Lotus Elan

Dynamo

PostPost by: George4th » Wed Nov 28, 2012 10:51 am

I seem to remember that alternators have bearings and dynamos don't. So I would imagine the resistance (spinning) on an alternator would be less?

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PostPost by: elancoupe » Wed Nov 28, 2012 11:13 am

Dynamos have a bearing the front, bushing in the rear.
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PostPost by: bast0n » Wed Nov 28, 2012 4:21 pm

You could always fit a Gilmer drive (toothed belt) to run the water pump and alternator. Can be run very loose, to relieve side loads on the water pump, with no slippage on the alternator


Or as I have said many times - fit twin pulleys - drawings on request.............free!
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PostPost by: YellowS4DHC » Fri Nov 30, 2012 3:00 pm

Galwaylotus wrote:After converting to an alternator I needed a slight longer fan belt but I can run it VERY loose with no slippage. Of course I'm not running a bunch of extra lamps, big stereo amp etc.
:wink:


ditto, except I didn't need a longer belt.

I like originality too, but I like (some) modern upgrades if kept subtle and innocuous. Basically this is the same philosophical issue as a 5 speed gearbox swap. The balance chosen here is a personal thing, no right or wrong.

I swapped out the alternator but kept the regulator box and all the original wiring neatly tied back with the new wires folded in so that unless you memorize wire color codes, you don't know it isn't original (unless you look down and see the alternator :D ). Can always go back if I want to.

Still have the generator (dynamo), but it sits in a cabinet not on the car. If I had the time and money, I'd do the 5 speed conversion a la Alex Black (looks original, but isn't).

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PostPost by: billwill » Fri Nov 30, 2012 3:32 pm

The other day I noticed that you can actually buy DUMMY dynamo control boxes, to fit if your old one is gone or crappy and you have fitted a dynamo.
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PostPost by: nomad » Sat Dec 01, 2012 1:58 pm

Save the RB106 for terminal connections. Gut the box and use it to hold a revised wiring diagram sealed in a baggy. Thats how I handle gen to alternator conversions.

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PostPost by: ricarbo » Sat Dec 01, 2012 5:56 pm

If you make the change, it's clear you will need new brackets. Does anybody know of a supplier of these, or do you have to try the hard route of getting some made?
Ideally, I'd like a toothed belt drive to the water pump and a separate crankshaft pulley driving the alternator, with whatever sort of belt it's pulley requires. Does anyone do a kit of bits?
At start up, an alternator puts out an enormous current, possibly over 100 amps, which no dynamo will match, and it's this that loads up the belt, requiring it to be tighter than everyone says is good for the waterpump. The advantages of the close control that a modern regulator give surely put the Lucas RB106 and RB340 into history.
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PostPost by: Galwaylotus » Sat Dec 01, 2012 9:50 pm

I went with a Lucas alternator and didn't have to change mounting brackets (from the one with the dynamo). Some careful spacing to align the pulleys and, as stated earlier, a slightly longer belt and everything works fine. The belt is very loose but still doesn't slip. Try it. :wink:
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PostPost by: Galwaylotus » Sat Dec 01, 2012 9:55 pm

AnthonyBelcher wrote:I'm sure that the fan belt for an alternator has to be tighter than with a dynamo. At the moment my wifes fan belt on her Ford Focus slips when the front and rear heated screens are first switched on together as the alternator struggles to replace the power loss in the battery. The fan belt obviously needs tightening up to stop it slipping. Mind you I also think we will need a new battery soon.


Since my Elan has neither a front heated screen nor a rear heated screen it's not an issue for me.
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PostPost by: Galwaylotus » Sat Dec 01, 2012 9:57 pm

ricarbo wrote:At start up, an alternator puts out an enormous current, possibly over 100 amps, which no dynamo will match, and it's this that loads up the belt, requiring it to be tighter than everyone says is good for the waterpump.

45A alternator = max current 45A!!
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PostPost by: billwill » Sat Dec 01, 2012 10:11 pm

Galwaylotus wrote:
ricarbo wrote:At start up, an alternator puts out an enormous current, possibly over 100 amps, which no dynamo will match, and it's this that loads up the belt, requiring it to be tighter than everyone says is good for the waterpump.

45A alternator = max current 45A!!


Probably not, the 45 amp rating will be what it is capable of generating continuously. For brief periods it can probably produce more.
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PostPost by: Quart Meg Miles » Sat Dec 01, 2012 10:22 pm

And even 45 Amps requires 1 BHP through the belt. BTW, Bill, violin rosin is about ?4 but I haven't tried it on my belt yet (to improve its grip, not its sound :)).
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PostPost by: ricarbo » Mon Dec 03, 2012 8:45 pm

That's interesting Galway L. Which model of Lucas alternator do you have? Do other models have different bracket requirements? It wouldn't be hard to spend more on brackets and pulleys than an alternator. I feel a trap to the local scrappie may be looming.

I might add that the high current readings I mentioned were based on observation of readings showing on an engine tuning using something like Sun or Crypton equipment. They were instantaneous peak values, not steady state. With a dynamo I understand the maximum is set by the resistance of the brushes, but with an alternator that's not the case, so it can exceed the continuous rating of the alternator for short periods. I think that's what causes the well known belt squeal on start up, hence a tighter belt or perhaps a toothed belt setup.
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PostPost by: Galwaylotus » Mon Dec 03, 2012 9:32 pm

Luckily I still have the box. It's a 17ACR. I went to a local auto electrician and he recommended it as the output was quite sufficient for my purposes and the unit was relatively cheap and easy to repair if needed. I don't get squeal at startup or any other time and the belt is very loose. It's actually looser than it was with the dynamo. I don't know why but I'm happy as I get a higher voltage output and it charges at much lower rpm.
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PostPost by: ricarbo » Tue Dec 04, 2012 2:03 pm

Many thanks, Galway. I'll have a poke round the local scrappie. I think that was a very common item a few years back, with a relatively low output by today's standards, but it should be more than enough on an elan.
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