So my mother and step-father have a pontoon they bought last year. They have been having trouble a few times this year with a dead battery. I knew they had 2 batteries but did not know they had a Perko switch installed. I thought he just had the 2nd battery and manually switched it. Anyway, we were going to go out on their boat today and it was dead. I went down to look and found that they had a local marina install the Perko switch He had a charger hooked up to what he thought was #1 battery (the newer battery) so I asked him if he tried starting it on #2. We tried it and it fired right up but stalled after about 15-20 seconds. After that nothing. No click, no power trim. But the depth finder and horn worked. We checked the emergency cutoff switch and it was in the Run position. We removed the older of the 2 batteries and put the charger on it and it read 1% charged. The other battery was still in the boat and connected and read about 98% charged but still could not get any click or anything no matter what battery position the switch was on. I'm thinking the old battery is bad but confused as to it not starting after we disconnected the old battery. Checked for breakers and couldn't see anything. It has a Merc on it if that matters. Even tried wiggling the throttle around to see if it might be the safety switch. Told him to take both batteries and get them tested but pretty sure the original one id bad. It came with the boat when they bought it so no idea how old it is. The other one was bought new last year.
Thoughts?
Thoughts?