battery dead

boatman37

So mother and step-father have a pontoon boat. Over the winter he had a local marina install a Perko switch and 2nd battery. A couple of times this year their battery was dead. I knew they had a 2nd battery but didn't know about the switch until today. So my mother calls me and says boat won't start and both batteries are dead. I ride down and see the switch set to #1. Turn the key and nothing. No click, no power trim, nothing. He has a battery charger connected so I turn the switch to #2 and it fires right up. Asked him if he had tried that and he said he did not. Well after about 20 seconds it stalls out and now nothing. No click, nothing, on either battery or any switch position. Depth finder and horn work. We removed the original battery that came with the boat (no idea how old it is) and check the newer battery and it's at 98% charge. Check the old battery that we removed and it's at 1% charged. Tried starting it again with just the newer battery on all switch positions and nothing still.

I told him to go get both batteries tested. I'm pretty sure it is either a bad battery or maybe a bad Perko switch but doubt that is it. We were limited with our tools so I couldn't check anything for continuity.

Ideas?

GMSLITHO

Maybe something left on drained #1 but not starting again with a good battery is strange we’re the cables tight when yo removed them 

rasbury

How old are the cables? I have heard of perfectly good looking cables being corroded on the inside...

boatman37

Cables are all new. Nothing left on as far as I can see. The only 12V stuff on it is the AM/FM radio and the nav lights and both were off. On top of that he turns the battery switch off when he leaves. Haven't talked to him today to see if he got the batteries tested yet but will update when I find out but I'm 95% sure the one battery is shot.

boatman37

So he took the batteries to Advanced Auto and the older one is junk. But my mother also said after I left he found a short cable with a pretty badly corroded end. I didn't see that. Maybe I overlooked it cause that switch and the cables were just installed this spring. I'm guessing the cable he is talking about is the ground jumper between batteries cause she said it was a short cable about 1' long. I guess he cleaned it all off and will be getting a battery tomorrow. The other battery was new this spring. Still not sure why everything was dead even after that battery was removed? That short jumper was still attached to the 2nd battery but not connected to anything. I will tell him to check the other ground cable real good too.

PickleRick

Id repair all the shorts and see if it happens again.  If it does there is a test you can do.  With 1 battery attached disconnect the neg. Cable.  Put a multi meter between the neg cable and battery neg terminal. Multi meter should read milli volt.  In a car you want sub 100,xxx.  Lots of things dont sleep in a car.  In a boat id ideally want 50 to 90,xxx

Many times its a simple fix like a starter solenoid or ignition switch.  

If you have a high draw go to the fuse panel. Pull fuses 1 at a time until the voltage drops.  If no change look at added items that may not be run to fuse box.  Gps radio fish finder.  Sticky bilge float is a huge one. Occasionally ill find a shorted diode in an alternator is killing a battery. 

The draw numbers are from memory and my memory sucks.  

boatman37

It's a pontoon so not much electrical on it. No bilge, no GPS. Just running lights and stereo. And I disconnected the stereo. Only thing left is running lights. Haven't talked to him today so not sure what he did since yesterday.

PickleRick

My dad's pontoon has a mercruiser 3.0 i/0 so just checking.  Has bilge in engine compartment.  

boatman37

nope. mercury outboard. didn't talk to him today so no updates

boatman37

So just left their house and he said he put a new battery in it but still no luck. He went to the shop that installed the Perko switch and they said they have had to replace 4 of them this year so the owner was going to stop tonight and take a look. Step-father said he cleaned all the terminals before he put the new battery in. I don't think the switch is the problem cause if I remember right the trim and fish finder worked even when it wouldn't start. So not sure now.

boatman37

Well the only thing I heard was that the shop owner thinks the switch is bad and ordered a new one. But mine is a Perko but it seems much more solid than his did. Maybe it's how it is mounted.