Newer Cummins engines use small frame Delco alternators. Those with the
air-heater start assist feature (again all new ones) have 105A alternators.
If you have twin engines, two 105A alternators is plenty to charge the bank
of golf carts below from 40% charge to 80% in 2 hours. If you have only a
single engine more time will be required but it's still within reason and
will work.

However, there are two problems he 1) the Delco alternators have internal
regulators designed for charging starting batteries and when used with deep
cycles will charge them pathetically slowly, and 2) 105 A from a small frame
actually pretty hard to achieve reliably in continuous operation. The
solution to the first problem is to take the alternator out and wire for
external regulator. Any alternator shop can do this for an hours labor.
Then you need to purchase an external regulator. I like the Balmars because
they are highly adjustable but many companies make them. With an external
alternator on you can charge at any rate up to 105A which solves problem one
but you'll then run into the second problem: a small frame alternator
producing 105A is on the edge of heat failure from day one and will likely
fail in under a day (I've seen them do it). Basically, 105A is marketing
and it will produce 105A with full field current for short periods of time
before burning out so they aren't lying but it'll over heat within minutes.

What I do is get an external adjustable regulator and tune the charging rate
such that the alternators don't go over 200 to 225F. At full field
producing 105A, they'll hit 350F very quickly. If you set the field to
produce no more than 200 to 225F in most installations, you'll be charging
at around 70A and they will run at that level all day.

So the short answer is that your alternators can be made to charge that
battery bank efficiently but you'll need an external regulator and you'll
need to ensure that the alternators are not charging at much more than 70A
to, at the outside, 80A each. In such a config, they will work well. It's
more money and more hassle but installing larger alternators is another
solution and you can get alternators of over 200A each but they cost real
money. Its up to you on whether you want to run the stock alternators
carefully tuned or buy an industrial 200A alternator and run that way.

--jrh


"Tamaroak" wrote in message
news
I have a 1997 Monk 36 with the Cummins 6BT5.9M 220 engine. I'm switching to
six golf cart batteries for the house bank and wonder if the stock
alternator is big enough for this application.

Does anyone out there know how many amps that alternator is likely to
crank out?

Capt Jeff
"Adirondack"