Battery Drain & electrical short trouble shooting problems

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TomR's picture
TomR
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Battery Drain & electrical short trouble shooting problems

I have a 2000 Catalina 36 MkII. In it I have 2 AGM 4D house batteries. At the beginning of the summer I noticed my #1 battery stared to lose voltage and finally went totally dead. I had it relaced at considerable expense, AGMs are not cheap, besides they weigh 130 lbs each. Things seemed fine with the new #1 battery initially, but after about 1 week it went dead again. The main dial switch has been in the off position so there has been no usage through the boats electronics. Now this past week my #2 battery is also dead. So I now have 2 dead house batteries despite the fact my main dial battery switch has been off. The only way I still have power to the boat is by shore power through my battery charger. 
Since the main dial battery has been off  and my batteries drained I thought my problems may be a short with the bilge bump which is hot wired to the batteries. I throughly checked the bilge pump wires and carefully replaced the float switch (thought that may be the problem), but everything seems fine with the pump. The pump works and so does the switch. Besides there is almost no water in the bilge so I figure shorting through the bidge water is not the issue.
   I do have a hand volt meter and tested some of the connections from the battery figuring I can find the drain with the main dial switch off. I did notice that there is a big drain from my #1 battery to the volt meter on my boats main circuit board where I can quickly test the voltage of my #1 and #2 batteries though a switch. The batteries also seemed to be hot wired to this circuit testing switch. 
Has anyone had this switch gone bad? Seems strange it would. I need to find this short and it's extremely frustrating.
Another issue is that I'm not sure if the AGM batteries can be recharged (seems they are not holding a charge any longer). If they need to be replaced I need to find this short first.
 
Any ideas or suggestions would be a big help. I'm at my wits end....

Tom R
ObLaDi ObLaDa
Catalina 36 MkII, Hull # 1998
North East, MD

Tom Runiewicz
ObLaDi ObLaDa
Catalina 36 MkII, Wing Keel, Tall Rig
Hull #1998
North East, MD
 

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TomR
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As a follow-up I did find Catalina Direct sells the electric pannel DC voltmeter and the 3 way test switch it uses.
Notice the voltmeter is $99.95 and the 3 way test switch is $11.50.
Not bad considering each of my AGM 4D batterieas cost close to $700.
Does anyone know if this switch or voltmeter have a reputation of shorting out and driaining the battery?
Tom R

Tom Runiewicz
ObLaDi ObLaDa
Catalina 36 MkII, Wing Keel, Tall Rig
Hull #1998
North East, MD
 

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Tom-
I would diagnose using an ammeter. Disconnect from shore power. With your battery selector switch in the off position, remove all your "hot" (positive red wire) electronical connectors from all your batteries, place the ammeter in series with each wire to the positive battery terminals and determine if any are drawing current. There should be no current draw unless there is a short circuit to ground somewhere. 

I've been on this site for 4-5 years, and never read of anyone experiencing a bad voltmeter/rocker switch on the breaker pannel- but do a site search to verify. 

Good luck. Tracing electrical problems takes patience and sometimes digs up unexpected things. Couple of examples: I had a dead battery problem originating from current backfeeding into a solar pannel at night. In another stuation, (with old wet cell batteries), the battery cells had an internal short-which seemed to redirect voltage around the battery selector switches, even when they were in the off position. Conductive deposites can build up on the plates internal to the battery cells and create shorts.  I would not suspect this to be an issue with your new AGM batteries. 

 

Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B

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Yes - an amp meter is needed to measure the rate of current leaving the battery. If the switch is off, there should be no drain on the battery. Regarding using an amp meter to measure the current - there is an internal fuse to protect the maximum current that flowes through the amp meter. If you exceed this limit - you will have to replace this very special internal fuse. You may consider using an external fuse which is of a lower value and is easier to find and replace to avoid damaging the internal fuse. Typically this internal fuse is 10Amps. It is possible that the current draw from your battery is more than 10Amps. It is not important how much the current draw is - but that there should be none when switch is turned off. 
It is very likely that you have a buildup of high resistance rust from the +ve bar to ground and it is drawing current all the time. Trace the wires - you should be able to find it by disconnecting wires one at a time and looking at the amp meter. Instead of amp meter you can also use a 12VDC light bulb. If the light bulb lights up then there is current draw.

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Tom wrote "As a follow-up I did find Catalina Direct sells the electric pannel DC voltmeter and the 3 way test switch it uses.
Notice the voltmeter is $99.95 and the 3 way test switch is $11.50."

Measuring voltage won't help you find the leak.  Measuring current will.

Thus, rather than  a voltmeter, a battery monitor (such as the Victron 702) will give you far more information for just a little more money (I installed a Victron 602 as a replacement for the analog voltmeter that came with our '85 MkI -- it fit into the same hole in the panel).   With a monitor, you'll not only get voltage readings, but you can observe the amps going in or out of the house bank (i.e., if the batteries are charging or discharging, and how much); plus lots of other stuff. 

With my monitor in place, were I experiencing your symptons on our boat, I would 1) unplug the shore power and my solar panels (so no power was going in), 2) turn the battery switch off, and 3) make sure the bilge pumps were off (since they bypass the battery switch).   At that point, the monitor should show 0.0 amps going in or out.   If there was a discharge showing on the monitor, I would know there's power leaking out somewhere, in which case it would be a process of elimination to disconnect cable and devices until the monitor indicated 0.0 amps and thus the culprit identified.

Analogy would be to your house.  A voltage test would only tell you that its 110 volts AC.  But to see if you've got some sort of parasitic electric leak, you could shut off every appliance and light in the house and look at the electric meter -- at that point it should be still; if not, theres a leak somewhere to be isolated.   The electric meter in this analogy serves as the battery monitor

For more on the subject of battery monitors, see the helpful  website of former C36 owner Rodd Collins: https://marinehowto.com/installing-a-battery-monitor/

 

Matthew Chachère
s/v ¡Que Chévere!
(Formerly 1985 C36 MKI #466 tall rig fin keel M25)
2006 Catalina Morgan 440 #30.
Homeported in eastern Long Island, NY

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Paul is correct it taks patience.
I not sure how your boat is wired. My first question is when you turn off your battery sw is that turning off the battery charging circuit to your batteries? Our boats never seem to be wired the same. PO's always seem to have a better idea. I would start by trying to draw my own schematic of how you boat is wired.
A good Volt meter is a must. Charge the batteries up. Do your testing with only one battery connected at a time.

I would bet your AGMs aren't ruined by running them down once. Didn't do them any good but maybe OK. Charge them up and do a load test in place. You can buy a load tester from about 25 bucks on up. 

Chuck Lennox
97 MKii Ventura Ca
Island Girl Hull #1611

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Thank you all for your suggestions. My battery chargers go directly to all 3 batteries. House #1 & #2 and my motor starting battery. It doesn't matter if the main dial switch is off. A long as I have my shore power on & my charger switch on, they wukk be charging. However, I fear both my house batteries may be shot enough that they will not hold a charge on their own (and one is new). So in order to test for the short I have to leave them continously hooked up to the charger. I did take the wires off one at a time at the positive side of the house batteries.With my multimeter I believe I found a 12volt load in the wire which goes from the #1 battery house battery to the to the electric pannel voltmeter even when the switch is off. I also found very low voltage (like 0.1) coming from the similar wire on the #2 house battery.

I'll need open up the back of the pannel and check things out next. But for some reason, after what I've read, I keep going back to that bilge pump.
Wiring all seens fine with the pump after close inspecting. And it works with float switch and the manual switch.
All  extremely frustrating, like a bad Easter Egg Hunt.
 
If all else fails I may need to have a marine electrician come in. Suggestions on how to find a good one?
.  
Thanks,
Tom R

 

Tom Runiewicz
ObLaDi ObLaDa
Catalina 36 MkII, Wing Keel, Tall Rig
Hull #1998
North East, MD
 

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Tom 
If you are hooked up to shore power I don't see why your batteries are dead? Is your charger on all the time? If not why?
Check your charger output. Too high or low?
If your bilge pump was running you would know it. I don't see a bad sw causing a current draw. If sw was bad it's failed open (pump off) of failed closed. (Pump) running. 
There are some good YouTubes out there on trouble shooting shorts. 

When you are trouble shooting behind the power to careful! There 120 volt lugs that can kill you. Go slow. 
Keep a open mind.

Chuck Lennox
97 MKii Ventura Ca
Island Girl Hull #1611

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Tom-
I think it will increase the challenge of trying to find an electrical leak with the charger running at the same time (plus increases the risk of zapping yourself). If you have a relatively good battery- use that one to track down the circuit creating the leakage. Turn off the charger, and battery selector switches. Disconnect all the cables and wires from all the batteries. With the good battery- reconnect each circuit and check for amperage flow. If the starter battery is the only good battery, you can use some jumper cables to reach the wires in your house battery area. (Be careful to keep the jumper cable clamps seperated on the free end) Again, you should have no current flow to anything you hook up to...measure with an ammeter. 

Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B

True Wind
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Posts: 139

Tom
Knowing the difference between voltage and current is important. Voltage just means capacity. Current is culprit here. Those little electrons are going somewhere and having a party at your batteries expense (Oh that's right, Your Expense). It's like a mystery novel. Don't be fooled by the voltage guy. He's just here to confuse who's draining your battery. You've had some good advice here and not so good advice here. 

Let me play detective for a moment. I know you said you have checked your bilge pump. You maybe correct that the pump is not the electron thief but let me say it may be stealing your electrons right under your nose. If the bilge pump is wired incorrectly (I notice you may keep your boat in salt water), with the positive and negative wires reversed, that would mean that the positive wire is going straight to the bilge pump and not to the bilge float switch. If there is an accumulation of any salt water (A very conductive medium) in the bilge then you may be using current that way and you maybe creating galvanic corrosion. Just a possibility. 

After charging your batteries, I would remove the shore power (So the charger is out of the mystery). I would check and see what items are wired directly to each battery (Hopefully there is a fuse on each these circuits and if not put the correct fuse on the circuit at the battery) and I would check each one individually to see if any circuit wired directly to the battery is the electron thief. 

I would also disconnect battery #2 and the starter battery by removing their main positive feed cables at the battery. Battery #1 will be the voltage source. With the main battery voltage switch turned off, check and see if there is any voltage at the electrical panel by using a voltmeter (Connect the negative lead to ground and probe around the circuits on the DC part of the electrical panel and see if you find any voltage). There should be no voltage there.

Isn't playing electron detective fun!!
 
 

2003 Catalina 36

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I think of voltage as the water pressure and current as the water flow. Discharging battery is similar to having a leak in the water tank. Find the leak.

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TomR
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Once again, thank you for all your advice. My boat is currently located in the North East River of the Chesapeake (northern part) so salt water is not really a worry.
However, I will continue my electrical hunting mission along with hurricane prep work as Florence looms in the Atlantic.
Wish me luck.I'll post if I fine anyting. 
Tom R

Tom Runiewicz
ObLaDi ObLaDa
Catalina 36 MkII, Wing Keel, Tall Rig
Hull #1998
North East, MD
 

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