"PeterS" wrote in news:1170165916.682938.227460
@j27g2000cwj.googlegroups.com:

Hi,

Has anyone had experience of fitting a 100A high output alternator to
a Bukh DV24 engine to either replace or supplement the 50A standard
alternator?

The standard alternator belt isn't wide enough to support an
alternator over 80A. Adding a second alternator would seem the way to
go as this means that a split device isn't required and simplifies the
wiring.

Thanks,
Peter



Doesn't matter if it's a 1000A alternator with 8 belts. Your batteries
will still charge about 25% of their AH capacity for about 5-8 hours to
recharge them. As long as the alternator has the capacity to drive the
loads plus 25% of the AH capacity of the house batteries (after the first
10 minutes when boaters DREAM the batteries are all charged up because
the current dropped off) the alternator is big enough. Overkill will NOT
recharge the batteries in 30 minutes, a pipe dream until the nanotube Ni-
Mh 3 minute batteries are delivered in the near future. THEN, you'll
need the 4000A alternator for 3 minutes to a 100% charge.

1920 lead-acid technology charges SLOWLY over HOURS not minutes....sorry.

80A is plenty....over 1100 watts, which would soon boil the electrolyte
and warp up the plates if the battery didn't prevent it at 14.2V.

Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

Larry, thanks for mentioning the nanotube battery (capacitor). I had been
out of the loop on that one. Very exciting technology. :-)


"Larry" wrote in message
...
"PeterS" wrote in news:1170165916.682938.227460
@j27g2000cwj.googlegroups.com:

Hi,

Has anyone had experience of fitting a 100A high output alternator to
a Bukh DV24 engine to either replace or supplement the 50A standard
alternator?

The standard alternator belt isn't wide enough to support an
alternator over 80A. Adding a second alternator would seem the way to
go as this means that a split device isn't required and simplifies the
wiring.

Thanks,
Peter



Doesn't matter if it's a 1000A alternator with 8 belts. Your batteries
will still charge about 25% of their AH capacity for about 5-8 hours to
recharge them. As long as the alternator has the capacity to drive the
loads plus 25% of the AH capacity of the house batteries (after the first
10 minutes when boaters DREAM the batteries are all charged up because
the current dropped off) the alternator is big enough. Overkill will NOT
recharge the batteries in 30 minutes, a pipe dream until the nanotube Ni-
Mh 3 minute batteries are delivered in the near future. THEN, you'll
need the 4000A alternator for 3 minutes to a 100% charge.

1920 lead-acid technology charges SLOWLY over HOURS not minutes....sorry.

80A is plenty....over 1100 watts, which would soon boil the electrolyte
and warp up the plates if the battery didn't prevent it at 14.2V.

Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

Larry wrote:

Has anyone had experience of fitting a 100A high output alternator to
a Bukh DV24 engine to either replace or supplement the 50A standard
alternator?
....

Doesn't matter if it's a 1000A alternator with 8 belts. Your batteries
will still charge about 25% of their AH capacity for about 5-8 hours to
recharge them. As long as the alternator has the capacity to drive the
loads plus 25% of the AH capacity of the house batteries (after the first
10 minutes when boaters DREAM the batteries are all charged up because
the current dropped off) the alternator is big enough. Overkill will NOT
recharge the batteries in 30 minutes, a pipe dream until the nanotube Ni-
Mh 3 minute batteries are delivered in the near future. THEN, you'll
need the 4000A alternator for 3 minutes to a 100% charge.

1920 lead-acid technology charges SLOWLY over HOURS not minutes....sorry.

80A is plenty....over 1100 watts, which would soon boil the electrolyte
and warp up the plates if the battery didn't prevent it at 14.2V.

Why are you so obsessed about this, Larry? Its gotten to the point
that you're just ranting nonsense!

The truth is that many cruisers have over 400 Amp-Hours of batteries.
My boat, for example, was designed to carry 4 6V golf carts (Trojan
T-105s), for about 450 AH as the house bank, or 520 AH if I use the
oversized T-145. A pair of 8D's will be in the same range.

I frequently charge with a 110 Amp Balmar and it puts out 105 Amps
when started, and it stays up of 90 Amps for quite some time. I
usually charge when the bank is down 200 AH, and bring it up 120 AH,
so I'm running for roughly 90 minutes. If I used a smaller
alternator, or a less aggressive regulator, that time would go up 10
or 15 minutes. While this might seem like a small thing, after
running for over 90 minutes one starts thinking the saving 15 minutes
might be worth some real money.

These aren't made up numbers; I've been doing this for about 6 weeks
every summer for the last 8 years, and with a similar but smaller
setup on my previous boat for 8 years before that. Lest you claim
that the high charge rate is cooking the batteries, there might be
some truth, but my first set of Trojans lasted 6 years, and might have
gone longer except illness prevented me from giving them proper care
one winter. Since the Trojans are cheap ($70 each) this is not a big
deal.

There's absolutely no reason why the OP shouldn't use a 100 Amp
alternator, assuming he has a large enough bank.

"Jeff" wrote in message
. ..
Larry wrote:
The truth is that many cruisers have over 400 Amp-Hours of batteries. My
boat, for example, was designed to carry 4 6V golf carts (Trojan T-105s),
for about 450 AH as the house bank, or 520 AH if I use the oversized
T-145. A pair of 8D's will be in the same range.

I frequently charge with a 110 Amp Balmar and it puts out 105 Amps when
started, and it stays up of 90 Amps for quite some time. I usually charge
when the bank is down 200 AH, and bring it up 120 AH, so I'm running for
roughly 90 minutes. If I used a smaller alternator, or a less aggressive
regulator, that time would go up 10 or 15 minutes. While this might seem
like a small thing, after running for over 90 minutes one starts thinking
the saving 15 minutes might be worth some real money.

These aren't made up numbers; I've been doing this for about 6 weeks every
summer for the last 8 years, and with a similar but smaller setup on my
previous boat for 8 years before that. Lest you claim that the high
charge rate is cooking the batteries, there might be some truth, but my
first set of Trojans lasted 6 years, and might have gone longer except
illness prevented me from giving them proper care one winter. Since the
Trojans are cheap ($70 each) this is not a big deal.

There's absolutely no reason why the OP shouldn't use a 100 Amp
alternator, assuming he has a large enough bank.

Essie has a Model 20 Universal (5416) 16hp Diesel, fitted with a 50 Amp
alternator. The biggest alternator I can put on this engine, according to my
research, is an 80 Amp. When I install my new batteries this year, I'll have
375 ah aboard, being charged by that small alternator and supplimented by my
two 35 watt solar panels. I have no illusions that I will be able to
fully-charge that bank with my onboard charging capabilities -- my aim is to
set out with as much amp-hours as I can get so that I don't draw-down my
batteries as much as I would if they were smaller. Back in the slip, the 50
Amp shorepower charger can complete the job. The 80 Amp alternator, if I fit
it, will be close to 25% of bank capacity, but not quite. The 50 Amp
alternator is only 15.5% of capacity, which will probably prompt me to go
ahead and upgrade the alternator. But that's not exactly cheap.

Thanks, an 80A alternator is the easiest way forward for me - like you
I'll be supplementing my charging with a wind generator and solar
panels.

KLC Lewis wrote:
....

Essie has a Model 20 Universal (5416) 16hp Diesel, fitted with a 50 Amp
alternator. The biggest alternator I can put on this engine, according to my
research, is an 80 Amp.

What is the limitation? I would agree that with size of the bank more
than 80 might not be cost effective, but the small case alternators go
up over 100 Amps.

When I install my new batteries this year, I'll have
375 ah aboard, being charged by that small alternator and supplimented by my
two 35 watt solar panels. I have no illusions that I will be able to
fully-charge that bank with my onboard charging capabilities -- my aim is to
set out with as much amp-hours as I can get so that I don't draw-down my
batteries as much as I would if they were smaller. Back in the slip, the 50
Amp shorepower charger can complete the job. The 80 Amp alternator, if I fit
it, will be close to 25% of bank capacity, but not quite. The 50 Amp
alternator is only 15.5% of capacity, which will probably prompt me to go
ahead and upgrade the alternator. But that's not exactly cheap.

Jeff inscribed in red ink for all to know:
KLC Lewis wrote:
...


Essie has a Model 20 Universal (5416) 16hp Diesel, fitted with a 50
Amp alternator. The biggest alternator I can put on this engine,
according to my research, is an 80 Amp.


What is the limitation? I would agree that with size of the bank more
than 80 might not be cost effective, but the small case alternators go
up over 100 Amps.

When I install my new batteries this year, I'll have 375 ah aboard,
being charged by that small alternator and supplimented by my two 35
watt solar panels. I have no illusions that I will be able to
fully-charge that bank with my onboard charging capabilities -- my aim
is to set out with as much amp-hours as I can get so that I don't
draw-down my batteries as much as I would if they were smaller. Back
in the slip, the 50 Amp shorepower charger can complete the job. The
80 Amp alternator, if I fit it, will be close to 25% of bank capacity,
but not quite. The 50 Amp alternator is only 15.5% of capacity, which
will probably prompt me to go ahead and upgrade the alternator. But
that's not exactly cheap.


Aside from any physical limitations, there is the matter of horsepower -
turning that laternator isn't free you know. At 12 V, a 100 amp
alternator is delivering 1.2 kw. At 100 % efficiency of conversion
(unrealistic), this represents nearly 2 HP. At more realistic
efficiencies, this is more than 2 HP. This is only a 16 hp engine...

bob
s/v Eolian
Seattle

RW Salnick wrote:
Jeff inscribed in red ink for all to know:
KLC Lewis wrote:
Essie has a Model 20 Universal (5416) 16hp Diesel, fitted with a 50
Amp alternator. The biggest alternator I can put on this engine,
according to my research, is an 80 Amp.

What is the limitation? I would agree that with size of the bank more
than 80 might not be cost effective, but the small case alternators go
up over 100 Amps.
....

Aside from any physical limitations, there is the matter of horsepower -
turning that laternator isn't free you know. At 12 V, a 100 amp
alternator is delivering 1.2 kw. At 100 % efficiency of conversion
(unrealistic), this represents nearly 2 HP. At more realistic
efficiencies, this is more than 2 HP. This is only a 16 hp engine...


That is an issue, but it isn't a big problem. My alternator is on a
Yanmar 2GM20FC, which is 18 HP. When at anchor, its actually better
to have the large alternator, because it means the engine isn't
running unloaded.

Underway, it can be a issue. Since I have twin engines on my cat, its
easy to so see how the load affects both the output and the
temperature of the engine with the big alternator. If I expect to
need full power, I set the regulator to 30 Amps; otherwise, the loaded
engine won't rev up fully, and will run hotter. Also, its SOP for
the cook to advise the helm when the microwave will be used - this
will have a quite noticeable affect on the power, as the DC draw of
the inverter is 86 Amps. Thus, it would be desirable to at least have
a shutoff; would that simply be a field disconnect?

One thing I will concede: I go through a lot more belts on the big
alternator than on the small!

"Jeff" wrote in message
. ..
KLC Lewis wrote:
...

Essie has a Model 20 Universal (5416) 16hp Diesel, fitted with a 50 Amp
alternator. The biggest alternator I can put on this engine, according to
my research, is an 80 Amp.

What is the limitation? I would agree that with size of the bank more
than 80 might not be cost effective, but the small case alternators go up
over 100 Amps.


Balmar has a chart of recommended alternators based upon both belt size and
engine hp, and while they do say that I can use a larger pulley/belt
combination and therefore a larger alternator, every 50(?) Amps means the
loss of 1 hp available for propulsion. Since I rarely run my engine over
2400 rpm out of a rated 2800 anyway, usually running it at 2200, I'm already
only getting maybe 12 hp at the transmission. I'd hate to drop that any
further, as it's just barely enough as is.

Why don't I just run it faster, you ask? Makes me nervous. When it's running
at high speed it just doesn't sound "happy." But it'll run at 2200 for as
long as I ask, and sing sea chanties at the same time. Short (very short)
periods of full-power are okay, but we're talking minutes here, not half an
hour or longer.

KLC Lewis wrote:
"Jeff" wrote in message
. ..
KLC Lewis wrote:
...
Essie has a Model 20 Universal (5416) 16hp Diesel, fitted with a 50 Amp
alternator. The biggest alternator I can put on this engine, according to
my research, is an 80 Amp.
What is the limitation? I would agree that with size of the bank more
than 80 might not be cost effective, but the small case alternators go up
over 100 Amps.


Balmar has a chart of recommended alternators based upon both belt size and
engine hp, and while they do say that I can use a larger pulley/belt
combination and therefore a larger alternator, every 50(?) Amps means the
loss of 1 hp available for propulsion. Since I rarely run my engine over
2400 rpm out of a rated 2800 anyway, usually running it at 2200, I'm already
only getting maybe 12 hp at the transmission. I'd hate to drop that any
further, as it's just barely enough as is.

You only use the HP that gets converted into electricity. If the
batteries are charged, or if the regulator reduces the demand, it
doesn't cost in engine power.

As for the HP, the torque peak on that engine is fairly low, so the HP
curve flattens out near the top end. You're still getting 14HP at
2100 RPM, a tad less at the shaft.



Why don't I just run it faster, you ask? Makes me nervous. When it's running
at high speed it just doesn't sound "happy." But it'll run at 2200 for as
long as I ask, and sing sea chanties at the same time. Short (very short)
periods of full-power are okay, but we're talking minutes here, not half an
hour or longer.

You're probably right that the Universal is happy at 2200. If I ran
my Yanmar that slow all the time, it would carbon up.