Can battery isolators ever let current through when off...

[casper ghost]

I only ask as I have just connected the leads to my battery and it sparked slightly as it was being touched, but the positive lead goes straight to an isolator, the standard type with the red key.. This is on an old vehicle, not on the boat. Can't see how there can be any connection to allow a spark, unless it's the isolator itself.

Casp'

[nicknorman]

I only ask as I have just connected the leads to my battery and it sparked slightly as it was being touched, but the positive lead goes straight to an isolator, the standard type with the red key.. This is on an old vehicle, not on the boat. Can't see how there can be any connection to allow a spark, unless it's the isolator itself.

Casp'

Yes anything a bit damp might "leak" but not, I would have thought, to the extent of giving a spark. Are you sure that the only thing going to the isolator's stud is the wire from the battery? Someone might have added a "permanently on" thing to that stud, but its out of sight at the back of the isolator? Perhaps whatever it is has a capacitor that charged up.

[casper ghost]

Yes anything a bit damp might "leak" but not, I would have thought, to the extent of giving a spark. Are you sure that the only thing going to the isolator's stud is the wire from the battery? Someone might have added a "permanently on" thing to that stud, but its out of sight at the back of the isolator? Perhaps whatever it is has a capacitor that charged up.

I will have to take a look. It's an old landy, and I can't see the back of the isolator without pulling a dash panel forward a bit. I've looked before but can't remember..

Casp'

[frangar]

On my boat the Voltage sense lead for the Victron Charger lets a small amount of current flow…enough to power an LED light or the aerial amp….its very annoying! Means that even if you isolate the batteries via the switch you still have to make sure everything is off or the fuse pulled.

 

Ive mentioned it to Victron…..they weren't very helpful!

 

I doubt this is the reason in your case though….I too would go for something connected to the live side of the switch.

 

Cheers

 

Gareth

[casper ghost]

Hang on.. I think I may have connected the stereo memory to the permanently live stud as I don't loose my channels every day when I switch the isolator off, but now I've had the battery out the channels are lost..

Casp'

[bottle]

I think you have found the 'problem' but those isolators are not the best.

If it is not 'breaking' fully then it has not isolated,

[Chewbacka]

My radio 'always on' feed sparks when I connect it.

I pull the fuse if leaving the boat for more than a few days.

[blackrose]

Someone once told me that cheap isolators can fuse together when switching and then remain on even though you think they're in the off position. Is that true?

[bottle]

Yes.

[WotEver]

Someone once told me that cheap isolators can fuse together when switching and then remain on even though you think they're in the off position. Is that true?

Yep.

[Radiomariner]

Someone once told me that cheap isolators can fuse together when switching and then remain on even though you think they're in the off position. Is that true?

Yes. To prevent this you should ensure all circuits are shut off before before opening or closing the isolator to avoid arcing (and subsequent welding) at the switch. Isolating in an emergency is of course the exception to this rule.

Edited November 25, 2015 by Radiomariner

[DHutch]

Hang on.. I think I may have connected the stereo memory to the permanently live stud as I don't loose my channels every day when I switch the isolator off, but now I've had the battery out the channels are lost..

Casp'

That would do it.

 

As would overloading the isolator such that the contacts weld themselves together and stick in the closed position even with the key removed. Quite easy to do if the set-up is incorrect as the smaller isolation switches simply are not rated at the currents large inverters etc take.

 

 

Daniel