First: To insure you do not overcharge you need a controller.
Second.. I would want at least 12 watts delivered.. this means around a 50 watt panel.. Just to be safe...
Or a good 3-stage converter and shore power.. Something like a Progressive Dynamics Intella-power 9260 would be ideal for that size battery.
Finally think of your Six volt pare exactly as you would one 12 volt size 4D.
I know they are not physically the same.. but Electrically they are.. This answwers many questions.
Can I replace just one? (Can you replace 1/2 of a 4D? same answer)
Must they be same, size, make, model, age, et-al? (Again think about the first and last 3 cells in a 4D)
how do I charge them? In series you treat them just like a 4D.
See how the questions go POOF.
