Dual V belts taking different paths?

[chris95040]

Hello,

I'm looking at swapping my alternator with a beefier 120 or 160-amp one that will likely require a dual v-belt drive.

There's other ways to do this but by far the easiest would be to have the 2 belts follow slightly different paths (one goes around the drive pulley, the water pump, and the alternator, the other just goes from the drive pulley to the alternator.)

Will this be a problem, will the longer one always end up loose or something?

-Chris

[dfelsent]

How will you tension the two belts? Why won’t one be looser and just along for the ride?
Those would be my concerns.
I do understand why it would be easier.

[Jubilee39]

Unless you have matched v belts even two belts following the same path have tension problems, one seems to carry much of the load. Two belts of different lengths, stretch etc would be a nightmare to keep tensioned

[Pauls]

You WILL need two belts. Belt life with a single belt driving that many amps will be short.

Two belts on two different paths is fine, but you must have a way to tension both. Normally your alternator pivots to tension the alternator/water pump belt. The second belt will need to be long enough to be loose when the alternator/water pump belt is tight. The second belt will have its own tensioner. With this system both belts can be well tensioned and you will have a long life, reliable system.

[dkenny64]

I like the idea, but it seems to me that you would need to
spring loaded tensioners. one for each belt. similar to a serpentine belt.
serpentine belt would fix the problem, but not all engine can have that option.
mine is one that without spending big bucks on a custom solution. I cannot even run dual belts..


best of luck
-dkenny64

[Pauls]

Spring loaded tensioners are convenient, but manual ones work fine too.

[dkenny64]

Pauls,


if there are 2 manual.. yes..
I would concur..


-dkenny64

[bcboomer]

If you have access to a small machine shop that will do small jobs you may find it surprisingly inexpensive to have serpentine pulleys made for your crank and water pump.
That way you can also customize the ratios so you get better alternator output at lower engine speeds.
I did that and put on a 200amp, brushless, industrial alternator that was only $320 CAD.

[stormalong]

Originally Posted by bcboomer

If you have access to a small machine shop that will do small jobs you may find it surprisingly inexpensive to have serpentine pulleys made for your crank and water pump.
That way you can also customize the ratios so you get better alternator output at lower engine speeds.
I did that and put on a 200amp, brushless, industrial alternator that was only $320 CAD.

bcboomer, Can you tell us more about the alternator you are using?

[vpbarkley]

I would recommend switching all to a serpentine arrangement. And increase the speed of the alternator by fitting a smaller pulley to it. That will increase both the output and cooling of the alternator. You can't do the equivalent with any number of V belts.

[dkenny64]

what engine?
not trying to get off the OP post.. but I have Perkins 4.154..yes I serpentine are available for the 4.107/108..


getting an alternator after that would be easy.. I cannot get the pulleys
do you have a source

[bcboomer]

Originally Posted by stormalong

bcboomer, Can you tell us more about the alternator you are using?

I bought it from All-Tek Industrial.
It is the "CH-12200-SS 200 AMP BRUSHLESS Alternator"
Made for the Alberta oil patch primarily.
I've been really happy with it.
It runs cool enough to charge 4 Firefly G31s from 20% without cutting back from overheating.
The frame is a tiny bit larger than the OEM junk the motor came with but with a little machining of the bracket I was able to squeeze it in.
I should have had them leave out the internal regulator because I am using a WS-100 regulator.
The 2 new pulleys are just sleeves bolted to the old pulleys, so pretty simple.
Everything lines up perfectly so no belt dust.

[chris95040]

I like the idea of adding a tensioners to the belts.. There seem to be ample spots (thick plates as part of the alternator mount assembly, etc) where I could attach tensioners. Seems like that setup would make life easy when replacing belts etc too.

Is there much science to this, can the tensioner be a simple flat-channeled idler pulley that pushes against the _outside_ of my vee-belt to tension it? Or would they have to be v-pulleys pushing against the inside of the vee belt? Perhaps there are generic kits? I have no idea what for example the idler's bearing ought to be (oillite? ball bearing? needle bearing?)

For those who asked, the engine is a Westerbeke 55B-4 which is a marinized Isuzu 4LE1.

Thanks for all the ideas!

[Cheechako]

You'll need an idler on one.
or
How about two 75-100 amp single belt alternators?

[ABJ87]

I like the thought experiment of the dual tensioners. But it’s kind of a Rube Goldberg approach.

The simplicity, efficiency and life of a flat multi groove belt can’t be beat. I would put my efforts into converting.