Charging the starter battery - Westy BBB replacement

[AdrianC]

Seeing this diagram linked from the other starter battery charging thread has got me thinking...



The BBB output goes to a three-wire multiplug.
- earth
- leisure battery +ve
- "other", which I'd expect to be the starter +ve.

If the charger is wired to the leisure +ve and earth, the charger charges the leisure, as you'd expect.
If the charger is wired to the "other" and earth, the charger doesn't see a battery to be charged, so does nothing.

If I put a multimeter to that wire, there's nothing. No 12v +ve. No continuity to earth.

I know the BBB's a dumb charger - I presume it just shoves voltage out to both, which trips the split charge relay, allowing both to charge. The modern charger, being intelligent, doesn't just shove voltage out, so doesn't trip it, so can't charge.

Yet this behaviour doesn't seem to square with that diagram, which would suggest that that wire should be connected to the output pin of the split relay, so always live. The wiring diagram in http://www.westfaliat3.info/1985JokerMa ... 211010.pdf" onclick="window.open(this.href);return false; seems to agree with it, though. Before I swapped out the BBB, it was charging the starter as well as the leisure.

I've not - yet - tried "tricking" it by trying to charge the master, and giving a short feed of +12v from the leisure to "trip" the split charge relay. I'm not aware of any wiring mods to our generally un-mucked-with van.

Thoughts?

[aisha]

Have you the original relay in yours?

I have a suspicion that the above diagram is wrong, and that originally the b-type twin make and break was fitted, with each of the 87 pins isolated from each other until the relay is activated...
As in this relay:
http://www.autoelectricsupplies.co.uk/p ... ategory/36" onclick="window.open(this.href);return false;

I'm only asking as I'm still tracing the leisure battery issue in mine, and will probably be replacing it with something where the 87 pins aren't isolated from each other. Which isn't really a problem I think, as it just means that the main and leisure batteries will both charge (always)

Although, even if I'm right, I'm not sure how the relay activates when the charger is on?

[AdrianC]

Have you the original relay in yours?

No reason to suspect not.

Although, even if I'm right, I'm not sure how the relay activates when the charger is on?

I rather suspect that the original BBB just shoved sparks out, which - as with the alternator output - would then trip the relay, whereas the modern charger actually looks for a battery before switching on.

[California Dreamin]

Have you the original relay in yours?

I have a suspicion that the above diagram is wrong, and that originally the b-type twin make and break was fitted, with each of the 87 pins isolated from each other until the relay is activated...
As in this relay:
http://www.autoelectricsupplies.co.uk/p ... ategory/36" onclick="window.open(this.href);return false;

I'm almost certain that you are right.....the original relay used was a b type where the 87 pins are isolated from eachother until the relay is switched.

Martin

[AdrianC]

I shall rummage for the relay in the morning...