Battery isolator/switch problems

[sea2sea]

Can anyone help me out with what I assume is a simple problem? (thanks in advance)

I think my battery isolator and/or selector switch has failed - but not sure.

Here's my problem. I have two battery banks - a starting battery and a house deep cycle. They are connected to a selector switch. When I physically disconnect the #2 battery but place the battery selector switch to #2, I get a reading on my dash volt meter.

Same if I reverse - if I disconnect the #1 starting battery and connect the house to the cables to what should be #2, but put the selector to battery 1, I get a voltage reading. I am also noticing that perhaps my starter is draining my house battery when I have the charger on - further leading me to believe there is something wrong with either the switch (which is turned "off" when I charge) or the isolator, or both.

Any suggestions as to how I can troubleshoot?

Thanks!

 

[Don S]

Re: Battery isolator/switch problems

When I physically disconnect the #2 battery but place the battery selector switch to #2, I get a reading on my dash volt meter.

What happens if you put the switch to the #1 postion with #2 battery disconnected?

 

[sea2sea]

Re: Battery isolator/switch problems

With the starting battery connected to the cables for switch 1, and the switch to the #1 position and #2 battery is disconnected, I get a reading of 12 volts
With the starting battery connected to the cables for switch 1, and the switch to the #2 position and the #2 battery is disconnected, I still get a reading of 12 volts.
When I reverse, I get the same. i.e. with the starting (#1) battery disconnected and the house battery (#2) connected, I get a reading of 12 volts when the battery selector switch is either switched to #1 or #2

 

[glenn property of pam]

Re: Battery isolator/switch problems

where is the main lead to the starter motor connected to.....the common of the selector switch or directly to the battery

 

[sea2sea]

Re: Battery isolator/switch problems

I'll have to check, but on the starter battery there are two smaller wires (one for pos and the other for neg) along with the main battery cables. Not sure if these auxiliary leads go to the starter or perhaps (probably) to the battery charger - I'll check in the morning.

 

[sea2sea]

Re: Battery isolator/switch problems

OK - the wires from the starter go into a corrugated hose wrap and "dissapear." I am unable to determine by tracing whether they go directly to the batteries or through the selector switch. However, if the selector switch is off, the boat will not start, so I presume they go through the selector switch. (and if the switch is set to the #1 starting battery position, it will start)

For what's it's worth, this is a "new" problem, meaning that my switch previously worked - i.e., . if battery #2 wasn't connected, I would not get a reading from my gauge if the switch was set to #2.

Does this help anyone troubleshoot whether it is my isolator, switch, both, (or something else???)

and just saw an typo in my previous post - what I meant to say above is:

"I am also noticing that perhaps my [starter] STARTING BATTERY is draining my house battery when I have the charger on - further leading me to believe there is something wrong with either the switch (which is turned "off" when I charge) or the isolator, or both."



Thanks!

 

[UncleWillie]

Re: Battery isolator/switch problems

With the starting battery connected to the cables for switch 1, and the switch to the #1 position and #2 battery is disconnected, I get a reading of 12 volts
With the starting battery connected to the cables for switch 1, and the switch to the #2 position and the #2 battery is disconnected, I still get a reading of 12 volts.
When I reverse, I get the same. i.e. with the starting (#1) battery disconnected and the house battery (#2) connected, I get a reading of 12 volts when the battery selector switch is either switched to #1 or #2

And when you disconnect the isolator does the problem disappear?

 

[sea2sea]

Re: Battery isolator/switch problems

I have not disconnected the isolator - seems like that would create an open circuit...

Looks like at this point I will simply buy a new isolator and a new switch. I'm hedging that it is the isolator so I'll replace that first and if it fixes the problem, then I have a spare switch.

 

[UncleWillie]

Re: Battery isolator/switch problems

The isolator bypasses the battery switch for purposes of charging both batteries simultaneously.
If you disconnect one of the output legs of the isolator you will only be charging one battery unless the switch is set to BOTH.
If the voltage on the un-powered side disappears, you will know it was the isolator leaking/Shorted.

Alternately, remove the wires from the Isolator and test it with a meter, It is just Two Big Diodes in a box.

Buying a new switch and a new isolator for test purposes is an expensive way to test.
Identify the problem first.

 

[glenn property of pam]

Re: Battery isolator/switch problems

one last guess. do you have a acr relay and thats what the smaller wires are for?

what happens if you disconnect the smaller wires of both batteries?

 

[bruceb58]

Re: Battery isolator/switch problems

I have not disconnected the isolator - seems like that would create an open circuit....

That would only be a test to do without the engine running.