Battery Issues

[BoBo_Wickersham]

2019 G25.
Winterized the boat in November. Turned the master battery switch to off.

Pulled her our yesterday. Turned battery switch to on. Didn't hear the bilge pump cycle. Looked at dash. Nothing. Pressed start button. Nothing. Put battery master switch on both. Nothing. hummmm.

Found the on board battery tender. ProSport HD12. Plugged it in last night. Cooked for 24 hours. Just checked for improvement. Nothing. Turned both batteries to the on position thinking that might need to be on for fill the batteries. Doesn't appear to be helping.

[GMLIII]

BoBo_Wickersham By chance do you think battery switch is toast ? I had to replace mine in my 2017 G23. It is a known issue on these boat.

[greggmck]

Its difficult to see the status lights on the charger. I would put a portable battery charger on each battery to see if the batteries are functional. 5 years is not unreasonable for batteries to fail especially when climate temperatures can be relatively hot and cold. Battery life can be extended by leaving the battery tender on all winter.

[BoBo_Wickersham]

I went out and put a trickle charger on it and bipassed the on board charger. although the onboard charger had gone from .188 to .190

[bturner]

I must be missing something here. I'm assuming you have the meter set to DC volts and you're seeing .188 volts? That would be a dead cell or multiple dead cells in the battery and IMO the battery would be toast. You basically have an open in the battery or it is completely discharged.

Odd that both batteries would do that unless you had some sort of drain on the battery that killed them over the winter. What do the red and black wires on the batteries attach to? If those bypass the power switch and go to something like a water sensing bilge pump it may have enough draw to kill the batteries over the winter. I pull my batteries completely out of the boat in the winter but if I didn't have a battery tender on the batteries I would at least disconnect the ground cable from both batteries.

My guess here is that something in the boat is directly attached to the battery that killed them over the winter or they just both aged out and died. Either way I would pull at least one of them, throw it on a good charger for a couple hours and check the voltage to see if it's going in a positive direction. If not, they're dead. Or you could pull a battery out of something else and correct it to see if the symptom changes.

My money (if you have the volt meter set correctly) is dead batteries.

[Scooter G]

2 cents, so the batteries saw no charge in 5 months?
I liked greggmck's 5 year rule, and bturner 's battery drain vs meter reading. It is strange they would both be toast.
I had a buddy over one day, ex-mechanic turned contractor. I neglected the charge on a mower battery, thing was toast. Charger wouldn't do anything. He said put a load on it.
I said what? He said, turn the lights on, bump the starter a few times. Heck if that battery didn't start to take a charge. Same battery is still running strong in that mower.
I'm still running the factory batteries in my '16 G, which is probably pushing it, you just need to keep a full charge on them, trickle over the winter.