I don't use one now, but if you use a 24-hour timer, and set it to charge ONE hour per day, it will keep your battery charged, without boiling the water out of your battery. The "automatic" ones will still fry your battery, if you charge it continuously. A Walmart cheapie timer will do fine.
I'm an Eighth Day Adventist. On the Eighth Day, God went fishing!
At the suggestion of an electrical engineer (for whatever that's worth ) I use a NOCO charger on a couple of my kayak batteries. For my big boat I have a Humminbird 3 bank charger. Batteries are always charged and I've had no problems.
Battery Minder Plus. It won't boil your batteries, and it uses pulse technology (pioneered by PulseTech) to remove sulfate crystals from the plates to keep the battery strong and clean. Speaking of PulseTech, I've used their equipment for more than a decade, and it delivers. My last set of TM batteries lasted almost 8 years, and I only replaced them because one of them developed a short in one cell. I still have the other one for starting/electronics in my boat, and it is now 12 years old. PulseTech's products do what they claim, and that 12 year old Optima blue top that starts my boat is a testimony to it.
Artie ________________________________ Dad took me fishing when I was 10, and I've been pretty much hooked since. He went to be with God on August 14, 2012. I miss you, Dad.
I have a Battery Minder Plus on the conventional battery in my Ford 4x4 truck that is parked 300+ days per year. I did just replace that battery, but it was SEVEN years old before it failed me.
The Battery Minder Plus never boiled the battery out in all those years, and the truck started readily every time until this Fall (at the 7 year point). There were numerous times it stayed connected for 6+ months without dropping the electrolyte level any appreciable amount. And yes, I am one of dem dar enjineres!