Battery Keeps Draining

[pa402 0]

Hi all

 

I'm having issues with my car constantly having a flat battery. It wasn't used much for a few months so the old battery died and a replaced it (albeit with the cheapest one I could find).

 

Everything going ok (for a couple of weeks) until the car was sat for a week whilst I was on holiday and then failed to start. Jumped it and gave it a good run on wednesday, then had two small journeys in it yesterday but yet again its failed to start this morning. I'm going to take the new battery back on ask for a replacement, but wondered whether I should get a more powerful one?

 

But my question is whether there is a way of working out whats draining the battery whilst the car is sat? I've made no changes to the electronics at all recently and the only things I can think draining the battery will be the alarm, the radio and the clock (that doesn't tell the correct time).

 

Any help appreciated - cheers

[Anthony 1,003]

A multimeter is your friend for finding current drains and checking that the alternator is charging correctly.

 

I had to do a friend of mine's 205 a few months ago that was suffering the exact same symptoms, and it transpired that it was the stereo - but, curiously, only when the face was left on.

[M@tt 77]

get a multimeter

 

• stcik it on current setting
  
• undo negative terminal on battery
  
• fit MM probes between battery lead and battery terminal
  
• note what the Amps reading is
  
• in turn remove a fuse at a time until you find one that makes the value drop significantly
  
• the fuse that caused the current drop look in your haynes and see which things run off it
  
• refit fuse and then unplug/disconnect (if possible) each of the things in turn on that fuse to identify which of them is causing the problem eg disconnect stereo, unplug window switches/window motors etc
  

 

HTH

Edited July 15, 2011 by M@tt

[smithy 1]

as above check for drains with a meter on amps,just make sure it is a decent meter and can handle a decent amount of current some of the cheap bongo ones will pop an internal fuse if it has a drain of more than a couple of amps.

 

I would also check the alternator charge rate just to make sure it is chucking enough out.

[Tom Fenton 1,542]

It doesn't need to be a huge current to drain a battery down. When I had this problem it was only about 0.2A but this was enough to drain the battery down over a few days. In addition after being drained flat too many times the battery itself was u/s so even with the drain fixed the old battery still couldn't hold charge. Fitted a new battery and now its great, can leave it in the garage a week or more and it cracks up 1st try.

[pa402 0]

Cheers guys

 

I'll see if I can get hold of a multimeter. I know alternator is charging at 14-14.5V as have a voltmeter and have already checked that.

 

Interesting point about the radio there - I do tend to leave the face of mine on rather than take it off. Will change that habit and see if it makes a difference.

[lemmingzappa 75 1 Cars]

It's quite common with stereos, they will still draw power with the face attached so that discs can be removed/inserted without having to be switched on first.

[mogsman 2]

It could be a knackered boot light switch keeping the light on.

Ian

[dch1950 37 1 Cars]

Hi all,

parasitic battery drain is usually a good likely source when you've eliminated your starter, your battery, alternator and battery wiring etc. My general belief is that things that been ok for ages usually stay OK, and things I've been messing around with are usually a good place to start when looking for culprits. My problem is probably the same as many on this forum, I'm not using the Pug as often as I did and it's sitting there doing nothing for long periods. Checked out my battery and recharged it and now I'm looking to find what is really flattening my battery. My alternator load tests were fine. with readings of 14.5V with everything I could switch on (lights,heater blower,rear demist,hazards,radio etc), then switch everything off and it setlles back to 14.8V (at around 1500 RPM - fast idle) I'm happy with this.

I've switched off my alarm and now will wait to see what happens tomorrow. As you probably gather I reckon it's my alarm draining my battery.

Typically it can be 7-10 days between starting her up and doing anything (as opposed to nearly every day 6 months ago) so I wondering what is a reasonable no load battery current (i.e. ignition off). That is to say what is a resonable value for the unswitched "accessories" to draw. I've googled this a bit and come up with figures of more than 50ma being regarded as parasitic. That is to say my 45Amp-hour battery (fully charged) should be able to last 10 days fairly easilt ( 10 days = 240 hours at 50Ma is 12amp-hours) ie 26% of my battery capacity. So in theory I should be OK. My question is what is a reasonable value for static (no ignition key in) current draw. I ask because I will measure mine tomorrow morning before I try and start my little baby. Hopefully things will be OK but I need to be able to put a measurement wrapper round this set of readings to check. If it starts OK I will repeat the exercise with the alarm switched back on and measure it again.

regards

Dave

PS Pulling fuses out is fine but there's a lot of stuff connected to sub circuits and I could lose the will to live before I checked everthing

D

[ORB 227 1 Cars]

I had this problem and it turned out to be a Tachy Relay jamming causing a draw. Changed it and all is well. I can leave my car for a month with no trouble should I choose to, even with the immobiliser on.

[dch1950 37 1 Cars]

I had this problem and it turned out to be a Tachy Relay jamming causing a draw. Changed it and all is well. I can leave my car for a month with no trouble should I choose to, even with the immobiliser on.

Hi,

what methodology pointed you to that? Did you measure your actual current draw? I'm trying to see what is a "parasitic" value and really don't seem to be able to get any real world values. Obviously a larger battery will last longer before it drains. I have been in touch with the firm that sold me the battery as I'd discovered that the 3 year warranty on it was actually still "current" (sorry about that one ) and they were helpful in confirming my voltage measurements as being OK.

The only figure they couldn't provide was a reasonable static current draw value.. This really proved to be a case of we don't know and if we did, telling you might leave us open.

The theoretical fully charged voltage per cell (i.e. no back emf) is 2.2v. giving us 6 x 2.2v = 13.2v (6 cells in a car battery). Because cells aren't 100% efficient it is reckoned that a fully charged battery will read between 12.6 to 12.8 volts.My alternator is fine and will keep the battery charged under most load conditions. When I'd charged my battery (prior to fitting it) it read 13.46v which came down to 13.22v when fitted to the car. Did all my tests (alternator etc) on Sunday an am now doing daily checks this week to see what's happening. Mondays value being 12.86v. Still fully charged then.

Because I'm a trained scientist I tend to shy away from suck it and see methodologies and the idea of going to see an auto electrician is equally abhorrent (practical experience being that they don't know either and will just keep swapping anciliiaries etc intil the problem "magically" disappears.

What an old cynic I've become

 

regards

Dave

[smithy 1]

My car holds charge really well so I can do a current draw test on it later and and ket you know what mine is if it helps?

[dch1950 37 1 Cars]

My car holds charge really well so I can do a current draw test on it later and and ket you know what mine is if it helps?

that would be really helpful mate - thanx in advance - Dave

[smithy 1]

First off my car is pretty standard got no alarm or immobiliser,it does have a Sony xplod face off which was still on when tested.

When initially putting meter on it was 0.12dca drain after 10 seconds or so it dropped down to 0.0dca and remained there,so assuming yours is similar set up I would think you should be looking for 0.0dca if you have a draw it shouldn't be too hard to isolate certain circuits and pinpoint fault.

Hope this is of some help.

[Rob_the_Sparky 9]

PS Pulling fuses out is fine but there's a lot of stuff connected to sub circuits and I could lose the will to live before I checked everthing

D

 

I'm afraid Electronic debug does involve a fair amount of checking. Once you know the circuit then you should be able to make an educated guess at the more likely culprits but rigerous checking is often the only way to be sure.

 

Note: the "normal" ignition off current draw is going to depend on what each car has fitted, in particular what alarm/imobiliser is installed.

 

Rob

[dch1950 37 1 Cars]

Hi,

I understand the empirical nature of isolating the fault. However, my philosophy says most things are OK (standard accessories wired into a standard loom through a standard fuse board.) So the items that are usually hacked in by installers are - aftermarket alarms and immobilsers., and in my case electric window conversion kits. So using that as my investigative basis I've quickly realised that the butchery of the wiring by "approved" installers is beyond belief. So pulling fuses I don't think will help much (see my first post of this series). If my alarm or immobilser are causing high current draws the question is - why? I've had this car for 12 years now and in general have not had this problem before now. I've replaced batteries 2 x now, but I thought this latest problem was down to my lower mileage creating a charging deficit.

So my question would be "what causes the existing accessories and ancilliary devices to go into a high(er) drain mode. The items still work so where am going to look? it's a tricky one to answer.

regards

Dave

PS there are at least 2 post fuse board fuses just put in line for the ignition elements of the immobiliser and the alarm. These guys having no sense of "good pro installation work" more Jim 'll F**k it".

D

Edited July 19, 2011 by dch1950

[dch1950 37 1 Cars]

HI all,

I've been monitoring battery voltage each day since the fully charged battery went back into the car. We started at 13.2 on Sunday and it's down to 12.66v this morning. Still OK but definitely going down. Disconnected the battery and measured the in-line resistance in the battery circuit itself (i.e. across the battery cable terminals) this was about 24 ohms which would give a draw current of 500mA, way to much!

Realised when I came back in the tailgate was open and the courtesy lamp was on (bugger). However, the logic is correct. I will measure it again with tail gate shut and see where end up.

My immobilliser is seperate to my alarm, so at the moment my alarm is off, but the immobiliser is on. Normal drain for the armed immobiliser is 10mA (according to the spec sheet anyway.) so I'm starting to get a feel for the numbers now at least. I don't have a spec sheet for my alarm (Clifford Eagle 2) so I don't know what the "armed" rating for that is.Could email Clifford I suppose). But as it's switched off it's not affecting readings at the moment. This is a bit of a pain but I will get there.

will keep you informed on my progress.

regards

Dave

[pa402 0]

Hi guys

 

Had another play over the weekend but don't think my multi-meter is up to the job. When connecting between the negative wire and battery negative I got no current...and I dont think anything flowed through it as I never heard the alarm/locks reset themselves.

 

However, I now have another problem...the battery postive lead no longer fits tight around the battery!! It keeps sliding up even if tightened fully. Anyone come across this before and can recommend a fix (other than shove some wire in there)?

 

I tried a spare connector (off a PH1 so different wiring loom) and that fitted tight.

[P_Monty 2]

Hi guys

 

Had another play over the weekend but don't think my multi-meter is up to the job. When connecting between the negative wire and battery negative I got no current...and I dont think anything flowed through it as I never heard the alarm/locks reset themselves.

 

However, I now have another problem...the battery postive lead no longer fits tight around the battery!! It keeps sliding up even if tightened fully. Anyone come across this before and can recommend a fix (other than shove some wire in there)?

 

I tried a spare connector (off a PH1 so different wiring loom) and that fitted tight.

I've had that problem with the battery connector. The bodies of the connectors crack and split open at the crack rather than gripping the post. Fit a new connector 9 a couple of quid from a motor factor) and you'll be fine.

It will have been cracking and loosing grip over time - you'll be amazed at the difference it makes...

[M@tt 77]

Had another play over the weekend but don't think my multi-meter is up to the job. When connecting between the negative wire and battery negative I got no current...and I dont think anything flowed through it as I never heard the alarm/locks reset themselves.

did you change the leads over as well? quite often (depending on multimeter) you have to change the positive probe lead into a different hole from the one that you use to read volts & resistance.ie theres usually 3 holes for the probe leads on the multimter, 1 is always used as the negative/black lead then one hole is used for the positive probe when measuring voltage/resistance and the other hole is used when checking current(amps)

 

HTH

[dch1950 37 1 Cars]

Hi,

I'm also going through this set of checks, and we are mirroring each others actions. I kept blowing the meter fuse when switching ranges on my DMM and so I purchased a 1 ohm,10W resistor and connected that in series on the +ve side of the battery. You then measure across it using the DC volts range which is effectively the current as you have a 1 ohm resistor in the circuit ( V= 1 * current).

Pull your fuses and find the worst circuit i.e the one which cuases the biggest change (decrease) in your readings.

In my case it was fuse #7. Great I thought - problem found. Not so - according to the fuse iequipment list the following are connected through this fuse Boot light,map reading light, interior light Radio,central locking and cigar lighter and clock.

All my 3 light switches are OK.Radio face plate not on, clock OK, So that points to central locking - plug X on the fuseboard. Only there is no plug there. The central locking operates through my Clifford Eagle alarm (with the remote radio key) according to the circuit diagram. The central locking works, although the passenger side motor is a bit sluggish. I'm wondering if this could be the problem, Will pull the passenger door trim and have a look and measure things. I also haven't managed to locate the Clifford box yet.

keep flogging one with i.

regards

Dave

[pa402 0]

did you change the leads over as well? quite often (depending on multimeter) you have to change the positive probe lead into a different hole from the one that you use to read volts & resistance.ie theres usually 3 holes for the probe leads on the multimter, 1 is always used as the negative/black lead then one hole is used for the positive probe when measuring voltage/resistance and the other hole is used when checking current(amps)

 

Well I did try a few options as I didn't have a clue which to use. I've got a choice of a 10A DC, COM and V(ohm)mA probe holes and used the 10A setting thinking that would be recording current. Which probe lead should I be using?

 

Cheers

[M@tt 77]

You want the black lead in the COM one and the red lead in the one marked 10A

 

then simply discconect one battery terminal clamp and fit the multimter in series (ie one probe touching the battery terminal and the other touching the battery clamp you've just disconnected)

 

Set it to Amps on the multimeter and away you go

[jackherer 543]

Well I did try a few options as I didn't have a clue which to use. I've got a choice of a 10A DC, COM and V(ohm)mA probe holes and used the 10A setting thinking that would be recording current. Which probe lead should I be using?

 

If you have put more than a few hundred milliamps through the mA socket you may have blown the multimeters internal fuse.

[dch1950 37 1 Cars]

If you have put more than a few hundred milliamps through the mA socket you may have blown the multimeters internal fuse.

I would think he probably has. I went through about 2 myself. The higher setting (usually 10 or 20A range) is un-fused. If you anticipate high current readings then don't linger too long with the probes or else - bye,bye meter. We should be looking at around 20-50mA draw (typically) though.But because this an un-switched feed any spikes will usually blow the fuse. That's why I put a 1 ohm (10W) resistor in series and measure the voltage across the resistor.Pulling fuses is then just a case of looking for changes (down hopfully) in the static reading.

I have spent most of the last 2 days trying to track down the cause of my 20mA (extra) draw caused by the sub-circuits fed through fuse #7. Typically though my alarm and immobiliser aren't wired through the fuse board, just hacked in where the "installer" thought was handy.So any parasitic draw caused by them can only be traced by disconnecting the device itself.

regards

Dave