Dave Tayside Posted April 18, 2008 Share Posted April 18, 2008 I considering installing a battery isolator switch on the vehicle battery on my 2005 2.2HDi Boxer based Ravenna. Does anyone have any idea as to what the cold cranking current is likely to be and therefore the current rating of any battery isolator switch I instal. Is it ok to put the switch on the negative pole of the battery. I'd normally opt for the positive, but it is very difficult to access. The reason I'm considering an isolator switch is that battery voltage is dropping to about 9 to 10V over a period of around 4 days. I've still to do a few more tests to try to trace what's gobbling the volts, but an isolator would be handy over the winter months anyway (also a good anti-theft device). The battery is new as I've only had the van 3 weeks. I thought the original battery was duff as the van wouldn't start a few days after getting the van home so I got the dealer to change it last week. Link to comment Share on other sites More sharing options...
gboden65 Posted April 18, 2008 Share Posted April 18, 2008 Hi Dave, should be ok,on negative, but you have paid a lot of money to a dealer, after three weeks,I think you should be knocking on his door, to sort this problem for you, best of luck. ;-) Link to comment Share on other sites More sharing options...
Clive Posted April 18, 2008 Share Posted April 18, 2008 1 You need to put an ammeter is series with the battery negative post to monitor the leakage current when everything is turned OFF then go round and find what is discharging the battery. 2 Your vehicle alarm will be non operational if you disconnect the battery If you still wish to fit an isolator put it in the negative connection, it needs to be good for at least 300 amps as this can easilly be the cold cranking current in winter. C. Link to comment Share on other sites More sharing options...
Guest Tracker Posted April 18, 2008 Share Posted April 18, 2008 Two potential culprits for secret current gobbling are the radio not being wired correctly or an alarm being set? I had similar problems with an Auto Sleeper talisman where the radio had been rewired to overcome the 20 minute cut off but it had left it drawing current even when switched off. If you have a multi meter you might be able to measure the current drain and pull each fuse in turn, starting with the radio, until, with luck, it stops? Link to comment Share on other sites More sharing options...
Clive Posted April 19, 2008 Share Posted April 19, 2008 Spot on Rich. Link to comment Share on other sites More sharing options...
Dave Tayside Posted April 19, 2008 Author Share Posted April 19, 2008 Many thanks guys. You've hit the nail on the head! I spent the morning with an ammeter and have confirmed that the radio is draining the battery. Even when OFF the radio is drawing 0.7A! There is a switch beside the bed marked "Radio Isolator Switch" which seems to be for switching the radio off remotely. It works, but when in one position even with the radio apparently off 0.7A is being drawn. Using the main on-off on the radio it doesn't matter which position the remote switch is in - the radio turns on and flicking the remote swich over turns it off. However with the remote switch in one position I'm getting significant battery drain. Very strange, but at least I now know that if I leave the remote switch in the right position I'll not end up with a flat battery. Link to comment Share on other sites More sharing options...
Guest Tracker Posted April 19, 2008 Share Posted April 19, 2008 Result eh! And much more cost effective than an isolator switch too! Well done Dave. Link to comment Share on other sites More sharing options...
colinfrier Posted April 22, 2008 Share Posted April 22, 2008 Hi I would advise against ever fitting a battery isolator switch on more than one ocassion I have experianced low starter motor speeds caused by failing switches but sounds like you got it sorted. Coln Link to comment Share on other sites More sharing options...
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