Isolation switches
Submitted: Thursday, Dec 07, 2006 at 09:10
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Ray Bates
I have been considering installing one of those swiches in my system. I believe that they are called Hersy. The switch that I was considering was the type that has two way. No1, No2 and both. What does concern me is can they be switched with the vehicle engine running and if so is there any danger to the alternator?
Thank you
Reply By: Notso - Thursday, Dec 07, 2006 at 09:29
Thursday, Dec 07, 2006 at 09:29
Especially with the computer controlled vehicles these days. Anything that can cause sparking or power surge can corrupt the computer.
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209111
Reply By: Member - andrew B (Kununurra) - Thursday, Dec 07, 2006 at 09:51
Thursday, Dec 07, 2006 at 09:51
Gday Ray
The better Quality ones have a switch that goes 1 to both to 2 to off with no gaps ie there is always at least one battery connected to the system (except the 'off position) If you are confident you will not switch it to the off position while the engine is running you should have no problems with it. I considered this option, but went with a simple solenoid hooked up to an ignition wire. To give me the option of not having the aux battery hooked up I have a simple isolater on the -ve terminal of the aux battery. So far no problems. Some vehicles don't have a problem if the battery is disconnected while running, but I wouldn't risk it on most modern vehicles.
Cheers Andrew
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209113
Follow Up By: Kiwi Kia - Thursday, Dec 07, 2006 at 11:10
Thursday, Dec 07, 2006 at 11:10
Repco and most marine shops have a device that goes between the cable and the battery terminal. It is a green knob that when turned isolates the battery. If you have one of these on each battery you can turn off either or both.
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Follow Up By: Member - andrew B (Kununurra) - Thursday, Dec 07, 2006 at 11:17
Thursday, Dec 07, 2006 at 11:17
Yep, thats the one I have on my aux battery - so far have chosen not to put one on the main battery as it would isolate both due to the solenoid I have hooked up to the ignition. having one of these on each -ve terminal and just hard wiring both batteries under the bonnet would be one of the cheapest solutions, but would require all accessories etc to be earthed to the chassis/body, wheras my fridge etc is earthed to the (aux)battery. Generally, everything should be able to be earthed to the body/chasis, bet enough people have suggested to me that if the planets all line up you may get a situation where a high amp devise may earth through the fridge, but if it has its own circut, this shouldn't hapen. I'm not entirely convinced this will never happen, but ran the earth wires back to the battery anyway
Cheers Andrew
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469135
Reply By: Member - Davoe (Nullagine) - Thursday, Dec 07, 2006 at 11:30
Thursday, Dec 07, 2006 at 11:30
with these switches they isolate the earth to the seperate batterys with the positives between the batterys joined. switching batterys should have no effect on the Alt as they are not that sensative and switching between batterys is pretty darn quick. I used to drive for hours with the ignition turned off in a previos vehicle so there was no interferance with the radio in weak signak areas (gotta be able to hear the footy/cricket)
as mentioned a computer controled vehicle may have issues but I dunno
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209124