Balmar Alternator for A4

[edwardc]

After a lot of thought, and a bunch of measurements over the 3-day Memorial Day weekend, I've decided to upgrade to a 3-stage external smart charger/regulator system for my alternator. I plan to do some offshore cruising, and my measured charge times and rates with the stock Mando 55A alternator will require just too many hours of engine runtime per day to make up our daily usage.

And based on the comments here about running the 55amp Mando at high currents for long periods of time causing it to run hot, I've decided to upgrade to a 100 A alternator instead of modifying the Mando. I know I still won't get more than about 40 or 50A out of it (due to the low RPMs in a normal A4 installation (sorry Hanley!)), but I expect it'll run much cooler.

So, after casting around, I found this:

http://www.defender.com/product.jsp?path=-1|328|6421&id=819457

It's a 110 A Balmar Alternator (712-110) with the ARS-5 smart regulator that I wanted. According to the Balmar selection guide, its 2" foot will fit the A4 mounting bracket. Has anyone here used the Balmar 712 alternator? Any issues with mounting it or belt size? The pulley is listed as a '2.7" deep V' pulley, but no width is specified. I know that Balmar normally specifies a 1/2" belt for 100A alternators, but since I'll only be pulling 40-50A out of it, I figure the 3/8" belt will be fine.

Can I use this pulley with the 3/8" belt, or will I have to find another pulley to fit? I'm down less than 3 weeks 'til we leave on a trip, and I'd like to get this installed before then, so I appreciate any help/info I can get.

[joe_db]

I used to sell Balmars. I can't say anything bad about them except you could probably get 3 or 4 100A marine Delco alternators off of Fleabay for the same price and have some spares

[lhbradley]

Balmar Alternator for A4

I've got the older model Balmar - a 90 amp version - I forget the exact number, and I'm at home, not at the boat. I'm using the MaxCharge regulator.

It works just fine with a 3/8 belt. BUT use the best quality belt you can buy. I use a Gates 3VX250. It is a v-notch belt. And try to get the belt tension right - too loose and you will burn the belt. Been there, done that.

Running at about 1800 RPM, I can get 60 amps or so into my 450 AH bank.

[edwardc]

...It works just fine with a 3/8 belt. BUT use the best quality belt you can buy. I use a Gates 3VX250. ...

Thanks for the info. So you found that you had to go back to the 25" belt? With the 55A Mando, Don recommended going to a 26" belt, and that's what I run now. How is your adjustment range? Are you close to the stops at either end when tensioned properly? Any interference with the distributor? These are all problems I've heard hints of, but haven't seen any hard data.

[hanleyclifford]

Ed, As you know I have the 712 -110. It will come with a sheave that wants a 1/2" belt. You should upgrade your acc drive sheave at a machine shop or get the larger size from MM. Both sizes are available. You will not be happy with a 3/8" belt and that alternator.

[edwardc]

Ed, As you know I have the 712 -110. It will come with a sheave that wants a 1/2" belt. ...

But I believe it is listed as a "deep V" pulley, which should accept a smaller belt. It'll just ride lower in the V. Larry Bradley seems to indicate this works for him. Correct me if I'm wrong Larry.

You should upgrade your acc drive sheave at a machine shop or get the larger size from MM. Both sizes are available. You will not be happy with a 3/8" belt and that alternator.

Like I said, I don't really need anywhere near 100 Amps. The 712-110 will put out up to 60A at 2000 RPM, and almost 80A at around 2500 RPM, which is way more than I need. With my current 200 Amp-Hour house bank (gel cells), I can only bulk charge it at 40 A (20% of capacity or 0.2C) anyway. I'm expecting that a 3/8" belt will work fine for that.

I have plans in the future to go to a 300-400 Amp-Hour house bank, and and at that time I would probably need to upgrade to a 1/2" belt to handle the 60 - 80 A bulk charging currents needed. Balmar recommends a 1/2" for anything above 75 A.

Make sense?

[romantic comedy]

I mounted a Balmer 100 amp to the flywheel end off a PTO. I use a half inch belt. The accessory drive powers the raw water pump.
When I was planning the job, I found that a 3/8 belt might not be enough. Since I had enough room, I did it this way.

I have posted 2 pictures, I hope.

[hanleyclifford]

Romantic Comedy, I am interested in your set up but could you resize those pics; it's hard to see stuff.

[Loki9]

Romantic Comedy, I am interested in your set up but could you resize those pics; it's hard to see stuff.

Right click->View Image helps.

[ndutton]

Ed,

If you're even thinking of a 1/2" belt you'd better get a replacement 1/2" auxiliary drive pulley on order mas rapido.

[tenders]

I have the 105 amp alternator on my engine and a 3/8", 26" belt on the stock sheave. My battery bank is relatively small, but even so, when running the inverter at 1500-2000 watts (heat gun + small shop vac) I haven't had the slightest issue with the belt slipping.

I've concluded that I'm not running the alternator at anywhere near its max output so there isn't a need for a wider belt.

[edwardc]

Ed,

If you're even thinking of a 1/2" belt you'd better get a replacement 1/2" auxiliary drive pulley on order mas rapido.

Neil,

Thanks for the warning. But I'm spoiled being almost local to MMI. I usually get parts in 1-2 days!

But based on all the inputs I've gotten here, plus other inputs off-list, I've pretty much concluded that I'd be foolish to rush this significant upgrade project at the last minute. Something is bound to not go smoothly and put our whole trip at risk, since we can't really slip it due to work constraints.

Guess I'll just have to put up with a lot of daily engine runtime this time.

[Bold Rascal]

So.....Ed

What are you going to do with your old Mando when you replace it?

[sastanley]

Ed, I agree. Something always goes wrong with a new system.

[edwardc]

What are you going to do with your old Mando when you replace it?

Haven't decided. Now that there's no (well, less) time pressure, I may take the longer approach of doing it in stages, first modifying the mando for an external regulator and getting the ARS-5 smart regulator installed & working.

Then, later, get a bigger alt and probably keep the Mando as a spare.