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Old 02-04-2014, 09:01 PM   #1
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Balmar 97 Max RPM

I have the Balmar 97-24-140-BL-IG alternator - I have ordered a set of pulleys that should fit my engine.

I trusted the company to come up with the right pulley ratio for the 2800 RPM engine. They decided on a 3:1 ratio, which I am questioning since the max RPM of the alternator is 6500.

With 2800 engine RPM I would get around 8400 alternator RPM....thats 1900 RPM more than the alternator is rated at.

I have asked Balmar to confirm the max RPM of this alternator, but no reply so far.

So the question is if the 6500 alternator RPM is the max RPM or just a RPM that makes the 140A?

I know some alternators have a max RPM of 10-12000...so 6500 sounds a bit low....
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Old 02-04-2014, 09:40 PM   #2
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I have wondered about the same thing. I suspect that 6,500 rpm is just where the output curve levels out and the alternator can turn a lot faster.

FWIW on sailboats with a Yanmar 3,600 rpm rated engine I have used a 2.5:1 pulley ratio with a Balmar alternator, which means the alternator can spin up to 9,000 rpms and routinely ran at 6,500 all day long. No problems.

David
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Old 02-04-2014, 09:52 PM   #3
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West Marine states that the large frame 94 and 95 models should not exceed 6500 RPM. They are similar in size to the 97 models....so maybe 6500 RPM is valid for the 97 as well.
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Old 02-04-2014, 10:12 PM   #4
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Go back to them and tell them your concerns.

Some alternators can turn up to 10,000 revs, some more, but you need to be sure of what you have.
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Old 02-04-2014, 10:37 PM   #5
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I'm still waiting for Balmar to confirm...

I vaguely remember something about Balmar's being made by Leece Neville, so I will try to look at the specs of the Leece Neville's....
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Old 02-05-2014, 07:06 AM   #6
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I vaguely remember something about Balmar's being made by Leece Neville, so I will try to look at the specs of the Leece Neville's....

Years ago they were rewinds by a co called lestech , its been years,,,,,,
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Old 02-05-2014, 08:04 PM   #7
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OK, got the reply from Balmar:

Max sustained (I assume this means continuous) is 6500 RPM.

The Balmar 97 turned out to be this Prestolite / Leece Nevile model:

Prestolite - Leece Neville
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Old 02-07-2014, 03:03 PM   #8
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What is the max. rpm of the engine and what is the normal cruise rpm you run at?
I would not install it but go back at them and tell them to get it right.
That is not just a small overage and under the right/wrong circumstances you could damage the alternator and have no claim. Actually it would not be hard to overrev this unit based on what you have posted.
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Old 02-07-2014, 04:16 PM   #9
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How can you guys be talking speed ratios without identifying the crankshaft and alternator pulley diameters?
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Old 02-07-2014, 06:30 PM   #10
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The company sorted it out - I'm not sure what they were thinking of....Glad I caught that error, it could have been expensive.
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Old 02-08-2014, 07:32 AM   #11
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The Prestolite Leece Neville in 12V 135A , is about $135 bucks at many big truck supplys.

The V reg is included , but it is car brain so is better replaced.

Happily it is external do any boat 3 or 4 stage unit can be mounted.

The proper sized pulley will also need to be purchased .

Dont forget to feed the field circuit the the rotary switch ALT termimals , so someone accidentally trurning off the rotary switch will not cause the alt death .
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Old 02-10-2014, 12:11 AM   #12
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It was already identified earlier as 3:1 , first post, so no matter what the sheave size is, the ratio is wrong.
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