Central locking incorrectly put onto leisure battery

[Alifriendee]

Many thanks for your valuable advice.

I'll try that and report onwards.

[Alifriendee]

The radio is a Sony CDX-GT740UI so I hope it's being sensible with it's draw but I can't see anything about this in the manual. That said, it's now running from the vehicle battery so can't be responsible for the drain on the leisure battery.

[Alifriendee]

OK I'll give that a try. The next chance I'll get is next weekend so please keep an eye out for my results.

Many thanks

Nick

[Alifriendee]

Help!

The engine is off, no circuits on, nothing in the cigarette lighter sockets
The red wire is connected to the disconnected -ve terminal.
The black wire is connected to the -ve terminal of the battery.
The meter is turned on and set to amps and to 200mA
The l/b is charged.

The meter just continues to show 0.00, i.e. no current?

There are only three wires into the relay.

[g8dhe]

That suggest that you have removed the drain from the battery, just to prove it put a small load ON that should come from the L/B, just to ensure that you have set everything up right, plug something into the cigarette lighter not a lighter how ever as it will go offscale, LED light, Ipod, Game box whatever you should then see acurrent being drawn.

Good thing its raining down here I can't get on with the painting

[Alifriendee]

I've posted some photos

Nothing happens when plug in an iPhone charger, or even put on one of the interior lights.

As the interior lights are connected to the l/b I turned one on and then removed the 40amp fuse from the lead from the vehicle battery leading to the relay. The light went out.

The mess of cables connected to the yellow fuse are a blue and brown which go to the Zig unit (both are live), a red wire goes off to near the fuse box via a 20amp fuse and is connected to all the wires the garage (yes a Bongo specialist) cut from the fuse box to connect to this cable - central locking, cabin, horn, radio, cigarette lighters, blinds.

The other red wire is from the relay.

It appears to me that the vehicle battery is still paying a part in the load coming off the l/b.

http://www.flickr.com/photos/24928332@N ... 9831/show/

it seems you need to click "please click here" or open in a new window the see the photos.

[g8dhe]

Humm, yes its not a well laid out system
The location of the first fuse next to the S/B is fine,
then via the relay, OK, but then the size of wire drops - it should be the same size,
and goes back to the second fuse before running across the bonnet to the L/B - the second fuse should really be close to the L/B as its function is to protect the wire which it can't do when its at the wrong end of the cable

Now as to your reading of zero, and yet the lights are working, two problems:-
First the reading of zero, it could be the meter itself, they have a protection fuse normally inside - which might have blown. Normally it would be about 1 or 2amp for a current range of 0.2Amps.
AND / OR it could be that the Fuse from the relay to the L/B is blown.

The second problem is that your lights keep working - that implies that the relay is operated at 12+ volts (which it shouldn't be, normally operates between 13-14 volts) or has welded closed as it is only rated for 30 amps, a good design will have a 40amp relay as minimum and some designs use a 70amp relay.
The fact that the lights go out when you remove the fuse from the S/B implies the above is the case.

[Alifriendee]

Tricky. The relay is brand new - replaced a few weeks ago.

I've opened up the multimeter. Yes the fuse has blown. Off to get a replacement.

[g8dhe]

Yes I should have added of course that if the relay has welded closed then that might well be the cause of the fuse in the meter blowing in the first place. The 200mA range isn't really adequate for automotive work where most currents are in the several Amps range, typically I would use a 20Amp range and then work downwards which is why I emphasised turning everything off first! If you can borrow / beg a different meter which has a much higher current range it would be cheaper on fuses, and possible confusion!

Suggest that the next step is to isolate the relay, by removing both fuses, and then checking the resistance between the two power feeds to the relay.

[Alifriendee]

With a working multimeter we get.

With Fuse 1 removed - 56
Turned on an interior light - 78.6

Pulled the 20amp fuse which is between the l/b and relay i.e. separated the cabin, blinds etc. etc. - 44.9

Pulled the 40amp fuse between the vehicle battery and the relay - shot up to 113.2
put it back - 43.4
then put back the 20amp fuse - 52.9 but then slowly dropped down to 19 then up to 29 and wobbled about.
then put fuse 1 back in - wobbled about between 52 to 64

[Alifriendee]

Sorry missed your earlier post when I typed my reply.

I now have a better multimeter which in the Amp range has choices of 200µ 2000µ 20m and 200m.

I'm afraid I don't know where to measure across having pulled both fuses as you suggest.

[g8dhe]

OK well all those figures indicate that the load is being shared across BOTH batteries (other than when you remove the fuse(s)), this is wrong either the relay is operated or something in the wiring is bridging the relay, given the affects of removing the fuses something bridging the relay is sounding more likely.
I think the first thing is to check the relay itself to either eliminate it or prove its faulty;
You will need to use the meter on the resistance/Ohms/Ω range of 200Ω or if it has a Buzzer facility even better, disconnect the two red leads from the relay and stick one probe into each socket that the red leads came out of - If the relay is working correctly then you should see Open Circuit (no Buzzer sounding), if the relay has welded closed then 0Ω or at least less than 5Ω, Buzzer sounds.

If the relay looks OK from above then something else appears to be bridging the relay contacts back into the wiring, possibly where the wires have been moved between the fuse boxs, this is not going to be as easy to check for without isolating several of the wires (and more difficult to describe doing than, actually doing it if you follow me!).

Looking at the photo's there seems to be the connection to the Zig unit using the twin mains cable from the fuse connections,

but looking at the L/B itself there is another two fuses the one on the left and the one coming out of the right hand side of the +ve terminal

Also there seems to be a -ve connection which is bypassing the isolater, I assume but can you confirm that the large Black cable just goes to the chassis of the vehicle ?
But where do those three extra wires go ?

[Alifriendee]

Just to explain, the red (fused) and the black wires from the l/b are just the cables for the plug in socket for my CTEK battery charger "comfort indicator eyelet" so they have no impact here. The eyelet connected wires go up to the black plug on the left (which I have clipped to the larger red wire for convenience) into which my battery charger plugs in. It's their way of saving you having to use the crocodile clips every time. I've got one attached to the vehicle battery as well. I just plug in the battery charger into their plug.

http://www.ctek.com/EN-GB/consumer/mxs-4003.aspx

http://www.ctek.com/files/productsheet/ ... uk_low.pdf

The thick black cable goes into the chassis of the vehicle.

I'm pretty sure something in the wiring is bridging the relay as at one time I had a "battery brain" fitted to try to solve the problem and protect the l/b. With it switched off there were times when I was still getting supply to items I thought should be disconnected. I have since removed the battery brain (it's some of the wiring for it you see still wrapped around the red cable as I disconnected it but the wiring for the "in-cab" switch is still there) and replaced it with the isolator with the black knob you see on the -ve terminal of the l/b as I rather like being able to manually isolate the l/b to stop it draining - but it turns off my central locking which takes us back to where this conversation started!

http://www.batterybrain.co.uk/productspage.php

I can pull out all the wires by the fuse box where the fitter cut them from the fuses and grouped them all together into the feed from the relay and test them one by one if you are able to guide me.

I have already pulled out the wires for the horn and radio and put them where I want them.

By the way - you are a supreme being. Thank you so much for the time you are spending trying to help me.

[g8dhe]

Brill, those extra wires shouldn't be involved then.

If your able to check out the relay as above then we can eliminate that, and if all the other feeds from the L/B come from the one cable which your able to access then yes we can break the connections there and measure the feeds one by one.
Given that the highest current measured seems to be 113mA then that will give something like 20-30 days life to the battery, which matches with my own setup, where I reckon to get 3-4 weeks if the vehicle isn't used at all and the temperature is above 20°C, but short drives and other loads on the L/B which don't get fully replaced on a run can rapidly reduce the time available down to 1-2 weeks.

My guess would be that the radio might be drawing 10-20mA when off, the remote door lock receiver might be drawing 30-80mA and the ECU itself may be drawing the difference 10-80mA at a guess, but I've never been in a position to isolate each one in turn to measure. If we can get the current down to less than 100mA, and we know what is drawing the power then normally that should be adequate. If the vehicle isn't going to be used for more than a month, then is the time to start isolating both the batteries and perhaps give them a top up before reconnecting them. I assume by the way that its a Diesel not a V6 ?

[Alifriendee]

It's a diesel.

Haven't had a chance to look any closer but you may be interested to know the Bongo had a flat vehicle battery when I went to start it on Saturday morning for a trip to Dorset.

I had isolated the leisure battery during the week so in it's wisdom the Bongo decided to draw whatever power it needed from the vehicle battery instead. What this seems to prove is that there is a connection between the two lurking somewhere.

This is the first time I've had the vehicle battery go flat on me so why on earth did the disconnection of the l/b make it go flat?

I charged up enough to start, connected the l/b and drove off. Both batteries fully charged upon arrival.