Leisure battery fun and unexplained electrical mysteries...

[walty666]

Hey folks. I've been having intermittent issues with my central locking system failing and then it stopped working completely the other day. I've got a leisure battery on a split charge relay (not Willinton and not originally fitted by me) that feeds cabin lights, stereo, sockets and I believe the central locking as well. Without the van running and with the ignition off there didn't appear to be enough juice in the leisure battery to operate the stereo and only just enough to give a dim glow on the cabin lights so I've whipped the leisure battery out and it's trickle charging as we speak. Figured that was probably the reason why the C/L had packed up...

However, since removing the leisure battery the central locking is now working which suggests that it's now drawing power from the main starter battery?! Is this meant to happen? Can anybody explain this please?

Also, when I turn the ignition to 'ON', the stereo works!? But then it stops working if I try to turn a cabin light on or depress the ciggy lighter. There's not enough current to illuminate the cabin lights or heat the ciggy lighter though? Also when I turn a light on or depress the ciggy lighter the 'DOOR' light comes on on the dash.

When I try and start the van with the stereo on it struggles to turn over. But with the stereo off it the engine fires up with ease.

And this is all with leisure battery out remember? Any thoughts about what's going on here? I was under the impression that if stuff ran off the leisure battery it wouldn't work when the leisure battery was removed (apart from the small supply to the stereo memory)

I'm concerned that whatever has caused my leisure battery to drain over winter is now likely to cause the starter battery to drain whilst the leisure battery is out. Also, if the starter battery is lacking enough current to run the stereo and one cabin light at the same time, how come it has enough strength to start the van?

Confused

[dave_aber]

Some split-charge systems are intelligent, and sense the alternator voltage level. If it rises above a pre-set level, the relay will close and the L/B gets a charge.

Willinton kits do this.

Other systems use a signal line from the ignition switch to drive the relay, so that as soon as your key is turned, the batteries are connected together. If you have this setup, then that would explain why the stereo works with the key switched on. As the leisure battery circuit is now all being powered through the split-charge relay in this situation, the live terminal which would be on the L/B is now live. You have insulated it, haven't you?

Now then, Stereo works with key on, but stops again if you use the fag lighter etc. Possibly high resistance through the split-charge relay? If so, then you wouldn't be getting a full charge to your L/B either. And it's gone flat. A pattern forming? Possibly.

Can't think why the C/L is working now though. AFAIK, the cabin is powered from fuse No. 1, which seems to have been swapped over to your L/B. That powers stereo, cabin lights and C/L. Geoff may be along any minute with a better remembering of the fuse layouts.

HTH

Dave

[g8dhe]

There are two fuses for the Door locks, the 10amp just powers the drivers door switch, then the 30 Amp is the fuse that supplies the power to the other three solenoids via the switching electronics and relay. I suspect that just the first fuse has been moved over to the L/B and not the 30 Amp one that is still on the S/B hence why when the first fuse does get volts it works just fine!

I would agree with Dave that you need to make sure all the connections, relay and BOTH (you do have two fuses one at each battery don't you ?) fuses are OK, I found one of my charging fuses had some corrosion the other day meaning that it was dropping over a volt from the alternator to the L/B when charging at 10 Amps thus taking longer to charge the L/B than normal.

[dave_aber]

I thought you'd be along with a natty fuse diagram Geoff!

Good point about the battery link fuses too.

[walty666]

OK. Thanks for the replies. How come the first 10A fuse is getting power now that the leisure battery has been removed though. Is this coming direct from the starter battery via the split charge relay? The feeds to the fusebox are still connected to the leisure battery lead terminals (albeit without the battery in place).

[EDIT]

Just checked and I've got a 30A fuse immediately downstream of the S/B on the cable to the split charge relay but no fuse between the SCR and the leisure battery. I've got two feeds running from the leisure battery into the cabin, both of which are 15A fused immediately downstream of the L/B terminal. I pulled the 30A fuse from the S/B feed to the relay and the central locking still works which leads me to believe that both the 10A and 30A fuses you point out are completely independent of the leisure battery circuit. However, with the 30A fuse out and the ignition 'ON' (or the engine running) neither the stereo, socket or cabin lights work so there's definitely a limited current coming through the split charge relay from the S/B. I'm assuming that this limited current is what 'trickle' charges the LB when it's in place to keep it topped up but isn't enough to run anything off.

[g8dhe]

First, rather worrying is that fact that you don't have a second fuse between the Charge relay and the L/B, imagine what happens when the cable from the relay to the S/B gets shorted to earth, first the 30 Amp fuse from the S/B will blow - its meant to excellent - but now all the power comes from the L/B via the relay, so your cable goes up in a Puff of smoke and the plastic air intake and everything else catches fire OK worst case scenario but seriously likely to happen. Even if the relay is connected very close to the S/B it still needs a fuse somewhere to blow if the cable gets shorted to earth, preferably before the relay but if not possible, then immediately after the relay.

Fuses are there to protect the cable from a source of power, if the cable connects to more than one source of power then a fuse is needed close to each source of power. This is very basic electrical knowledge - who ever fitted the extra's to your vehicle is an idiot who doesn't understand basic safety and is playing with your life!

There was another case of this on the forum recently, he also was having other electrical problems, he did the obvious thing - took it back to the original garage demanded that they remove it all and refund him and then went to a proper Auto Electrician who knew what they were doing. Here is the thread http://www.igmaynard.co.uk/bongo/forum/ ... 72#p474172

As to the radio and other oddities, life is never as simple as that!

The Top left fuse will get power either from the L/B when connected, or if its disconnected then when the Charge relay operates from the S/B and/or Alternator.

The Top left fuse provides only the standby power to the Radio, not the main power i.e. it keeps the memories intact when you turn "off" the radio it also provides power to everything else that needs to be kept working when the Ignition is OFF. The main power for the radio is via the top right fuse if that one hasn't been swung across to the L/B then your radio is not really connected to the L/B at all!