Searching for solar battery maintainer kit

Harbor Freight has a Solar Panel Kit.
But, it's only 45 watts. And then there is the questionable HF Quality issues.
I'm sure there are others available, this is just one option.

I think 5W - 10W is big enough. Something I can leave on all the time to maintain my battery during the summer

I have some solar marine info, was looking into this for our boats as well. I kept this below from D.C. I hope this info is helpful.
(Don Casey has been one of the most consulted experts on boat care and upgrades for 30 years, and is one of the BoatUS Magazine's panel of experts.)


If you have a wet cell marine battery they self-discharge at about 1% of amp hour rating per day depending on outside temp. (less on hot days-more on cold days)

A watt panel has an output of approx .33 amps. But that's at peak power = noon . The rest of the time it's less. On average, we expect about 5 peak hours per day out of any solar panel.

The expected daily output of a five-watt panel about 1.65 amp-hours (5 x 0.33).

Allowing for recharging inefficiencies, this is still about 50% more than necessary to float a 100-amp-hour battery. A good rule of thumb is 3.5 watts per 100 amp-hours of battery capacity. But throw in an occasional sunless day, put blocking diodes in the circuit, and let the bilge pump run once in a while, and five watts will be about right. A small amount of extra capacity won't damage the batteries as long as you maintain the water level in them.

Whatever size panel you select, it should have at least 33 cells. Count them. Panels with fewer than 33 cells will have inadequate voltage to fully charge the battery. This assumes crystalline panels, which deliver the most output from the smallest package, but if you sail where overcast days outnumber sunny ones, you might consider a thin-film panel, as this type can have better low light output.

I have been using a battery tender brand 5 watt panel maintainer for my dirtbike for the last year and am very happy with it. Even with a layer of dust, it will keep the battery maintained at full charge.

I have the 15 watt BatteryMinder by Deltran and it will keep the battery charge up but it is marginal at best about recharging the batteries. I use it on the house batteries in my rig and there is also a five watt that was included in the rig's design. Even Winnie says it will not fully maintain the batteries.

I have very careful in eliminating all parasitic charges in my rig. That is for the chassis and the house batteries.

Deltrans are very(or were) for maintaining trailer batteries that are removed for the winter and taken home. Their products are great but they are expensive.

https://www.solarblvd.com/product-category/solar-panels-systems/12-volt-solar-kits/

Do use a charge controller.

pianotuna wrote:
https://www.solarblvd.com/product-category/solar-panels-systems/12-volt-solar-kits/

Do use a charge controller.

X2

Home Depot sells a 50w module for $73. For $22 more, you can double that to 100W. I'd suggest to start at 50W, buy a cheap charge controller with adjustable voltage, and monitor your batteries. I think you'll find that maintaining with a solar panel will save on your battery expense to "break even" within 5 yrs.

The smaller modules are easier to deploy and that may mean a lot in a boat, depending on size of boat, but the > 50W modules will get a charge into the battery quicker and that means extended battery life.

Be careful of what size you get. My class C came with a 5 watt...useless.

Thank you all for the information. I've never dealt with solar, so I came here to start after seeing other threads on bigger setups.
Just to clarify, I'm not looking for the ability to recharge with solar, just maintain the full charge while my boat is sitting at home on the trailer. That's why I was guessing 5-10W. I should have said this is a small fishing boat with only one deep cycle battery.
Thanks again - I've got some good info to get started!!

Based on my limited needs, it looks like this one with a controller would do the trick.
Solar