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+--- Thread: Dynamo overcharging? (/showthread.php?tid=9908)
Dynamo overcharging? - jamesheath - 20-03-2025
Hi,
I'm getting up & running after a while - and found I needed a new battery.
Looking at the ammeter, and watching the battery voltage, I think that I'm over-charging the battery - it's pushing the battery voltage up to over 8 volts on winter, and summer doesn't charge at all.
The car is a special, electrics are pretty early coil setup (declared reg date is 1927, but it's coil, not magneto) - I think the dynamo is probably a DEL
This is a fairly early dynamo, which I think has a shunt.
I'm pretty confident that all the wiring is correct - when on summer charge, I can see that the ammeter needle moves up just a fraction when I rev the engine lots - though not enough to charge!
Video explaining issue
I think my choices are:
1) Try and get the summer charge working and use that
or (probably preferred)
2) move to an electronic charge controller - which I'd be very happy with - it's a special (quite a tatty one!).
If I go for 2) does anyone have experience of one they've used successfully on a DEL Dynamo?
Thanks,
James
RE: Dynamo overcharging? - "Slack Alice" Simon - 21-03-2025
Looks normal for system where the half charge resistor is missing or broken.
Full charge of 8 is ok, if you regularly use the starter.
Half charge resistor is either on top of the dynamo, or in the base of the cut-out, in a "standard" set-up.
If missing it is replaced by a high wattage (3.3 or 2.2 ohm - can't remember) modern resistor.
Wiring has to be ok, looking at your floating switch panel, that might be the problem.
RE: Dynamo overcharging? - jamesheath - 23-03-2025
Hi - thanks - that makes sense.
So I could replace the shunt resistor, but I'm rather leaning toward an electronic regulator - does anyone have any recommendations for one suitable for an early DEL type dynamo?
RE: Dynamo overcharging? - Dave Mann - 23-03-2025
Talk to Peter at Classic Dynamo & Regulator Conversions, they are very helpful.
RE: Dynamo overcharging? - AustinWood - 23-03-2025
The charge can be adjusted bt moving the third brush. Reducing the charge to about 4 Amps is easily done as a temporary measure while the half-charge problem is resolved.