[C320-list] Alternator upgrade

[Scott Thompson]

Troy, on your last point, I have the shunt for my battery monitor between the house bank and my Victron smart battery combiner so that it measures amps going in or out of the house bank only, irrespective of whether the banks are combined. Do you have a different arrangement?

Scott

> On Aug 25, 2020, at 7:33 PM, Troy Dunn <troutwarrior at gmail.com> wrote:
> 
> 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