Do Battery selector switches go bad ??

[bob_deb]

Hi Everyone,

My boat has a Xantrex trucharge charger, a Balmar Alternator, 1 start battery and 2 on the house bank. My start battery was loosing its charge and would not charge up from the charger. I figured it was bad so I bought a new battery. The new battery is not getting a charge from the charger but the charger appears to be working OK. My Alternator won't kick in because I think it is only recognizing the house bank that is fully charged, even though the selector switch is on BOTH. When the fridge kicks on it appears to only be drawing from the house bank even if switch is on Both. I suppose my charger may have a blown fuse, but if so, why won't the alternator kick on ? My battery monitor is continuously showing an amp drain of about -00.3 on the start battery, regardless of the selector position. HELP !!

Thanks - Bob

[Capt Hook]

Hi Bob,
Your selector switch could be at fault. Do you also have battery isolator switches? We get through one of these nearly every season but if the isolator switch was faulty you'd have problems starting. It's easy to check the selector switch. Disconnect the alternator cable at the selector switch and use a connector block to wire it to the cable that goes to your start battery so taking the selector switch out of the circuit. Start her up with a voltmeter across the start battery and if it's charging it'll show close to 13 volts.
Chris

[Divecoz]

Chances are your selector switch has not gone bad.
Its a very heavy duty mechanical switch, capable of handling twice the load its "rated" to handle.
I would look else where for the problem If you have a simple Multi meter, it should NOT be that hard to tell is your start battery is IN THE CIRCUIT or if its ( the switch)permanently open not allowing current flow to that battery so as to charge it.

[georgelewisray]

A clamp on dc ampmeter and a digital voltmeter will allow you to see what is going on. What battery voltages are and where the current is or is not going.

Nigel Caulder's books are a GREAT way to learn what is happening and what to look for.

[Rick]

The start battery cannot have a "drain" current unless IT has a HIGHER voltage than the house bank and if all are in parallel by a selector switch.

Something else is going on here...use above suggestions to troubleshoot!

[scotte]

Check all your connectors, too. On more than one occasion I've seen good mechanical connections making poor electrical connections. I spray some WD40 on them, then loosen and tighten each for a temporary fix or check - but to really fix I take everything off, get all the corrosion off with some light sanding, and reassemble.

In fact, just a few days ago neither alternator was charging properly. One was a bad connection on the +12 to the external smart regulator for the alternator. The other was exactly what I described above on the connectors to the alternator's battery isolator.

[Divecoz]

WD 40 is fine but I prefer JB 80 as its twice as good.....

[bob_deb]

Thanks everyone for all the good feedback.
I checked everything suggested and found some loose connections and learned a lot about my electrical stuff.
What I did find out, I think, is that my batteries were charging okay,
But my battery monitor system, for some reason, was showing a discharge on the start battery and showed it was dead today.
I turned everything off and started it all backup, and it appears to be okay. We'll see.

thanks again - Bob

[Divecoz]

Never Seize ( silver paste ) and JB 80 both stand the test against salt water for electrical and mechanical connections. JSYK