Battery is draining. Bit of help please

[jamesdean2112]

Hello everyone
Got a new battery in the Three Thousand Five has been left plugged in for a few days and is flat now. The old one used to drain overnight if i kept it plugged in. The old battery had had it i think. Im now wondering what could be draining the new battery. The guy i bought it off used to unplug it so it has been going on for a while. It has had an electronic ignition fitted and a new alternator at some point in the past. I have taken some pics of the engine bay wiring. Is there anything that looks out of place?
There is a new black wire from the alternator to the bulkhead like an earth?
I have borrowed an old altimeter to mess with

Any advice would be grand
I will keep taking the positive cable off for now so the battery doesn't get knackered

 

[SydneyRoverP6B]

Hi James,

Leakage current, which is what you are describing usually originates from electronic components with associated connections to diodes and capacitors. So a likely culpit is your alternator and/or the voltage regulator. If you connect a multimeter on the current setting in series with the alternator and the battery, you'll see a reading, that is with the engine off but the battery connected. That value is the leakage current.

With an 11AC, the voltage regulator is separate from the alternator, so try disconnecting wires from the voltage regulator one at a time and see if that has any impact on the leakage current. If it does make a difference, then you'll have narrowed down the problem.

Ron.

 

[harveyp6]

Boot light staying on.

 

[Ethelred]

Boot light staying on.

That occurred to me too but would it drain a battery overnight? I have had this happen but only when I have returned to a vehicle after leaving it for a week or so.

I have long since got into the habit of isolating the battery whenever I park the car.

 

[hindsight]

If you have a Altimeter then you will at least be able to find how far above sea level you are. he he

But seriously, with your multimeter set on amps it might be worth disconnecting your battery terminal and connecting your meter in series. ie the red of the meter on the pos batt cable and the black of the meter on the batt terminal. If no boot light is working then the reading should be nearly zero. Its only your clock that should be taking any power.

If any current is being drawn then you could start by disconnecting different items... ie your alternator , maybe wires from the ignition switch etc. ( might be worth removing the interior light bulb) Eventually you will disconnect something and the reading will go to zero. That will be the culprit.

Hope this helps

Steve

 

[jamesdean2112]

Thank you very much for the fast reply guys. you are stars!
i'm not great with wires so this is excellent advice As for the boot light, mine never worked and i took the bulb out incase anyway. Will have a go with the meter at some point and let you all know how i get on. need to read the instructions properly yet. Thanks again

 

[ghce]

Rear window heater?. Another approach is measuring the leakage current try removing from the fuse panel 1 fuse at a time the only caveat n your case is that appears to have been a number of wiring mods that may make tracking down the offending part harder to find. As previous poster has said the only thing that should be drawing current is the clock and it is possible that this is your culprit however disconnection of items 1 at a time will find the problem fairly quickly.

Graeme

 

[hindsight]

Hi James

If you get no luck then its not the end of the world. You can get a battery dis-connector that you put on one of the terminals so that you simply turn a knob to dis-connect the battery. It works as a anti-theft option as well. I use one all the time to stop any battery drain. Saves using a spanner and removing a battery cable.

Steve

 

[redrover]

Hi James

If you get no luck then its not the end of the world. You can get a battery dis-connector that you put on one of the terminals so that you simply turn a knob to dis-connect the battery. It works as a anti-theft option as well. I use one all the time to stop any battery drain. Saves using a spanner and removing a battery cable.

Steve

Steve makes a good point. I had battery leakage about 3 years ago, but fitted an isolator shortly after for security/safety. It's now in my habit to switch it off at the battery every time I leave it, so I forgot about the problem altogether. It was only last year when I fitted a new alternator (bearings knackered on the old one and ignition light circuit dead) that I noticed it didn't drain any more when I accidentally left the battery connected over night.
Moral of the story? Listen to Steve, then listen to Ron!

Michael

 

[amcdonald]

I recently discovered a very sneaky and irritating gradual battery drain. The alternator connection to the indication light relay was giving a continuous 12v all the time, instead of either nothing or 5v ish as I understand it, cooking the relay and heating it up. The nice little 24/7 heater gradually killed the battery over a few days/week. I only discovered it when I brushed against it and burned myself (almost), with the keys out. Aha moment there. Now alternator repair......

 

[jamesdean2112]

Thank you every one going to a friends in it tomorrow might have a mess with it on sunday when i get home. Ill try and get a battery dis connecter will make life much easier

 

[hindsight]

Hey Michael

"Steve makes a good point" and "Listen to Steve".............

Can you please tell that to my wife ????

Steve

 

[j_radcliffe]

Do do what I did when trying to see if I had a current drain. I used an ammeter, and tested with the car doors open. Low and behold I found a current drain as the interior lights were on!

James.

 

[Tor]

Hope you find the culprit. If you don't mind the hijack, what is the consensus as to how long it takes for a parked P6 to drain its battery under normal circumstances? My recently replaced battery died within three months or so. When I eventually took it out after a full five months it was so flat in fact that my new smart charger wouldn't detect it and I had to 'spike' it with an old style charger before I could properly de-sulphate and revive the battery.

 

[ghce]

Hope you find the culprit. If you don't mind the hijack, what is the consensus as to how long it takes for a parked P6 to drain its battery under normal circumstances? My recently replaced battery died within three months or so. When I eventually took it out after a full five months it was so flat in fact that my new smart charger wouldn't detect it and I had to 'spike' it with an old style charger before I could properly de-sulphate and revive the battery.

A brand new lead acid of average size will self discharge at around 100mA so with a given size of say 50 Amp Hours you could reasonably expect that battery to be flat with in 500 hours so about 3 weeks. Self discharge rates do vary so maybe allow a 50% margin which would land you in the approximate territory you experienced.
Its likely with a P6 of a suitable sized battery to fit the Battery box that the Battery would be about 72 amp hours so again a little more time before it get flat.

After 2 or 4 years of service a good serviceable battery will have that self discharge current increase to an order of magnitude of 3 or 4 so that self discharge current of up to 300 or 400mA could be expected with a consequent shorter time before it goes flat there are ways around this such as buying a gel cell start battery however I am informed that these can pose a fire risk but I am not too informed on hard facts on this.

Graeme

 

[Tor]

That's great information, thanks! I've always thought of a battery as largely maintaining most of its charge over X amount of time, and also that the electrical self-winding Rover clock draws too little current to drain one on its own. I'll keep that smart charger connected on a trickle, then.

 

[ghce]

Yes a trickle charger is the best solution, traditionally best trickle charge voltage has been stated to be 13.8 Volts however believe this to be wrong! as I have had batteries "sulphate" and fail at this charge level.
My P6 battery had been loosing capacity and when checked on a discharge meter at a high current discharge the battery was showing signs of an increased internal resistance with a reading of Weak, a sure fire indication of age and sulphation.
Knowing my battery was on the way out but not wanting to spend the dollars to replace I put it on my high current battery charger set at precisely 14.40 Volts and then left for a 2 month journey to China.
On my return on checking the battery I found that the test discharge meter now showed the battery condition to be Excellent as opposed to the previous Weak reading.
This indicated that the battery had undergone rejuvenation and that the internal resistance was now very low and in the realms of a brand new battery, I was to say the least surprised.
14.4 Volts represents the voltage experienced by a car being driven with a good standard alternator and will not overcharge the battery or boil it.

The mechanics of this change I am not to sure of as I say 13.8 is the theoretical sweet spot for maintaining a lead acid, my theory for the better result is that the higher charge voltage is bubbling the electrolyte more than the 13.8 would, this in turns means better circulation of the electrolyte from top to bottom of the battery case, my supposition is that this stops battery electrolyte stratification which is also a well known killer of flooded lead acid batteries which are left in an unmoving position.
I am sure that this is only part of the explanation as sulfation appears to have been reversed also.

Graeme

 

[jamesdean2112]

Thanks a lot guys. My new one went down in about 3 days to the point where the car just clicked. My interior light dosent work at the moment need to try a new bulb in it. I'm going to get an isolator for the battery soon. Will be driving the car this weekend so will look at it over next week with the ammeter.