[C320-list] Alternator upgrade

[Troy Dunn]

Hmmm...

I think there is some mixed advice in here so I would like to offer up my
experience thus far with my upgrade.   There are pictures of my upgrade in
my owners gallery.

I converted from the OEM configuration to a new configuration which
consists of the following items: Balmar 120A Alternator with Serpentine
Conversion Pulleys, MC 614 Regulator, SG200 smart shunt, ACR for charging
Reseve, 4 GC2 House has a Group 27 Reserve.  I kept the 1/2/BOTH/OFF switch
and cruise with the house bank selected (position 1).   In the event of a
dead battery I would use the Reserve to Start the engine and Run the
house.  So far I have not had to do that.  232 usable amp hours appear to
be plenty for our 1 week cruising needs.  We now just leave the fridge at
its highest setting,  we have yet to see our SOC drop below 70% even after
2 days with no engine running.

Some things to consider.

1) Alternator sizing.  Highly encourage you to go read all about this topic
on marinehowto.   Converting the stock alternator with an external
regulator and attaching it to a large house bank is likely to simply wear
out your alternator a lot sooner.  It was not designed for continuous
operation.   Now some of the bad news...  none of these alternators...not
even Balmar can really withstand the continuous operation cruisers are now
hitting with crazy large banks, especially the LiFePO4 batteries that not
only have high capacity but can be discharged way deeper with no ill
effects.   So what does this all mean?   It means you have to oversize the
alternator significantly and still have a regulator that can manage the
output to control heat.     I thought by having a 120 amp alternator backed
off to about 66% I should be safe.   So...how's that working in reality.
Well...not quite as well as I hoped.   Even with my smallish (ha, when did
464 amp hours become small?) bank, I’m still drawing 80 amps initially and
after about 15 minutes, the alternator gets hot enough that the regulator
cuts output 50% and this cycle continues until my draw gets down around 20
amps, then the cycling stops.   The issue of course is the ridiculously
tight engine compartment and no where to really dump the heat.   The blower
doesn’t really buy much to resolve this issue.   I've been contemplating
some 3D printed shrouds that direct and extract air around the alternator
and a fan designed for heat extraction to replace the blower..dunno if I'll
do this however since I only draw high amps for about the first hour of
charging and then it tails off rapidly.  It's nice to know the alternator
is way oversized.  Was it worth the pulley hassle?   Probably not.   Unless
you are willing to upgrade cooling the alternator...I'm guessing 80A
 backed off to 60A might be the sweet spot.  For me anyhow the smallish
increase in charging time...figure 30 minutes max wouldn't be worth it.
AGMs and LiFePO4 would of course change the equation.  Be advised...if you
upgrade to serpentine pulleys on a Yanmar, you will have to modify the
engine cover to make it all fit.

2) SG200... like my old Xterra...I love the idea of this device, i.e. what
it aspires to be.   Execution of the product leaves a lot to be
desired...just like..well..any Nissan product in my experience.   The
software continues to get upgraded but continues to do weird things when
computing SOH and that will hose up SOC reported which can be confusing if
you don't understand how the thing works..which of course is the exact
opposite of the dream for this thing,  it still meets my needs so I won’t
be getting rid of it.  I wait patiently for the day they get the software
completely right....it may never come.  For more about this check out
cruisers forum post for SG200, I believe it is up to 58 pages now or
something ridiculous like that.

3) GC2s.  Getting these to actually fit correctly and securely was a real
hassle.  I had to completely redo the entire space.   So far...totally
worth it.

4) ACR.  Like this thing a lot.   I have an always on positive bus.  This
prevents the alternator diodes from ever getting blown by an inadvertent
switch of the battery selector, and the ACR ensures that my reserve bank
stays topped up.  The SG200 has a secondary voltage monitor so I can see
that on my cellphone app too...all from the cockpit.   One item I need to
run to ground is kind of esoteric but something to think about.   When I
anchor and stop the engine at full charge, and select the house bank the
ACR 'sees' the high surface charge of the reserve battery and the house
battery and stays on.  This means for some period of time even with the
house bank selected I'm actually running off both banks.   With large banks
and fairly low current draw (less than 2A).  This condition persists for
quite a while.   I can’t help but wonder how this affects the smart shunt...

FWIW

Troy Dunn
S/V Wonky Dog
Hull #515