Isolator switch - how essential are they?

[Nos4r2]

Originally Posted by Chris

Won't that fry the alternator?

Might do-depends what protection they've got-but it's just as likely to fry your alternator after it fries your electronics.

Point is, if you're in a situation where you can't safely stop to bolt the two terminals of the isolator together then it's a good idea to turn your electronics off to protect them.

[jwalker]

I have a main switch but I only switch it off for security reasons. With the exception of the starter motor, the whole electrical system should be protected by a fuse as close to the battery or the main switch output as possible. Cables on fire should not be an issue. The fuse rating should be chosen so that in the event of a system short circuit the fuse will blow quickly. Individual pieces of equiment will obviously have their own fuses too. A 20amp rating for the main fuse is probably ample for most installations.

I guess this doesn't cope with those situations described above where devices have inexplicably activated themselves.

There is a train of thought that bilge pumps might be better on a separate circuit and not fused because the alternative to one failing could be a sinking boat. Though, in the case of a rib, this isn't likely.

[J S]

Originally Posted by Leapy

Is this true? In what way does the switch cause the ecu trouble that is avoided if you disconnect the power cable from the battery?

Yes,It doesn't it would be the same as disconnecting the power cable from the battery as you say. Was just letting people know from experience that when power is disconnected from a running engine it can cause those problems.

James

[Nos4r2]

Originally Posted by J S

Yes,It doesn't it would be the same as disconnecting the power cable from the battery as you say. Was just letting people know from experience that when power is disconnected from a running engine it can cause those problems.

James

You may well be right. However, it's exactly the same as running with a defective isolator and if you're not in a safe place to rectify the problem it's not a good idea to stop and try.

[IBWET]

Originally Posted by waverunner

From personal experiences I would certainly fit one.

When I put my rib package together I was advised (by a dealer) not to fit an isolator because apparently ECU,s don't like them, just connect from the battery direct to the engine starter solenoid.

I had a good day out, recovered the rib onto the trailer, sat with the family having a sandwich and brew, suddenly the engine started to turn over and I had no means of isolating. It was a mad rush to find a spanner to disconnect the battery, by the time I had done this the starter motor had burnt out. I had to have a new starter motor and pump impeller fitted due to it being out of the water and running dry.

The culprit was found to be a loose connection on the starter solenoid.

I had the same thing happen to me years ago with a merc 60,(solenoid wouldn’t disengage) if i'd had a 13mm I could have got the battery clamp off, as I didn't, I just had to wait until the battery was flat, resulted in me needing to buy a £160 starter motor. I've wondered myself if the isolator was really needed. You have just reminded of the above.

And another thing I have a basic set of tools on the boat always...

[GED]

Had an isolator fail, my a johnson 200 overcharged and went on fire

[Nos4r2]

Originally Posted by GED

Had an isolator fail, my a johnson 200 overcharged and went on fire

!

What Johnson was it?

[gtflash]

Ive seen some thru bulkhead battery switches on ribs recently........... Are they waterproof from front?? Think it was on a pascoe and one of those big white italian things with even bigger engines on back!

[Nos4r2]

Originally Posted by gtflash

Ive seen some thru bulkhead battery switches on ribs recently........... Are they waterproof from front?? Think it was on a pascoe and one of those big white italian things with even bigger engines on back!

Depends what switch it is I guess-the one on my boat is sealed inside a box with only the bit the key goes through sticking out yet it still failed last year. No water can get to the back at all.

[Chris]

Originally Posted by gtflash

Ive seen some thru bulkhead battery switches on ribs recently........... Are they waterproof from front?? Think it was on a pascoe and one of those big white italian things with even bigger engines on back!

http://www.power-store.com/view-item...d=1116&id=190&

These are vgood and easy to fit. Not fully waterproof though, when looking at Isolators I could not find one that was sufficiently waterproof to be mounted on the outside of the console so I opted to mount mine so that it goes from the inside of the console into the suicide seat where I can access it by lifting the seat.

[GED]

Originally Posted by Nos4r2

!

What Johnson was it?

this one