect the batteries together while cranking and the second battery would receive no charge at all.

Si