Sam:

There seems to be a lot of alternator overheating going around. See my reply
to Craig and Marcia below. But you seem to already have done all of what I
suggest below. But if your temperature probe is mounted to the case screws
and the regulator is not cutting back on current, then you probably are
operating within an acceptable temperature. FWIW however when I installed my
muffin fan and duct, I sensed a noticable drop in case temperature with my
highly calbrated index finger. And I don't think that the increased airflow
was only cooling the temperature probe. I think it was cooling the whole
alternator.

David

Craig and Marcia:

230 degrees is too hot. BTW, how are you measuring this temp?

There are two solutions:

Some regulators, Balmar's MaxCharge in particular, have a temperature probe
option. With this, at least on the Balmar, it will reduce charging current
to about one half when it senses temperatures that are too high. The lower
charging current will reduce the case temperature rather quickly- in a few
minutes, then it will return the alternator to its original charging rate.
This will cycle on and off to keep the alternator temperature within bounds.
I recall talking to the Balmar tech, who told me that it reduces charging
current when the case temperature reaches 180 deg F.

But this is only a stop gap fix. The real fix is to increase the cooling
airflow to the alternator. The standard air flow is from the back of the
alternator to the front. On my sailboat with a very tight engine enclosure,
I added a small 12 volt muffin fan which ducts cool bilge air up to the back
of the alternator. With the fan running, the temperature control circuit in
the Balmar alternator never cuts back the current. Without it, the current
is reduced at least half the time, thereby cutting your charging rate
significantly.

David

"Craig Stuart" wrote in message
nk.net...
I have a Balmar alternator and when it is charging the temp of the
alternator is around 230 degrees. Is this normal ?

--
Craig & Marcia Stuart

The output of the alternator is but one factor or source for a charging
current.
We have been cruising for 4 years and can stay in an anchorage for
weeks without starting the main engine (no gen set)
We have 4 x 80W solar panels, AirMarine wind generator and when we are
under sail a tow along generator (.75A/Knot)
The fridge is 12V eutectic with enough insulation around the box for
prolonged tropical cruising.
Even on max demand the alternator never exceeds 75% of max output for
greater than 10 mins.
I guess the lesson we learned was have enough alternative energy
sources to cover most of your day to day needs.
Lyn & Tony
S/V Ambrosia

wrote:

The output of the alternator is but one factor or source for a charging
current.
We have been cruising for 4 years and can stay in an anchorage for
weeks without starting the main engine (no gen set)
We have 4 x 80W solar panels, AirMarine wind generator and when we are
under sail a tow along generator (.75A/Knot)
The fridge is 12V eutectic with enough insulation around the box for
prolonged tropical cruising.
Even on max demand the alternator never exceeds 75% of max output for
greater than 10 mins.
I guess the lesson we learned was have enough alternative energy
sources to cover most of your day to day needs.
Lyn & Tony
S/V Ambrosia



Lyn & Tony, you bring an excellent point to the table.
If one smokes the alternator, one can install a bigger alternator just
to see if it will last.
That can be done without too much consideration for anything else is on
the boat.

On the other hand, if one wants to do the substitution only once one
needs to do a system redesign.
The weakest link breaks next time.

And speaking of system, what criteria did you use for refer insulation
(off topic I know...)?

Skip

Skip,
The yacht is a Swedish design that had 25mm of polystyrene insulation.
No match for Aust or the tropics.
New fridge/freezeer has a min 75mm polyurethane all round. The fridge
is 70l and the freezer 20l. Average daily power consumption (once at
operating temp) is 30 - 35 AHours. The hull is white which cuts down
power consumption considerably.
If you need more details on the fridge setup email me on yachtambrosia
at the hotmail address
Lyn & Tony
S/V Ambrosia