Split chargers

[Cardiffboy]

Hi, I have just bought an elderly Vw lt35. There is no display/control panel for the leisure battery, I’ve bought one to fit. The seller left me a hand written bookie which says that if you run the engine the LB will charge but you have to remove o key from port 1 to port 2???? I don’t have a multimeter handy but a friend checked and said it wasn’t charging, is anyone aware of this setup

 

[68c]

Can you give any more information? What does port 0, 2 refer to? Perhaps a picture would help. On older vans there is normaly a relay that connects the alternator to the LB when the D+ line outputs after the engine starts.

 

[Itsmcb]

Hi, I have just bought an elderly Vw lt35. There is no display/control panel for the leisure battery, I’ve bought one to fit. The seller left me a hand written bookie which says that if you run the engine the LB will charge but you have to remove o key from port 1 to port 2???? I don’t have a multimeter handy but a friend checked and said it wasn’t charging, is anyone aware of this setup

Sounds like they have fitted a DIY method of switching the charging to the leisure battery. Usually it's done with a relay. Some photos of any 'extra' electrical stuff might help but it sounds like the sort of thing that needs to be traced whilst actually at the van.

 

[Cardiffboy]

I’ll sort a pic later or Tomorrow, there is wooden box with a red plastic key and 2 ports

 

[Itsmcb]

Can you give any more information? What does port 0, 2 refer to? Perhaps a picture would help. On older vans there is normaly a relay that connects the alternator to the LB when the D+ line outputs after the engine starts.

Beat me to it

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[Phill D]

I’ll sort a pic later or Tomorrow, there is wooden box with a red plastic key and 2 ports

it would help to know whats in the box if you are able to photo that also. certainly sounds a diy affair. you defo need to invest a tenner in a multi meter.

 

[headlight]

I’ll sort a pic later or Tomorrow, there is wooden box with a red plastic key and 2 ports

Sounds like a battery selector switch to me.

 

[Cardiffboy]

Thanks, I have n idea where that is, or what it is but I’m learning new stuff

 

[headlight]

Thanks, I have n idea where that is, or what it is but I’m learning new stuff

The red plastic key is used to select either the starter battery or leisure battery is what I meant.

 

[Cardiffboy]

Here’s what I have

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[Phill D]

The smartcom is a split charge relay, so the blue box must be just an isolate switch.
It needs to be switched to charge leisure battery whenever the engine is running.
It’s likely that the leisure battery has been isolated from charge and the habitation electrics used , dragging the battery down without realising it.
Looks a very simple system with a lot of insulation tape

It’s likely there is no charge going to the leisure battery as the split relay is preventing it as the leisure battery is too low.

 

[Phill D]

The leisure battery needs to be removed and charged externally to see if it can be saved.

 

[Cardiffboy]

So how do I overcome that? Is it a case of connecting to the mains for a few hours

 

[Cardiffboy]

You beat me to it , can it be charged with a normal car charger

 

[Phill D]

I think it may need more than a few hours,
Yes a normal car charger is ok but it’s so low it may not accept a charge.
I would remove it from the van to charge it just in case , it’s screwed and gassed off. If it will accept charge It’s likely to draw as much current as the charger will give.

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[Phill D]

You beat me to it , can it be charged with a normal car charger

Did you get a chance to charge the hab battery?

 

[Cardiffboy]

Hi mate, it’s been on charge most of the day, I got a meter, was showing 9v before and when I left it it was over 12v. How long should I leave it on charge? It’s got a window that is supposed to go green when fully charged???

 

[Phill D]

If you are checking voltage while it’s on charge it should be well up into the 13.6v area.
Then after charging and resting for say an hour should be 12.7v.

If it’s not getting up to those figures then the battery is either not getting enough charge or it’s shot.

12v is barely 50% state of charge when rested.

 

[Cardiffboy]

Ok, is it safe to leave on overnight?

 

[Phill D]

Ok, is it safe to leave on overnight?

As I believe the battery is suspect it having been as low as 9v I would not leave it on overnight.
Until you know if the battery is ok or not I would want to keep going back to it at regular intervals to ensure it was not overheating or gassing off. It could be a bit risky.

Not trying to overstate the risk but better safe than very sorry

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[Cardiffboy]

Ok mate cheers again

 

[DBK]

I've found this wiring diagram for the smartcom.

The smartcom is voltage sensing and will charge the leisure battery once the engine is running. With a multimeter you should be able to measure a voltage on the input side (the one with two terminals) even with the engine not running. If you can't, have a play around with that key and see if you can connect it. However, this is a bit trial and error, it would be better to take that blue box apart first and see how things are wired up.

 

[Cardiffboy]

Champion

 

[headlight]

Hi mate, it’s been on charge most of the day, I got a meter, was showing 9v before and when I left it it was over 12v. How long should I leave it on charge? It’s got a window that is supposed to go green when fully charged???

I'm sorry to say that if the battery has been down to 9v then even if it charges up to full, which is about 12.7v, it will probably have lost a chunk of capacity.
Only way to know for sure would be if it does get up to 12.7v then say an hour after taking it off charge do a capacity test.
Personally I think you need a new battery though.

 

[Cardiffboy]

Bloody typical

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[Cardiffboy]

I’ll let you know tomorrow

 

[headlight]

I’ll let you know tomorrow

Cardiffboy
Also you need to open that blue box and see how it's wired.
My guess is that the 2 red keys are just on/off isolators allowing you to select one battery or the other.

 

[Cardiffboy]

Ok

 

[headlight]

Cardiffboy where are you located ?

 

[Cardiffboy]

Pentwyn in Cardiff