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Parasitic Battery Drain #1598778
18/04/2017 11:29
18/04/2017 11:29
Joined: Aug 2007
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Southsea
Gunzi Offline OP
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I have a parasitic battery drain, I'd not driven my Coupe since returning the Practical Classic show on 2nd April and yesterday after getting my son excited about a trip out in the Coupe he and I were rather disappointed when nothing happened when I tried to fire it up - battery flat as a pancake, not a single light on the dash.

What is the best way locate what is causing this drain on my battery?

Re: Parasitic Battery Drain [Re: Gunzi] #1598779
18/04/2017 11:35
18/04/2017 11:35
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Try a earth drain check with a ammeter, disconnect earth lead and place the meter from the lead to the chassis, this should register a reading but from memory we discussed your amp in the boot and this likely being the culprit as it went flat on me a couple of times while in my care.

Re: Parasitic Battery Drain [Re: Gunzi] #1598784
18/04/2017 12:45
18/04/2017 12:45
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Kent
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was going to say the 'stereo'. Left mine on mute all day and night etc many moons ago, lesson learnt.

Re: Parasitic Battery Drain [Re: Gunzi] #1598818
19/04/2017 06:19
19/04/2017 06:19
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Southsea
Gunzi Offline OP
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OK, so I am a *complete* novice when it comes to testing electrics. Here are some perhaps silly questions:

I can get hold of a voltmeter - is this suitable?
What do I turn the dial to on the voltmeter?
Do I disconnect the battery and place the voltmeter cables between battery and earth lead?
Does it matter which way round the red and black cable goes?

Re: Parasitic Battery Drain [Re: Gunzi] #1598830
19/04/2017 10:00
19/04/2017 10:00
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Hemel in the Hempstead
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You're trying to measure current drain. Most multimeters will measure up to 10A internally fused, usually through a different socket on the meter. Some only do 300mA, which might be low for your system.

So the meter needs to be on the 10A range, and the wires in the common and the A socket.

Don't disconnect the battery - you can, but better to look at the current on various circuits by removing the fuse and measuring the current through that particular fuse by sticking the meter across the holder tags. You might need to make some tag adaptors.

Once you've identified the circuit (refer to the drawings, I'm afraid, and don't forget to close the door so the interior light goes off) then you're in a better place to continue investigations.

Most meters will be able to measure positive and negative current, so no issue there with red and black - just swap the leads round if you want to see positive.

There should certainly be nothing pulling anything like 10A - that would kill the battery in five hours or less - but be aware that the alarm and door lock circuit pulls a few tens of milliamps at all times.

*DON'T TRY AND START THE CAR* while doing this.



Don't get no respect! Coupe Fiat 1994-2000 - an owner's guide <-- clicky!
Re: Parasitic Battery Drain [Re: Gunzi] #1598831
19/04/2017 10:01
19/04/2017 10:01
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Also - if your radio is code locked, make sure you have the code before you start...



Don't get no respect! Coupe Fiat 1994-2000 - an owner's guide <-- clicky!
Re: Parasitic Battery Drain [Re: Gunzi] #1598832
19/04/2017 10:11
19/04/2017 10:11
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Lightwater, Surrey, UK
DaveG Offline
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You'd need a multimeter that measures DC amps, and these are not very common. Or a "clamp" meter that clamps (loosely) around the earth cable. And even if you do find a suitable DC amps multimeter at a sensible price one (say less than £100) you have to make sure you plug in the leads to the right terminals on the meter (often there are 3 or 4, and one or two are specifically for DC amps, different ranges). Some cheaper meters might not be sensitive enough to register much of a reading. I've tried both (multimeter and clamp) without much luck to measure similar small current drains.


1996 Portofino 20vt & 2000 Pearl White Plus
1985½ & 2016 2017 Fiat 124 Spider + XF Sportbrake
Re: Parasitic Battery Drain [Re: Gunzi] #1598834
19/04/2017 11:04
19/04/2017 11:04
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szkom Offline
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You could try one of these off the bay:

400433639239

Re: Parasitic Battery Drain [Re: Gunzi] #1598856
19/04/2017 18:11
19/04/2017 18:11
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Hemel in the Hempstead
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Exactly the part, Szkom.

What I was suggesting with my blade adaptor and multimeter. Clamp meters are a waste of time in the tight bundles you get in the car, hence my measure the current through the fuse holder.



Don't get no respect! Coupe Fiat 1994-2000 - an owner's guide <-- clicky!
Re: Parasitic Battery Drain [Re: barnacle] #1598863
19/04/2017 19:09
19/04/2017 19:09
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szkom Offline
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They're a nice little bit of kit. As you mentioned earlier most DMM will run up to 10amps. For a few quid these will do ~20, and a reasonable outlay gets you to the 60s.

To Gunzi: I'd consider changing the battery. If you've got a drain and a very flat battery, I'd put money on it not holding a charge properly.

Re: Parasitic Battery Drain [Re: Gunzi] #1598885
20/04/2017 07:23
20/04/2017 07:23
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Going North on the A9
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Hey Gunzi-

With reference to the advice given above- here is an example of what a voltmeter might look like if it was being used more conventionally to measure voltage only;

click to enlarge

And here, is how you might want to configure such a voltmeter to measure current, on your car- note the change to both the lead position, and rotary control;

click to enlarge

Last edited by dante giacosa; 20/04/2017 07:24.
Re: Parasitic Battery Drain [Re: Gunzi] #1598919
20/04/2017 13:50
20/04/2017 13:50
Joined: Aug 2007
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Southsea
Gunzi Offline OP
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Thank you to everyone posting here to help. I changed the battery late 2016 so hope I don't have to do it again, but if it's knackered because of this, it'll get changed.

I will be giving this a go at the weekend once I've jumped the car and after a long drive! I'll be sure to have the keys out at all times!

Re: Parasitic Battery Drain [Re: Gunzi] #1598976
21/04/2017 04:38
21/04/2017 04:38
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Hemel in the Hempstead
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Remember that the fuses aren't just pretty colours - make sure you put the same ones back in where they came from!



Don't get no respect! Coupe Fiat 1994-2000 - an owner's guide <-- clicky!
Re: Parasitic Battery Drain [Re: Gunzi] #1599159
23/04/2017 10:16
23/04/2017 10:16
Joined: Aug 2007
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Southsea
Gunzi Offline OP
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Cheers Neil!

Re: Parasitic Battery Drain [Re: Gunzi] #1599175
23/04/2017 16:10
23/04/2017 16:10
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Gunzi Offline OP
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So I jumped her this afternoon then went for a half hour drive to charge the battery.

I had spoken to a chap at work who suggested focussing on the things I'd added to the car. He suggested pulling the fuses for these items and checking the current at the fuse points. This is what I found with the keys out

Amp 1: 20 milli amp drain
Amp 2: 15 micro amp drain
Boostcontroller: 70 milli amp drain
Direct wiring to the fuel pump: 0 micro amps

I knew the boost controller would drain the battery so I unplug it after every drive, however I didn't realise the issue with the amps.

Both amps have direct fused live feed from the amp, negative to chassis (metal behind rear seats with paint scraped away), and a shared remote switch in series from the head unit (1 cable goes to amp 2 then onto amp 1).

Could the issue with the amps be the remote cable in series?

The HDI boost controller takes the switched live from the cigarette lighter in the dash, the same as the head unit. I can only assume the drain here is an inbuilt issue inside the boost controller? Is there a way I could test this?

I assume that amp 2 is the real issue with a 20 milli amp drain vs 15 micro amp drain of amp 1?

Re: Parasitic Battery Drain [Re: Gunzi] #1599182
23/04/2017 17:02
23/04/2017 17:02
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Battery capacity is about (depending on type) 50-70 Amp hours = 50,000 mAH

50,000 / 20 = 2,500 hours, aka about 15 weeks... that's not your problem; the battery will probably self-discharge at around that rate.

Microamps are two-tenths of bugger all... I worry about them at work, when I'm trying to make a tiny battery last six months, but you don't need to.

Keep looking, Chris!



Don't get no respect! Coupe Fiat 1994-2000 - an owner's guide <-- clicky!
Re: Parasitic Battery Drain [Re: Gunzi] #1599184
23/04/2017 17:07
23/04/2017 17:07
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70mA from the boost controller though is getting significant - you're looking at closer to a month to completely drain the battery, so probably only a fortnight to drain it to a works-but-won't-start state.

It's probably not a fault per se on the boost controller; it needs to drive the solenoid on the bypass valve and that's not usually a low-current standby. I'd suggest that unless the installation manual suggests otherwise, you should find a switched ignition feed for it. If it needs to remember settings internally, it might want a permanent-but-low-power feed and a switched feed.

Last edited by barnacle; 23/04/2017 17:07.


Don't get no respect! Coupe Fiat 1994-2000 - an owner's guide <-- clicky!
Re: Parasitic Battery Drain [Re: Gunzi] #1599188
23/04/2017 17:22
23/04/2017 17:22
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Have you checked that head unit isn't outputting to the amp switch wire continuously? I stand to be corrected, but I don't see why the amps should be pulling any current while switched off.

It's a simple check. Put your multimeter to volts on the correct DC scale. Put the positive probe to the switch connection on the amp, and the negative to ground. With the keys out of the ignition you should see no volts.

Re: Parasitic Battery Drain [Re: Gunzi] #1599196
23/04/2017 18:14
23/04/2017 18:14
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Something doesn't sound right there... the cigar lighter is ignition switched so how can the boost controller be drawing 70ma from it with the keys out?

What current drain is it showing directly at the battery with ignition off? If it's less than ~100ma then the battery itself is probably in need of replacement if it's not holding enough charge to start the engine after a week.

Re: Parasitic Battery Drain [Re: Gunzi] #1599203
23/04/2017 19:04
23/04/2017 19:04
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szkom Offline
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I don't think they're all switched, Graham.

Re: Parasitic Battery Drain [Re: Gunzi] #1599204
23/04/2017 19:32
23/04/2017 19:32
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Southsea
Gunzi Offline OP
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Thanks again all, I'll digest all the information here and continue investigating this week.

Re: Parasitic Battery Drain [Re: Gunzi] #1599452
27/04/2017 11:41
27/04/2017 11:41
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Gunzi Offline OP
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Ok some results from the next round of testing:

Pull the negative off the battery and with the keys out I measured 130 milliamp drain

The logic being to understand the total drain on the battery

I disconnected the boost controller and repeated the test = 25 milliamp drain
I disconnected the suspect amp & boost controller = 25 milliamp drain

I'm confused as to the different results when I test pull negative cable vs testing directly at the fuses.

Will run the test szkom is suggesting next.

Regardless by pulling the earth cable it appears that my only drain is the boost controller.

I am starting to map out what additional wiring I've added to the car for boost controller and amps, as I suspect this may be part of the problem.

My Coupe gets driven once per week for about 10 miles, with the occasional longer drive once per month. I know this isn't helping matters, but still feel it shouldn't get flat in the interim.

Re: Parasitic Battery Drain [Re: Gunzi] #1599467
27/04/2017 16:01
27/04/2017 16:01
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Some of that current will be going to the under-seat window/lock controller and the theft alarm.



Don't get no respect! Coupe Fiat 1994-2000 - an owner's guide <-- clicky!
Re: Parasitic Battery Drain [Re: Gunzi] #1599496
28/04/2017 05:40
28/04/2017 05:40
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Gunzi Offline OP
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And clock?! So am I right in thinking a 25 milliamp drain could be considered 'normal'?

Re: Parasitic Battery Drain [Re: Gunzi] #1599500
28/04/2017 06:11
28/04/2017 06:11
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A manufacturer will generally expect the car to start after two or three weeks in an airport car park. Experience suggests that two weeks is rarely an issue.

That implies that the battery will hold at least half a charge, so you're looking at around 25Ah - that is, you could drain 25 amps for an hour, or 25 milliamps for a thousand hours (about six weeks) so on that basis, I'd suggest 25mA is an acceptable standing drain, *provided* the car is run sufficiently often to charge it (or a battery conditioner/trickle charger is used).

But you're losing six times that, which is why your car won't start after a week... you mentioned earlier I think that your boost controller is taking a continuous 70mA - I'd say that's your culprit there - it doesn't need to be powered when the car's not running, so find a switched supply, move it to that, and then see what the total at the battery is.

With any optimisation, you go for the low-hanging fruit first. There's no point worrying about a few milliamps here and there *until* you've got rid of the juicy big current drains.

(For what it's worth, I spend a lot of time at work doing the calculations and experiments as to what's the most efficient way to make batteries last - but in my case I'm dealing with currents sometimes in billionths of an amp. But the rules are the same...)



Don't get no respect! Coupe Fiat 1994-2000 - an owner's guide <-- clicky!
Re: Parasitic Battery Drain [Re: Gunzi] #1601049
21/05/2017 14:37
21/05/2017 14:37
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I would like to add a suggestion. I had this problem some time ago especially when leaving for long periods in airport carparks, etc.
I have fitted a disconnect switch on the battery, easily obtainable from ebay, halfords, etc. Never have any starting issues after long periods of idleness (the car, not me!). Good theft device also. Downside you have reset the clock and the radio, that's all.

Re: Parasitic Battery Drain [Re: Gunzi] #1601159
23/05/2017 11:21
23/05/2017 11:21
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dante giacosa Offline
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thanks for that lendickins- food for thought

any movement on this, Gunzi..?

Re: Parasitic Battery Drain [Re: Gunzi] #1621647
09/06/2018 18:23
09/06/2018 18:23
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Uk
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in the past I found faulty alternators to be a issue with battery drain.

you could try unplugging it for a night


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