Cutting out.

Post by **Ardenrun** » Fri Mar 06, 2009 11:57 pm

Today my Minor just suffered total electrical failure. The first instance was whilst idling, there was no cough or splutter it just died.

The second instance was after a ten mile journey, I had the headlights, radio and heater blower on, as I got out to open my garage door the car stopped and didn't have sufficient power to restart, which seemed odd given its 10 mile trip home.

The Minor had a new battery, points, coil and condenser two weeks ago. Can a battery be so low on charge that it will just stop working like this. I did notice the wiper speed was also very slow, when I used the windscreen washer. The ignition light was not illuminated either. I still have a dynamo fitted.

When I checked the battery an hour or so later and despite showing 12 Volts on my test metre it still wouldn't turn the engine over. Could I have got a faulty battery or is it something more sinister. I have now put the battery on charge.

Any help gratefully appreciated.

All the best

Gary.

Post by **bmcecosse** » Sat Mar 07, 2009 12:18 am

Bad connections at the battery and/or earth connections to the engine? Loose fan belt - it needs to be tight - but not too tight! When engine is running at fast idle (nothing switched on) battery should be at ~14 volts. If not - then the dynamo is not charging!

Post by **Ardenrun** » Sat Mar 07, 2009 9:19 pm

Thanks bmcecosse,

I wish it was the Fan belt, after a lot of tinkering today it looks like the culprit is the Voltage regulator

I can't moan though as it looks like the original regulator, 39 years of reliable service is pretty good when all is said and done.

Ardenrun.

Post by **bmcecosse** » Sun Mar 08, 2009 10:48 am

Run a bit of fine emery between the contacts - may be ok. The battery hasn't been removed/refitted wrong way round has it ??

Post by **rayofleamington** » Sun Mar 08, 2009 2:26 pm

The battery should be 12.5 to 13v when the car is switched off (if all is well).

If the battery get low enough the car can stall - but usually you'll get missfiring first.

Post by **bmcecosse** » Sun Mar 08, 2009 4:29 pm

It's rarely the voltage reg - have a look at the dynamo brushes before rushing into changing anything.

Post by **Ardenrun** » Sun Mar 08, 2009 8:53 pm

Thanks everyone for all the advice.

More by luck than judgement the Voltage regulator now seems to be partially working, although at idle my Ammeter is still showing a discharge. Is it worth preservering with the old one or should I just get a replacement.

Gary

Post by **PSL184** » Sun Mar 08, 2009 8:59 pm

It is quite likely that, if you have a dynamo. you will get a small discharge at idle. If it comes up when running at normal speeds then I wouldn't worry.

Post by **bmcecosse** » Sun Mar 08, 2009 10:06 pm

Yep - discharge at idle is common - which is why the alternator was invented! If you want it to charge - just lift the idle speed slightly. But it does mean that you should be 'economical' with the headlights/heater fan/wipers when in traffic, and only switch them on when out on the open road!

Post by **bmcecosse** » Sun Mar 08, 2009 10:09 pm

Yep - discharge at idle is common - which is why the alternator was invented! If you want it to charge - just lift the idle speed slightly. But it does mean that you should be 'economical' with the headlights/heater fan/wipers when in traffic, and only switch them on when out on the open road!

Post by **rayofleamington** » Mon Mar 09, 2009 12:15 am

And many decades after the introduction of the Alternator they have invented one that turns off* at idle...
This helps to reduce the load on the engine at idle and therefore reduces city drive cycle emmissions when long periods are spent stuck in traffic.

(* Well ok, it turns off unless the battery is low, as part of a smart charging system)

Post by **Ardenrun** » Mon Mar 09, 2009 12:31 am

I have a feeling I will be going down the alternator route shortly. I'm intending to drive the Minor far more than I have done in the past, which means there will be occasions when I will need to use my lights, heater and wipers all at the same time!

Gary.

Post by **PSL184** » Mon Mar 09, 2009 5:27 am

Ardenrun wrote:I have a feeling I will be going down the alternator route shortly.

Carry a spare for when it packs up on you - not as easy as a dynamo for just putting new brushes in

Post by **bmcecosse** » Mon Mar 09, 2009 7:47 am

Ahh - I thought the whole engine was turned off 'at idle' unless the battery was low - to reduce city emissions. Not heard of an alternator that turns off - or am i reading it wrongly Ray ?

Post by **rayofleamington** » Mon Mar 09, 2009 10:58 pm

Ahh - I thought the whole engine was turned off 'at idle' unless the battery was low - to reduce city emissions. Not heard of an alternator that turns off - or am i reading it wrongly Ray ?

both options you mention are already in series production.

I was reffering to a smart charging system - where the alternator is taken off load until needed.

On the vehicles where the engine has an auto stop/start system, the stop/start mode is disabled when the battery is low (this allows more time to charge up the battery, but also not a good idea to turn the engine off and expect it to start again if your battery is nearly flat!)

In addition to smart charging systems there are systems avaialble where the starter motor and alternator are combined (a starternator). The mild versions are belt driven so not a million miles away from what you'd expect but the more radical versions have the windings built into the flywheel area allowing additional electric motor power when accellerating and brake energy regeneration when slowing.

I expect the recession will slow down or sink a lot of these developments, but rather like the stuff dreampt up in the 50's a lot of it may resurface later.

Personally I'm very happy to use a dynamo on an everyday car. Leaving the battery charger on the car overnight once or twice in winter as a preventative measure is a lot less hassle than sitting on the side of the motorway for hours waiting to be rescued due to a failed alternator (been there done that far too many times, including on the 2007 LEO)

Post by **Cam** » Tue Mar 10, 2009 1:24 am

rayofleamington wrote:Personally I'm very happy to use a dynamo on an everyday car. Leaving the battery charger on the car overnight once or twice in winter as a preventative measure is a lot less hassle than sitting on the side of the motorway for hours waiting to be rescued due to a failed alternator

Totally agree, Ray.

My everyday car has a dynamo and personally I prefer them as they do seem more reliable than the alternators.

Post by **bmcecosse** » Tue Mar 10, 2009 2:39 pm

Just carry a spare alternator - £1 at autojumble. With spare on board - the one on the car will never fail!