One Side Electrical Problem

Flytrade

Active Member
Feb 20, 2018
302
Bradenton, FL
Boat Info
2006 320 Sundancer
Engines
Twin 6.2L Mercruiser
My recently purchase 06 Sundancer 320 had 4 great batteries. However, they were each 4.5 years old, so I thought I would be smart and replace all 4 batteries so I won't have any problems. The way the electrical system is set up is each of the two batteries is connected in parallel, so I wind up with two very strong batteries on each system.That worked great until just today a bank of two batteries are completely dead.

I can start the left engine normally, but the right engine ignition is completely dead. So, to start the right engine I have to use the switch that connects all the batteries. That works fine, but now I also have problem with the right outdrive trim, etc.

My original thought was I got a bad battery, and it wad draining down the other good battery that was connected in parallel. It was easy to find the two batteries that are used for the right engine, so I disconnected them, and reconnected the battery terminals to one battery at a time. No luck - the engine will not turn over. And, each battery, not under load, checks out with 12.9 volts.

Now, do I have a pair of bad brand new batteries, that go bad under load, or is the problem in the electrical wiring. I used a jumper cable to connect a known good battery - one that will state the left engine - to the electrical wiring of the right engine, and it also will not start the engine. Everything on that side is completely dead.

So now I know the problem is not with the batteries, but somewhere in the battery cables, or more likely, what they are connected to. Is there a circuit breaker, switch or something else that has been tripped? Any ideas would be appreciated.
 
One other piece of info to the above. When I try to start the right engine, I can tell it's getting some "juice". It turns over just a little, but not a full revolution. Like it's getting a very weak electrical input.
 
Another piece of info to the above. The engine hatch is electrically operated, and it won't work either. Evidently it's powered by the same system that starts the right engine. However, I can get the hatch to work properly by using the same electrical switch I use to gang the batteries together to start the engine. That tells me it's not an engine problem, or a battery problem, but an unknown electrical problem.
 
I hope you don't get sick of me giving you more pieces of info, but I think this is important. In preparation for a trip, just a couple days ago I turned on all the batteries and opened the engine compartment to check the oil in each engine. Everything worked fine. Now, as I stated above, the only way I can open the hatch is with the switch by the engine start switches. So, what happened in a couple of days with the boat just sitting there?
 
start from scratch. Make sure all batteries are charged fully. Then load test each one. NOT just voltage. You will start to isolate the issue as far as whether you need to eliminate the batteries as your potential problem. Do this and get back to us.
 
I disconnected both batteries from the battery cable on the "bad" system, and then used jumper cables to connect the two good batteries to the battery cable I just disconnected. This completely eliminated the two batteries from the system. Same problem.
 
Check the rocker on the switch the dash by swapping wires. Also may want to check the slave solenoid. Not sure if that side is part of the start circuit when you use emergency start but worth a look.
 
Everything at the helm station seems to be working as it should - the right and left start switches and the one that connects both batteries work fine. That is the only way I can start the right engine. What gets me is that everything was working fine one day, and without me doing anything, it's not working now. Go figure.
 
I think there’s a solenoid that controls the battery banks. This sounds like a possibility except for the fact that u say the engine tries to crank. I would assume it would just be dead completely. I’m not entirely sure how the battery parallel switch works. Obviously it supplies power from the other bank of batteries but I’m not sure if it supplies ground as well. If this is the case and it does supply ground my assumption is that u have a loose ground issue somewhere in the system. In other words the parallel switch is working because it’s supplying a needed ground and not because it’s supplying power.
 
Are you positive you have all the neg cables connected to the batteries , should be neg to neg on both batteries and a main neg one going to the engine block
 
I think there’s a solenoid that controls the battery banks. This sounds like a possibility except for the fact that u say the engine tries to crank. I would assume it would just be dead completely. I’m not entirely sure how the battery parallel switch works. Obviously it supplies power from the other bank of batteries but I’m not sure if it supplies ground as well. If this is the case and it does supply ground my assumption is that u have a loose ground issue somewhere in the system. In other words the parallel switch is working because it’s supplying a needed ground and not because it’s supplying power.
I believe I checked for a good ground by disconnecting the battery cable, and then using a jumper cable to connect the good batteries to the bad system. This gave me a good positive and negative to the bad system. Thanks, but still no luck.
 
Are you positive you have all the neg cables connected to the batteries , should be neg to neg on both batteries and a main neg one going to the engine block
Yes - there is only one way to attached the battery cables. Also, the entire system was working when I opened the hatch to check the engine oil, etc. The very next day the hatch would not open without using the parallel switch. Same with the right engine. What could change overnight? Could I have used something - air conditioner, fridge, etc - that could have upset the system?
 
Yes - there is only one way to attached the battery cables. Also, the entire system was working when I opened the hatch to check the engine oil, etc. The very next day the hatch would not open without using the parallel switch. Same with the right engine. What could change overnight? Could I have used something - air conditioner, fridge, etc - that could have upset the system?
I would check battery selector switches and possibly all of your circuit breakers. Not sure how your boat is wired so can't be more specific than that. Also, there is a big red "circuit breaker" on your starter. Looks like a red button. You need to get a 12volt test light and start to trace where you have lost the electric. Possibly even get a schematic. This is a simple issue.
 
I also thought it would be a simple issue. I have two battery switches. All the helm functions are controlled by switch #2. Since the left engine works normally, that tells me the switch is working. If both engines have the same problem, then the switch could be the problem. The same with the hatch.
As for circuit breakers, I checked all I could see. But, I am getting some electricity to the right engine - just not enough to do anything. When I press the start button for the right engine I do get a short beep, and I can tell the engine is trying to turn over, but that's it. That would tell me the circuit breaker is not the problem.
I woke up and started thinking about this, and what is so puzzling is everything worked one day, but not the next. What could change overnight?
 
I like the idea about the battery switch, and it's something I have not considered. I would think the battery switch would be designed to send power to 2 DC busses - a right and left buss which each would be used to start the right and left engine. A parallel switch (PS) would connect the two busses when needed. Now, suppose the switch is only powering one buss? That could be the answer.
 
I had a somewhat similiar problem late last season. now . I only have 1 battery switch and single engine but still relative. So, upon uncovering the boat this spring, I decided to check every battery cable connection everywhere + and-. I found 1 slightly corroded and loose ground connection on the engine block.I also completely removed battery switch and dissasembled it. There was considerable amount of corrosion on most of the line side + connections and some corrosion on the load side connections. There are a few buss bars in the switch that were corroded also. I wire brushed every cable end and terminal making sure every connection point was clean, applied dielectric grease and reassembled. That turned out to be the whole problem. No issues this season. Not saying thats your problem, but, It might be worth a look.
Garry
 
Here is the latest. I installed a new battery switch today, but no change.
I then switched the batteries - side one to side two, so the opposite set of batteries are now being used to start the right engine. Again no change.
When I try to start the right engine, sometimes it will turn over slowly, and other times it will just sound like the stater solenoid is not engaging - just making a clicking sound like it's not getting enough voltage. However, when I use the PS the right engine turns over very well and starts.
That tells me the ground to the engine must be okay. However, I must be losing voltage someplace. It's still a mystery, but I appreciate all your comments.
 
Here is the latest. I installed a new battery switch today, but no change.
I then switched the batteries - side one to side two, so the opposite set of batteries are now being used to start the right engine. Again no change.
When I try to start the right engine, sometimes it will turn over slowly, and other times it will just sound like the stater solenoid is not engaging - just making a clicking sound like it's not getting enough voltage. However, when I use the PS the right engine turns over very well and starts.
That tells me the ground to the engine must be okay. However, I must be losing voltage someplace. It's still a mystery, but I appreciate all your comments.


Check these areas.

ink (1).png
ink.png
 
I like a good mystery.....

Let me see if I have this right:

-This is a new boat to you
-You replaced all four batteries on two banks (port/starboard)
-The starboard bank went dead overnight but the Starboard engine will start using the Emergency switch
-You are still chasing the problem

What is interesting is that problem appears as an almost dead battery Bank (or a dead cell on the battery bank). There is still some voltage but not enough to do anything.

So, I don't think it is a coincidence that you changed the batteries and now the Starboard bank doesn't work. The first thing I would check (which was suggested by CapeCodCruiser) is the condition of the Starboard bank batteries. I appreciate you put a volt meter on them and used jumper cables to the Port bank .......but that isn't the way to do it. If you want, you can replace the Starboard batteries with the Port batteries since they have been proven to work.

Then if the "new" Port batteries start the Port engine....you can be assured that the batteries are not at fault. If the problem continues with the "new" Starboard batteries.....you have a wiring problem.

I would swap the batteries and see if the problem follows it (keep the hatch open). If it doesn't.....then things get more complicated.
 

Forum statistics

Threads
112,950
Messages
1,422,877
Members
60,932
Latest member
juliediane
Back
Top