Morris Minor Owners Club

Ok so it's my Minors 43rd birthday (yesterday technically). Thought i'd treat her to a wash to get the grit muck off her. Went out for a drive and she only turned over twice on the key and wouldn't go. No problem, parked on a slope, bump started her. Figured as she hadn't been driven for a day or two, and it's been cold, it can be expected.

Drove for half an hour to the pub. Came to leave, turned on the key twice and wouldn't go. Cue a friendly push to the nearest slope to bump start her again.

The battery is about 18 months old i think, a Hellfrauds special jobby. I've got a voltage gauge on the dash which, when no lights or anything are on, it gives me 13.5V. This evening coming back with the lights on it was down to 12V, but that's nothing new. She's got an alternator on her, so she should be kicking out plenty of oomph despite my Halogen lights.

Has the cold weather just eaten my battery, or do I have a useless charging circuit? I've had problems like this before that are often temporarily (12 months-ish) cured by a new battery.

I've done nothing to the wiring that could have affected it. Are halfords batteries useless? Is the 38 Amp/hour (or whatever the units are) enough?

The car came fitted with an alternator but god knows what the guy was smoking when he did it. It looks strange but seems to work... usually.

I can't get mad at the old girl. it is her birthday afterall!

Any help would be appreciated! Electrickery is not my forté.

start the engine and pop the lights on. when you rev the engine, they should become brighter (a helper in front of the car helps) if they dont, then it could be the control box has died. if they do get brighter, then work your way back and check that the fan belt is tight, but not too tight and that dynamo is wired up,
if that dosent help, i suggest waiting for Roy to come on, he should be able to help

does the brightness trick work when you've got an alternator too?

my dad suggests the alternator could be wired up oddly. enough to give it a reasonable charge, but as soon as it gets to winter and everything is switched on, it put too much of a drain on it. as i said, the guy who fitted the alternator before i got the car did something very strange, seems to have thrown away the control box, not even using it as a connecting block.

emm, i dont think it would work with an altinator, it produces electricity all the time at a constant rate, a dynamo produces electricity at a variable rate, depending on the engine revs.
also an alternator dosent need a control box, but it should be tidied up, so no loose wires.

the alternator on my minor has 3 connections on the back of it but only 2 wires going to it.

i've got a midget on the drive with an alternator too, and that's got 3 wires, one to each connection.

i cant make out where the wires go on that, they're all hidden in the bussiest engine bay ever.

I have an alternator conversion and to check the alternator is charging the battery. I connect my volt meter to the battery terminals and check the voltage which is usually 12.5v start the engine and check again and if the battery is being charged it should read 13 to 14v. Switch the heater & headlights and anything else with large electrical load( spotlights, screen heater) then check that the voltage is still above 12v and in 13 to 14v at a fast tickover.

Batteries can give up without much warning and usually most places that sell batteries can test them for you.

thanks for your input, i've got through too many batteries for it to just be a spate of dodgy batteries!

it keeps manifesting itself as that, and always come up duff on halfords battery tester so they give me another freebie. but my warranty is up on that now. i've got a voltage gauge permanently wired in. with lights on even at speed it's down to 12V and never goes higher.

my old man thinks i should run an extra wire from that spare termination on the back of the alternator, to somewhere on the solenoid (not sure where he means yet, i'll grill him!) any hint as to whether than could do the trick?

Your alternator will have 3 terminals. 1 terminal should just be a small wire which is for the red ignition warning light (puts it out once the battery is charging) and there should be a thicker wire going where the control box used to be (sorry I can't remember to what wire it should connect but if you search this site I am sure there have been other post about this). You can connect a third thick wire to the alternator to the battery side of the solenoid if you are running large loads, like heated screens.

You really need to beg/borrow or buy a volt meter as the one fitted in the car might not be very accurate. Or even connected properly? Does it move when you switch on lights, heater, indicators?

You also need to look for anything drawing power off the battery when the car isn't in use radios,alarms, interior lights. I think if you connect your volt meter to the battery and see what the Volts are and see if the display fluctuates then this might point you to something drawing current with the ignition off.

Also have a good look round all the earth connections - battery to chassis, front inner wings, in the boot area as corroded connections can affect the power taken from the battery. Clean them up with some emery cloth or similar and refix with some vaseline applied to them.

thanks jefftav. it's the one from the alternator to the solenoid i'm missing i think. i haven't got a control box on my bulkhead anyway. it was replaced with a big bank of connectors that everything runs through!

i'll find myself some thick cable and some connectors and run a wire accross. cheers for the help!

By all means install the extra wire but I'd check the battery is being charged with a separate voltmeter 1st as if all you have is halogen lights your existing set up should function OK.

Looking through my MGB diagrams it appears the early cars had 2 connectors and later cars had 3 , BUT the two large wires go to the same place so I think this might just be to spread the load across 2 wires. The small wire goes to the ignition warning light and the larger wire(s) go to the + on the solenoid.

I will second all of Jefftav's suggestions.

Found this on the Mog Free Forum which might help with the alternator conversion bit?
http://mog.myfreeforum.org/Alternator_C ... ut746.html

it produces electricity all the time at a constant rate, a dynamo produces electricity at a variable rate, depending on the engine revs.

An alternator does produce a speed related electrical output, the same as a dynamo. There are 2 main differences with an alternator:

Because the rotating part is much lighter and doesn't have a commutator and brushes, it can spin much faster, up to double a dynamo. This means that it has a smaller pulley, so that it can produce more current at lower engine revs.

An alternator design is 'inside out' to a dynamo, the output comes from the outside part, the stator, which can have heavy windings to cope with high current outputs. A dynamo output comes from the rotating armature, via the commutator and brushes, which limit the current that can be drawn for a car sized unit.

also an alternator dosent need a control box

Yes it does, apart from some of the early ones in the 60's, such as the ubiquitous Lucas 11AC that had an external control box, and was available in +ve and -ve earth, but it is built in to the alternator itself.

The Lucas ACR range, which is the most common for British manufacturers in the 70's and 80's has 2 large terminals and 1 small. The larger terminal is rated at 35A max, so they need to spread the load. Both should be connected to the battery side of either the starter solenoid or pull switch.

Even with a fully charged battery you should see 13.5v - 14v from either a dynamo or alternator, just to maintain the charge, and 12.5v - 13v across the battery terminals without the engine running and nothing switched on.

Something is definitely very wrong if you are only getting 12v with the engine running at speed. I would check the voltmeter, then with a good, fully charged battery, check out the charging system itself - I have used Halfords batteries, usually a 55Ah model, and had no problems with them. The last one was 8 years old, when I replaced it as a precaution!

First check - is the fan belt TIGHT, and in good condition ? May be fine when no great power required - and slipping horribly (without necessarily squealing) under load. The alternator is a 3 phase machine - if one or even two phases are down it will charge fine on the remaining phase(s) but is obviously very limited on power. Thus it can be fine when running about in daylight with nothing much switched on - but hopeless when lights etc are required. With the engine doing decent revs - it MUST give 13.5/14 volts at the battery with heater and headlights on. Note halogen headlights actually take slightly LESS amps than sealed beam headlamps........ So - if it's not the fan belt - it will be a problem in the alternator. Easiest check/fix is by substitution with a spare!

thanks bmc. i've been doing some other odd jobs to the old girl the last few days, finally fitted an extra wire from the alternator to the batt side of solenoid. before the only power getting to the battery from the alternator was going from one connector on the alternator which went up to where the regulator used to be (now a connection block... ) everything else in the car then ran off that connection block, with one wire going down to the solenoid. i guess that being the route of most resistance, the power would 'prefer' to power the lights and things rather than go and charge the battery. this extra wire straight to the solenoid should theoretically force the alternator to charge the battery (that's my guess anyway).

had it running briefly in the garage 10 mins ago and the voltage gauge on the dash was giving me 14V. i happened to press the plunger on the carb (to check mixture) which made the engine die. popped back into the car and kept my eye on the voltage gauge (still reading fine as the ign was still switched on). the voltage gauge immediately started falling down to 12V (maybe a little lower) i didnt keep watching to see how low it went as i didnt want to burn the coil out.

is it normal for the voltage to drop so quickly as soon as the engine stops? i guess it is as the source of charge has stopped. as i say, electricity is all witchcraft to me

just been out in the garage again...

fast idle with nothing on: 14V
fast idle with headlights on main beam, heater on, interior light on, and stereo playing T-rex : 13V
fast idle with above and Kenlowe fan switched on: 12.5V
fast idle with nothing on: back up to 14V

i was pleased that after leaving it an hour it still started, suggests battery isnt discharging, will try again in the morning to make sure it hasnt discharged over night.

You need a bit more than 'fast idle' to get decent output. Yes - it will 'charge' at idle when a dynamo won't - but for decent power you really need ~ 2000 rpm or more. Try again with decent revs - and again - that fan belt must be TIGHT. It should hold almost 14 volts - although Kenlow fan is power greedy - and would generally only run in short bursts - and generally only in 'summer' when lights etc are not in use....... So perhaps a little unfair to expect it to be balanced along with everything else. Should certainly get good ~ 14 volts with headlights and heater running.

fast idle was all i dared as it was 10pm and my exhaust is noisy at the best of times

i will take her for a drive today and see what i get.

thanks for your help

bad start. turned over slowly 4 times on the key before giving up. so the battery has gone flat in the last 12 hours. nothing was discharging it as the earth was disconnected last night, so the battery must not be holding its charge surely?

new battery time?

Indeed! Costco is best for batteries........