Balmar 100a Alternator on M25

Christian Williams · May 1, 2014

I've ordered a Balmar 621-VUP-100- alternator, with the external regulator, for my M25.

A boat mechanic just told me this was asking for trouble with the water pump, as a result of increased stress on the belt.

It seems to me this alternator is a common replacement for the original Motorola 51 amp, and I have not seen dire warnings before.

Comments?

Maine Sail · May 1, 2014

Christian Williams said:
I've ordered a Balmar 621-VUP-100- alternator, with the external regular, for my M25.

A boat mechanic just told me this was asking for trouble with the water pump, as a result of increased stress on the belt.

It seems to me this alternator is a common replacement for the original Motorola 51 amp, and I have not seen dire warnings before.

Comments?

You will want to set the reg to Belt Manager level 4..... The water pump is not the issue a 3/8" belt driving 100A is what is problematic.. If you want to drive more than 75-80A then a serpentine kit will be a good choice... With a perfect alignment & perfectly clean pulleys you can do 85-90A but you will have dust. The Dayco Top Cog is the best belt I have found to handle these loads... Be sure you get a 3/8" pulley for the Balmar they often ship with a 1/2" in the 100A size....

Also be 100% sure you have the upgraded bracket for the M-25!!!!

Universal/Westerbeke says alts up to 190A are fine but you would need the belt to drive them.......

Rick R. · May 2, 2014

After all the upgrades you've done to the wiring on Thelonious you can now charge away with confidence.

One thing I've read is that you might experience more heat with that alternator and need a more robust belt.

Stu Jackson · May 3, 2014

Chris, I've had a 100A on my M25 for many years. I have a Balmar MC-612 regulator. Instead of the belt manager I use the Small Engine Mode via a simple toggle switch. I'm sure you can find my posts on that forum-to-be-unnamed in the "Electrical 101" topic I sometimes refer to here. Maine Sail has reminded us, and me, that belt alignment is critical and he's written a good article on it on his pbase website, as have I on ours. I use a 3/8" 7395 Gates belt. I also employ a simple alternator belt tensioner, also on our website. Good luck, you'll love it. Twice the output of the 55A OEM which means you'll probably see 50A on a 50% SOC 400 ah house bank, which is a nice load. What regulator did you buy?

Your boat mechanic is both right and wrong. Right if you over tension the belt. Wrong in every other regard.

Christian Williams · May 3, 2014

Balmar recommended their kit, which includes the ARS-5 regulator. The best price I found was from Baltimore Battery, $815 for everything.

The unit arrived with a deep-v pulley which looks like it accepts a 3/8 belt. The literature says, in effect, a 3/8 will ride low in the pulley, but that that's all right.

Thanks Stu and Maine Sail, I've read your stuff. And as a result, I'm pretty sure I'd have no problem setting the new alternator up.

Even so, I've asked a local pro to help me install it next week, and go over the many electrical upgrades I've made guided by forum advice.

I'd like to have him give me a vote of confidence.

As usual, I;m already wondering how much confidence I have in him.

Tom Metzger · May 4, 2014

The unit arrived with a deep-v pulley which looks like it accepts a 3/8 belt. The literature says, in effect, a 3/8 will ride low in the pulley, but that that's all right.

Christian - I've had a 100 amp Balmar w/ the standard pulley on my M-25XP since '97 without any start load reduction and have not had a problem since I ran out of cheap 3/8" belts. I use a 1/2" Gates or NAPA (made by Gates) power rated green belt. I don't think I've ever replaced one, but I'm not sure. I do carry a spare. I max out under 80 amps.

The 3/8 and 1/2" belts have the same angles so the 1/2" belts work well in the 3/8" pulleys, just riding a little proud. The alternator pulley has half the groove length of the crankshaft pulley so it can take advantage of the larger belt.

Sorry, I'm busy this week and can't get out there.

Christian Williams · May 5, 2014

Thank you. I'm sorry the trip fell apart. I was able to exchange the plane tickets I owe you for electrical consultation to Krugerrands, and have sent them Federal Express. A signature is required, so stay near the doorbell for a week or two.

Stu Jackson · May 5, 2014

Chris, did you get the email I sent to you with the link to the regulator wiring diagrams? Hope all goes well with the installation.

Christian Williams · May 6, 2014

Did not get an email.

Tom Metzger · May 6, 2014

Christian Williams said:
Did not get an email.

Christian - Don't feel badly. I'll send you one. :esad:

Christian Williams · May 6, 2014

Stu, I found the email (in the wrong folder). Thanks.
I feel emotionally better all around, and they have wheeled me into the solarium for lunch.

Rick R. · May 6, 2014

That happened fast Christian!

Try the Jello through a straw, it's fun and yummy at the same time.

Christian Williams · Jun 5, 2014

I've posted a blog entry on installing the Balmar 100 alternator with ARS-5 regulator here. (click the link)

The installation wasn't hard, but I was unsuccessful in hiring a local boat electrician to do it for me.

"You can do that yourself," he kept saying.

I didn't get it until I was finished, and he agreed to come on board an check my work.

"So, what, you're too busy to install an alternator?" I said after writing him a small check which could have been much larger.

He shook his head and smiled sheepishly.

"Glad it was easy. But let me tell you, installing a different alternator, that can turn into a such a problem you wouldn't believe."

Hmmm. Nice when the existing bracket fits, I guess. .

Lawrence B. Lee · Jun 12, 2014

Existing Bracket

That's a big time alternator on your M25. Lot's more stress. if you are using the existing mounting bracket keep a serious eye on it. Case hardened brackets can be found at Westerbeke and they are highly recommended by contributors to this site. The bracket also comes with new tougher mounting bolts. I did this upgrade with a Leese Neville 90amp about five years ago...same smart regulator. The new bracket seems to be solid but I am getting some mis-alignment where the alternator arm fits between the bracket knuckles. Not sure it it't the alternator arm or the bolt holding it all together but right now it does not look like the new bracket. I am going into it tomorrow and if I discover something important I will post it asap.

Larry Lee
Annabel Lee
E 32-200
Savannah, GA

Christian Williams · Jun 12, 2014

Sorry, don't quite understand. Are you having problems with the replacement bracket--the one that goes under, rather than over, the alternator? Or do you still have the old bracket?

Lawrence B. Lee · Jun 12, 2014

A picture is worth....

Chris. This picture may illustrate what I was trying to say. What I am calling the mounting bracket is the silver piece to the left bolted to the block holding the alternator case "arm" between two knuckles. This piece is new and is supposed to be more robust than the original bracket. Nonetheless you will see that the alternator arm is not square with the knuckles. At this point I don't know if arm is worn or the knuckles are worn from vibration after five years. Could be the bolt holding all this together is at fault. Tomorrow I am going to pull the alternator off and see what is casing this problem. The best I can tell so far is that the new mounting bracket is square with the block. Stay tuned.

Curious in Savannah

Larry

Christian Williams · Jun 12, 2014

These comments are from Maine Sail's article available here: http://www.pbase.com/mainecruising/universal_alternator_bracket

It may be that you have the incorrect pivot bolt shipped sometimes with the kit--causing a wobbly bracket connection.

These T

True Friend 03-Apr-2014 03:21
MaineSail thank you for this and all your sharing.

I just did this upgrade and the Universal kit is still shipping with the wrong pivot bolt as of Feb 2014. It also shipped to me with two belts; the notes on the schematic stated that the belt #302190 had been replaced with #300817, which was on the parts list. But in the box were both belts and it's a good thing as #300817 is too long, and #302190, the one you recommended as the Gates XL. It was a very tight fit and I had to open the decompression lever to turn the engine to get it on the pulley. Fits great.

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Tim W 17-Mar-2014 06:01
After reading a year ago about the Leece Neville alternator upgrade, I made this very same installation last summer. I already had the upgraded alternator bracket on my M25XP. I did notice the sloppy fit of the original pivot bolt as mentioned and changed to a 10mm as suggested. One tool I have found invaluable over the years is a proper belt tensioner. Also just wanted to add that pulley alignment can be greatly simplified by using a 1/2" wood dowel about 24" long that can be placed in the crankshaft pulley and it will "point" to where the alternator pulley needs to be.

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Lawrence B. Lee · Jun 12, 2014

Bigger pivot bolt

As Chris and others suggested my pivot bolt was wobbly. It was a 3/8" dia. So I replaced it with a 10 mm bolt. It's still a bit loose but not like the 3/8th one. A serious thunder storm chased me off the boat but I will try and put all back together tomorrow paying attention to the brackets position in aligning it all.

Larry Lee
Annabel Lee
E 32-200
Savannah, GA

sharonov · Feb 23, 2018

cable gauge

Christian, what cable gauge did you use for wiring the alternator? I feel 6 AWG will probably suffice but 4 AWG would be better. Also what fuse did you use with it?
Thanks,
Sergei

Christian Williams · Feb 23, 2018

Sorry, but somebody else will know.

As for the fuse, I recall it was 25 amps, probably the biggest on the boat.

True Friend		03-Apr-2014 03:21
MaineSail thank you for this and all your sharing. I just did this upgrade and the Universal kit is still shipping with the wrong pivot bolt as of Feb 2014. It also shipped to me with two belts; the notes on the schematic stated that the belt #302190 had been replaced with #300817, which was on the parts list. But in the box were both belts and it's a good thing as #300817 is too long, and #302190, the one you recommended as the Gates XL. It was a very tight fit and I had to open the decompression lever to turn the engine to get it on the pulley. Fits great.

Tim W		17-Mar-2014 06:01
After reading a year ago about the Leece Neville alternator upgrade, I made this very same installation last summer. I already had the upgraded alternator bracket on my M25XP. I did notice the sloppy fit of the original pivot bolt as mentioned and changed to a 10mm as suggested. One tool I have found invaluable over the years is a proper belt tensioner. Also just wanted to add that pulley alignment can be greatly simplified by using a 1/2" wood dowel about 24" long that can be placed in the crankshaft pulley and it will "point" to where the alternator pulley needs to be.

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