So, despite my severe OCD and control freak nature, I am leaving my AR250 at a marina dry stacked for this summer about an hour from my home. One of my concerns is that the batteries will be sitting for 2-3 weeks at a time in some cases with no boat usage. The boat is sitting up high on the rack (has to be on top of three level rack due to tower clearance), so I don't see any way to install Noco or similar trickle charge - actually most times I'll be driving away from the marina while the boat is still in a wet slip waiting to be pulled so I have no personal control over whether the Noco would be plugged in etc. I've seen portable jump starters but not anything that you can leave attached to the battery to charge it up. The marina will jump start the boat when they put in in the water but ultimately if the charge gets run down I'm concerned that after a 15-30 minute boat ride the battery will still be low and I could get stuck.
Am I overthinking this?
No, you are not overthinking this. “Luck favors those that are prepared” and ”Be prepared”- Boy Scout motto are two of my favorite sayings.
Could you go 2-3 weeks with the battery switches off with no issue? Probably as long as your batteries are in good shape, and were properly charged to begin with. Should you not go boating and or use the boat because you do not have the onboard charger and such hooked up, absolutely not.
What are you doing right now to keep your batteries in good shape? It does not sound as though you have an onboard charger, like a NOCO installed yet. Have you checked the batteries with a hydrometer? A volt meter is okay to check batteries with, but it does not tell the whole story, the best is to use the volt meter AND a hydrometer to check the specific gravity of all cells, then do an equalize charge to make all the cells match up.
And let’s be clear about something, a NOCO or MinnKota battery chargers are NOT trickle chargers, they are smart chargers that can deliver a decent bulk charge current of 10 Amps (this is the minimum charger amperage that should be used in my opinion) then back down to a lower current after reaching 80% charge to reduce electrolyte boil off, then go into a maintenance mode-no charge- until the voltage drops to 12.7 or 12.6 at which it will go through a charge cycle automatically. A trickle charger delivers a small current that stays constant and will roach your battery in the shorter term as it does not shut off.
There was another post similar to this recently and this is what that person did. They installed a NOCO genius 10A x 2 battery charger with the bulk head mounted male plug for the power cord. Then they bought one of those small LiFePO4 portable battery packs that has 120 VAC out of it.. a jackery I believe… something like this
Jackery Explorer 1500 Portable Power Station
Whenever they use the boat they simply brought the battery bank along and plugged it in to the bulk head mounted plug that feeds the onboard charger when they were stopped and charged the batteries.
You should have a jump pack along with you anyway for emergencies… you may have a problem, or someone else may have a problem that you want to help.
Another variable that you did not mention is how much time you run the engines at cruising speed when you go out boating.. if you are doing some decently long transits 45 mins plus, the engines will charge up the batteries pretty well, but, and this is a big but, the engines do not have the charging capacity to properly charge the batteries since they don’t put out enough amperage for a long enough period of time. Whereas the NOCO with its charge profile will properly charge the batteries.
