12v problem Split charger ?

[centro]

I have a sub woofer under the back seat which has suddenly stopped working when the engine is running.

It works fine when on main hook-up - as do all the other 12v things like lights and water pump.

I dont have a leisure battery installed at the moment but I am wondering if the split charge relay is faulty?
I have tested ALL the leads and wires in the van for continuity and they seem OK.

What is the best way of testing the split charge relay for faults when a leisure battery is not installed?
or, what else could the problem be?

Cheers

[CovKid]

You're using a regular car battery as a leisure then? Test the voltage on this battery and see what it says. If its low or flat you can then look at why.

[centro]

No, not using a car battery as a leisure. My usual set up is: I have a car battery doing its normal thing and and a leisure battery to run lights when not on hook-up.

The leisure battery is dead – died months ago and is now in landfill. I have yet to replace the leisure battery, but will do in the coming weeks.

I know if I did have a leisure battery installed I could take 2 readings of the leisure battery to determine if the split charge is working. One reading without engine running and a second (hopefully higher) reading with engine running.

What I want to know is, how do I do this without the leisure battery installed? – do I take the 2nd reading from the 2 leads which would normally fix to the leisure battery terminals?

Cheers

[centro]

… I am assuming this is the splitt charge relay ? If not then what is it?

http://centrodesign.co.uk/images/IMG_0007.JPG" onclick="window.open(this.href);return false;

http://centrodesign.co.uk/images/IMG_0008.JPG" onclick="window.open(this.href);return false;

http://centrodesign.co.uk/images/IMG_0009.JPG" onclick="window.open(this.href);return false;

[Hacksawbob]

do I take the 2nd reading from the 2 leads which would normally fix to the leisure battery terminals?

yes that would work to determine whether the split charge relay is working or not. Make sure the battery terminal for the leisure battery is isolated when its not connected as it will short against metalwork whilst driving wrap some electrical tape around it. if it has already earthed then there may be a blown fuse somewhere.

Yours is a switch over relay rather than just an isolator, something is attached to the driving battery (87a?)without the engine running, it'd be a good idea to trace that.
pin 87 I am guessing is connected to your leisure battery and joins the driving battery + to the leisure battery + while engine is running.

[centro]

do I take the 2nd reading from the 2 leads which would normally fix to the leisure battery terminals?

yes that would work to determine whether the split charge relay is working or not. Make sure the battery terminal for the leisure battery is isolated when its not connected as it will short against metalwork whilst driving wrap some electrical tape around it. if it has already earthed then there may be a blown fuse somewhere.

Yours is a switch over relay rather than just an isolator, something is attached to the driving battery (87a?)without the engine running, it'd be a good idea to trace that.
pin 87 I am guessing is connected to your leisure battery and joins the driving battery + to the leisure battery + while engine is running.

Funny you should mention isolating the terminal ! That has been giving me grief until last weekend. I insulated the area where the Leisure battery is with that buublewrap/foil material. This was causing the system to short when on hookup as I hadnt isolated the terminals ! – thats how much I know about electrics!

Do you think this has caused some damage some where? I have checked fuses and they are all ok.

Does the switch over relay have a fuse in it which may have blown ?

[Hacksawbob]

no that switch over relay has no fuse, usually when they go bad they melt! if it has definitely shorted then it would be wise to trace all the wires as best you can and check them along the length for melted-ness, if there is wire damage then you may need to rewire as it is a fire risk. The melted cable could expose bare wire which can then earth somewhere in the van and cause a fire. It looks pretty home brew, if the installer was nice he may have put a fuse somewhere near the positive connection on the driving battery just for this sort of eventuality.

[centro]

OK. I will check everything. I have already checked every wire for continuity and found no problems. Would a burnt out wire still have continuity?

[Hacksawbob]

continuity from what to what? End to end I guess, yes that would be a good start but not conclusive. Disconnect the live from the driving battery and test for continuity to the earth (neg battery terminal) there should be none, If there is then your positive is earthing somewhere. Then test for end to end continuity (which there should be) Make sure the leisure battery + is isolated as discussed. Could be earthing on movement with van (unlikely though), visual inspection with the above test is your best bet just to be sure, And check the output at the leisure battery terminals with and without the engine running to confirm there is 0 volts (as leisure not connected ) and around 13-14V with the engine running.

[centro]

Thanks for being so thorough - its a real help.

when testing for continuity to the earth (neg battery terminal) – do I put a probe on each on of the earth lead ?

[Hacksawbob]

Disconnect positive lead. test positive lead to negative battery post with neg still connected you are testing to see whether there is a break in the positive lead and it touching the chassis.

[trentjim]

died months ago and is now in landfill.

ooh! you must be made of money... thats at least a fivers worth if weighed in...

[centro]

died months ago and is now in landfill.

ooh! you must be made of money... thats at least a fivers worth if weighed in...

+ another fiver to take it to the tip ! How frivolous !

[centro]

Disconnect the live from the driving battery and test for continuity to the earth (neg battery terminal) there should be none, If there is then your positive is earthing somewhere.

Got round to trying this. This is what happens on the multimeter when I do the test:
http://youtu.be/yknX5QFqhp4" onclick="window.open(this.href);return false;


Yesterday I spent the whole afternoon inspecting every wire. I even took the fridge out and had look behind it. I cannot find any melted wires.

Gonna have to pay someone to have look me thinks.

[centro]

Well it turns out the switch-over relay had failed. No visible signs of damage to it. All sorted now.