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I have a dual battery setup with a battery switch. Battery one works (the motor can start off of it and the horn works) but battery two does not. At first battery two appeared to be dying because using the tilt/trim went very slow and sounded different compared to batt one. Now it does not work at all. Please see a diagram of my battery setup below.
Battery one is dated year 2000 and battery two is dated 2004. So the older battery works and newer battery does not. I hooked up a volt meter to both batteries with them disconnected from everything and they both approximately have the same charge from what I can tell. I also tried cleaning the terminals and wire connections with sand paper but that did not fix the issue.
Any idea as to what may be wrong? Do I just need a new battery?
Do you have two or one engine. I have a very similiar problem going on and my local mechanic said I could have a bad voltage gauge in the engine. This gauge converts the power to the battery and charges it is does not charge it if it isn't working properly. The first thing I would do is pull the batteries off and take it to an Auto Zone and let them test it. New batteries is an easy fix. I replace my batteries every 3 year regarless of condition. I don't want to be stuck offshore b/c of a bad battery that costs less than $100. Just my .02 . I have Yamaha 4 Strokes as a fyi.
Check for voltage at the switch , could be bad connection or coroded
Leon
I forgot to mention that I switched the battery connections around so battery one became battery two and battery two became battery one on the switch. Still no luck. I am thinking a bad battery but its weird that they both show the same voltage output on my voltmeter.
Do you have two or one engine. I have a very similiar problem going on and my local mechanic said I could have a bad voltage gauge in the engine. This gauge converts the power to the battery and charges it is does not charge it if it isn't working properly. The first thing I would do is pull the batteries off and take it to an Auto Zone and let them test it. New batteries is an easy fix. I replace my batteries every 3 year regarless of condition. I don't want to be stuck offshore b/c of a bad battery that costs less than $100. Just my .02 . I have Yamaha 4 Strokes as a fyi.
One engine. My other battery has been working without issue so I am assuming its being charged. I might just grab a new battery and if that doesn't fix the problem, return it. I like the suggestion to get my own tester from the poster below you but it won't arrive in time. I may try to find an Auto Zone though.
Josh, check the switch itself. Is it a Perco? There are some comments on THT about switches and failures. You may wish to replace the switch if the battery can be charged and has not failed. Also, in "both" mode it is my understanding that a discharged battery will drain your good battery.
I just went through the same thing. Switch the batteries and see if it still works the same way. U might find u have a ground problem between the two. Check the ground cable very good for rust.
When you swtched batterys around did the same battery fail or was it post #2 on the switch and battery 1 didn't go, if it was still post 2 seems like the switch, the same battery i would have it tested its probably bad.
just voltmeter dont tell you anything. If its a conventional, check the gravity of the electrolyte, if not then you need a load tester.
My battery switch doesnt work for some reason on batt 2 when I go from Off to 1-both-2 , but If I go from Off directly to 2 it works fine. I dont understand it , but I just know thats the case.
Battery issue - two batts, one doesn't work 
