Over the last few months my Bay has suffered a number of blown fuses on the split charge circuit to the leisure battery. This led to me installing a VDO voltmeter on the dash so I could see when the leisure battery was not getting a charge. Consequently I discovered that it was the original relay at fault. Rather than replace it with an identical unit I chose to fit a Smartcom Self Switching Relay which monitors the charge in both the starter battery and leisure battery and (in theory) will not a) allow the starter battery to go flat and b) not overcharge the leisure battery and consequently keep blowing fuses.
So here's how I did it - very straight forward. I purchased the Smartcom unit via Ebay. It was £17 including delivery and turned up very quickly. It needs 3 connections: positive from the starter battery (fused), positive to the leisure battery (fused) and a good earth. That's it.
It's handy if you have a voltmeter/circuit tester for the job as you can check what's getting what. Replaces the original split charge relay Wiring for new relay It's vital that you have a 20amp fuse near to both positive terminals on the starter and leisure battery: Now I can see when the leisure battery is getting a charge - it does what it says - after the alternator has recharged the starter battery the amount of power it took to start the engine the relay then switches power to charge the leisure battery. I had to adjust the output of the relay initially (clockwise) by about 1mm to get the right power output from the relay but now all seems good and most importantly no more blown fuses.
________________________________________________________________________________ Max SportsKombi - The Bay Racer @brazilianvwbay
TimV Admin
Cabin : Flight 001 Location : Brighton, East Sussex U.K. Posts : 14341 Join date : 2009-09-27
Just a footnote to this install. I recently had to change the leisure battery as it was only returning 10.5 volts regardless of how much charge it was getting. (It was replaced by Tayna with 1 month of the 3 year warranty to run! All I had to cover was the delivery of the old battery back to Tayna.)
When I first installed the new battery it was drawing more charge from the alternator than the previous one - evident by what I could see on the voltmeter. The Smartcom should only allow charge through to the leisure battery once the starter battery is up to peak. However I could see when activating the starter motor that it was pulling voltage from the leisure battery instead of just the starter battery, so I adjusted the Smartcom to get the balance right. This wouldn't be so obvious if there was no voltmeter in the circuit, however if something as basic as a bulb was fitted on the charge feed to the leisure battery, this could then indicate when the leisure battery is receiving voltage when it should be.
________________________________________________________________________________ Max SportsKombi - The Bay Racer @brazilianvwbay
dizzylizard
Cabin : Exec 018 Location : Bradford-on-Avon, Wilts and Bristol Posts : 2241 Join date : 2011-09-20
My dash voltmeter constantly shows the voltage of the leisure battery, so I can see when the Smartcom starts to allow charge through - the needle moves up to around 13 volts. It doesn't show the starter battery charge.
The bulb would need to go in between the output from the Smartcom and the positive terminal of the leisure battery, so that would require some lengthy wiring if you wanted it on the dash. I am suggesting you put it between the Smartcom and the leisure battery as a means of setting up the Smartcom, there's an adjustment screw, so you can check that the feed to the leisure battery is 'coming on' appropriately.
________________________________________________________________________________ Max SportsKombi - The Bay Racer @brazilianvwbay
dizzylizard
Cabin : Exec 018 Location : Bradford-on-Avon, Wilts and Bristol Posts : 2241 Join date : 2011-09-20
My new leisure battery has a small light on top which shows green when charged and red when not, as well as having the circuit tester that Danbury fitted which shows the chagre in the leisure battery.
Hi Tim just out of curiosity what is the output from your alternator measure this on your engine battery, just above tick over should be around 13.6 volts.
TimV Admin
Cabin : Flight 001 Location : Brighton, East Sussex U.K. Posts : 14341 Join date : 2009-09-27
