Motors Off, Throttles Forward, Drained Batteries?

[jackmmf]

We've been having some electrical issues lately but thought we had em all figured out... until last night! Here's the setup:

Motor 1: switch to battery one only
Motor 2: switch to battery two only

The other day we cleaned the connections to both batteries and hooked everything back up. Things seemed ok, had a good charge in both batteries.

Came back two days later and both batteries had been drained quite a bit and it seemed like there was already a little corrosion on the (+) terminal.

Prior to us mucking around they seemed to hold a charge fine. There are only a couple variables I can think of, particularly since both batteries were affected (drained) but they should have been separated by the way the battery selection switches were set up (I think):

1. We did clean the contacts on both batteries but not sure what that would have to do with draining them
2. I did notice that we had left both throttles in the forward position after we had turned off the motors the other day. Would this draw any energy even with the motors off and keys out?

Any help would be appreciated!
Thanks

 

[Silvertip]

Re: Motors Off, Throttles Forward, Drained Batteries?

Are we talking I/O engines or outboards? Your description seems to indicate you have only two batteries -- one for each engine. Without a diagram we have no idea how the switches are wired. I would assume since you only have two batteries, the theory with two switches is to be able start engine 1 from engine 2 battery (or vice versa) should the need arise. That would mean there is a connection between the two switches. If you have one bad or weak battery and the switches were set so they were essentially parallel connected, the weak battery would have drawn down the stronger battery until the two were equal. You might have also connected a negative cable to a positive terminal and vice versa which may have taken out a voltage regulator.

 

[jackmmf]

Re: Motors Off, Throttles Forward, Drained Batteries?

Clarification...

Twin outboards, two batteries. Each side has a switch with selections of 1, Both, or 2. So yes there is a connection between them.

If the starboard switch is on 1, and the port switch on 2, would the batteries still equalize? I was assuming that at that point they would basically be isolated from each other unless a switch was turned to Both. I haven't checked the wiring from the switches yet but hoped it worked that way...

So I'm guessing the throttles being left forward with the boat off would not draw any current, correct?

How do I know if a voltage regulator went out?

Got the motors running with a booster pack and they seemed to charge the batteries back up OK. Need to go back out tonight to see if they're drained again.

Thanks for the help.

 

[Boatist]

Re: Motors Off, Throttles Forward, Drained Batteries?

If both of your switches have a off position try that and see if they still discharge.

If both batteries charge with the motor running and your volt meters show 13.5 to 14.5 volts then the regulators are good.

What kind of electronics do you have on the boat? Some units come with no power switch. Also do you have automatic bilge pumps and could something be stuck under the float switch? Could you have a water leak that causes the pumps to run? Have you had a lot of rain?

How old are the batteries and do they have proper water levels?

 

[jackmmf]

Re: Motors Off, Throttles Forward, Drained Batteries?

Thanks for the ideas. The aft bilge is on a float but I'm pretty confident it hasn't been running much if at all with the weather we've had and the time I've been on the boat without it kicking on.
Hopefully can get out there and check on the batteries this evening and if drained I'll try leaving it with both switches off as you suggested boatist.
Thanks!