Parasitic batter drain.

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Parasitic batter drain.

Postby Nigel Blandin » Sat Mar 13, 2021 18:35

Hi there, Has anyone got a battery drain problem.
My fist Cappuccino used to go flat when it was brand new! My current one enjoys doing the same.
All the star are checks done.
Connecting a meter in series, sows a small current with every thing off. The only change is when I pull the fuse for the rear fog light...the one on the side of the fuse box.
The wiring diagram shows no separate earth for this, as it’s a Uk addition, I suspect.
Considering adding a direct earth for the light. Any ideas!
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Re: Parasitic batter drain.

Postby Martin Williams » Sat Mar 13, 2021 21:04

The way the rear fog is wired it will still draw some current if you leave it switched on with the ignition off. I have seen posts in the past about minor circuit modifications to address this. I just try to remember to turn it off after driving in poor visibility!

See page 8-25-2 of the Service Manual for the circuit diagram.
A cure is suggested in the FAQ viewtopic.php?f=29&t=1715
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Re: Parasitic batter drain.

Postby Ian Linden » Sun Mar 14, 2021 14:57

Unless you use the Cappo a great deal, you could do what I have done - fit a battery isolator to the battery negative post. That way there is no drain when the car is out of use. Work of a moment to pop the bonnet and de-isolate.

With the Cappo, there is no downside, as the ECU, unlike more modern cars, has no memorised parameters which would be lost when the battery was disconnected. Of course, the radio would lose its presets, if it is the type which requires a keep-alive voltage.
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Re: Parasitic batter drain.

Postby Murray Betts » Mon Mar 15, 2021 13:23

Yes, the fog light relay switch/coil is supplied by a permanent feed, so if you accidentally leave the switch in the "on" position when you switch the ignition off, the light goes out but the coil is still energised and drawing something like 100mA.
I killed my first battery due to this when I went away to work for a month and the battery was totally drained and didn't recover.
I'm sure it can be relatively easily rewired for an ignition switched feed to the switch/coil, I just double check it is off.
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Re: Parasitic batter drain.

Postby Nigel Blandin » Mon Apr 05, 2021 06:26

Thanks guys, I have pulled the fuse on that circuit to see how it behaves over a couple of weeks and, so far so good. I have been considering the isolator Iain, but that’s an admission of defeat!
The answer is, of course, use the damn thing more!!
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Re: Parasitic batter drain.

Postby Ian Linden » Mon Apr 05, 2021 09:00

Murray Betts wrote:Yes, the fog light......
I'm sure it can be relatively easily rewired for an ignition switched feed to the switch/coil, I just double check it is off.


Yes, a scheme has been in the FAQ since 2004 :D

http://www.suzuki-cappuccino.com/phpbb3/viewtopic.php?f=29&t=1715

It allows the fog to be on when the ignition is off, but the headlamps are on, to cater for an emergency situation. I'm not sure whether this is a statutory requirement.
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Re: Parasitic batter drain.

Postby Ian Linden » Mon Apr 05, 2021 09:15

Nigel Blandin wrote:...... The only change is when I pull the fuse for the rear fog light...the one on the side of the fuse box.
The wiring diagram shows no separate earth for this, as it’s a Uk addition, I suspect.
Considering adding a direct earth for the light. Any ideas!


The wiring diagram for the UK Spec rear fog lamp is at Page 8-25-2 of the online Service Manual (UK Supplement page, so the index shows the page number in red). The scheme for overcoming the drain takes this rather convoluted circuit into account.
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