When "they" refer to battery cycles, what actually does this mean?
For example does it mean using up 25% of capacity and then a recharge? Could it be as little as using 5% and then recharging?
Batteries capacity changes as they age (apparently) in use. They seem to discharge quicker over time, which seems to equate with reduced capacity.
So let's say you have a 500AH bank and use your autopilot
for 5 hrs with a brand spanking new battery. At the end of the 5 hrs the voltage might read say 12.6. Do the same with the battery after 5 yrs of use and it might read 12.4 (even though the starting voltage for both was 12.7. Assuming the load (drain) was the same, this means you battery capacity has been reduced it might be only 250 AH. I don't know how to do these calculations, but that seems to be what happens as batteries age - they shrink in "capacity" but continue to weigh the same!
So suppose you have plenty of charging capacity and you are topping off at the same rate as you are draining down. This would be NO CYCLES! Or more realistically your cycles would not be very deep. Is this good or bad?
We're also told that getting the last bit of recharge into a battery is much harder than the first bits so it like getting to the peak of a parabolic curve, which flattens out as you move alone the X axis (time). And of course your charge regulators don't or can't push lots of amps in to almost charge batteries since they base their charge regimen on sensed voltage and if it's high they cut back. It's lke filling a glass of water
, as it gets to the top the tap slows to a drip.
What I would like to know is how to best maintain a battery to get the most out of it (matching my needs) for the longest term. Do I let it go way down before charging it back up? Or do I try to maintain it as full as possible with constant trickle charging and high output charging sources? How about smaller capacity (cheaper and lighter) and more frequently replaced batteries? If you had a spare to use, when bank A went south, you could then go to Bank B which is all new and waiting and then replace bank A. Not switch back and forth between A and B? The thought of replacing large batteries is not a pleasant one.
Does anyone actually know the best strategy?