Alternator sizing and water pump side loads?

[sailingca]

I am considering upgrading my current 105 amp alternator to a Balmar AT-165 amp alternator on my Yanmar 55 HP diesel but have gotten differing opinions on whether this will cause too much side loading on the water pump and cause bearing problems and premature failure. Technical support at Balmar indicate that changing from a single v belt to serpentine or double v belt arrangement should reduce the excessive tensioning required and not induce excessive side loading. There are off the shelf conversion kits for serpentine pulleys (or double v's) for the engine PTO, water pump pulley and the alternator can be order this way as well. Any real world experiences would be helpful as the parts are expensive. Ideally, I would leave the current arrangement and add a second high capacity alternator that would only be driven off the engine PTO but I do not have enough real estate for that arrangement.

[Lepke]

When your alternator is outputting close to max amps, a single belt will probably slip. Even if not slipping, the belt will wear much faster and be hot to the touch.
I put 140 amp alts on my Detroits and had to go to dual belts. Couldn't find wide belt pulley to fit aux.

[sy_gilana]

I have done this and in each case I went to double V belts.
The side load is a function of amperage divided by the area of contact and belt tension. Increasing the area will allow less tension but I was still not happy about pump side-loads, so I did it a bit differently. I had a long belt around the pump pulley and a shorter belt around the Crankshaft to Alternator only.

I have photos somewhere...The most expensive part was the mating half pulley bolted to the original single crankshaft pulley.

Hi, I just found one of my mods online here...
http://www.comships.com/b/61_b_51074...51074_44_g.JPG

[Cheechako]

A single belt will not be good with a 165 amp alternator... unless you have a crappy regulator!
Personally if the dual belt goes around the water pump on the same belt, I would be a bit concerned with the side load probably.
My 100 amps single belt slipped some on startup, my 125 amp definitely slipped/squealed a lot. Had to go with a lesser regulator eventually.

[sy_gilana]

Found another better photo, I see the brokers watermarked the photo, but I actually did the job and took the photo so

[a64pilot]

Go with a 10 rib serpentine kit, then you can run the belt almost loose and it still won't slip.
Double belt systems should use matched belt sets, and those are getting hard to come by as almost everything automotive etc has gone serpentine


Sent from my iPad using Cruisers Sailing Forum

[sailingca]

sy gilana, interesting real world solution but one that I've been told should never be undertaken as the belt tension on 2 different belts of different lengths is impossible to match. Could be just the theorists versus those like you who have done this and found it works.


At this point I think I'm going to replace all three pulleys with an 8 or 10 groove serpentine and hope the tension can be reduced to the point where no slippage occurs and it does not increase the side load on the water pump.


Since my engine PTO also drives an engine driven refrigeration compressor I will go with a double serpentine pulley on the engine PTO and drive the compressor directly off the second outboard pulley position. Found a company that claims to do lots of specialized pulleys like this called ZRD - anybody have any experience with them?


I appreciate all the feedback and help on this.


Ciao Bella

[tinkrman69]

go serpentine if you can. side load is low. the more contact, belt to pulley the less pressure needed. That's why just a spring loaded idler pulley is all that is needed to tension a serpentine belt. they are easier to replace too.

[sailingca]

Awesome - I think serpentine is the way to go. I also like the idea of adding a spring loaded idler pulley to increase contact area and control belt tension but can't find any off the shelf idlers for marine applications - possibly an auto design would work for this just as well?

[Boston Blackie]

We replaced the stock alternator with a 160A Elektromaxx on our 47 HP turbo Yanmar with serpentine belt conversion 2 years ago. It has performed well and is a great upgrade for AGM batteries when the solar panels are obscured. No issues with side loads as the others have posted.

[Doug Brown]

The other side load that everyone has missed talking about is to the "front" engine crankshaft seal (behind where the pulley is) and the front crankshaft main journal bearing.

These can also suffer additional wear from side thrust when you really tighten up the belts and cause the crankshaft to deflect (bend), so going with serpentine belts makes the most sense to reduce these loads.

[Jd1]

An additional thumbs up for serpentine belts. The only issue I have run into is that without a tension pulley I get a whipping/snapping kind of sound. The belt is fairly tight but there is a good 1/2" deflection either side of the center line under power in the longest section of my belt. I would love to put a tensioner in but there are no mounting provisions and I can't be bothered to manufacture something from scratch. I might eventually .....

[sailingca]

Boston Blackie - your setup sounds identical with similar size engine and alternator to what I was proposing and it sounds like you've had no issues. How was Elektromaxx to work with?

[Jd1]

FWIW, I was not happy with my experience with Electromaxx !

[Boston Blackie]

I bought the Elektromaxx thru Bruce Schwab. Bruce is a great resource for blue water energy systems and has been great with my Solbian upgrade.
I did speak to the Elektromaxx guys a couple times and they were very helpful resolving document vs delivered issues. We have a new Balmar regulstor with temp sensing, and can toggle bsck to the Ideal or rewire to use the EM intermal.