Only in my 3rd year cruising (Chesapeake bay), wanted to run this by you guys. I was on a weeklong trip to Baltimore
and on the last day, my batteries
were discharged quite a bit (showing 11.9V). It worried me. We only spent the first day sailing
for about 8-10 hours, then 4 days at anchorage. Even at winter, my 100W solar
array will output from 0.5 amps to 1.8 from sunup to sundown even in some overcast weather
(I have silicone polycrystallaine panels). It turns out my alternator
belt was broken at some point, so when I ran the engine
at anchorage for about 30 mins, it might not have charged anything. (55amp alternator
running off of an atomic 4).
I actually don't know how well my amp meter is reading. The panels
should top out at something like 5 amps. With suboptimal angle to the sun and my boom/sail covering some of the panels
, I figured I should see 2.5 amps in the summer. I use the Wattsup device hooked up between the MPPT
and the chargers.
I want to map out my hypothetical daily usage on an open passage
as I am planning on trying a delmarvar penninsula circumnavigation
this year. Does the below sound right to you guys? The number for the CPT autopilot
, I mainly pulled it out of my a** based on what I read on different forums
on the CPT autopilot
Batteries- two group 27 80AH AGM batteries
in parallel. I also have a 90AH deep cycle lead-acid starter bank.
CPT autopilot - 72 AH capacity needed
- assuming 3 amps on average, 24 hours
cell phones via microUSB - 6AH capacity needed
- 2 devices, 0.3 amps, 10 hours (my primary nav device)
- 0.5 amps - 24 hours
nighttime running lights - 12 hours - 33 AH capacity needed
- 0.6amps x2 (bow lights)
- 0.1amps x1 (stern light LED)
- Spreader Lights 2 amps
Total: 133AH capacity needed
- assuming spring/fall use - 2 amp output @ 7 hours - 14AH capacity provided
- at low RPMs, assuming 20amp output at 1 hour a day - 20AH capacity provided
Areas to save - switch spreader lights to LED (+18a). change bow lights to LED (+12a). Change pulley ratios on alterator to bump up output (+10a)
I'm getting a new mainsail
soon and adding a bunch of mainsail
controls (vang, outhaul
, possibly cunningham), and hoping that'll cut down on the power draw of the CPT unit as well.
I should get a load tester to get a better idea of my battery
usage as well, even just for bay cruising.
Even with that I'll be drawing down a third of my batteries every day.
I guess I better add a windgen. I don't really have any room to add another solar charger
- I had to construct a dodger
frame to mount the panels.
I understand this is not enough for extended cruising
, but wanted to see if you think my assumptions are correct. I'd appreciate any tips as well.