Battery Switch Problems

J

Jonah

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Hi all,

I seem to be having trouble with the "1–2-Both-Off" battery switch on my '96 Adventure. Both batteries are in good shape, and no matter which one I hook up to the "Battery 1" cable, the motor will fire up as long as I put the battery switch on "1". But if I put the battery switch on "2", then no matter which battery I hook up to the "Battery 2" cable, the motor will not even respond.

Sometimes, with the battery switch on "2", I do get the boat electronics to turn on, and the check engine lights flash and beep like they always do, and the battery gauge shows a strong reading, as if the boat were ready to go. But once I turn the key further to crank the motor, everything turns off, and then I can't even get the engine lights or battery gauge to respond. (I can't figure out why I sometimes get the lights and beep, and why sometimes I don't.)

So, I got out my multimeter, and followed some suggestions by Seasick in an earlier thread (link below). Here's what I found:


  • Voltage between positive and negative terminals of battery "2": 13.02V. (Just making sure!)

    Voltage between positive terminal of battery "2" and negative terminal of battery "1": 13.02V. (To check the cable that connects negative terminal of battery "2" and negative terminal of battery "1", which has the ground cable attached to it.)

    Voltage between end of battery "2" positive cable (where attaches to back of switch) and negative terminal of battery "2": 13V. (To check the positive cable going into the switch.)

    Voltage between output cable of switch and negative terminal of battery "2", with battery switch set to "2": 13V. (To check that the switch wasn't broken, preventing current from exiting the switch.)

    Voltage between end of switch output cable (where it attaches to the 40A breaker) and negative terminal of battery "2", with battery switch set to "2": 13V. (Just making sure!)
So, I'm lost.

Thanks for any advice!

(Old thread with Seasick's suggestions: http://www.greatgrady.com/forum/viewtopic.php?f=2&t=23430.)
 
Just measuring voltage through the switch does not mean much - unless there was a complete disruption. For example, even one little strand of a battery cable can show that voltage. But it won't be anywhere enough to supply enough amps.

Take the switch apart and inspect - from what you've written, it sounds as though there's either a loose nut on the #2 switch post, or the internal workings of the switch have failed. That last one is very rare, but I have seen it. The same thought applies to the actual Battery #2 cable (corroded/broken internally). I assume you've at least given the cables a good visual goings-over for corrosion (it can wick up inside the sheathing so it may be hard to spot)?

If you don't find anything wrong with the switch - swap the cables at the switch and see if the problem follows the cable. If it does, replace the cable (consider replacing both). If the problem doesn't follow, the switch is likely failed internally at a spot you didn't notice.
 
Make sure that there is a battery cable connecting the negative terminal of battery 1 to the negative terminal of battery 2.
If there is and it is good, use your voltmeter to measure the voltage between battery 2 ground and the common output terminal of the selector switch both with no load and when you try to crank the battery. If there is a significant voltage drop under load, you have a bad connection, bad ground, bad tie cable between ground or a defective switch. The cable and connections at the motor are OK. I would check the ground cables first.
 
Dennis and Seasick, thanks very much! Following your instructions, I found a loose connection on the Battery 2 input cable on the back of the switch. Tightened it up and now it works fine!

I was surprised by how tight it was, actually—just the littlest bit loose made all the difference.
 
Excellent!

Yes, there's a lot of juice (amps) that needs to flow through there and the contact needs to be solid. Add in a little bit of corrosion - or at least not "bright and shiny" metal - and it makes the problem even easier to happen.
 
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