Yet another battery drain topic!

[Captain Sparkle]

Hi people,

I've been having a problem for a while, I've searched many threads and learnt about testing for drains and that, but,

sometimes (not always!) it's showing a drain of around 5amps after the car has been running.

Auto electrician had it for a day but could find nothing wrong (it was OK for him).

As I say it's not every time. Have pulled every fuse from the engine bay fuse box & the interior box, to no avail.

Battery was replaced for a 77ah Exide about 2 months ago (that failed after 5 weeks and was replaced),

then alternator went about 3 weeks ago (replaced with higher output one to try and ease my paranoia!)

Have pulled out stereo and disconnected it but no difference to the drain.

When I break the circuit when testing with the multimeter the drain then goes down to around 1 amp, not perfect, but an improvement!

It's a 'classic', so doesn't have a lot of electrickery  to go wrong, and as I don't know a lot about such things I'm now stumped!

Anyone got any suggestions?

thanks.

[Tilt]

How did you find out about the battery drain in the first place bud?

 

Assume your battery kept going flat????????????

 

Also, be careful removing fuses unnecessarily! I did this trying to reset an airbag light, (it didn't work) and it caused a window control module to blow. (well it didn't work the very next time I tried to use it).

 

What happened to the 5 week old battery?

 

Does your hazard switch remain illuminated???? (probably only noticeable at night).

[Captain Sparkle]

Battery went flat a couple of times, but I put it down to the battery itself, and replaced it.

Then the new battery went flat over night, and when I took it back (europarts) they stuck it on their tester and said it was only showing 49%, therefore faulty, so replaced it. No one mentioned the possibility of something draining the battery, it was me being paranoid after all the hassle I'd had!

No sign of illumination on the hazard light switch.

 

BTW also loosened/sprayed contact cleaner on all the wires leading to the fusebox, and even remembered to tighten them up again!

Took off main Earth lead (near fusebox) and wirebrushed/contact cleanered/WD 40 before replacing it again.

 

Drain just now was 5.4 amps, it's been 4.5 or even up to 6, or thereabouts,

as I say, until you break the circuit, then its around 1 when you make it back up.

[paddypaws]

Can I ask how are you measuring the current draw of 5.4 amps as normally a meter in series  would break the circuit as you put it in circuit as you mentioned, and then the current draw  would be 1 amp. Perhaps you have clamp meter capable of measuring DC?

 

Taking fuses out shouldn't damage anything unless you have a very unlucky coincidence , its just the same as disconnecting the battery which it sounds like you've done before. To find which circuit is drawing current you could replace each fuse one at a time with a conventional multi meter on the 10 amp range. (normally meters are internally fused with a 10A fuse, so will be fine for short term testing purposes). You may need a couple of spade terminals to push in to the fuse holder or use a blown fuse and touch the metal end of the terminals on the blown fuse with the meter probes. The meters fuse then becomes the car fuse temporarily whilst you read the current. See the metal terminals on the top of the plastic fuse blade here:

 

http://valuestockphoto.com/stockimages/Technology/Audio/car_fuse0932.jpg.html

Edited 17 May, 2015 by paddypaws

[Captain Sparkle]

I have been loosening the negative battery terminal, then holding 1 multimeter probe on the battery terminal and the other on the earth lead, so the circuit is not broken when the earth/negative is removed.

Then the reading is around 5a.

When I (inadvertently usually!) move 1 of the probes the circuit is broken, then when I stick it back on it's around 1a reading.

I will try measuring the fuse terminals, but I can't understand how that can be any different to removing each fuse in turn?

I'll try anything!!

 

 

 

Thing is, since I had the battery replaced it hasn't gone flat, If it weren't for my paranoia I wouldn't have known anything about this 'draining' problem and just carried on life quite happily!!

 

[ryan-re]

you need to use a clamp which goes over the cable and can read the amps going through the cable.

 

You can get them for similar prices to multimeters, or if you are feeling flashy buy a Fluke 337

[meta55b]

Is the boot lights going off. I worked in an auto-electrical garage when I left school, we had a car in once that we couldn't find the drain till somebody said get in the boot and closed it, couldn't believe it. We had about 6/7 after that in one year with the same problem.

[Captain Sparkle]

Must investigate that 'magic' multimeter, would be easier!

regarding the boot, it's an estate that I have and I haven't seen the light on through the window.

Also, I'd virtually given up on the lightbulb scenario, being as the drain is around 5amps,

would that be the right train of thought?

[Ampere]

Just a random thought - you're not leaving anything plugged into the cigarette lighter socket overnight? The socket stays active all the time ...

 

Hope you get it sorted!

 

[Captain Sparkle]

Thanks, 'tis a good point!

No,  cigarette lighter socket is empty (now!).

 

 

Re; magic clamp multimeters, I'm having difficulty finding one to measure DC amps, the ones I've seen so far only seem to read AC amps.

[pikpilot]

Thanks, 'tis a good point!

No,  cigarette lighter socket is empty (now!).

 

 

Re; magic clamp multimeters, I'm having difficulty finding one to measure DC amps, the ones I've seen so far only seem to read AC amps.

I use a Tenma 72-7224 which you can buy from Farnell for about £28. It is also a good multi purpose meter apart from clamp on dc current measurement. I bought it for other purposes apart from automotive but the price was considerably more back in 2008. See the Farnell site for full spec.

[paddypaws]

Thing is 5 Amps is a lot of draw, about the same as a headlight, if your battery isn't flat over night then there's a mistake in your readings, and its 5 milliamps or something.

[Captain Sparkle]

Thanks for all your help, thus far.

I thought it must have been my meter, so I called in a friend & his meter, the reading was 4.5a, mine was 5a.

The car is a taxi, and is only left for about 5 hours at most. It's a new 77a battery.

Before anyone asks, I have disconnected the taxi meter & radio as well , to no avail!

Could there be a short, e.g. starter motor?

or would the fact I have pulled all the fuses prove otherwise?

I'm right at the end of my technical abilities now!!

[smileonimpact]

Whilst finding the fault is the immediate problem, if you need a short term solution you could fit a battery isolator switch in the negative battery cable, this will buy you time until you can organise professional help.

http://www.halfords.com/motoring-travel/bulbs-wiper-blades-batteries/car-battery-chargers/halfords-battery-isolator-switch-hef390

Just remember to switch it off when you park the car up overnight.

Edited 18 May, 2015 by smileonimpact

[Captain Sparkle]

Whilst finding the fault is the immediate problem, if you need a short term solution you could fit a battery isolator switch in the negative battery cable, this will buy you time until you can organise professional help.

http://www.halfords.com/motoring-travel/bulbs-wiper-blades-batteries/car-battery-chargers/halfords-battery-isolator-switch-hef390

Just remember to switch it off when you park the car up overnight.

That may well be the way forward, albeit temporarily.

I'll investigate the options.

[pikpilot]

Just a thought from the far left. Does your car have an alarm?

In non automotive applications of batteries I have seen batteries at the end of life refuse to reach fully charged voltage so the charger keeps pumping in current. Normally the opposite is the case as the capacity reduces with age but it does happen. I just wondered if it could be your alarm battery is still trying to charge from the main battery.

Easy to check with a clamp on ammeter once you have found the alarm feed wires from the main 12V.

Skoda recommend changing the battery at about six years old.

[Captain Sparkle]

Just a thought from the far left. Does your car have an alarm?

In non automotive applications of batteries I have seen batteries at the end of life refuse to reach fully charged voltage so the charger keeps pumping in current. Normally the opposite is the case as the capacity reduces with age but it does happen. I just wondered if it could be your alarm battery is still trying to charge from the main battery.

Easy to check with a clamp on ammeter once you have found the alarm feed wires from the main 12V.

Skoda recommend changing the battery at about six years old.

I presumed so, but as it's only a classic, it only has key operated central locking. No press button fob.

Could the alarm drain 4.5 - 5amps?

 

Just been out to it this very minute, showing 4.22amps, 'til I took the probe off the terminal, then when I placed it back on .98amps!

[smileonimpact]

It sounds like a relay is remaining energised (and supplying power to something) after the key is removed, by disconnecting the battery you guarantee the relay is de-energised and the resulting drop in current until you turn the ignition key again.

Next time you disconnect the battery listen for any relays dropping out, if possible see if any relays are warm to touch (after the car has sat for a while and before you disconnect the battery) pull the relays out then refit them one at a time while measuring the current drain to see if the 5amp drain drops off.

Hope this makes sense.

[Captain Sparkle]

It sounds like a relay is remaining energised (and supplying power to something) after the key is removed, by disconnecting the battery you guarantee the relay is de-energised and the resulting drop in current until you turn the ignition key again.

Next time you disconnect the battery listen for any relays dropping out, if possible see if any relays are warm to touch (after the car has sat for a while and before you disconnect the battery) pull the relays out then refit them one at a time while measuring the current drain to see if the 5amp drain drops off.

Hope this makes sense.

That sounds hopeful, thanks.

Are these where ALL the relays are to be found? -

http://www.briskoda.net/forums/topic/162617-octavia-fl-scout-access-to-relays-fusebox/

[Nikonite]

I presumed so, but as it's only a classic, it only has key operated central locking. No press button fob.

Could the alarm drain 4.5 - 5amps?

 

Just been out to it this very minute, showing 4.22amps, 'til I took the probe off the terminal, then when I placed it back on .98amps!

You likely don't have an alarm, look in the vents in the ceiling alarm sensor housing behind the interior light. If you can see sponge you don't have one.

[Captain Sparkle]

You likely don't have an alarm, look in the vents in the ceiling alarm sensor housing behind the interior light. If you can see sponge you don't have one.

All I can see is black sponge!

[Nikonite]

No alarm then

[skodacarman]

The wild variation in consecutive readings on the ammeter could be down to a bad contact at the meter probes/connectors. Particularly a problem on chrome plated probes or clips where a fine oxidation layer forms and effectively insulates them.

[Captain Sparkle]

No alarm then

I'm a little shocked!

I took it that it had, as the indicators flashed when locking, I take that is just to confirm central locking.

 

The wild variation in consecutive readings on the ammeter could be down to a bad contact at the meter probes/connectors. Particularly a problem on chrome plated probes or clips where a fine oxidation layer forms and effectively insulates them.

Have tried a different (new, but cheap!) meter and that was within .5a of mine, but I'll try sanding them down a little!

 

I am trying to get some time to take off the footwell cover to access the relays and see what is happening down there.

[Nikonite]

I'm a little shocked!

I took it that it had, as the indicators flashed when locking, I take that is just to confirm central locking.

 

Yeah I was too lol, you should also have a switch inside the car to deactivate interior sensors if you had an alarm. Its part of a long list of things you will be missing I'm afraid. Do you have a switch to dim dash lights, a remote fuel cap release? For what its worth alarms are pretty cheap on ebay and they work okay, also there is a really cheap central locking kit that looks oem and is easy to fit if you want one. Search my posts you will see all the things I have changed on mine.