Battery Isolation Switch

Muzz · #1 08-11-2005, 05:40 AM

Help please?

I want to fit a battery isolation switch to my cranking battery.
I have purchased a very simple one, pic attached.
Do I connect all the positive leads already on my battery straight to the switch and then run a short positive lead to the battery from the switch?
Do any of the connections have to be grounded at all to the boat?
I did not think any leads should be in connection with the hull, is that right?
Do the negative leads and wires stay where they are on the battery?

Thanks Muzz

BIG PETE · #2 08-11-2005, 05:50 AM

Muzz
im pretty sure that type of switch just goes in the main power lead
never ground anything to the hull as electrolisis will eat the hull away in no time

BIG PETE

Rosie · #3 08-11-2005, 06:04 AM

The only leads you need to put onto the switch are the ones you wish to isolate. You would usually want to isolate all of them for safty. maybee you want to leave the tilt/trim which for some reason is often seperate and we have seperate ignition so we can just pull start it if the electronics short circuit. i hope that helps.

crabcrusher · #4 08-11-2005, 06:09 AM

Definantly dont ground anything . Yes you do run all the positives back to one side of the switch and securely fix with lugs . Then run another piece of cable back to the battery from the other side of the switch . Be sure that the cables size is rated at the correct current rating ,to elimante any chance of "wireyfirey syndrome".
If the distance from where the positives are all located now are to far from where you want the isolation switch , you could possibly junction them all and run a single piece of wire to the active side of the switch . You can obtain an insulated busbar complete withplasic cover from your local electrical wholesaler , (part -Clipsal L5 Insulated neutral Bar). Best of Luck

And as Benrose said you may not want to isolate everything so remove each positive from the battery one at a time to investigate what it controls . You may want ot leave you nav light off , or even your sounder . The world is your oyster...

Muzz · #5 08-11-2005, 07:21 AM

Thankyou guys.
I thought this was the case.
The reason I was asking about wiring to the hull was I was in Millards tonight. On my way out I thought I would check out the battery isolation switch on a brand new 400 Hornet Trophy. I used to have a 400 so I knew it would have an isolation switch.
It had the Negative leads attached to the hull in the battery box compartment. I thought that cant be right?

Hence the post
Thanks again people
cheers Muzz.

Alex · #6 08-11-2005, 08:01 AM

Hi Muzz,
Firstly, I think you'll be better off if you wired all of your negatives and positives from you onboard electrics to two separate bus bars-one is "positive" and the other is "negative", instead of running all positives to one post of the isolation switch as previously suggested. These bus bars are available from Whitworth's (cat. no 33504 or 33500) or similar.

Secondly, once you have done that, then run a wire (appropriately sized) from the positive on your battery to one of the switch contacts. Then, the same sized wire from the second switch contact to the "positive" bus bar.
Run "negative" wire from the battery to the "negative" bus bar. This is a simple solution to isolate all of your electrics. If you want to keep some of them oermanently connected to the battery, then you either should use a control switch for each of the loads or connect them directly to the first contact of the switch.
Cheers,
Alex