Engine driven generators (240V)

I saw one where the gubbins involved a hydraulic pump.

But possibly idiot boy question: is use of the van's alternator clearly a non-starter? IIRC beefed up alternators for vans used to be rated to about 3000 VA even when running hot.

[snip]

A quick google found:

From which some appear to be an uprated replacement for the vehicle's standard alternator, so able to deliver a variety of voltages. Others require a PTO from something like a Unimog or agricultural tractor.

They generally need an engine controller to maintain constant revs.

Power up to about 4KVA which is probably the limit of what can be drawn through the typical alternator belt drive. More than that might be a stand-alone generator on roadwheels with a towing hitch.

I have seen people like UK Power Networks with a lorry-sized generator feedng a whole large village when there is a supply cable problem. I imagine this is a specialist, possibly custom, market.

I have too, where the alternator can be remoted, possibly much closer to the batteries. This was for some hairy equipment in the back of a Land Cruiser.

There are some Chinese clones of/and Bosch alternators which will provide this sort of output. A big problem is the wiring!

There are systems to utilise the alternator to charge extra batteries etc- they are fitted to ambulances etc. They have safety systems to monitor the alternator (and batteries). One manufacturer is Adverc- a friend used to be the local agent and fitted/maintained them for the local health authority. As I recall, some alternators are capable of far more output than normally delivered in normal use, at least for short periods. The system relied on this. If the particular vehicle didn't have a suitable alternator, an uprated one was fitted.

Thank you.

Some of that sounds similar to the Adverc systems a friend of mine used to fit/maintain. I'm sure what the power limit was on those and he is no longer with us to ask. Most of his work was for the local health authority but I recall seeing a system he'd fitted to a VW camper. As VW campers go, it wasn't the best equipped- in fact almost spartan- but it must have had plenty of battery capacity. He gave a lecture at the local radio club about the system but I can't recall the details- this was 10+ years ago.

I'm amused to see that in the USA, the slang for a ham radio transmitter capable of running above the permitted limit was a "kilowatt transmitter"

Some vehicles come with dual batteries as standard, as did my mates SL63 AMG.

A relatively small battery (for a 6.3l lump) in the engine bay to start and run the engine and a much bigger one in the boot to run everything else.

As I was driving it about to sell it for him it first came up with an 'alternator fault' on the dash and then before I could find somewhere safe to stop, it cut out. ;-(

I managed to then slowly coast it a few yards to a farm drive and waited for the AA.

He determined the big battery was dead and that was pulling everything else down, so replaced it. That allowed me to drive it to the Merck dealer and they also fitted a new alternator that was something like £700+ on it's own. ;-(

I understood it was a dual output alternator with two different regulation paths (and so it should have been for that money), as opposed to a split charge system.

Cheers, T i m

Electrical and electronics have never used Imperial units.

1.341 bhp transmitter anyone?

An alternator basically delivers the amps needed when in use. If that exceeds its maximum, it will limit at that maximum. Makers don't normally fit one capable of delivering more than the maximum load (plus a bit for charging and safety) once running at its best speed. Of course it's not usually that difficult to fit a larger one. About 100A (12v) is the limit for a V belt, and about double that for serpentine.

However, if using the main engine to drive a generator when stationary, you'd need to provide speed control. Which might be tricky with modern engine electronics. There might also be cooling system problems.

An alternator basically delivers the amps needed when in use. If that exceeds its maximum, it will limit at that maximum. Makers don't normally fit one capable of delivering more than the maximum load (plus a bit for charging and safety) once running at its best speed. Of course it's not usually that difficult to fit a larger one. About 100A (12v) is the limit for a V belt, and about double that for serpentine.

However, if using the main engine to drive a generator when stationary, you'd need to provide speed control. Which might be tricky with modern engine electronics. There might also be cooling system problems.

But you wouldn't want a normal idle. The whole point. An alternator does not develop its maximum output at idle.

Well okay, but surely hardly beyond the wit of man to program in a ?fast idle? (or whatever rpm required) mode? The hardware is all already there, just needs a software tweak.

Tim

Good luck doing that. ;-)

If its drive by wire it needs a resistor and switch on the throttle pot signal. The electronics have to allow the engine to be revved in neutral as that's the high emissions test.

80A alt 22A@1300rpm 60A@2500rpm That's alt speed the engine speed will be lower as the alt pulley is smaller than engine pulley.

Just use a stick between pedal and seat. ;-)

Odd thing is having been around portable generators for longer than most - location TV etc - I've never ever seen one where the vehicle engine is used to run the generator. Closest might be those old ice cream vans where the fridge compressor was engine driven.

I've seen some advertised when looking a s/h vehicles used for things like specialist radio work.

I'm pretty sure a friend who lived on a boat had a generator coupled to the main engine, as well as another generator. The former was used when underway.

Oh, indeed. Running a generator from the main engine when that is doing its main work is I'd say normal. It's running it do provide power when parked up that isn't. My guess being the efficiency would be dreadful.

Small generator

my Series I land rover had a very large dynamo connected to the PTO when I got it but I could never get it working so later replaced it with a compressor

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