Parasitic power drain from main battery

[thelal]

I've an electric "leak" that will drain my main starting battery in 4 days. Will drop from 12.7v to 11.85v with all doors closed, no alarm system
Have tried tracing 'usage' across main fusebox without any real answer.

Any ideas on how to diagnose further?

1997 80 4.5L v6 petrol 1FZ-FE - 330K miles with Yausi AGM batteries from Halford (approx 2 yrs old)

 

[ianmcoutback]

I've an electric "leak" that will drain my main starting battery in 4 days. Will drop from 12.7v to 11.85v with all doors closed, no alarm system
Have tried tracing 'usage' across main fusebox without any real answer.

Any ideas on how to diagnose further?

1997 80 4.5L v6 petrol 1FZ-FE - 330K miles with Yausi AGM batteries from Halford (approx 2 yrs old)

Yes your battery is dying you Ned a new one if you charge it up and then let it sit for days it will discharge over time if it on its way OUT.

 

[Towpack]

Does the petrol 80 have any fusible links on the batteries feeding high draw systems/components, similar to the diesel version? If the ‘leak’ isn’t through one of the fuse boxes it could be through one of these. How big is the current drain?

 

[thelal]

Forgot to say if I disconnect the positive cable on the main battery it's fine over a week with very little drop

 

[thelal]

Does the petrol 80 have any fusible links on the batteries feeding high draw systems/components, similar to the diesel version?

There is nothing "extra" on the main battery. All extra accessories is off the leisure battery

 

[nick_the_fish]

I'm no expert, but I would put an ammeter in series onto the positive terminal and see how much current you're pulling with the ignition off. Then start pulling fuses until it drops. I think you can expect the radio/ alarm to be pulling a minimal amount, although not enough to discharge a battery in 4 days. Remember there will be fuses in the footwells in addition to the ones under the bonnet.

Let us know how you get on.

 

[StarCruiser]

Check your charge voltage. If it’s less than 14.4v then it could be that your alternator has a bad diode. This will drain the battery quite quickly.

 

[goodoldboy]

A similar issue on our Honda was driving me mad - it turned out to be a faulty door switch that was triggering the alarm - but I went for a quick fix & had a battery switch fitted inside the car.This also gives an extra level of security.If course finding the problem in the long run is important.

 

[uHu]

Do check drain directly on the battery terminal. The alternator can be the culprit, and it doesn't go through the main fusebox.

 

[steverjuk]

Easiest way is multimeter between the positive and battery positive, don’t try to start the car otherwise you will blow the multimeter that way you can get a base drain, then start pulling fuses to see what drops the drain.

 

[IRLGW]

Should that amps test not be through the negative for safety? I think most DIY multi meters will support 10amps. have you one or two batteries. I have had issues with batteries from Halfords in the past TBH if the battery is good you should be able to remove it for months without a detrimental voltage drop.

 

[IRLGW]

Close al the doors when doing the battery test and tape down the bonnet switch as well so the car thinks its closed. Immobiliser no more than .3amps I would think

 

[steverjuk]

Doesn't really matter which terminal you test but for christ sake don't try to crank the engine otherwise you will kill the meter.

 

[thelal]

Did all the multi-meter in series tests to check each fuse etc.
Nothing out of the ordinary.
Pulled all relays & fuses overnight and still dropping.

Disconnected the 4-pin connector & main battery connector (v-post) to the alternator and its holding battery power for last 2 days. Will check and see if bad diode or regulator now.
At least making some progress as its been annoying for a long time

 

[Shayne]

Lights stay on with ignition off and they all connected to the tow socket .

 

[thelal]

Lights stay on with ignition off and they all connected to the tow socket .

no. Mine is 'normal' with IGN off

Running the additional checks - appears to be a bad diode in the respect I get 31v on AC reading between POS & NEG on main battery while engine running

Anyone replace a regulator/diodes before?
Seems to be cheapie ebay offering (quick check) or approx $130 off Amayama/Partsouq

 

[thelal]

Lights stay on with ignition off and they all connected to the tow socket .

no. Mine is 'normal' with IGN off

Running the additional checks - appears to be a bad diode in the respect I get 31v on AC reading between POS & NEG on main battery while engine running

Anyone replace a regulator/diodes before?
Seems to be cheapie ebay offering (quick check) or approx $130 off Amayama/Partsouq

 

[frank rabbets]

If you have a genuine OEM alternator they are VERY well made and designed and easy to work on. I stripped mine right down and reassembled it just for maintenance. You might need a camera or mark certain items, can't remember exactly. No special tools or soldering iron required.

 

[Shayne]

What i meant was the lights can still bleed power even unlit with ignition off . Simple cheap and common issues should always be ruled out first . Remove bulbs in your tail lights and find sockets are crusty white with corrosion and there's your problem . If not open your tow socket and see how clean inside it isn't .

Two wires that shouldn't are touching each other and its typically corrosion creates the connecting bridge .

 

[Grimbo]

no. Mine is 'normal' with IGN off

Running the additional checks - appears to be a bad diode in the respect I get 31v on AC reading between POS & NEG on main battery while engine running

Anyone replace a regulator/diodes before?
Seems to be cheapie ebay offering (quick check) or approx $130 off Amayama/Partsouq

Check with your local agricultural dealer.... most will have the name of a good refurb company who will strip and fully rebuild the original unit using genuine Denso parts for less than the cost of a rubbish quality new one from china