Morris Minor Owners Club

I suspect I have a duff battery. It does not seem to be holding its charge.

I inspect the cells regularly, haven't ever had to top-up, I don't know how old it is but it has had a hammering in the past. The charging system appears to be functioning properly, in that the 'no charge' lamp goes out when the revs pick up, and the headlamps brighten when the engine is revved.

I have charged the battery on the bench a few times but it only lasts a couple of days before it really runs very low again.

Today, after getting back home with the very dim lights and heater on, the multimeter showed 9.8 volts.

I think I need a new battery.

No - you need a new charging system....

u have dynamo ? Ur battery led asid battery ? Ok when u full charge battery it 12.5 - 13 v then remove conection check volt back next day - how much volt ? - how much ur out put voltege of daynamo ? it want 13.5- 14 v - chack ur wires some time it may be short + and -

I will check the output of the dynamo in volts... it was a new one last year though.

What else should I be looking for?

Local motor factors should be able to check your battery, but as sadun has said, check the output of the dynamo first.

You say you arrived home with dim lights and heater on - so this indicates that it WAS NOT CHARGING !!! Tighten the fan belt - and then check the volts at decent revs - and then with the lights and heater on, again at decent revs..

OK, the charging is erratic and ineffective to say the least. The dynamo by itself gave a solid output but only at higher revs - with the multimeter on the battery and revved up it didn't indicate much other than a single surge and then back to 12v.

The thing that is bothering and worrying me is the 'no charge' warning lamp not coming on when driving... which is why I suspected the old battery.

For a quick answer take it to a battery specialist,who can check the charge and the state of the battery in terms of it's potential.The new digital testers are very good much better than the old big piece of metal and a dial

Also check the brushes on the dynamo, this may lead to erratic charging.

Thanks - the thought occurred to me that the brushes mightn't have been adjusted by the springs. But only after I'd removed the dynamo.

Does sound like sticking brushes to me - or a problem in the Regulator. The problem is killing the battery.... Stick on a spare dynamo and see if that solves the problem - and fit an ammeter!!! After the oil pressure gauge, it's the second most valuable accessory.

You have to set an Ammeter and Volt meter to ur car - then u can see where the problem has come - if Ammeter work , Dynamo work - the Volt meter will show ur battery condition -other one Battery Hydrometer ,it show manually battery condition - remember before any voltage adjustment of regulator ,u must full charge ur battery 12.5 -13 v - bad battery if full charge no more days work some time it work 2 or 3 days and bad battery can not properly recharge from ur dynamor - it is not a problem of ur dynamo - good condition Battery when it full charge 3 month has fine voltage and Amp without back charge- remember if ur car has wire short it drain ur battery

Thanks Sandun - I've not checked with an ammeter yet.

The brushes can be ruled out because they are correctly adjusted and have plenty of life in them.

Whatever the fault is it is intermittent, as when I was testing it today with the multimeter the volts at the battery, when holding revs, would jump up to almost 14 and then back down to just over 12. Also, driving home tonight I left the panel lamp off and there was a very dim glow from the charge warning lamp - you couldn't see it in daylight - which went on and off intermittently.

For what it's worth, I took the cover off the voltage regulator to see what my untrained eye could see - I found one of the thick copper wires on the left winding touching the thing it was wrapped round, and a burn mark underneath it on the paper. So I carefully prised it off, but this hasn't made any difference.

Ur car has dynamo normally it get more time to charge battery - if it is not a good condition battery ,the dynamo cant full charge the battery with on light - running with ON light some drain battery it is normal of a dynamo car - Dont worry Next time Full charge ur battery again 12.5v then light oN (when u light on ,ur ammeter show ( - )value ),then start and run ur car while u running look ur ammeter it must be ( + )side - if it is (+) we can say ur battery charging -if it is (-) ur battery not charge it will going to drain - it is depending ur car speed - check normally speed ( (not more slow not more past ) to do this test not want to be night - just Remember Dynamor want to run 15 minutes to charge a battery in good speed- ok - good luck

Simple test for the dynamo JJ - take the wires off, use a length of cable to join the the two dynamo connections together - then - with engine already running at decent revs, connect the wire to the non-earth terminal of the battery. This throws the dynamo to full charge - and the battery volts will be v high - possibly in excess of 14 volts as it soaks up charge. Switch on the headlights and the heater and check the volts remain high and steady. If they do - then your Reg is on the way out......

OK I have some test results.

The dynamo, when only the two terminals are joined together and connected to a multimeter earthing on the dyn. bracket, puts out as many volts as you like when revved - at a decent engine speed it showed 20v.

Then I did the next test - with the two dyn. terminals connected, ran a length of wire from the dynamo to the non-earth, i.e. negative in my case battery terminal. Then I connected the multimeter to this terminal aswell and earthed it on the cyl. head. It is here things went wrong. At decent revs without lights and heater it showed 12v at first and then after some time it struggled to 14v. Then, with lights and heater on the multimeter showed no more than 11-12v, no matter how high the engine revs were held.

This was with the battery fully charged and started with the handle.

bmcecosse wrote: Switch on the headlights and the heater and check the volts remain high and steady. If they do - then your Reg is on the way out......

Check if the volts do remain high and steady or don't remain high and steady? The volts went down to 11-12v with lights and heater on.

I am getting confused but I think I can rule out the dynamo now - right?

No - your tests show a major problem with the dynamo......it's not charging as it should!

I think I've finally cracked it, touch wood.

I had an old Lucas dynamo in the shed which needed new brushes, so I did that job and put it on the car. Now the volts readings at the battery look good, the charge lamp doesn't often come on at idle, and in the cold and rain today with lights, heater and wipers on, the wipers sped up when the engine speed increased.

Now this raises the question about the faulty dynamo, which was brand new in Nov. 2011. Surely I shouldn't had to have done this?

Also, to add to the fun, the old problem of misfiring has reared its ugly head again, just after I'd fixed the charging system. Old cars - don't you just luv 'em.

'Brand new' from where?? Two years ago now -so I doubt you can claim warranty - no harm trying!!