What if turn ignition when only leisure battery connected?

[petervw]

I have replaced both my starter and leisure batteries with fully new ones.
I also fitted a circuit breaker on startey battery to be sure it can't drain while camping or parked up for a while.

With starter battery disconnected, all the same electrics work as if it was (radio, dome lights, etc). I hope the relay is working correctly. But what if its not? What happens if the engine tries to start from the leisure battery. Can any damage be done?
****
BTW, on the advice of battery manufacturer Varta, I fitted a gas vent to the leisure battery (because its INSIDE the vehicle cabin). I plugged one vent hole, and connected a 6mm tube to the other, driled a hole through the battery box to the outside of the vehicle and pushed the tube through (and tried to put the end where it hopefully won't clog up with dirt). I gather the risk of hydrogen gas build up is small, but having been warned, I couldn't feel relaxed without installing a vent.

[MidLifeCrisis]

With starter battery disconnected, all the same electrics work as if it was (radio, dome lights, etc). I hope the relay is working correctly. But what if its not? What happens if the engine tries to start from the leisure battery. Can any damage be done?
****

That does sound a little like your leisure battery is permanently connected to the starter battery circuit (i.e. that you split charge relay system isn't working correctly).
It's often the case that people will wire their radios to the leisure battery so that the radio can be used when parked up - have you done this? But aside from that I wouldn't have thought that your dome lights would be wired up to the leisure (but stranger things have happened).
If you turn the ignition key to the first position - do the dash lights/warning lights etc light up??

[California Dreamin]

I have replaced both my starter and leisure batteries with fully new ones.
I also fitted a circuit breaker on startey battery to be sure it can't drain while camping or parked up for a while.

With starter battery disconnected, all the same electrics work as if it was (radio, dome lights, etc). I hope the relay is working correctly. But what if its not? What happens if the engine tries to start from the leisure battery. Can any damage be done?
****
BTW, on the advice of battery manufacturer Varta, I fitted a gas vent to the leisure battery (because its INSIDE the vehicle cabin). I plugged one vent hole, and connected a 6mm tube to the other, driled a hole through the battery box to the outside of the vehicle and pushed the tube through (and tried to put the end where it hopefully won't clog up with dirt). I gather the risk of hydrogen gas build up is small, but having been warned, I couldn't feel relaxed without installing a vent.

With the starter battery disconnected the only things that should work are those that are connected to the leisure battery. The split charge relay should effectively isolate the leisure battery from any other electrics (if it is working as it should).
The interior lights/radio/cigarette lighter, may well still function but things like ignition/side and main lights, blower motor should not. If they do then you do have a problem and it could be that the contacts in the split charge relay have welded themselves together.
Don't try and crank the engine...but try the side lights/ignition lights and report back.

Martin

[petervw]

Yes, with the starter battery disconnected, everything seems to work as if it is connected. Dash lights, headlights, indicators, etc. I didn't try to crank it though.

I can see there is the standard relay next to the leisure battery (small steel box). Presumably I need to check that somehow.

[MidLifeCrisis]

Yes, with the starter battery disconnected, everything seems to work as if it is connected. Dash lights, headlights, indicators, etc. I didn't try to crank it though.

I can see there is the standard relay next to the leisure battery (small steel box). Presumably I need to check that somehow.

Right - so something is definitely wrong then!!
So, don't be trying to crank the starter unless you are sure that the main battery is connected - without the starter battery and with the leisure connected permanently to the starter circuit I would expect that trying to crank the starter would create lots of nasty, burny type damage to the thin(ner) cables between the starter circuit and the leisure!!!

So, either the relay is damaged and needs replacing.
Or it is being permanently activated ....
it'll be one of those two problems - time to have a little poke around!!

[CJH]

So, either the relay is damaged and needs replacing.
Or it is being permanently activated ....
it'll be one of those two problems - time to have a little poke around!!

...and since the starter battery is out of the circuit, then to be permanently activated it would mean the activation terminal must be directly connected to the leisure battery. That would be very odd. But who knows, maybe a previous owner misread the wiring instructions somehow.

[petervw]

The 'activation terminal', is that no. 30?

I know there are numbers 30, 85, 87, 86. I got that from the Wiki.

Any easy way to check if relay works as it should? Or should I just get a new one and try with that?

Bear in mind, until about 6 weeks ago, I knew zero about the mechanics or electrics of a T25. And have learnt quite a lot in just the past 2 or 3.

[petervw]

I've checked the wiring on the relay. Going by the lead colours, it looks ok - assuming the lead colours are correct against the diagram I have (which I think I got via the Wiki).

My next move is to buy a new relay, fit it and see what happens.

[petervw]

The relay looks as if it could be original - ie, 25 years old. Is that beyond a sensible life?

[CJH]

The 'activation terminal', is that no. 30?

I know there are numbers 30, 85, 87, 86. I got that from the Wiki.

Any easy way to check if relay works as it should? Or should I just get a new one and try with that?

Bear in mind, until about 6 weeks ago, I knew zero about the mechanics or electrics of a T25. And have learnt quite a lot in just the past 2 or 3.

The signal wire is on terminal 86 in this diagram. 30 is the feed from the starter battery and 87 is the output to the leisure battery. 85 should go to earth (the vehicle chassis or the (starter) battery -ve.

A couple of simple checks, if you have a multimeter.
1) With the starter battery disconnected, is there a voltage on terminal 86 (with the other meter probe on the chassis earth)? If you can see where that 86 wire comes from, if there's a voltage on it then it can only be because it's connected to the leisure battery.
2) Set your multimeter to the resistance setting (touch the meter's probes together to see what 'zero' resistance looks like on your meter), them put the probes across 30 and 87. If the relay has failed and the terminals are fused together (and there's no voltage on pin 86), then you should see no resistance across these pins. Open circuit (i.e. infinite resistance) would rule out this fault.

[California Dreamin]

Peter.....split charge relays are usually fairly reliable UNTIL.....one of the batteries dies and causes an excessive amount of current from across the split charge circuit. The normal maximum, typically around 35 amps rises dramatically way above the designed current handling abilities of the original relay. As a result the main contacts either burn out or just weld permanently together.
If I were you...this presents a perfect opportunity to upgrade the relay (at least) to something more substantial. Even if you don't make the wiring any heavier, a heavier duty relay will prove more reliable in the long run.

If it is a standard 4 pin relay then fit one of these....all you will need to do is replace the two main spade terminals (carrying the high current between the batteries) for larger 9.5mm female spades, then straight swap.

http://www.autoelectricsupplies.co.uk/p ... ategory/36" onclick="window.open(this.href);return false;


9.5mm insulated crimped female spade connectors bottom of the page:
http://www.autoelectricsupplies.co.uk/p ... category/8" onclick="window.open(this.href);return false;

Martin

[petervw]

Thanks Martin.
When trying to understand some electrical issues on my newly acquired van, I found the leisure battery was completely dead. An old make, DETA, which does not seem to exist anymore, and with no electrolyte fluid in it. I replaced it with a new one, which is when I discovered this current apparent problem. Thus the relay is probably 'done-in'.

So, I'll get a new relay.

5 pins. My existing one has a 5th pin in the middle underneath. Judging by the wiring diagram, and the positioning of the terminal lables, I think its a second 87. Does that sound right?

Peter

[California Dreamin]

Ahhhh! do you drive a Westfalia? it would appear that what you have is a 'Double make and break' not to be confused with a 'twin make and break'. The difference is ...as you say two terminals that say 87 (which is wrong) or the correct type that has an 87 & 87b (sometimes 87a & 87b) .

If I am correct? the extra terminal serves to isolate the 12volt feed to the fridge to prevent it flattening the leisure battery whilst parked up.

Again..if I am correct about your relay? an upgrage is available is the shape of one of these:

http://www.autoelectricsupplies.co.uk/product/824" onclick="window.open(this.href);return false;

However, you will need to change terminal ends on 4 of the 5 wires: heavy current wires use 2 X 9.5mm insulated female spades & switching the terminals use 2 X 2.8mm again insulated if you can get them (the one '6.3mm terminal left is the fridge feed)

You will struggle finding a replacement relay of the same rating. So the above is a good option albeit, having to change 4 of the terminals.

Martin

[petervw]

Yes, Martin, I have a 1989 Westfalia California.

For pins 30, 85, 86, the stamped lable is on the outer side of the pin. For the 87, the stamped lable is between the outer pin and the middle one. No reference to A and B. I assumed these two pins were two of the same, connected together internally.

So, if I get a 4 pin relay, can I not connect the two '87' connections of old to the single 87 connection on the new one?

[California Dreamin]

Yes, Martin, I have a 1989 Westfalia California.


So, if I get a 4 pin relay, can I not connect the two '87' connections of old to the single 87 connection on the new one?

No because that means the fridge has a permanent live as the 87's are connected all the time......on a 'Double make' the 87 & 87b are kept separate and become live at the same time (only joined with the engine running) I can only assume that the relay you have at present is not the original and someone just fitted a twin make not knowing the difference.

In practice you wouldn't tell the difference UNLESS you just happen to stop somewhere and forgot to change from 12 volt supply to gas or mains...after 7 - 8 hours the leisure battery would be completely flat.

Do ask me how I found all this out...trust me if I say I found out the hard way.

Wrong type:


This one is the correct type.



Martin