dynamo or alternator

[morrisminormonkey]

Hi guys,

For those that don't know me, i'm new here having recently inherited my dads 56 splitscreen..

My brother and I used it as our support vehicle on our charity bike ride a week or so ago, it made around 1200 miles but wouldn't start 180 miles before the end, bit of a shame but pleased it did so well.

so onto the starting or lack of it, i'm guessing the dynamo has gone, seems to be juice in the battery but not enough to start, so i'm now wondering on the value of replacing the dynamo with an alternator. any advice most welcome.

Thanks

[katy]

Nothing wrong with a properly working dynamo and regulator.
BTW, in my lingo it's called a generator.

[lambrettalad]

very popular topic (do a search if you have a wish for an hour to spend reading ),me an alternator every day
others feel strongly that there's no need to change

[JOWETTJAVELIN]

Did you not have a starting handle?

If the dynamo wasn't charging the warning light should have come on, and stayed on all the time.

Switching to an alternator might not solve the problem - you need to pinpoint it and find out exactly what it is. Could be wiring or poor earth for instance.

Might just turn out to be brushes or slack belt.

[bmcecosse]

No need to go for an alternator - tighten the fan belt and get it running. Measure the battery volts with the engine running at decent revs (give it 5 mins running to settle first) - and then do the same again, this time with the headlights and the heater fan ON. Tell us the results!

[morrisminormonkey]

seems like the jury is out then and i should first make sure that it is indeed the dynamo before throwing money at a replacement,be it a new dynamo or an alternator.

the reason for considering an alternator is that i'm hoping to use the car more regularly and am considering a number of 'upgrades' to make it more user friendly for modern road driving.

Anyway, i'll dust off my old voltmeter and see if i can get her running to do the tests, i'll have a look for the warning light too.

as for a starting handle! you mean the sort like laurel and hardy would use!?!?

[bmcecosse]

Laurel and Hardy had a Morris Minor ??????

[morrisminormonkey]

just the same starting device i think

[bmcecosse]

[Boomlander]

Laurel and Hardy had a Morris Minor ??????

Laurel and Hardy used Model T Fords in their films but It would have been great to see Stan and Ollie in a Moggy!

[JOWETTJAVELIN]

It's worth getting a starting handle because even when there is not enough charge left in the battery to operate the starter (which draws a lot of current), you can start it with the handle and the engine will run for quite some time before the battery completely runs out.

[IslipMinor]

just the same starting device i think

Completely 'off topic', but I read yesterday the while Frank Whittle was designing and developing the first jet engine, he needed 'something' to act as a starting device to spin the engine up to 'self-sustain' speed. Since the whole project was grossly under-funded, apparently FW went to a scrapyard in Luton, bought 2 Austin 7 engines, made one good one from the two and used it as the 'starting device' on the world's first viable jet engine!

[bmcecosse]

Excellent!

[rayofleamington]

Personally I'd keep the dynamo but check everything until you find the cause. Starting handles are great for partially flat batteries provided your car is well serviced and starts easily. if not, then get servicing ;-)

Most common cause of conversion from Dynamo to Alternator is failing battery...
The battery looses the ability to supply cranking power (massive current + low internal voltage drop) over lifetime.

An alternator is generally capable to provide more charging power, and can charge at idle, where a dynamo is limited.
If you spend 2 hours a day in stop start traffic, then I'd rather stick a 14w solar charger on the passenger seat than do an alternator conversion.

The biggest issue for the dynamo is regular hours of stop start in winter when using lights, heater , wipers etc.. This can discharge a good battery over time, whereas an alternator would be a potential way out of the issue. If you're getting flat battery at other times, you shouldn't be!

Alternators have lovely little bits of sensitive electronics - with a pretty high failure rate.

As for routing round for scrap parts to get your 'high profile project' tested... that practise isn't gone for good ;-)

[ampwhu]

alternators are cheaper and easier to replace.

http://www.ebay.co.uk/itm/bek098-HIGH-O ... 2a218cf3af

all day long

[morrisminormonkey]

thx ray for all of that good information.

so to add to the thread some more, i've had a solar panel on the battery for the last couple of days and bought my voltage meter home from work today to check things out.

i unclipped the solar panel and checked the voltage on the battery via the terminals, it read 12, not sure what it was on before i clipped the solar panel but will have to check that some other time now, anyway, the car started first time though it felt like it wouldn't, wasn't the spriteliest of turnovers.

as soon as it was running i checked the voltage again, 12 volts, left it running for 5 mins and checked a third time and got a reading of 14-15volts, so does this now mean the dynamo is not at fault?

thanks again all.

[JOWETTJAVELIN]

If it falls below 12v there is a discharge and the battery will run low if it's like this all the time. Anything above 12v when running (but not excessively) - 14v sounds fine, means the batt. is charging and all is well.

Note the charge warning light comes on sometimes at idle with a dynamo, this is nothing to worry about, it simply means that the engine is not running fast enough for the dynamo to cut in and start charging.

[bmcecosse]

Now read the volts when doing decent revs - with the head lights ON, and the heater fan running. It should be ~ 13.6/8 like that (again at decent revs and held there for a at least 30 seconds). 14 volts should be the maximum you ever see. The solar panel only puts a tiny trickle charge in the battery - so it will 'keep' a battery charged if left say over winter - but it is not really capable of recharging a flat battery. It will do it - but may take a month of sunny weather to get there!

[mike.perry]

Apart from anything else, an alternator would look completely out of place under the bonnet of a Series 2

[morrisminormonkey]

Ok, i'll check the voltage with revs next then, thx again for the advice.

So am i looking at a new battery then based on the fact that it looks like the dynamo is working and the voltage at the battery terminals means it should be charging?