Battery parasitic draw

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kimbo
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Joined: Mon Oct 09, 2017 12:44 pm
Location: Michigan

Battery parasitic draw

Postby kimbo » Tue Aug 21, 2018 3:59 pm

Fellow M boaters,

This is my first summer with my new to me M-39 double cabin. Every time I go out for just 15 to 20 minutes, the starboard engine crank battery is to weak to start the motor. The only way to re-start the starboard engine is with the parallel battery button that uses the port engine crank battery. All three of my batteries, port, starboard and house were new last fall. I checked all three batteries with a battery tester and all are 100% perfect. While motoring, the volt meters show both batteries are being charged and while in the slip all three batteries show 13 plus volts after charging on shore power. So, something has an excessive power draw. Being new to this boat can anyone direct me to the location of the buss board so I can check for amp draw? Any other ideas as to the excessive power draw are welcome. The boat alternators are Marine SAE J1171.

Thanks in advance,

Kim

jralbert
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Re: Battery parasitic draw

Postby jralbert » Tue Aug 21, 2018 4:07 pm

Sounds familiar - was plagued with this for years and I do not recall how it was resolved. Always the stbd battery bank (2 batteries) which carries a greater load of things to power. One suspect was one of the monitoring devices (CO2/fuel?) and something else that always stayed on. Perhaps, there was a leak in the bilge pump arrangement (always on) though the pumps themselves rarely ran - the boat was pretty tight except, I suppose, when it rained. It's been so long and I haven't thought about this for years but I may have bitten the bullet and decided to turn off the bilge pumps and sniffers and that, I think, may have ended the problem.
-joel-
former owner 1988 '32 FB Sedan
Chesapeake Bay
twin 318 / 240 hp
Potomac MD

kimbo
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Posts: 10
Joined: Mon Oct 09, 2017 12:44 pm
Location: Michigan

Re: Battery parasitic draw

Postby kimbo » Wed Aug 22, 2018 2:44 am

Joel you are right. The only items switched on are the bilge pumps front and aft . I also leave the shore power switch on after leaving the slip. Not sure if that makes a difference.
Kim

ddependo
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Re: Battery parasitic draw

Postby ddependo » Wed Aug 22, 2018 10:13 am

Do you have your frig switched to DC?
Did you test the batteries with a load tester?
It's always something, good luck
Wayne
1973 32 express fly bridge
Chattanooga
"Southern Lady"

jralbert
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Posts: 546
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Re: Battery parasitic draw

Postby jralbert » Wed Aug 22, 2018 12:11 pm

I, too, left shore power on to provide fridge service on AC and for a while, the battery charger. Later, I was never sure whether the charger was overcooking the batteries so I stopped that practice.

(by the way, Wayne, if he were running the fridges on DC while away, the batteries would quickly be exhausted, totally flat, not just low. So, that doesn't appear to be a factor here)
-joel-
former owner 1988 '32 FB Sedan
Chesapeake Bay
twin 318 / 240 hp
Potomac MD

Fastjeff
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Location: Rock Halll, MD
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Re: Battery parasitic draw

Postby Fastjeff » Wed Aug 22, 2018 3:20 pm

Is the port starter battery being charged by a separate charger, or is it tied in with a second battery (in parallel)?

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

kimbo
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Posts: 10
Joined: Mon Oct 09, 2017 12:44 pm
Location: Michigan

Re: Battery parasitic draw

Postby kimbo » Wed Aug 22, 2018 3:52 pm

Wayne, Jeff,

I'll check the frig switch tonight. I have yet to use frig, ice maker or any other electrical device on the boat other than bilge pumps and windlass. Only use windlass when dropping or raising anchor. I also keep the house service water pump off. All batteries tested excellent with a battery tester. I have only one battery charger on board and will check battery wiring tonight.

Thanks guys,

Kim

Fastjeff
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Re: Battery parasitic draw

Postby Fastjeff » Thu Aug 23, 2018 6:36 am

..." I have only one battery charger on board "

See if it's a multi-bank design with a circuit for each battery. I learned the hard way that each battery needs a dedicated charger.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

ddependo
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Joined: Mon Jul 14, 2014 10:00 am

Re: Battery parasitic draw

Postby ddependo » Thu Aug 23, 2018 8:30 am

Jeff, explain about battery charger. I have a 2 bank charger that has fused circuits for each bank. Have not had any trouble.
Give me some wisdom.
Wayne
1973 32 express fly bridge
Chattanooga
"Southern Lady"

kimbo
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Posts: 10
Joined: Mon Oct 09, 2017 12:44 pm
Location: Michigan

Re: Battery parasitic draw

Postby kimbo » Thu Aug 23, 2018 4:40 pm

Jeff,

Visited the boat last night. All batteries were charged up. With the charger off, each battery had 13 plus volts and with the shore power/charger off started checking batteries for amp draw. Have three on/off (no both) switches, one for each battery. House battery is on starboard and two crank batteries on the port side of the boat. I always assumed the three switches would each control batteries in the same sequence ie. starboard switch - house battery, center switch - middle battery and port switch port battery. After turning two switches off to isolate the starboard engine crank battery, I found that the port switch controls the starboard engine crank battery, the center switch controls the house battery (I think) and the starboard switch controls the port engine crank battery. Unfortunately I ran out of time and was unable to confirm which crank battery goes with which engine. Before leaving the boat the far port battery was down to 12.7 volts.

The bilge pumps and frig were all off the last time I was out on the open water. Believe they can be eliminated as a problem.

Thanks all for your comments,

KIm