Isolator switch

[FARKIT]

Does anyone else suffer from a quick to drain battery? Mine's less than a year old, and is charging properly, so I was thinking about fittin an isolator switch to a) help stop te drain, and b) as an extra security/safety feature - any advice/comments?

[ChrisGadd]

Only problem may be that if the battery is totally isolated the ECU will have to re learn the settings again. I think someone on here fitted an isolator with a fused feed to supply enough power to keep the ECU memory.

[FARKIT]

That's an interesting point - what happens if the vehicle is laid up with the battery disconnected? Does the ECU have to relearn? I thought they were mapped and that was that - although I have heard of ECU learning tricks on later cars.

[Roy C]

Parasitic draw?

http://www.wikihow.com/Find-a-Parasitic-Battery-Dr...

How To Perform a Parasitic Draw Test (video)

AFAICR the Ford EEC-IV ECU does "re-learn" after reconnection.

Even if you have a low-rated fused feed (for the radio memory, alarm, etc), a parasitic draw will still drain the battery.

Edited by Roy C on Tuesday 22 May 10:22

[phillpot]

Have an isolator fitted to mine, easy way to disconnect battery when working on car and never noticed any ECU issues when switching back on (just have to re-set clock )

[FARKIT]

I was hoping someone would say that!

[GreenV8S]

I have an 'intelligent' isolator on mine that only cuts the power when it senses the battery is getting low (and the engine is not running) and automatically reconnects afterwards. It's great for preventing 'lights on' type flat battery situations, or any other situation where you don't think to isolate the battery. It's a V8S so not the same system as the V6, but I never had any problems with the ECU or alarm.

[phillpot]

GreenV8S said:

I have an 'intelligent' isolator on mine

Mine's definately the non intelligent type

[Maffe]

I have a simple isolator fitted since it was a requirement from the insurance company.
Always cut the power during winter and put a maintenance charger on the battery, have had no problems with it.

[tvrgit]

Discussed on this thread about 3 years ago (I know that search is down but I remembered the thread so knew where to look).

http://www.pistonheads.com/gassing/topic.asp?t=666...

If you look at my post about 6 posts in, I pointed out that the Ford EEC IV ECU does have a "learning" facility, and that those will reset if the ECU is disconnected. Mine certainly does - if I disconnect and reconnect the battery, the car isn't right till it's been through a couple of cold-hot-cold cycles.

An isolator switch would have the same effect.

Fortunately (or rather, not just fortunately, I have made sure that it is so) the battery and charging system work properly, and the engine is set up properly, so that it always starts first turn of the key, every time, even after being left unattended for months on end, even in winter. So I don't need an isolator anyway.

Famous last words....

[Maffe]

I think the isolator switch is more a safty thing. If you get some electrical error and need to cut power quick a switch do the job.

[tvrgit]

Maffe said:

I think the isolator switch is more a safty thing. If you get some electrical error and need to cut power quick a switch do the job.

Exactly. It's a safety thing. It's not the solution to a charging / battery problem where its regular use might do your car more harm than good.

[Ozzie54321]

My S will sit in the garage for over 3 weeks between use (over the winter) with out draining the battery and its got an alarm and imobiliser blinking away all the time. So there has to be some unusual electrical drain somewhere.

[shoab]

Althought the battery is only a year old it could still not be holding charge, maybe get it tested first.

Graham

[FARKIT]

I think you're right - test the battery first!

[gerradiuk]

phillpot said:

Have an isolator fitted to mine, easy way to disconnect battery when working on car and never noticed any ECU issues when switching back on (just have to re-set clock )

+1 never had any problems regarding ECU etc.
Did have one though, the previous owner had fitted one of those cheapy switch's with the large plastic key, it did not like the heat under the Cerbera's bonnet & split along the seam to let moisture.
I have since fitted one of these to the outside which is well made & save's opening the bonnet each time.
http://www.ebay.co.uk/itm/Durite-0-605-20-Battery-...

[tvrgit]

gerradiuk said:

+1 never had any problems regarding ECU etc.
Did have one though, the previous owner had fitted one of those cheapy switch's with the large plastic key, it did not like the heat under the Cerbera's bonnet & split along the seam to let moisture.
I have since fitted one of these to the outside which is well made & save's opening the bonnet each time.
http://www.ebay.co.uk/itm/Durite-0-605-20-Battery-...

Fair point, but the Cerbera doesn't have a Ford EEC IV ECU, does it? That ECU does lose its learned settings (much the same as "adaptives" on the Cerb's ECU) when it's disconnected.

Maybe the difference between the "learned" settings and the "default" setting varies from car to car, depending on how it's driven and what other faults it might have (sensor signals etc) but the Ford ECU WILL lose them if it's disconnected.