OT - goodbye alternators?

One more step further from being able to fix your car by the side of the road with a bent coat hanger and elastic band!

BTW are automotive alternators really only 50% efficient?

Very true.

That was mech to elec, not overall from chem to elec.

You haven't really been able to mend most cars/vans for the past few years, fly-by-wire injection systems and 'electronics for everything' means that even the dealers can't always sort them out.

As far as efficiencies go, I'd have thought 50% was being generous....

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

Even so, with the heating losses, power to drive the alternator cooling fan, drive belt slippage and electrical losses, I still reckon that 50% is over-generous, I'd have thought 40% was nearer the mark.

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

I work on nearer 20 - 25% at best. My smaller show engine is driving a car alternator with 45A max output. It will stall a 2.5HP engine dead.

John

Fairy snuff, I bow to overwhelming opinion ;-) I recently picked up a brand new 50A Honda one for next to nothing which I intend to try on the little Chinese 'Marshall' diesel (probably around 3HP). Unfortunately it is the type with no internal reg so I'll have to sort something out - any advice?

Do you mean the alternator or the engine has no regulator/governor? I assume it's the alternator. At the risk of being a defeatest, I would look for a second hand alternator with an internal regulator. Modern alternators are controlled from the car's ECU. I'm not sure how to build a control box for them but, if you want it to work with suitable protection, it's likely to be complicated and electronicary. If you REALLY want to know how, I think I've got a circuit diagram for a regulator at home. It's for a Lucas ACR series but may help. If you do couple the alternator to the engine, I would limit the output by keeping the speed low. Start at 1:1 with the engine and see how it goes before increasing any more.

John

"John" wrote

Correct.

Thanks John. There are external regs aimed primarily at the marine market (charge controllers they call them) which I believe can be retro-fitted to standard alternators giving characteristics more suitable to the deep cycle 'leisure' batteries rather than automotive starting types. Trouble is they are expensive so I was hoping our resident battery / charger expert might have some info. Though I'm a bit rusty now, I used to know which end of a soldering iron to pick up ;-)

Have a look at:

Lots of basic info there and I think we also have the other CAV/Lucas alternator manuals waiting to be put on the site.

You can't jump from page to page at the moment, and the selection menu is at the very bottom of the Injection menu page:

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

That's interesting. I had assumed that the solid state regulators would be linear, but they pulse modulate the field current just like the old electromechanical jobs! Means you don't need such high wattage output TR of course. Thanks for the info.

You could always try running it unregulated - you should get something like

38 volts if memory serves - 'pends what you intend doing with the electrickery oozing out of the wires ;o))

Regards,

Kim Siddorn

ISTR that there were plans floating around to get 240V mains from modified car alternators a while back. Be careful

John

Nick, I've found my alternator book. It looks like the Lucas equivalent of the information on Peter's site. If you want a copy, drop me your address and I can put it in the post on Monday.

John

J> Nick, J> I've found my alternator book. It looks like the Lucas equivalent of J> the information on Peter's site. If you want a copy, drop me your J> address and I can put it in the post on Monday.

J> John

Very kind of you John, but the one I have is Nippondenso and I'm sure the CAV stuff from Peter is pretty generic.

BTW ISTR that the mains conversion info was in 'alternator secrets' one of the Lindsey books stocked by Camden.

nickh=== Posted with Qusnetsoft NewsReader 2.2.0.8

J> Nick, J> I've found my alternator book. It looks like the Lucas equivalent of J> the information on Peter's site. If you want a copy, drop me your J> address and I can put it in the post on Monday.

J> John

Thanks John, but I imagine the CAV stuff from Peter is pretty generic.

BTW ISTR the mains conversion is covered in "alternator secrets",one of the Lindsey books stocked by Camden. No particular desire to go in that particular direction (if I want direct mains, I'd prefer to try a motor as an asynchronous induction generator). But if I can run the Marshall on veg oil and charge a battery for my invertor, I can play at being green ;-)

nickh=== Posted with Qusnetsoft NewsReader 2.2.0.8

And eventually I might even learn how to drive the newsreader on this @#$%^ handheld!

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