Battery!!

R

Rover-tragic.

Member
Hi all,
I have a scenario for you.
Picture, if you will, another place, another time, another dimension.......
Anyway on a serious note. I have 1976 P6B, it is not licensed so is not driven regularly, but it is started religiously once a week and run for some time to keep the battery fresh. It has a brand new battery. After several weeks it suddenly lost all charge and would not turn over. I charged the battery using a standard, domestic charger and it showed that it had charged but still would not turn over the motor.
I took the battery back thinking it was faulty and it was exchanged. The auto electrician said that the battery should not be faulty and it may be a problem with the car.
Now, several weeks later the exchange battery has lost charge again and the car wont start.
My question is this: Should a battery fail after being discharged just once?
I have known batteries to sit in appalling conditions for years and still charge up and operate properly.
Do you think there may be a short in the electrics or could it be as simple as the clock draining the battery?

All suggestions appreciated. :D
 
Modern lead acid batteries are not designed to deep cycle and in fact you would be likely to get few than 4 to 6 full charge to full flat cycles without ruining it, however in your case 1 week seems to short a time for the battery to get flat or even more than a 10% discharge, the clock in my S2 p6b draws and the other ancillary bits and bobs draws about 50 mA which I consider to be too high. My solution to that was to install an isolator switch on the battery post so that when not in use the car has no juice being expended into it.
If you have access to a DC current meter it would be worth your while to check your cars off current drain as I would suspect you have something untoward going on somewhere.
In my setup I also have about 15 watts worth of solar panels (connected to 2 cars) to maintain the batteries so I dont need to start the car at all (a 4 or 5 watt panel is more than sufficient on a new battery).

Graeme
 
I remember a previous owner of my current S had this problem. The garage rebuilt the alternator & changed the battery to no avail. I suggested they get someone in the boot & close the lid - which they did. The boot light was on all the time & was sufficient to drain the battery. :wink:
 
Phil Robson said:
I remember a previous owner of my current S had this problem. The garage rebuilt the alternator & changed the battery to no avail. I suggested they get someone in the boot & close the lid - which they did. The boot light was on all the time & was sufficient to drain the battery. :wink:
Click to expand...

That actually happened with our Vauxhall Astra some 2 or so years back! As the car was used every day (but not for long enough trips), I noticed the starter did seem laboured (but it did actually start the car for a few days) Sure enough, it was the boot light not turning off!

I hope I don't seem to question/insult your intelligence, were/did the lights dim 'enough' when you tried to start it? I have actually seen a neighbours car have the symptoms of a flat battery, but the lights stayed bright during turning the key to the 'cranking' position. Turned out to be the solenoid contacts (they had burnt!). Even in the recent cold/snowy spell, the car (with it's new solenoid) always started first time!

BTW:-
The auto electrician said that the battery should not be faulty and it may be a problem with the car.
Click to expand...

My reply to him would be something like : " 'Should not be faulty' doesn't mean it's not faulty."
 
Hi Rover tragic,
I've recently had a similar problem, mine turned out to be a two part problem and I hope that this can possibly give you some pointers, firstly my starter motor was very "gummed up" so I pulled it out stripped it and cleaned it including all solenoid contacts and commutator ring, replaced it and the difference was instantly noticable. Secondly my clock had been getting noisier and noisier until it began to sound like a tommy gun being fired everytime it self wound, now this was drawing a lot more current than it normally would, I've disconnected the clock now until I get chance to repair it and I've noticed the battery has a longer "shelf life" now, the combination of these two problems led to my battery giving all the signs of a faulty battery.
Hope this helps.
 
Hello All,
Thanks for the input chaps. I'll try and address some of your valuable pointers in turn....
I thought about the boot lamp, but being 6' 2" and several beers south of being an athlete I won't fit in the boot. Several attempts at convincing my wife that I would re-open the trunk once she was in failed miserably. Which left me with the simple option of bunging my video camera in the boot and filming the lid closing.
The light switched off, so eliminating that as a fault.

The clock is the next option. It is a little noisy and seems to act like Dr. Who, travelling backwards and forwards in time....
I will disconnect it and look for repair or replacement.

I get the feeling that there are no electrical faults, but stand to be corrected. The final question still remains. Should 2 brand new batteries both fail and be unable to be recharged after a single discharge occurs?? Let's face it, how many of us have left the lights on, yelled Bugger several times, recharged the battery and gone on our way??

Look forward to comments Gents.
 
Rover-tragic. said:
I get the feeling that there are no electrical faults, but stand to be corrected. The final question still remains. Should 2 brand new batteries both fail and be unable to be recharged after a single discharge occurs?? Let's face it, how many of us have left the lights on, yelled Bugger several times, recharged the battery and gone on our way??

Look forward to comments Gents.
Click to expand...

2 brand new batteries showing the same fault of being damaged/taken to such a state of resisting charge? Not impossible, but very very unlikely IMHO.

I assume (making an "ass" out of "u" and "me"!) the battery has been tested off-and-under load and it is in fact totally flat. (I mean using a voltmeter to measure the voltage on the battery posts themselves, rather than judging by the car's lights, etc)

I also assume (again!) that you would notice if the map reading or internal dome lights were on continuously. (You wouldn't believe, but some people don't notice and/or forget about internal lights being left on!)

Maybe it is the clock. If the innards get gummed/sticky, it will need more current to turn the stiff mechanism.

I can't remember if the heated rear window is wired through the ignition switch or not. If it's not wired through the ign switch and the HRW was left on inadvertently, that would certainly flatten the battery.

However, the others on here have in the past suggested the main +ve cable running from the boot through the car to the starter solenoid does sometimes become brittle and break internally, sometimes even wear through the insulation and short circuit a bit. (Or something like that anyhow, but definitely an ailment affecting the main +ve cable)

I wish you luck! Would be good to know what is the cause of your problems, so we can store it in our brains for future reference!
 
When I used to hose under my P6 it would not start afterwards and need a jump start . I assume either the ceramic insulator in the driver's footwell or the starter motor had got wet and caused a current to flow , draining the battery
 
DaveHerns said:
When I used to hose under my P6 it would not start afterwards and need a jump start . I assume either the ceramic insulator in the driver's footwell or the starter motor had got wet and caused a current to flow , draining the battery
Click to expand...

I'd be surprised if that was the case. Driving in rain, through a ford, puddle, etc would potentially cause the motor and/or the outer of the footwell to get wet, and therefore the same effect. Cleaning the engine with gunk (or whatever is the now gunk-equivalent) and spraying off with water might cause the same.
 
It surprised me but happened often enough to rule out anything else as the cause .I'm not saying the battery would go absolutely flat , just enough to get the machine-gun rattle from the solenoid on trying to start

You don't need to get in the boot to see if the light switches off .You can adjust the switch to break contact when the lid is about 2" from closed and by looking between the lid and tip of the NSR wing you can see the light actually go out
 
I would suggest that seeing as the vehicle isn't driven or run regularly, that you disconnect the battery after each run, just pull the +ve lead off.

I put a brand new battery on an 827 once, and then left it for 3 months connected, when I tried it was totally flat and wouldn't take a charge at all, scrap.
 
DaveHerns said:
You don't need to get in the boot to see if the light switches off .You can adjust the switch to break contact when the lid is about 2" from closed and by looking between the lid and tip of the NSR wing you can see the light actually go out
Click to expand...

Yeah, but where's the fun in that? Much better to get the apprentice in there and then take him out for a quick spin over all the bumpiest roads.......... :LOL:
 
DaveHerns said:
It surprised me but happened often enough to rule out anything else as the cause .I'm not saying the battery would go absolutely flat , just enough to get the machine-gun rattle from the solenoid on trying to start

You don't need to get in the boot to see if the light switches off .You can adjust the switch to break contact when the lid is about 2" from closed and by looking between the lid and tip of the NSR wing you can see the light actually go out
Click to expand...

Hmm... that's surprising! Not that I am an expert, but I'd wonder if the water spray was doing/causing something else which was then causing the apparent discharge.

The only other thing that I can think of would be that water was entering the starter and/or solenoid and causing some 'mayhem' there.

Certainly is weird!
 
Hello R-T,

Have you measured the leakage current from your alternator?

I can recall many years ago that after starting the engine, there was a noticable positive charge showing on the Amp meter which was not characteristic. So I too went searching and found that my voltage regulator in the alternator when the engine was off was drawing current from the battery to the order of 40mA. I replaced the regulator and all was well again.

Ron.
 
SydneyRoverP6B said:
Hello R-T,

Have you measured the leakage current from your alternator?

I can recall many years ago that after starting the engine, there was a noticable positive charge showing on the Amp meter which was not characteristic. So I too went searching and found that my voltage regulator in the alternator when the engine was off was drawing current from the battery to the order of 40mA. I replaced the regulator and all was well again.

Ron.
Click to expand...

Ahh! Yes, that could definitely be a possibility. Maybe not necessarily (just) the regulator, maybe one of the main rectifier diodes has popped or is leaky. The car is 1976, so should have the 18ACR alternator (no external regulator)

It's quite possible a leaky diode would (maybe slightly) energise the excitation circuit, and therefore draw some current from the battery.

When the battery was replaced, it was not wired the wrong way by accident, was it? That could blow the diodes.

Definitely would be worth checking the alternator.
 
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