Vsr switching

[Dave H]

Have fitted a 100ah leisure battery to my van along with 30amp vsr if I stick a meter on at idle it reads 13.9v then with engine off 12.2v however if I run round the block then stick meter on at idle it reads 12.2v then if I restart engine it goes back to reading 13.7v does this mean the vsr is turning off at anything other than idle speed? And if so what's the answer to stop this happening? Higher ampage vsr? Just seems that the switch is switching off at anything other than idle speed.
Tia dave

 

[Pfcmike]

Not sure if I’m asking a silly question, anyway I’ve been caravanning for 35 years and I don’t know what VSR is. Can someone explain??

 

[Dave H]

Not sure if I’m asking a silly question, anyway I’ve been caravanning for 35 years and I don’t know what VSR is. Can someone explain??

Hi Mike it's a voltage sensing relay when it senses the engine has started it switches open to allow the leisure battery to charge off vehicle but when it's off it stops the leisure battery drawing on the starter battery.

 

[Pfcmike]

Thanks for that. We learn something every day.

 

[RogerL]

Some VSRs are adjustable - in any case you'll need to check the make-break voltages for the specific VSR you're using.

If the cable run to the leisure battery is significant, you'll need to use oversize cables to avoid voltage drop.

 

[Dave H]

Some VSRs are adjustable - in any case you'll need to check the make-break voltages for the specific VSR you're using.

If the cable run to the leisure battery is significant, you'll need to use oversize cables to avoid voltage drop.

Hi Roger cable run is around 2ft just strange as it all runs OK on tick over but as soon as I drive it itturns off then comes back on after restart. Waiting for a caravan engineer guy to contact me. The relay I have is only a 30amp so wondering whether to stock a 120amp one on see if it works better?

 

[ProfJohnL]

It could also be the car. Some modern cars have "smart" alternators which only produce charging power when certain battery and load conditions are met.

 

[Dave H]

It could also be the car. Some modern cars have "smart" alternators which only produce charging power when certain battery and load conditions are met.

Hi John vehicle in question is a 2012 merc vito van.

 

[ProfJohnL]

Hi John vehicle in question is a 2012 merc vito van.

I don't know which cars have smart alternators or not. That is something you would have to establish about your particular vehicle.

 

[Gralay]

Hi
Don't know if this could be relevant but I a similar problem with my mondeo, it would seem to charge OK but didn't, I got a cheap plug in voltmeter to find when started it would charge at 14v then as I drove the voltage would drop, after some research I found that in the charge circuit was a BMS (battery monitoring sensor) that could be reset easily on mondeo by putting ignition on and turning on fog lights and hazards in a sequence which I did and cured the problem no more drops in charge voltage,may be something similar on your Vito
Gra

 

[Dave H]

Hi
Don't know if this could be relevant but I a similar problem with my mondeo, it would seem to charge OK but didn't, I got a cheap plug in voltmeter to find when started it would charge at 14v then as I drove the voltage would drop, after some research I found that in the charge circuit was a BMS (battery monitoring sensor) that could be reset easily on mondeo by putting ignition on and turning on fog lights and hazards in a sequence which I did and cured the problem no more drops in charge voltage,may be something similar on your Vito
Gra

Thanks will do some research

 

[bertieboy1]

Have fitted a 100ah leisure battery to my van along with 30amp vsr if I stick a meter on at idle it reads 13.9v then with engine off 12.2v however if I run round the block then stick meter on at idle it reads 12.2v then if I restart engine it goes back to reading 13.7v does this mean the vsr is turning off at anything other than idle speed? And if so what's the answer to stop this happening? Higher ampage vsr? Just seems that the switch is switching off at anything other than idle speed.
Tia dave

Hi,
30amp is just the rating of the relay contacts and nothing to do with voltage sensing operation.
Have you tried cleaning the relay contacts.