True a field test is the only way to see if you have done your homework properly. But the basic calculations should have been done beforehand and the idea of not checking the soc for 2 weeks is ridiculous. Batteries should be monitored daily and if getting anywhere near 60% during the day we have a problem Houston
. Our daily usage on passage
is around 250ah per day. At anchor
around 160Ah per day. Big difference. So it will depend on the type of cruising and number of days on passage
to size. I do t expect to ever have a low battery
when at anchor
and even if that happened, turning off equipment
is easy at anchor to save power.
We have 1180w of solar
and 840Ah of batteries so 250 Ah draw should last almost 2 days without any charging
. The only other charging
source is the alternators so we do have a backup but ideally we would rather sail without having to run the engines just for charging. Our system will be tested in November when we cross the Atlantic, but until then it is all just theoretical. I will be checking the soc regularly during that passage and taking measures while underway to ensure the batteries stay healthy!