www.iFourWinns.com

My holiday weekend got off to an interesting start. Back in late July, I stored my boat knowing that I would not be back until either late August or Labor Day Weekend and so I turned my dual battery switch to "Off." When I returned, my batteries were COMPLETELY dead. Not just run down, but toast.

I jump-started the boat and ran it for about 15 minutes, then shut off the engine and waited a few seconds. I started it right back up under its own power. I went inside to take care of a few things and, about 40 minutes later, we were ready to tow to the ramp. Just in case, I checked my power again before leaving. Again, nothing. Completely dead. So, no trip to the ramp.

Instead, I pulled the batteries and took them to the local Napa store. The battery charger/tester there had one battery at 0% charge and the other at 6% charge. They recharged the batteries for me in an hour, and they tested out fine under a load.

I was starting to wonder if maybe my alternator was bad, and if I'd just been running on raw battery power all summer. When I got out on the water, the volt meter was reading at just a bit above 13 and everything worked just fine for the rest of the weekend. I pulled the negative terminal off of one of the batteries every time I anchored for an extended period and on the dock overnight just in case there was something drawing a current that I didn't know about.

I'm still confused about what caused this condition, though. Does anyone have any ideas? What would draw power when the batteries are turned "Off"? The only things I can think of are the trim pump and the automatic bilge pump. I verified that the bilge pump wasn't running when the batteries were turned on (by listening, not with water). What else could it be? I was under the impression that my Bravo III's Mercathode system was controlled by the battery switch.

Thoughts?

_________________
Paul
2007 Four Winns Horizon 220
Mercruiser 350 Mag MPI w/ Bravo III Drive
2004 Ford Explorer Limited (V8-AWD)
Pomme de Terre Lake (Southwest Missouri)

Stereo memory? But even if that was connected I don't think it would drain your batteries in that amount of time (though I'm not certain). Leave your docking lights or other lights on that maybe you don't see during the day (fishing here for one of those "is it plugged in" type of things)? It's hard to imagine anything that could, under normal circumstances, drain your batteries in 40 minutes (although your ~15 minute run time may not have put a whole lot of charge in it/them).

Mercathode - I thought this was through the switch also, but maybe they wired it "wrong?" On your batteries you have the obvious (large) cables, but also some smaller individual wires. Have you followed all of those to see where they go?

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Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

Sounds like a good time to put an ammeter on the batteries in the off position and check the current draw. I had a van that would go dead in a couple of weeks and traced it back to the aftermarket DVD player I had installed.

My thoughts would be like Mike said about the Mercathode system wired wrong or the something wrong with the clock/memory in the stereo. The beauty of using the ammeter is you can isolate each device from the system and determine the exact cause.

Steve

Well, all of the switches on my helm have those BIG red lights that let you know when something is turned on. I'm not so worried about the batteries being dead after the jump-the engine only idled on the trailer on muffs so I'm not sure I ran it anywhere NEAR long enough to charge them up to a state where they'd hold power for very long.

I'm much more concerned about them being dead in the first place. If it were docking lights or something like that, they wouldn't have been turned on with the battery switch to "Off" even if I'd left them on. I checked the battery leads. There is a set of cables on each battery leading to the switch. There are leads for the trim pump on one battery. On the other battery, there is a single red lead that runs up toward the front of the engine. It then runs into a wiring loom and I lose track of it at that point. I can't imagine it is for anything OTHER than the auto bilge pump, though.

Neither of my manuals have a Mercathode wiring diagram, and I didn't take the time to find the system in the bilge and trace the wiring. Funny, I was doing an "improvement" when I discovered I had no power. The "improvement" was to run a lead directly to one of the batteries to the radio memory lead. My previous complaint had been that I lost all my presets when I turned my battery to "Off". So, at the time I discovered the problem, I had no radio memory lead hooked up to drain the system. Even if I had, though, there is not enough draw from one of those (of functioning properly) to drain 2 batteries in 6 weeks' time.

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Paul
2007 Four Winns Horizon 220
Mercruiser 350 Mag MPI w/ Bravo III Drive
2004 Ford Explorer Limited (V8-AWD)
Pomme de Terre Lake (Southwest Missouri)

The ammeter idea is a good one. You may not have any choice but to try to find out where that red wire goes (easy for me to say).

I knew you didn't leave lights on, etc. - just trying to think of anything that might bring a clue to the surface. What a weird problem.

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Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

Paul,
You're looking at a pretty low amp draw. Remember Ohms Law. (E=I*R)....
At 12V, a 1 amp load should show only 12 ohms; My cup-holders pull less than that!

May I suggest.....
1) Remove all batts and disconnect all wiring attached (Mercathode, auto bilge pump, stereo memory, etc)
2) Check with VOM using resistance from either Batt Positive to motor ground as reference. Should read Infinity Ohms. This is checking "leak" is not on Batt side (not suspected).
3) With all lights/loads off, turn batt disconn to "On"; verify Infinity Ohms. This should indicate if "leak" is on load side of disconnect (not suspected), but before any switches.
4) Turn the disconnect back to "Off" and start re-attaching potential loads. I'd start with the auto-bilge pump. Check readings after each "attachment". Any big change is quite possibly the source of your troubles.
5) If this doens't yield the culprit, try the same on the "load" side of the disconnect.

Because of the nature of LED's and Diodes in general, you may have to repeat all of the above steps in the opposite polarity (reversing leads) if you don't find the problem the first time around.

It's time consuming, but an ammeter won't have the sensitivity for the low amp draw you are checking for. You've already checked the obvious..... the batt's, and they are good.

I would also recommend anyone get a cheap ($20-30) batt/alt load tester. They save the need to pull the batts (a pain for all of us to get too), and wait in line at Autozone (because the batts always fail after 5 on a Sunday). You can check the batts individually, then start up and check the alt in seconds.

Good Luck!

_________________
Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.

Just this past weekend I noticed that I hadn't quite turned off my bat switch and the nav lights stayed on... No dead batteries (3 total) but it could have been a bad situation. I also carry a jump start pack in the boat. I usually attach the leads to the #1 battery after we are underway to freshen it's charge. This could just be a bad situation and won't happen again... that would be your best scenario. I usually always wait for something to either fail catastrophically or atleast happen a second time before I dig too deep.

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Marc, Kathlin & Nathalie


'89 Chaparral Laser 32

'93 Vista 245, 5.8L w/ King Cobra

Former Boats
'01 H260, 7.4 VP Duoprop
'98 H200, 5.0 GL w/VP SX drive

Walt, a current-reading DVM wouldn't show the draw (assuming it isn't intermittent)?

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Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

We're talking on the order of a half amp or less. Too little for the sensitivity of most VOMs I've used (as an electrician). A reading of, say 6 ohms, would be easier to spot. It may show up on a continuity tester.

_________________
Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.

OK, just curious, thanks. I have one Fluke that goes down to .01mA, and another that goes down to 500uA.

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Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

Thanks for the tips, guys. I'm not great with a multimeter, but the instructions seem pretty clear on what to check. Won't be able to get to it until the end of Sept., but I appreciate the help. I'll let you know if I find anything. If I don't, I'll just let the stealer handle it under warranty.

_________________
Paul
2007 Four Winns Horizon 220
Mercruiser 350 Mag MPI w/ Bravo III Drive
2004 Ford Explorer Limited (V8-AWD)
Pomme de Terre Lake (Southwest Missouri)

I wish all my problems were only electrical.

_________________
Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.