I used a battery check device the other day and found that my batteries were below 50% of their rated power, so I think it is time to replace them (9 years). What I have are 2 (house and start) Deep Cycle Power Tech Group 24 AGM. I went back and read Maine Sailor’s excellent article on batteries (https://marinehowto.com/what-is-a-deep-cycle-battery/ <https://marinehowto.com/what-is-a-deep-cycle-battery/>) and found one aspect confusing. He advocates strongly for using 2 golf cart 6V batteries wired in series: ("In virtually the same foot print as two Group 24 12V light cycle batteries, only slightly taller, two 6V batteries wired in series for 12V will yield approximately 850 lab cycles vs. 350. “). But he seems to discount that you need two 6V batteries to replace a group 24 12V battery. A Group 24 is 10.7 x 6.8 x 8.6 and a GC2 is 10.3 x 7 x 11. So if you put two GC2 batteries in, it will take up nearly twice the space. I did a rough measure of my battery compartment, and I don’t think two GC2 batteries will fit. Am I missing something? He is usually so accurate about advice so I was surprised. Also, I have the engine alternator and a 50W solar panel that trickle charges the batteries during the week through a dual controller. One battery company I talked to said that going to a larger battery (group 27) would be a problem with a small solar panel due to the low charging amps with the solar panel. I don’t understand now that I have thought about it. The panel says it can output 18 volts, which is much higher than the battery voltage. So I can see that it would take longer to charge the larger battery, but wouldn’t it eventually charge the batteries given the many hours of charging? Am I missing something? The battery rep said that the long charging at low amps would damage the battery because it would cause the temperature to be raised. I can find nothing on the internet that supports that idea. Everything I read agrees with me that it will be slow, but will work with a small panel. Dave
S/V Aries 1990 C&C 34+ New London, CT
