Been awhile since boat has had a run & who knows how long it will be until it does, so would probably be timely to give the batteries a charge

Yeah, I have a female 12 Volt plug connector permanently attached to each of my batteries. I fit male plug connectors to two of my smart battery chargers and its simply a matter of plugging them in until they reach float level... Saves taking battery covers off. 

Yeah, I have a female 12 Volt plug connector permanently attached to each of my batteries.

 I saw these sort of battery box with the lids with connections (fused under the lid) directly to the battery terminals at burnsco a few yrs back.
So I got a double sealed marine cig lighter fitting and put into my std lid.. connected with a generous amount wire directly to battery terminals with a 5 amp fuse.. think 10amp should have been , but my thinking was 5amp bit more insurance and doubt would go over 5amp anyway)

So I have a male cig lighter fitting with a wire that I can connect my  battery charger...usually the 10W solar panel and monitor unit to as a maintance/ trickle charger.

If get the smaller supercheap 5w (think) there is no need for a monitor unit.. just connect and maintain..to use it and expect to charge a flat battery thu will take a long  long time..
The cheap super cheap panel I opened up and sealed all the joins to make totally water proof.. worked for well over 20yrs.

The marine cig units , even thu have rubber covers, a light spray inside with lanocoate every so often is still required.
 Mine are still working after 6 or 7yrs.

They are also handy to plug a lamp or cell charger, radio in  down at the stern end of the boat... maybe even a electric reel??

Only blown the fuse once...hooking up the solar charger dropped the clamp connections and they banged together.. direct sort

I think Ctek make good chargers. Ive got a 5amp charger. 

If you are going to leave the battery connected you must use a smart charger like a ctek or you will run the risk of blowing one of the diodes in the charging system of the motor.

I have my jetski battery continuously attached to an appropriate rated CTek when not in use. The battery remains in situ and connected to the ski. Never missed a beat!