I think I have an overcharging problem on my 500D

At tickover, voltage is around 13v with charging light on.

Revving the engine , the light goes out as expected but the voltage goes to 16v plus.

My understanding is that the voltage regulator should limit to 14.3 max.

I therefore swopped the regulator box with a service exchange unit having carefully noted the wiring.

Result was no change , exactly the results with charge going to 16v plus on revving.

Any ideas anyone, is it possible my original wiring was wrong?

hamiltos2 said:

I think I have an overcharging problem on my 500D

At tickover, voltage is around 13v with charging light on.

Revving the engine , the light goes out as expected but the voltage goes to 16v plus.

My understanding is that the voltage regulator should limit to 14.3 max.

I therefore swopped the regulator box with a service exchange unit having carefully noted the wiring.

Result was no change , exactly the results with charge going to 16v plus on revving.

Any ideas anyone, is it possible my original wiring was wrong?

Click to expand...

Alternator or dynamo?

Sorry dynamo

Is this possibly a dynamo fault then ? Not sure how that could be the case as I thought the dynamo gives out lots of voltage ( ie in excess of 12v) and the regulator box did the rest?
Not as simplecas that no doubt...

hamiltos2 said:

Is this possibly a dynamo fault then ? Not sure how that could be the case as I thought the dynamo gives out lots of voltage ( ie in excess of 12v) and the regulator box did the rest?
Not as simplecas that no doubt...

Click to expand...

This was mentioned in a thread sometime ago and it seems as though the dynamo will show a very high charge rate. On the car I recently sold, a 62D, I saw a charge rate well above 15v and from what I remember reading it wasn’t anything to be concerned about although, like you, I was alarmed when I first saw it I also swapped out my regulators and it gave the same result. I didn’t have any battery problems over the nearly four years of owning that car.

Thanks and I guess 16v would normally be OK

My issue is that I have fitted an Accuspark that doesn’t like 16v+

I guess I could try a ballast resistor as used on a coil to limit the voltage into the Accuspark but it still begs the question as to why the regulator isn’t limiting to 14.3v.

Thanks for your input.

Hi again. After giving further thought to your problem I’ve searched back to find the thread that I started back in July 2017 regarding this. See https://www.fiatforum.com/500-classic/452195-generator-light-but-battery-charging.html and in particular post #16 where Tony (Vitesse) kindly explained fully what he had discovered of dynamo charging rates on 500D by researching through several different workshop manuals.

Ian,

Very much appreciated, this issue isdriving me bonkers!

Ian,

Interesting reading and I guess 16v it is.

On that basis , can you recommend anyone who knows what current an Accuspark unit draws as an electronics friend of mine is going to design/ make me a 12v regulator box .

Also this might explain why some people have had bad experience with Accuspark units . They may not realise that they have cooked them with overvoltage.

Ian,

OK . Got it from Accuspark , about 2 amps.

Also for anyone interested, I have just sourced a cheap inline regulator which I will test on the Accuspark giving it a guaranteed 12v max. S
Should be interesting!

hamiltos2 said:

Ian,

OK . Got it from Accuspark , about 2 amps.

Also for anyone interested, I have just sourced a cheap inline regulator which I will test on the Accuspark giving it a guaranteed 12v max. S
Should be interesting!

Click to expand...

Hope that sorts your problems. I’m afraid I can’t help you with regard to the Accuspark as I run the original points ignition. Did you change over because of a problem with the original ignition system or because of its reputation? I ask because I firmly believe that many change from points for the latter reason. I’ve had many classics over the years and the last time I suffered a break down that could be attributed to points or condenser failure was in the mid ‘70s!

May I relate a tale: When I went to look at my ‘62D, prior to purchase, the chap couldn’t get it to fire up. I unclipped the distributor cap and saw the points were closed so asked him for a screwdriver. I set the points by eye and guesswork and never altered the setting for the 4 years I owned it and it ran like a sewing machine.

Ian,

You are probably right, in the end probably more trouble than it was worth changing to Accuspark.

Done something similar on a few of my cars so just force of habit in hindsight.


So if the next step doesn't work , I may very well go back to points!

Thanks for your input.

Best rgds,
Simon

Ian,

Guess what , gone back to points!

Thanks for all your guidance and advice.

hamiltos2 said:

Ian,

Guess what , gone back to points!

Thanks for all your guidance and advice.

Click to expand...

I would suggest that a Swiftune condenser might be a good idea, highly rated on this forum.

BTW I was obliged to help as our daughter is a Hamilton!

Might just get one of those just in case the incumbent packs up.
Thanks sgain