I took the new battery down to Sprite yesterday. It was blowing F4 and threatening to rain, so no sailing.
The first problem was getting the new, larger battery in the locker below the bunk where the old one(s) were.
The old batteries were wedged into place with baulks of timber so I took those out to make room, then threaded the new bigger battery into the locker. It's a lot harder getting a huge single battery in place rather than a couple of smaller batteries.
Then the battery stuck. It was too tall to fit. and wedged itself under the locker sides. Oh dear!
So, with a lot of fiddling about I took more baulks of timber out of the locker and lowered the battery.
I think the easiest thing to do is make up a new battery shelf under the locker and hold the battery in place with a strap, so that's what I'm going to do. I've got an ideally sized bit of external/marine ply that can do for the shelf, Just need the straps. Pound shop here we come.....
I've also removed the eBay Chinese solar panel controller. Far from being useful, I think it's been the cause of the demise of the old batteries. I'm pretty sure it's reduced the amount of charge going into the batteries and then taken current out of them at night when the solar panel isn't charging. So the batteries have been running on empty and sulphated.
So, it's back to the old setup of the solar panel being directly connected to the battery, which should be fine. That way there's nothing draining the battery at night. The Solar Panel originally had a diode across the terminal, but a while back I changed it to a blocking diode, which means the solar panel doesn't drain the battery at night:
Here's the original configuration, to prevent the panel being damaged from reverse polarity, but still allowing the panel to drain the battery at night:
Here's the new configuration in blocking mode. It stops reverse poliarity AND stops overnight power drain. The downside is a small voltage drop across the diode which means slightly less charging current, but it's still worth doing I reckon. Time will tell.
There's a rule of thumb when using solar panels that you don't need a controller if the panel's wattage is 10% of the battery's capacity. i.e. 10W and 100Ah. Which the new setup will be.
With the controller ditched, the solar panel connected directly and the blocking diode, the battery should keep fully charged. All I need worry about is overcharging, but that shouldn't be such an issue with such a big battery. I just need to check on the electrolyte levels regularly.
Here's hoping anyway. I'll let you all know.