Recommended Tools/items for 12v 18650 boat lift solar project

I've been harvesting cells and mah rating them for the past 6 months, and would like to attempt my first 18650 project. Id like to start small with a battery pack for my 12v boat lift.

Currently I have a solar panel and controller mounted that feed a 12v AGM battery that powers my 12v boat lift and some led lights that are on a motion sensor.

I'd like to build a battery pack out of 18650's to replace the AGM battery, not because I need to, just because I want to so that I have a better understanding for when I attempt a bigger project. If this goes well then I'll move up to a Powerwall to supply my shed, and ultimately one for my house.

I have been doing some lithium battery repair to fund my project, and have already accumulated some tools including but not limited to, Sunkko 709AD+ battery spot welder, multimeters, side cutters, Dremel, Pace MBT desoldering station, Solder rework station, other solder guns/pencils, opus bt-c3100, and skyrc m3000.

The two questions that I have is What other tools would you recommend that I add to my arsenal, and What components will be needed to complete this 12v boat lift battery pack?

And once again 12V is the one size you really cant build out of 3.7V nominal Lithium.
3s is to low and 4s is generally to high for it to be optimal. Most equipment cant cope with either or. Just newer solar equipment can.

With that said 3s is often the easiest start even though voltage is to low.
You need battery and a BMS for it. You need to understand how much current is needed and design by that. Then you need to aquire something that can charge the battery. A normal LA is far from ideal to charge LiIon. LiFepo4 is easier since its more well matched towards LA voltages.

Have you looked into the FAQ here?

What about using a 12v DC buck module to regulate the output voltage of a 4S? The lift can run anywhere between 12v-24v, but the lights need 12v.

https://www.ebay.com/itm/DC-DC-3A-a...rentrq:9d2f9e7f16a0abc555970fa6ffe44d9b|iid:1

I would try to run your boat lift with your 3s pack, it should work especially since its a low rpm motor. I have yet encounter a situation where my 3s 11.1 volt lithium pack couldn't work with. I never had one of my inverters stop working because of low voltage. A 3s will be easier to build as a 1st battery pack.

But find out how many amps the boat lift needs? If the amps are too high 3s or 4s of laptop batteries might not be enough. You might need power tool batteries that can handle high discharge.

3s will be too low for the 12V motor. As the voltage goes lower, the amps will need to go higher for the motor to have enough power to run. That is, until the battery fails.

If the motor can handle up to 24V, then go with 6s or 7s and use a buck converter for the lights. This is better as you won't need as heavy wiring, plus the buck converter for the lights is better than trying to have one for the motor.
Agreed with jonyjoe505 on finding out what the max amps are on the motor. This will determine your pack size. But, as mentioned, going with 24v setup it won't need as many amps to run. So this is probably your best option to get the best performance out of the cells and the motor.

If the amps is 10A or less, then I think if you went with 20p you'd have sufficient power to run the motor for short durations. If you plan on using it quite often in an outing, then you'd want more in parallel. The solar helps a lot in this regard, but can only recharge so fast as I doubt you plan on having solar as a roof for the whole boat, and possibly even the decking.