1999 340 Sundancer Battery Issue

Jeff42899

Member
Jun 23, 2018
98
Lake Erie Islands
Boat Info
1999 340 Sundancer
Engines
Twin 7.4 Horizon
We launched the boat from storage last week and the port motor needed the emergency start parallel to start. I had the boat on the charger for a few days at the dock, and when I tried again I experienced the same thing. Starboard motor, house 12v systems all seem fine. I figured the port must be the stand alone motor and decided to replace the battery. I have a 3 battery system without a generator. Two are wired inline, one by itself. I disconnected the stand alone battery and toggled the ignitions to see which motor was isolated. To my surprise, both motors fuel pumps turned on and cranked. I did not have a load tester on me of course, and changed that battery anyway. When I got home, I tested the battery I pulled out and it tested fine. I have the other two batteries on order (they only had one in stock) so I'll be starting fresh but I'm very concerned that I don't have a house / motor batteries and an isolated motor battery.the wiring is all original, as are the battery solenoids and charger. This doesn't feel right to me. Am I wrong?
 
We launched the boat from storage last week and the port motor needed the emergency start parallel to start. I had the boat on the charger for a few days at the dock, and when I tried again I experienced the same thing. Starboard motor, house 12v systems all seem fine. I figured the port must be the stand alone motor and decided to replace the battery. I have a 3 battery system without a generator. Two are wired inline, one by itself. I disconnected the stand alone battery and toggled the ignitions to see which motor was isolated. To my surprise, both motors fuel pumps turned on and cranked. I did not have a load tester on me of course, and changed that battery anyway. When I got home, I tested the battery I pulled out and it tested fine. I have the other two batteries on order (they only had one in stock) so I'll be starting fresh but I'm very concerned that I don't have a house / motor batteries and an isolated motor battery.the wiring is all original, as are the battery solenoids and charger. This doesn't feel right to me. Am I wrong?

What are the symptoms when you try to start? Does it turn over slowly without the Emergency switch? Or nothing at all?

Are you sure the charger is working properly? There may be inline fuses in the wires from the charger to to battery side of the battery switches. Check to see if the port one is blown.
 
It turns over slowly then stopped. After swapping the battery both started without using the emergency switch but I'm more concerned that eliminating the single battery did not eliminate power to one motor. That would seem to me to mean that all three batteries are somehow tied together instead of two / one where I would always have one good battery to start an engine if I were to drain the house side on the hook or off shore power.




What are the symptoms when you try to start? Does it turn over slowly without the Emergency switch? Or nothing at all?

Are you sure the charger is working properly? There may be inline fuses in the wires from the charger to to battery side of the battery switches. Check to see if the port one is blown.
 
It turns over slowly then stopped. After swapping the battery both started without using the emergency switch but I'm more concerned that eliminating the single battery did not eliminate power to one motor. That would seem to me to mean that all three batteries are somehow tied together instead of two / one where I would always have one good battery to start an engine if I were to drain the house side on the hook or off shore power.
That does sound odd and not the way it would be wired normally. Is the battery charger the original one? Is it possible that somehow the charger is bridging the banks in some way?
 

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