The Morris battery. Again.

Suspect dynamo control box.

I have a morris 1000 workshop manual somewhere. Send me an email and I'll try and find the relevant info, scan and send it to you. Bob

If he has disconnected te battery entirely and put a meter in the circuit and no current is flowing, then no current is flowing and the battery cannot be discharging *via any external means*.

So:

Cannot be relevant.

My gut feeling is, that te battery is *intermittently* self discharging due to old age and crap in the cells.

If its driven about its a toss up as to wehether mechanical vibrations and shock will leave it in a position where it will self discharge or not.

As I related earlier, my experience was of a battery that appeared 100% sound one day, and had done for years, and was dead flat the next day.

Replacing the battery fixed the problem entirely.

My point is that not all batteries fail gracefully.

Bits of broken off s*it that short them internally, or leaks between cells can happen suddenly

Graeme formulated on Tuesday :

Any discharge, other than internal ones of the battery, much be going out via the battery lead(s). Sometimes extra connections are made directly to the battery, are you sure you have checked all leads for any discharge current?

Other than the above, then the most likely issue is the battery, or secondly that you are being fooled by the sometimes poor cranking speed into thinking the battery is near flat....

Poor brushes or connections to the starter motor, or a bad solenoid can sometimes give similar symptoms as a near flat battery. Try cranking the engine over with the lights on, to see how much they dim. If it barely cranks over, yet the lights remain bright, look to a starter motor issue.

..or a bad connection post solenoid

Nowhere in the question does the op say "If he has disconnected te battery entirely and put a meter in the circuit and no current is flowing, then no current is flowing and the battery cannot be discharging *via any external means*. "

Well actually he did

Fit one of these

Its a good theft deterrent as well.

Mike

He actually said he had disconnected the earth lead. Personally for this type of fault I would first ensure good earth connections. Is it linked to the engine block via the chassis?

In message , Bob Minchin writes

Thanks Bob. I do have both Haines and proper BMC workshop manuals, but have always been wary of fiddling with the control box. For twenty quid, or thereabouts, fitting a reconditioned unit could be worth a try.

It would have been even more effective as a theft deterrent if they'd used a self healing (poly)fuse instead. All the symptoms of a completely knackered battery, fixed at the turn of knob. Of course, its effectiveness as an anti-theft device relies completely on the would be thief not being able crack the bonnet (hood) open to discover this ruse.

A heavy discharge meter is your friend (but not your batteries, if it is on the way out, it may expedite its demise).

In message , Bob Minchin writes

Just to be clear, if I park the car for a couple of days, with the battery connected, the battery goes almost flat, but left 4 1/2 days with the battery disconnected (earth lead removed from battery terminal), the battery remains fully charged.

This morning, battery fully charged, I put an ammeter between the battery terminal and earth lead. No movement. Repeating, with a door open and courtesy light therefore in circuit, then I can see the ammeter needle move. Not much, but enough to know it is working. Ammeter is a standard car 2 inch circular 30-0-30.

Repeated but with a small 12v MES bulb between the battery terminal and earth lead. No light until door opened.

The only other thing is a high resistance somewhere which is intermittent making the battery not have much guts on a high current. Could you, by disconnecting the earth have managed to clean the connection perhaps? Brian

Just a thought.... If you have a voltmeter of some sort - connect it across the 12v mes bulb in the above setup. Naturally, there'll be a voltage drop across the bulb when the door is opened, but is there any volt-drop across the bulb when the door is closed..? If there is, that indicates that there's a small current 'leaking' through the interior light, via the door-switch. Car batteries are designed to provide lots of current for a short period of time, to start the engine. They're not good at long-term supply of smallish currents... - and the car ammeter won't indicate accurately down at that level...

Come to that - can you put a test meter across the in-car ammeter? With everything off there should be no voltage. A sensitive voltmeter will tell you if there's a small current being drawn from the battery, even when everything on the car is 'officially' off..

No. You parked the car for a couole ofd days with te battery connected and it did go flat and you parked it with it disconnected and it didnt.

Coincidence is not causation

You are looking for milliamps not amps

To flatten in 48 hours needs about an amp. Your meter says you are not drawing an amp.

Ergo its not being flattened by the car.

Had this on my daughters car once Sometimes it would hardly turn over SIL fitted two new batterys as he was Positive it Must be a faulty battery replacement started motor fixed it :)

Can't really help, but an online friend had a similar problem. AA said battery. Halfords thought the same but did not try to sell him a new battery.............. hmmm. It seems that stuff can come apart in a battery and flatten it. I did not know this. He bit the bullet, bought a new battery and all has been fine for weeks.

In message , Mark writes

Well, yes, I haven't really discounted anything!

OK, point taken.

OK

Hear what you're saying, but reluctant to throw 60+ quid at a new battery unless I'm fairly sure.