Batteries in 12 easy lessons:
Real world. From a "battery research" guy, and one who installs, tests, and uses batteries 24/7.
1.
Flooded LA batteries are still in 2016 the best bang-for-the-buck, and the best choice for most cruising sailors;
2. With caveats,
AGMs could be OK, too, but are more pricey, less tolerant of abuse, and more tricky to maintain. But, to really take advantage of their properties, you may need to completely revise your charging system and plan;
3. For some sailors,
gels make a lot of sense, but are more expensive;
4. LiFePO batteries are very expensive, but when
systems are well chosen, installed, and monitored may be a good choice;
5.
Firefly batteries look very good. Expensive, but good experience so far. Unfortunately, they only come in Group 31 size so far;
6. Most boats are
way underprovisioned with charging capability. You can't have too much charging capability. More is better. Less will cost you
money over the long term, especially if you depend too much on mechanical means;
7.
Solar panels are an excellent investment, when paired with a reliable
MPPT or PWM controller;
8.
Wind generators are good, too, but are sometimes a hassle to install, maintain, and control;
9. Among the several ways to
monitor state-of-charge (SOC), the Smart Guage is perhaps the best and ONLY reliable means; amp counters need constant calibration (which on the average
boat they don't get), and can be very misleading;
10.
The ONLY reliable way to measure the residual capacity of your batteries is by using a controlled 20-hour discharge test; expensive inductance meters can approximate, perhaps better than other tests, but cannot match the accuracy of a 20-hour test;
11.
Specific gravity tests on FLAs may be good for identifying deficient cells and need for
equalization, but they do NOT relate to
battery capacity; and
12.
Larger battery banks are better than smaller ones for several reasons: lower cycling levels, faster charging, increased available AH, etc.
... in a nutshell :-)
Bill