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General Generator Question

Mike Cushway

Subscriber
Last Subscription Date
05/28/2020
I would like to throw this out to you guys.....

Would a vintage 24v Delco-Remy generator/regulator in good condition and properly adjusted for speed/output be a viable option for occasional charging of a 24v battery bank? I would enjoy the challenge of putting something like this together with an old engine. Mike in the frozen north.
 

Vanman

Subscriber
Last Subscription Date
06/10/2020
Re: General generator question

Absolutely! The power available will be determined by the HP of your engine, up to the limit of the generator, of course.
 

Mike Cushway

Subscriber
Last Subscription Date
05/28/2020
Re: General generator question

Is there a general formula for determining the HP needed.....I can do the math if you can just get me started on the correct path. How do I determine what is a safe output from the generator?
 

Mike Cushway

Subscriber
Last Subscription Date
05/28/2020
Re: General generator question

Looking at my well frozen '48 JD-A this afternoon, it looks like the generator is turning engine speed +/- a tad. Crank to cam at 1:2 and then cam to fan bevel gears at 2:1(29:15 actuall). Say around 1000 rpm. This suprises me. I would have thought a lot more. The 24v two cylinder diesel models will be close to this as well. So I am looking at generators in this speed range.....I think:shrug:
 

DKamp

Registered
Re: General generator question

As you increase the rotating speed of the generator armature, it's output voltage will increase.

There's no need to spin it any faster than what's necessary to charge, but...

Your charging rate is determined by cell acceptance at the applied voltage...

And the output voltage rises as you apply more current to the generator's FIELD...

To make it more complicated... as you apply more voltage to the generator field, it's current rises, causing the armature to produce a higher output voltage.

So it's a balancing game. It will work... it'll require a little tweaking to get it where you want it... BUT... what you DON'T want to do, is put a really small pulley on the generator shaft to make it spin faster. While this DOES work, the amount of belt contact surface decreases, which limits the amount of power that the belt can transmit (traction surface) and also makes the bend on the belt much tighter, which increases wear and tear on the belt, and increases side-load on the generator. If you really need to increase the speed, use a larger engine-side pulley, or a jackshaft with small driven and large drive to step up the speed ratio.

Yes, you can get a fair estimate of how much generator input power is required to make the generator's required input for a given charging power.

1 Horsepower = .745 Kilowatt hour...

Or also said... 1hp equates to just under 750w.

Now, 750w equates to 31A....

SO... if your generator is CAPABLE of pushing 31 amps at 24v, you'll need AT LEAST 1hp at the generator's DRIVE SHEAVE to pull that load.

If it's a small belt, on a small pulley... then you won't get there, because there's not enough tractive surface for the belt to transfer that much power.

If you run a larger sheave (greater contact radius) and larger belt (larger contact sides), then it certainly WILL pull 1hp. Running larger sheaves at BOTH ends will reduce the belt surface load, so it'll be come more capable of handling the load. Also realize that this also increases the transmission efficiency of the belt drive... if you choose a less-efficient belt setup, you'll need more shaft HP to drive the generator.
 
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Mike Cushway

Subscriber
Last Subscription Date
05/28/2020
Re: General generator question

DKamp,
Thank you for the nice explanation. I was planning on using a vintage Wisconsin ABN and Lovejoy couplings inline. I can regulate the speed of this engine very well. Longterm, I hope to convert it to LP.
 
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