Morris Minor Owners Club

My Traveller has a dynamo (It's in good order) but I have noticed that if the heated rear screens are switched on, the wipers run a touch slower. This suggests that the dynamo is a little over stretched. Its not a big probelm, as the heated screen is only on for a short period, until it demists but if the headlights were also on, that would increase the load still further.

Has anyone else noticed this?

It is to be expected really - If you are going to run high loads on a regular basis an alternator would be better (that is probably the only time you will hear me say that )

It should be fine - as long as you are aware of it, and don't leave them on over long. It's likely the wiper speed will soon recover as the dynamo ups it's charge rate as the voltage dips. It would be an idea to feed the relay for these screens from the A1 terminal on the regulator - that is designed to boost the charge slightly when the headlights are on - they are fed from there already. Good idea to fit an ammeter - then you will see what's going on!

if you have a stereo fitted, and drive in the rain with your lights on / wipers going heated screen on for any period of time the dynamo will really struggle.

A change to alternator is straight forward and should resolve the problem.

How easy is it to change to alt, car is neg earth?

Very easy once you assemble all the parts you need, ie alternator and mounting brackets (either off a late Mini or make them yourself). There is a wiring diagram on the site but I've copied it here for you....

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Thanks everyone. It is only the rear screens that have caused this slowing of the wipers (I have no radio in the car, though I have a couple of spare radio cassettes but no big "Woofers").

I'm a believer in "If it ain't broke don't fix it" but I will improve something if it is lacking. I've saved the diagram so if I ever need to overhaul the charging system, I could look at going alternator. This Traveller is the only car I have ever had with a dynamo, the MGs are both on alternators, as have been all the other cars.......apart from the one with a bike engine .

I rather like dynamos, they are as tough as old boots and you can usually fix them with a set of brushes and a clean.
I believe you should disconnect your alternator when you are (electric) welding or they may get the vapours and need replacing.

Yes true - always disconnect any alternator when MIG or TIG welding - I always take the battery off too as an additional precaution....

The heated rear screen is a great thing on frosty mornings - if it was me I'd be keeping the dynamo.
The time it takes to charge a battery a few times in winter adds up to less time than fitting an alternator. I just run a mains cable to the car and put the charger underbonnet - about 1 minute to put it on and same again to take it off the next morning.

However if the car spend over an hour each day in stop-start commuting traffic, with all the lights on + heater + wipers the dynamo isn't going to keep up and you'll need to manually charge a lot more often. For regular commuting an alternator makes more sense (even though I hate to say that). Using a heated rear screen on frosty days (as long as it's on a limited timer!) will be much less of an influence than the amount of time you spend with the engine idling (no charge) + lots of consumers on.

I have a dynamo and no probs at all, yes the wipers go a bit slower on a slow tickover but that's all. I keep the glass clear on old cars by wiping the inside of the glass with a cloth and a bit of Ecover washing up liquid, stops fogging and doesn't attack the rubber

When I fitted an alternator to my minor I was advised by my local motor factors to fit the later LRA series alternators as fitted to the last a series mini's, rather than the older acr series alternators as these were a higher output and much more reliable, they said they often got faulty ones back under warranty for the acr series, but hardly ever for the LRA series. the price was about the same for both versions.