Dynamo or Alternator?

[mad-4-moggywhite-1]

Hello all!

I have a 1957 4 door saloon. I was driving her recently after a period of non use due to awful weather! Any way she took a while to start but I wasn't surprised at this as she had been stood for a little while and it was a very cold frosty morning. Once on my way I noticed the red ignition light was on. I didn't have any issues on that journey but a couple of days later we went out in her again and had to put our side lights on. We noticed a distinct drop in power and when we turned off the lights we accelerated once more to our normal speed. My husband thinks we need to replace the dynamo but says he thinks we should upgrade to an alternator. As we don't use the car that regularly, she is our Sunday drive out car, I feel this isn't really necessary.

Anyone got an opinion on this? I would be grateful to you.

Many thanks

Maddie.

[myoldjalopy]

If the red ignition light was staying on then the battery wasn't being charged. That's why you lost power when you switched the lights on. Might be a fault in the wiring of the charging circuit, the dynamo or the control box. Possibly the fan belt needs tightening.
If you can identify the failure then, even if it is the dynamo, I wouldn't bother changing for an alternator. After all, its been doing fine on a dynamo for the last 49-odd years!

[myoldjalopy]

Oops! 59 years! Can't count! But that's even longer it has been OK with a dynamo.
A dynamo is fine, especially if its just a Sunday drive car.....

[bmcecosse]

The brushes may be worn -or just sticking (it's rare for anything more serious to go wrong with a dynamo) - or the contacts in the Regulator box may just need cleaning. I would check all that before worrying about an alternator. And indeed as above - is the fan belt ok?