"The stock system was so adequate for that that I didn't even notice a dead 
alternator for an entire season.”

Lol, I think that’s what happened to me.  I bought Grenadine in January 2016; 
this is my sixth season with her.  She came with a pair of group 29 Everstart 
lead-acid batteries manufactured 5/14 and 6/14.  I accidentally drained them a 
couple times with cycling bilge pumps a few years ago.  Brought them home, 
checked their water levels, charged them up on a cheap smart charger, put them 
back in the boat, and didn’t give it another thought, but installed check 
valves downstream of my bilge pumps. :)  Grenadine also has a small 15W solar 
panel and charge controller for topping up the batteries (and a shore power 
charge controller, which I don’t use because my slip doesn’t have shore power).

I use the boat a couple times a week for lake racing and leisure sailing.  Ten 
minutes of motoring twice per use to leave and return to the marina.  Aside 
from starting the A4, I typically run a stereo system, and possibly some nav 
lights / cabin lights if at night.  That’s it.

A few weeks ago I went down to the boat for a Wednesday night race and the 
batteries were dead.  Left and returned to the slip by sail power, raced in 
between.  Got a jump afterward from another guy’s battery and measured my 
alternator output at 9.8V (it’s supposed to be 13.7V).  I don’t know when the 
alternator petered out; it could have been years ago, and the solar panel was 
enough to keep the batteries charged until they became too worn out to hold a 
charge.  I did bring the batts home and put one on my charger, and it took over 
24 hours and couldn’t get from 99% to 100%.  So I lost trust and bought new 
ones.

Thanks for confirming that amp-hour capacity is the upside of lithium.  Now 
that you mention it, some of my camping buddies have outfitted their rigs with 
solar and lithium so they can go off-grid for days.  In fact one guy’s system 
can power low-draw 110V loads like phone chargers.

If I was using a boat to cruise for days without running the motor to charge 
the batts, I could see the benefit of a higher-capacity system.

Cheers,
Randy Stafford
S/V Grenadine
C&C 30-1 #79
Ken Caryl, CO

> On Sep 14, 2021, at 12:22 PM, Dave S via CnC-List <cnc-list@cnc-list.com> 
> wrote:
> 
> Which is more or less what I paid for a group31 LiFePo battery...  When I 
> really shopped it (industrial sources) I was pleasantly surprised at the 
> price.
> 
> Whether it's of benefit really depends on your use as Randy stated.   When I 
> first bought windstar I only daysailed and plugged in every night.   The 
> stock system was so adequate for that that I didn't even notice a dead 
> alternator for an entire season.  I did finally replace it even though the 
> cost clearly wasn't justified.  ;-)   
> 
> My more recent scope was to have multiple consecutive days off the grid so I 
> needed to do something.  (all well documented along with the arithmetic on 
> the blog) 
> 
> I too thought that LiFePo was cost prohibitive for less than 5 year time 
> horizon, however the lower than expected first cost and utterly carefree 
> electrical system have made them a slam dunk. From memory, vs AGM the cost 
> difference might have been C$400 max.  as I worked my way though the project, 
> I had an epiphany as I climbed a ladder with two group 31s in one hand, and 
> had further epiphanies when I managed to fit ALL my new batteries and battery 
> management hardware in a much smaller footprint than previously, while 
> simultaneously doubling my usable house bank capacity.  I was also surprised 
> at how quickly they charge.  After one season with solar/lithium I have 
> enough confidence in the system that when I renew my marina contract next 
> year, I will decline the need for shore power and will save C$400/season as a 
> bonus.
> To be clear, my enthusiasm is as much about a successful solar install as the 
> LiFePo batteries themselves.
> 
> Dave
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