Design Help Alternator Serpentine Upgrade

[Stevens 47]

After a season in MX it became apparent that my current alternator system was sub standard. Lots of belt wear and burn. I have a large output dc watermaker that draws a max of 120 amps at full output.

I currently have a Balmar 120 amp driven by a 1/2" v belt.

My plan is to remount the 120 alternator and add another 165 with serpentine belt.

I have the space and ability to mount both these on a serpentine pulley on the outside of my normal 1/2 engine crank pulley. Separate from the engine water pump and water pump">raw water pump.

The advise I am looking for is should Iinstall a idler in the design system or make one of the alternators adjustable for belt tension. I am leaning towards an idler but would appreciate opinions.

I need to read or understand the serpentine belt pulley specs, any suggestions.

I am also looking for a source to purchase an idler and the crank driven serpentine pulley.

I am located in San Diego.

[leftbrainstuff]

An idler works well with serpentine belt systems. You'll find most automotive systems use an idler because it provides a consistent preload and allows you to solidly mount all the ancillaries.

[deluxe68]

I just bought a Balmar 165 last year with the serpentine belt. First problem was that the pulleys did not line up and the boatyard had to add spacers to the crank pulley. Second is that the alternator quickly overheats and will only put out about 70 amps. Lots of internet complaints about the smaller Balmars not able to run at their stated capacity. I cannot remember the exact temps but after less than 5 minutes the unit cuts output by 50% due to reaching about 105C. This spring I am going to rig the engine compartment exhaust fan ducting to cool the alternator. All told, so far I spent $3000 to go from 50 amps (ancient Yanmar alternator) to 70 amps (140 before the new pos heats up). Good luck.

[john61ct]

Best to find an experienced pro.

Try to size pulleys for say 60-70% output at lower rpm.

Balmar MC-614 for adjustability and load control.

[tanglewood]

Just for clarity, I think you are asking about a belt tensioner which is an idler on a spring loaded arm that maintains belt tension. Is that correct? Because a belt system can have fixed idlers as well, sometimes quite a few of them. They aid in belt routing, but do not inherently add tension.

[S/V Alchemy]

You may wish to send a query on this to Mark Grasser, who builds high-output specialty alternators and has plenty of the accessories you want to know about. List of Products

[iabmatos]

Do your alternators come with a cooling fan?

[roland stockham]

I have used poly V belts and they work very well. No slip and much better power transfer which give a longer belt life. My battery bank tops out at about 65A (it is only 500ah) so don't have as much load as you. Because of the better load transfer you also don't need as high a belt tension (better for alt and pump bearings) plus it is less critical so never felt the need for a tensioner. One trick I have used is to replace the slide and clamp bolt with a rigging screw, makes adjustment easier and never slips.

[john61ct]

Originally Posted by iabmatos

Do your alternators come with a cooling fan?

Not all but should. Make sure you know left or right spin, or get one that goes both ways.

[flyingnut40]

Have a look at the tensioner assembly that is used on a 2009 VW Jetta Diesel with the CBEA motor. Nice compact idler assy with a gas shock.
Look at this on eBay
https://rover.ebay.com/rover/0/0/0?m...2F130994140312

Good luck, Dennis

[pitlaw]

Originally Posted by roland stockham

I have used poly V belts and they work very well. No slip and much better power transfer which give a longer belt life. My battery bank tops out at about 65A (it is only 500ah) so don't have as much load as you. Because of the better load transfer you also don't need as high a belt tension (better for alt and pump bearings) plus it is less critical so never felt the need for a tensioner. One trick I have used is to replace the slide and clamp bolt with a rigging screw, makes adjustment easier and never slips.

Roland, what is a riggig screw. Since my Westerbeke is reversed for a V drive I cannot use the Balmar designed adjusting screw and bracket. I think its the exhaust hose that goes over the top of the adjusting arm in a way that prevents use of the Balmar device. But I would really like a better way of adjusting belt tension. I have dual belts and one is always a bit looser than the other.

[Yellowjacket]

I converted my system to serpentine with equipment from www.electromaax.com I found them to be helpful and the website easy. I had wondered if I should have gone with Balmar, until I read posts today on this site.

[kryg]

Originally Posted by Stevens 47

After a season in MX it became apparent that my current alternator system was sub standard. Lots of belt wear and burn. I have a large output dc watermaker that draws a max of 120 amps at full output.

I currently have a Balmar 120 amp driven by a 1/2" v belt.

My plan is to remount the 120 alternator and add another 165 with serpentine belt.

I have the space and ability to mount both these on a serpentine pulley on the outside of my normal 1/2 engine crank pulley. Separate from the engine water pump and raw water pump.

The advise I am looking for is should Iinstall a idler in the design system or make one of the alternators adjustable for belt tension. I am leaning towards an idler but would appreciate opinions.

I need to read or understand the serpentine belt pulley specs, any suggestions.

I am also looking for a source to purchase an idler and the crank driven serpentine pulley.

I am located in San Diego.

Stevens, good question, One I asked myself.

To answer your question and more, to give you an idea of my experence as to what is doable, my engine is a Perkins 404c 22 the same engine as a Volvo D2 55 converts to marinize and rebrand. (The spare parts are 2/3 less expensive!)

In my engine the kit manufacture told me because of the short belt to pulley distances, I did not need a belt idler. As turns out they are correct. Out of interest, I have installed a kit that was designed for Volvo engine D2 55, it fit perfectly on my Perkins.

Installing idler just complicates the conversion installation for lack of space and mounting position, for no real gain. If your engine is bigger then say a 4 cylinders then I would check the belt length, in my case I can fit a belt from 39” to 42” to three pulleys and not require an idler.

Also, just in case, I treated the new serpentine belts for half an hour with a 303 protectant for rubber, The YouTube video engineer claimed to extend belt life in car serpentine belt from 38,000 miles to over 350,000 without cracking. No reason it should not work on my marine engine as well. As backup I have a spare 40” belt.
Below are my comments in my life Journal, on yesterday’s start-up with the new kit conversion. Attached is a photo of my engine running with the kit installation, note, my engine is behind the mast so I can’t take a front photo but you get the idea.

As this conversion was a real struggle for trusted information, supplyer and installation. I hope my information is of some service to you.

Last 3rd Personal Life Journal

Skoiern engine running - 27-28- 3 2018 Completed installing on Sko’s engine, new water pump, completed engine and bay clean-up. Finished installing new serpentine pulleys and belt for crank water pump and old 120 Ah alternator. Topping up coolant.

I ran the engine for an hour to check for faults, great outcome, there is No more leaks from the new water pump, no more fan belt dust from v belts, no more alternator belt slipping, resulting in good charging battery’s. It fact much to my surprise the battery charging is better and more efficient than the 60 Ah sterling smart charger I also installed! Engine is running a bit cooler!

[01kiwijohn]

Good grief. I went from 55A on my little Yanmar, to 80A for less than $500 in parts but I did all the work myself and kept the original 3/8" section belt. It's worked fine for the past 5 years. Maybe there's something I'm missing?

[john61ct]

That's approaching the limit for a plain Vee belt.

120A is well over, polyV/serpentine is required.

Obviously talking loaded.