Battery size to run a small auto bilge pump

[solosail]

I have an auto bilge pump on a Typhoon that will be kept on a mooring. The model is RuleMate 800 GPH 12V 3 Amps. I also have a small 3 watts (0.168 amps) solar Panel that I would connect to keep the battery topped off when leaving the mooring. Considering that the pump will probably run a few minutes to maybe an hour per week on average and depending on the weather, what size of battery do I need? Would a 7.5 amps be enough? The idea is to get a small battery that the solar panel will be able to keep charged. Thanks for your suggestions.

[sloopjohnl]

FWIW I used a 5W solar panel in combination with a regular car battery for years to power a bilge pump on my typhoon. if you are looking to go small i imagine 3W with a small tractor/motorcycle battery would suffice.

[Paul D.]

I agree, I bet you could get away with a 12 volt motorbike battery with a solar trickle charger hooked up to it. Generally, panels that make less than 1.5% of a battery's rated capacity in amp hours don't require regulation. I bet there are online panel charger options though that are regulated. Battery size/capacity should depend upon how much pumping you expect to do before it is discharged. Good luck, we loved our Typhoon. My good buddy still has her after 20 years and sails her often every summer!