"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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