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post #11 of 12 (permalink) Old 29-05-2019, 16:00
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Originally Posted by eurajohn View Post
An alternator generates ac power, a dynamo generates dc power.

Alternators fitted to vehicles will be self contained with the necessary components for the control and rectification components to convert the ac to a usable (to the vehicle) dc current.
Dynamos however require and have a separate "regulator" to control the already dc current.

Typically both devices will supply in the region of 14 volts, to the system it is attached, this of course refers to a 12 volt system and not a 24 volt one as found on many commercial vehicles.

How or where the 18 volts discussed is coming from would need some more basic information on the vehicle in question i.e. is the base vehicle 12 or 24 volt.

Yes, I understand that John.

I meant upgrade the vehicle to an alternator set-up like any contemporary van.

To go travelling with an (sorry,no offence meant) old fashioned system, if there are problems there is less likelihood of finding someone to fix it or supply parts.

I'm daft and proud of it.
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post #12 of 12 (permalink) Old 29-05-2019, 16:46
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Id agree a dynamo system has a regulator that ensures the dynamo output is only switched to the battery when its above the battery voltage (otherwise the battery will feed the dynamo as a motor!) and a second component that disengages the feed when the battery voltage reaches a certain level (typically 14 or so volts) The black box regulator normally has 2 coils in it to do these two functions.
Its possible the pre regulated output has been fed back to the second battery but it would then have to have its own regulator or you risk massively overcharging the second battery.
Dynamos are less effective at low revs so the move the an alternator would be a smart choice. In which case the stock regulator would need to be removed and bypassed and a splitter added to ensure the two batteries are isolated from each other.

When measuring a dynamo system you need the revs to be quite high to get a decent output tick over or a low rpm won't produce much output.
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