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alex park

1997 D1 v8. battery discharging in 8 hrs

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i have a 1997 disco v8 efi with lpg conversion.

about 6 months ago it developed a starting problem which kept isolating the fuel pump.

with the help of the forum i traced it to the "alarm spider" and succesfully followed the fantastic thread which showed how to sort the problem. i bought the spider bypass part which effectively took out the problematic spider which had completely burnt out.

two days ago i went to start the car and found that it was turning over and the fuel pump working but not starting. although it would appear to have been trying.

scratching my head and reading some of the posts in the forum, i tried the inertia manual switch which cured the problem and the car started first time as usual. with no problems.

the next morning i went to start it and found that the battery had drained so much it wouldnt even open the doors on the fob.

no dash lights no nothing.

a quick re-charge after taking the battery leads off and the engine fired up no problems.

i left it recharging on the alternator for a while and turned it on and off to make sure it was charging as it should be.

with the engine running it was showing over 13v across the battery terminals so the alternator was working.

but again i go to it this morning and find it dead.

I'm thing that there must be a serious drain somewhere that will drain this much.

any ideas?

whist i am faily mechanically minded, the elctrical side i'm not great at.

thanks in advance

Alex

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Sounds like you need to get a multimeter on it and have a test to see what current is being drawn when it is off, and try and track down what is drawing the current.

Could also be a duff battery

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Sounds like you need to get a multimeter on it and have a test to see what current is being drawn when it is off, and try and track down what is drawing the current.

Could also be a duff battery

hi, i have my multimeterready, can you tell me exactly how to check for the culprit.

thanks

battery has always been strong and never had any problems with it.

thanks

alex

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13v at the battery is not enough whilst running, should be around 14.2v ideally but near 14 is ok.

& remember an alternator charging a 75Ahr battery could take a couple of hours running.

What I would do is charge the batt with a mains charger first.

Disconnect the charge and then let it rest for a couple of hours. THe voltage should be about 12.6V any less then the battery's not charged fully or duff

Then if your multimeter has a 10A setting, startiing with the battery disconnected connect the car's +ve lead to the battery +ve terminal and then the multimeter's +ve lead to teh car's -ve lead and the multimeter's -ve lead to the battery -ve.

If there's any drain then this should now show on the multimeter.

Any more than say 100mA is too much, although it might peak then settle after a few seconds. If there is a drain then leave the meter connected and start pulling fuses until the drain disappears. You should be able to pin down the drain to a circuit and then fault find that circuit.

If there's no drain start looking at the charging circuit measure the voltage out of the alternator whilst running - should be around 14.2V when off idle if ok on back of alternator check voltage at battery terminals, if there's much difference then there's a bad connection somewhere

HTH

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chraged up the battery with all the leads off then checked as requested with multi meter for a drain.

there was nothing showing up as a drain whatsoever.

the car started no problem with the battery charged and showed 14.09v over the battery terminals and similar at the back of the alternator.

I'm pretty sure it's not the battery being a dud although won't rule it out, even if the battery is flat there's normally just enough juice to open the doors or operate the alarm isn't there?

which leaves me to think that there might be an immobilser problem, maybe i'm just clutching at straws?

Alex

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If there is no drain but it's still going flat then take the battery off and leave it in the garage for a couple of days and see if it's flat then.

Sounds to me like a duff battery though

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Not sure what the best way to test is, but I think you can go to most quick fit type places with the battery and they'll put it on a machine and tell you if it's duff.

I've got an optimiser charger which when you plug that onto the battery it will tell you after about 30 mins if it's not holding the charge properly.

If it is the battery then you should be able to pick up a replacement for about £30-£40

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thanks for that. i have left the battery on charge all day and have left it unconnected overnight to see if it discharges the charge overnight.

thanks for all your help.

Alex

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there was nothing showing up as a drain whatsoever.

Hmmm now I wouldn't expect that!

Try it again and switch the sidelights on, just to check the meter's working properly on the 10A scale (they've got a fuse inside)

It certainly sounds as though either your battery has lost a lot of capacity or that there is a drain.

To check capacity (roughly) with a freshly charged battery turn your headlights on for an hour or 2. Switch them off disconnect the battery and let the battery rest then measure the open battery voltage.

Leaving the headlights on consumes about 11Ahr so assuming a 70Ahr battery & 1 hr of headlights the Voc (open circuit) should still be close to 12.5V

The voltages for various states of charge are below if it's of any use to anyone

HTH

State of        Specific       Voltage    
Charge          Gravity        (12 Voc) 
------------------------------------------
100%           1.265          12.68      
75%           1.225          12.45       
50%           1.190          12.24       
25%           1.155          12.06       
Discharged     1.120          11.89  

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well i let the battery rest overnight after being fully charged and it has not shown any drop in voltage whatsoever. it shows 12.8v.

It was disconnected all night. if it had been connected it would definitley have been flat.

this does point to a drain.

I'll double check the multimeter.

i'm just wondering if that when i had the initial problem of the car turning over but the fuel not being pumped thru. when i pressed the manual button on the inertia switch it may have stayed in contact and be draining it this way?

thanks for the help.

this is infuriating.

i would love to take it to a auto electrician, but unfortubately i cannot afford it at the moment.

i'll persevere.

Alex

to to check that i'm using the multimeter the right way. i am set on 10Amulti002.jpg

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The 10A selection looks right, have you moved the red wire to the 10A input terminal on the multimeter? As suggested above connect the multimeter up and switch on the lights you will see the figure rise on the screen. If it doesn't you're not using it correctly. If it does then you are using it correctly so switch off the lights then see what number it goes to, it should go down to zero. If it does go down to zero try leaving it connected and do things you would normally do, ie lock the car set the alarm etc and see if it starts to drain - could be a faulty alarm backup battery which is trying to charge constantly.

Also make sure you are not just putting the wires across the battery - to test for amps you must put it inline, so you must disconnect the positive lead from the battery, then connect the black multimeter lead to the battery and the red multimeter lead to the wire which is normally connected to the battery

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yes have done that, moved the leads over, connected battery positive terminal to battery positive cable, then positive mm lead to neg battery cable and neg mm lead to neg battery terminal. just keeps bringing up a 1

like this

k001.jpg

i'm just about at witts end now. bloody thing.

strange it just decided to do it..

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ok, just tried it again, when i turn the sidelights on and test it, it flashes up 9.4. when i turn them off it retuns to 1.

when i put on th hazzards it again flashes up 9.4 and returns to zero again once i turn them off.

with just the multimeter leads in line it just continues to say 1.

i obviously flattered myslef when i did the alarm spider, this has brought me back down with a bump lol

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what did you do to remedy the spider, did you replace it with a bypass plug or did you solder up the old one?

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I can't remember if my multimeter shows a 1 or not, I always use the positive side of the battery rather than the negative but I don't think that would make any difference.

If you are confident that the current draw is low then most mm's allow you to move the red wire back to the standard input on the mm, this will now give a more accurate low reading so I'm guessing it just shows 1 when it is between 0 and 1 amp, at this point you should move the red wire back and it will give you a better reading (just don't switch anything on which will increase it over 1amp as it will probably blow the fuse.

So try moving it back (if you've got the manual for your MM read it first to make sure it can do this function) and it should then show your current drain, then once you get the current drain on the screen remove fuses 1 at a time until you can figure out which circuit is draining the battery.

Also whilst you are there with your MM just check the earth strap is OK, move the dial to resistance and measure the resistance between the negative terminal and various bare bits of metal

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have you tried the multimeter with the wire not in the 10A input yet?

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To check capacity (roughly) with a freshly charged battery turn your headlights on for an hour or 2. Switch them off disconnect the battery and let the battery rest then measure the open battery voltage.

Leaving the headlights on consumes about 11Ahr so assuming a 70Ahr battery & 1 hr of headlights the Voc (open circuit) should still be close to 12.5V

Did you try that bit?

You could have 1 cell bad, it will charge up ok but have very little capacity.

Your current drain is ok, less than half an amp so it's not that.

Starting to look like a duff battery

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well the battery has held its charge and with all the leads off stayed at 12.8v for several days.

so i guess this means that the battery is ok.

i connected it back up today and now although the engine turns over strongly it does not fire.....

i have checked the fuel pump rwlay which is working ok.

i have already replaced the spider with a direct bypass.

i'm now stuck..

there is fuel pressure at the rails, (i undid the little cap and pressed the plunger to check for pressure)

Am i still looking at a dud battery with not enough power.

or is everything just going t**ts up?

help me pleeeease .....

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I thought multimeters usually showed zero when there was nothing happening and the most significant bit then blank (in this case 1___) when they were off the top of the scale?

It really sounds like a battery drain, the way to check is to put the multimeter inline and then remove fuses or disconnect things until it drops to zero (or thereabouts) the one that makes the biggest difference is your culprit. I would try disconnecting the alternator charge wire as the regulators can go bad and discharge the battery, whilst still charging when running.

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I would try disconnecting the alternator charge wire as the regulators can go bad and discharge the battery, whilst still charging when running.

I was going to suggest this earlier in the thread ........................ this type of alternator failure is quite common and due a short circuit diode, allowing the battery to back feed into the alternator. the current drawn is nominally 5 amps............... but I have seen it as low as 2 amps and as high as 10 amps.

Make sure you insulate the wires when removed, as the large wire is a direct feed (via the starter motor) to the battery and a short on it will cause a fire.

If you are not sure about your multimeter, just connect a spare H2 headlight / foglight bulb between the battery and the positive lead (wire in series) and see if it glows. If it does, then at least you have identified the problem.

:)

Ian

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I thought multimeters usually showed zero when there was nothing happening and the most significant bit then blank (in this case 1___) when they were off the top of the scale?

Yup...

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