strange battery blip

[docgibbons]

Can I relate the following scenario in the hope that someone knows what might have happened? I was returning home the two weeks ago on a longish trip of about 2 and a half hours, at night time, and had around half an hour to go when I pulled over for a five minute doze. When I was ready to go again, I pulled the starter button, and..........nothing. Well, just a tired groan, but not enough juice to turn the engine at all. As luck would have it I had parked at the top of a hill, and bump started the old boy to get going again and complete my journey. When I got home, and turned off the engine, I tried to restart the car, and once again, just a groan and no sign of battery life. Next day I trickle charged the battery, and it needed about five hours to go from no lights at all on the chargeometer to register 50 per cent charged, and another couple of hours to reach 75pc. Next morning, I reconnected, and it took just half a minute to return to 75pc, and another half hour or so to register fully charged. And it has fired up first time and powerfully ever since. Just to say that on that journey, the headlights were on for the two hours before I stopped, and the heater blower was also working away, but it was a dry night, and I didn't need the wipers. The car is a 1958 converted saloon, with no alterations, and has a dynamo not an alternator. Any thoughts on what might have caused the battery to fail just that one instance? I am obviously concerned that it might happen again, and next time I have a long journey involving lights and maybe wipers also, and need to stop, i'll probably make sure I'm at the top of a hill again. I do have the cranking handle option, as well, of course.

[busguy]

Probably in the situation you relate to, it's just the dynamo didn't keep up with the high power usage on that trip and hence left you with not enough power to restart when you need it most.
Maybe the dynamo is not charging as well as it might for some reason, but this is the reason so many Minors are now fitted with alternators.

[chesney]

Indeed. My 58 saloon dynamo would struggle in the winter with the heater/lights/wipers on, when sat in traffic the engine would stall after a few minutes. For safety's sake I fitted an alternator.

[kevin s]

Dynamo's were just about up to the job in the traffic conditions when the cars were new, with more stop start traffic (so lower engine RPM) and the inevitable wear and tear they struggle nowdays.
It may be adjustng the voltage regulator would help , I have not done one for ages so can't remember the details but I remember you can set the way it charges by adjusting the cut in and out points on the coils.

[docgibbons]

so is the recommendation to change to an alternator? and if so, is it a straightforward job? I think I remember reading somewhere that you need the earth changed.

[bmcecosse]

A dynamo should balance that load - but how tight is the fan belt - and how good are the brushes? And did you sit with lights on while you had a sleep? The battery could also be getting on in life - so may not have much capacity now. An ammeter is a great thing - you can see right away if the generator (dyn or alt) is keeping up with the load. Simple test with a voltmeter (Maplins) - run the car at decent revs with lights and heater on - and measure battery volts. It should be ~ 13 volts minimum - better if nearly 14 volts. If not at least 13 volts - loose belt/regulator needing adjusted/new brushes needed in the dynamo.... So I suggest - tighten the fan belt, and fit an ammeter - and perhaps consider buying the car a new battery for Christmas........ Many do fit alternators - but really a dynamo should cope.

[chesney]

You 'can' keep it positive earth, but it really isn't worth the effort finding the correct alternator (11AC?) and control boxes.
Instead, simply change to negative earth, and fit one of the Lucas ACR alternators (16/17/18/19). Very easy to do, you need the alternator (£40 ish new from suppliers?), the mounting bracket, adjuster bracket and loom. It made a huge difference to my Minor, but everyone's driving style is different!

[docgibbons]

I made sure the lights were turned off when I took my five minute doze, and the battery is fairly new.
as I said, it fires up fiercely even on frosty mornings, but somehow this journey with lights and heater drained the thing. upon recharging though its been as good as new again so I don't think it needs a new one. the fanbelt also seems tight enough to me. but that voltmeter test with the lights and everything else all on sounds like a good idea, so will see if it's registering the right amount of volts.

[docgibbons]

I ran the old boy down to a battery place, and when they tested it they said it was only working to 19 per cent capacity, and was registering 12.2 volts. it did not change when they tested it with the lights, heater and wipers going. the bloke said he was amazed it started at all. not quite sure what to do now, as this is my third battery in about two years and I suspect something is draining them.

[bmcecosse]

It's not being charged properly - give it an extended charge - and nip down to Maplins for a wee cheapy multimeter (or get this from ebay http://www.ebay.co.uk/itm/DIGITAL-LCD-V ... 2c6b04b30d
to check the charging volts. If the belt is good and tight - then it probably needs the regulator tweaking - all detailed in the workshop manual. A good run in daylight with nothing switched on should give it a good charge - but meantime leave the trickle charger on whenever the car is at home.

[docgibbons]

ordered the voltmeter from ebay, thanks. and will either do the regulator check you advise, or let the local garage take a look as i'm pretty hopeless. does this mean you think the battery itself is okay? given that I keep getting through them at a rate of knots, I'm beginning to think they can't all be faulty.

[Trickydicky]

I use one of these when the car is not being used as it isolates the battery and prevents any drain when the car is stood. You dont have to use the fused connector if you dont need it, its only for keeping the memory on a radio active. It also compliments the security devices I have fitted too.

http://www.ebay.co.uk/itm/like/12109915 ... 80&ff14=95

Also I have one of these too, http://www.maplin.co.uk/p/solar-powered ... rger-l58bf
I connect it when the car is parked in the garage with the above isolator disconected and as yet I have had no problems with flat batterys etc.

Obviously a system like this only works well if the electrical system is working as it should. It could be that your dynamo is not giving out the correct volts due to simply the brushes need replacing. It maybe that the regulator contacts need cleaning.
The only way to check is as stated earlier to connect a multimeter across the battery, rev the engine and check it registers between 13 and 14v.

[docgibbons]

well in that case I guess there's something up with the dynamo brushes or regulator contacts as the garage reading was 12.2 both without the engine running, and the same with revs, lights, wipers on etc.

[bmcecosse]

Get your own meter - invaluable tool. The garage have an interest in selling you a new battery!

[DAVIDMCCULLOUGH]

On one of my cars the battery went flat a few times and I eventually had a proper look at the dynamo. One of the brushes was still like new and seized into place and the other was free but almost completely worn away. A clean and oil and some new brushes and it always kept it charged up ok.