[On a 2014 170 MONTAUK with a 2014 Mercury 90 FOURSTROKE, [I have a ] two-battery set-up with a PERKO brand OFF-1-BOTH-2 battery switch. Accessories include an entertainment audio amplifier, a multi-function display with GNSS receiver and SONAR, a sump pump, and navigation lighting.
At the end of the 2018 boating season the batteries failed. I chalked it up to the batteries being more than four-years-old.
In March 2019 I replaced both batteries with new Interstate-brand batteries [no size information provided].
The boat sits on trailer in heated garage, without a batter charger connected.
After running the boat with the battery switch set to "1" for few days, I went out on a Saturday. The boat ran all day with no problems. On the next day, a Sunday morning, I tried to start the engine: there was no battery power from the #1 battery.
I moved the battery switch to "2" and went about my day just fine.
While the engine was running, I switched the battery switch to "1' in order to put charge into battery #1, but [a] low voltage [aural alert alarm would] BEEP after a few minutes. Battery #1 didn't seem to pick up any charge.
I then shut off the engine. I tried to re-start the engine on battery #1, but the engine would not turn over.
I have only run on battery #2 for one day on water.
I cannot determine if [the problem] is with just battery #1 or possibly both.
Oddly enough I believe the failure at end of last year was with Battery #1. I do not know if is related.
Boat electrical isn't my fort.
What could be the cause of the problem?
Battery Problems
Re: Battery Problems
Based on your narrative, the likely cause is a failure of the outboard engine to charge the battery. This is a late reply, but I just came across your post.