Finding a current leak

[SmokyMtnGrady]

Hi Yall:
Ever since I bought my 288 in 2009 I noticed if I left the battery selector switch to battery 1 for more than 2 or 3 weeks that it would ultimately drain battery 1. I do not have an on board charger. I met Doc Stressor this fall at my humble shop here in Dillsboro and he gave me some tips on how to trace the current leak. Unfortunately that was 3 or 4 months ago. I am now in a position to work on my boat.

I have an Alpine Marine audio system, and Icom VHF transceiver and a Garmin chart plotter. I think the Alpine and or the Garmin might have a slight current while they are "off". I have a multimeter and know a thing or two about electrical circuits, but I am sort of at a loss in where to start looking for the problem, if there is actually a real one here. I have killed 3 batteries since owning the boat simply because I left the battery selector switch to 1. I have west marine's agm group 27 batteries and their warranty is awesome and I will be replacing this battery. I know, I know I should have either contacted the dealer while the boat was under warranty or simply found this issue when it first cropped up.

So does anyone have any idea where I should start here in finding the current leak? I would greatly appreciate any and all tips. Thanks.

 

[Curmudgeon]

You have a significant draw if you kill an AGM in 2-3 weeks. I'd start with the audio system, I've never known a Garmin or VHF to have a current draw when 'off', I'm pretty sure they have a CMOS. Backyard way of checking for a current draw, remove a battery cable in the dark and look for the spark, then disconnect electrical stuff one at a time. I suppose a multi-meter would work, but that's pretty high-tec for me ... :wink:

 

[wspitler]

You can use either an ammeter or simply put a low wattage light bulb in series with the circuit. You should see a glow from the bulb or read amps (or milliamps) if you have a load on the circuit or a resistive short to ground. Then you can start disconnecting known subcircuits such as a radio, etc. When the amps go to zero or the bulb stops glowing you've found the culprit, but remember it could be more than one small resistive load. A corrosive short to ground can act just like a component load. Remember that your sensor must be in series, not parallel. What you're doing is looking for the component or ground fault that causes the current draw. No current, no battery drain. Otherwise you'll have to disconnect components one at a time and wait to see if the battery goes dead, much more time consuming!

 

[ocnslr]

Do you have an NMEA 2000 network? If so, it is supposed to be separately switched, but might have been installed to be "always on".

I don't think the minor current drain to maintain the memory on the stereo would drain a battery in two or three weeks.

Is the boat kept in the water? Possible bilge pump cycling a lot?

Brian

 

[seasick]

Do you have an NMEA 2000 network? If so, it is supposed to be separately switched, but might have been installed to be "always on".

I don't think the minor current drain to maintain the memory on the stereo would drain a battery in two or three weeks.

Is the boat kept in the water? Possible bilge pump cycling a lot?

Brian

Since the battery only runs down when in position 1, whatever equipment doesn't work when the switch is in position 2 are eliminated as the drain.
The most likely culprits are as mentioned, stereo, network and those pesky automatic electronic bilge pumps that run every two minutes. See if you have one of those

 

[SmokyMtnGrady]

Ok, guys. Read them all and thanks for the advice. The boat is trailer kept under cover of a big car port. Would I not hear the bilge cycle on and off?

the part I am confused here is where to start the search? I suspect it is the fuse panel where the radio et al at wired into? The Garmin 4208 is part of Garmin's network hub system. I have GSD 22 digital sounder connected to it and the sounder has a 1kw Airmar shoot thru the hull transducer. I need to get the wiring schematic and verify some things. I know the aft bilge pump is wired to by pass the battery selector switch and is wired ( I think) to battery 1 and the forward bilge pump is wired to battery two. I do think the minimal draw of the memory on the alpine should not drain the battery as well.

Let's say the alpine is drawing 2 milli-amps for illustrative purposes, as I understand what you guys are saying, I should see that current draw where? at the battery? Between the Alpine and its fuse connection? ( I guess since electricity is like water in a pipe it matters now where you measure the flow).

I kind of wonder if it is a corroded ground...and if it is that, where do I start the search for that? I appreciate you guys for tolerating my confusion here.

Would of any you be willing to PM your cell phone and perhaps I can talk with you about ? I am a visual thinker and talking about it may help. Thanks.

 

[Shutterbug]

I solved my leak basically as stated above.

Couple years ago a battery would die within a couple days. Everything appeared to be off. I have a 12v tester, looks like an ice pick with a small bulb near the handle and a ground wire with alligator clip out the end of the handle. Only doing this one time I'm a little fuzzy as to the procedure so I hope someone else can correct me if what I say in wrong. Remove positve connections from battery, attach the alligator clip to a positive end of one of the wires, then touch the pointed (ice pick) to the positive battery post. If you see a the light that's your drain.

My problem was that particular wire was the main wire that powered all the electronics and more. So process of elimination I would disconnect the gps, check the tester, disconnect the radar, check the tester and so on. Finally found it when the fm/cd player was disconnected, even though it was off somehow was causing the drain.

First thing I checked though were the b. pumps.

 

[seasick]

I solved my leak basically as stated above.

Couple years ago a battery would die within a couple days. Everything appeared to be off. I have a 12v tester, looks like an ice pick with a small bulb near the handle and a ground wire with alligator clip out the end of the handle. Only doing this one time I'm a little fuzzy as to the procedure so I hope someone else can correct me if what I say in wrong. Remove positve connections from battery, attach the alligator clip to a positive end of one of the wires, then touch the pointed (ice pick) to the positive battery post. If you see a the light that's your drain.

My problem was that particular wire was the main wire that powered all the electronics and more. So process of elimination I would disconnect the gps, check the tester, disconnect the radar, check the tester and so on. Finally found it when the fm/cd player was disconnected, even though it was off somehow was causing the drain.

First thing I checked though were the b. pumps.

Note that if there is a relatively decent current drain, you may blow the bulb in the test lamp since when connected as you mention it is in effect a fuse.

 

[seasick]

Ok, guys. Read them all and thanks for the advice. The boat is trailer kept under cover of a big car port. Would I not hear the bilge cycle on and off?

the part I am confused here is where to start the search? I suspect it is the fuse panel where the radio et al at wired into? The Garmin 4208 is part of Garmin's network hub system. I have GSD 22 digital sounder connected to it and the sounder has a 1kw Airmar shoot thru the hull transducer. I need to get the wiring schematic and verify some things. I know the aft bilge pump is wired to by pass the battery selector switch and is wired ( I think) to battery 1 and the forward bilge pump is wired to battery two. I do think the minimal draw of the memory on the alpine should not drain the battery as well.

Let's say the alpine is drawing 2 milli-amps for illustrative purposes, as I understand what you guys are saying, I should see that current draw where? at the battery? Between the Alpine and its fuse connection? ( I guess since electricity is like water in a pipe it matters now where you measure the flow).

I kind of wonder if it is a corroded ground...and if it is that, where do I start the search for that? I appreciate you guys for tolerating my confusion here.

Would of any you be willing to PM your cell phone and perhaps I can talk with you about ? I am a visual thinker and talking about it may help. Thanks.

If possible, pull the fuse that powers the bilge pump ( any that are automatic, manual or electric) and with the battery switch to pos 1, see if the battery runs down. If not, it is a bilge pump issue. Of course the down side to this test is that it will take a few weeks to find out if that is the problem.

I have head about some stereos that mysteriously turn themselves on when the temperature changes. A stereo turned on even at very low volumes would drain the battery. The issue with finding this is that you probably won't see a drain at first.
So excessive current drains are usually but not always present when you are looking for them.

I would also recommend that you see if the Garmin network is powered when the Garmin display is turned off. Find the battery feed at the hub (assuming it is powered) and see if it is live when the 4208 is powered off.

 

[wspitler]

A bulb will work and it shouldn't blow since current (I) is a function of resistance (R) and putting a bulb in series results in the addition to resistive elements and that increases R: where I = Volts/R. Volts really don't change much and should never be higher than about 12-14.4V when being charged. A better way is to use an ammeter (measures smaller current than a bulb might be able to detect). With the problem battery switch on, having removed one battery cable and connected one of the ammeter leads to the cable and the other to the empty post on the battery, then depending on how high or low the scale on the ammeter goes you can now see exactly how large the current drain is. Most smaller (home type) ammeters won't measure whole amps, only milliamps. For such things as stereo memories, milliamps are all you should expect. It is standard practice for electronics such as NMEA 2K networks, VHF, sonar etc. to have a master switch to turn them all off. Also a good safety factor should you have a electrical fire in a component. They are preferably all bussed to a single bus bar. Not hard to do.

When I said "ground fault," I didn't mean a corroded ground wire. What that means is that somewhere in the wires you have a path to ground from the positive (hot) side that may not be feeding a component, such as hot (positive - red normally) wire that has worn through or corroded and is touching a source that is grounded back to the battery, boat, water, etc. That allows a path for current to go back to ground. A corroded ground wire on the other hand simply increases the resistance of a circuit and reduces the current flow through that circuit.

Hope that helps. Let us know how it turns out for future reference and Good Luck!

 

[seasick]

A bulb will work and it shouldn't blow since current (I) is a function of resistance (R) and putting a bulb in series results in the addition to resistive elements and that increases R: where I = Volts/R. Volts really don't change much and should never be higher than about 12-14.4V when being charged. A better way is to use an ammeter (measures smaller current than a bulb might be able to detect). With the problem battery switch on, having removed one battery cable and connected one of the ammeter leads to the cable and the other to the empty post on the battery, then depending on how high or low the scale on the ammeter goes you can now see exactly how large the current drain is. Most smaller (home type) ammeters won't measure whole amps, only milliamps. For such things as stereo memories, milliamps are all you should expect. It is standard practice for electronics such as NMEA 2K networks, VHF, sonar etc. to have a master switch to turn them all off. Also a good safety factor should you have a electrical fire in a component. They are preferably all bussed to a single bus bar. Not hard to do.

When I said "ground fault," I didn't mean a corroded ground wire. What that means is that somewhere in the wires you have a path to ground from the positive (hot) side that may not be feeding a component, such as hot (positive - red normally) wire that has worn through or corroded and is touching a source that is grounded back to the battery, boat, water, etc. That allows a path for current to go back to ground. A corroded ground wire on the other hand simply increases the resistance of a circuit and reduces the current flow through that circuit.

Hope that helps. Let us know how it turns out for future reference and Good Luck!

You got me thinking. I guess you are correct about the test lamp being self limiting. I must admit I am a bit embarrassed. I am a retired electrical engineer. Just one of those signs of aging I suppose. Then again, I could convince myself that if the load is heavily inductive, the initial current draw would be higher than the steady state draw and that could blow the bulb (maybe?)

 

[Doc Stressor]

Hey Bob, sorry that I didn't see this thread earlier.

Locating a current leak of the magnitude that you described is fairly straight forward. The only things wired directly to your batteries are the aft and forward bilge pump float switches. These are connected to the #1 and #2 battery posts via the respective terminals on your battery select switch. These are not the source of your problem, so go to the next step.

The main lead from the battery select switch goes to the fuse block under your steering wheel via the 40 amp main circuit breaker. To be sure that you do in fact have a current leak, turn off your battery switch and all of your electrical components. Disconnect the main lead from your fuse block. Set your multimeter to a mA range and place the positive (red) probe on the main lead wire ring and the negative probe (black) on the fuse block terminal post where you just removed the main lead. Have somebody turn you battery switch to the #1 position. With all the components turned off, you should see no current flow. However, if you have a draw, you will see current. If you see a negative value, just switch the probe positions in the circuit.

Assuming that you see current, the next step is to determine the source of the draw. Reconnect the main lead and then disconnect each component lead from the other side of the fuse block one at a time. Test for current flow with the multimeter as you did with the main lead. Be sure to test the line to the switch panel as well.

I don't know what type of sound system that you have, but many will draw a small amount of current in order to maintain you channel settings, etc. If that is the case and you don't want that to happen, just run the system off one of the extra circuit breakers in the switch panel instead of directly from the fuse block. Be sure to match the circuit breaker with you component system with respect to amperage. Turn the rocker switch off when you aren't using the system.

If you find than any of the other circuits are the source of your leak, just rewire them. Use marine grade wire and heat shrink terminal connectors with adhesive. Do a better job than Grady did. If you find any breaks in the insulation of the original wires, support the new wires at those points with wire ties.