Mysterious battery drain... where to begin?

[rognvald]

"DEFAULTS are factory settings that are made to be modified to suit your setup." StuJackson


This is very good advice, Stu. But, on the older Xantrex units it is, in my opinion, a waste of time. I believe they sold a "defective" unit, based on my experience with their product. As I said in my previous post, I only use the monitor for an immediate picture of the charging system and would not rely on battery history for the Xantrex unit. Good luck and safe sailing.

[rwidman]

Carbon Monoxide detectors can draw significant current, especially the older models. These are typically wired to bypass any power switches.

Smoke detectors and propane detectors are other possible power draws. A stereo with memory will draw a little power. I have a TV antenna preamp that is unswitched.

If the boat is hauled, you could just disconnect the batteries but identifying any constant power consumption is a good idea.

[Stu Jackson]

20 Hour Capacity Test by Maine Sail

Battery Replacement - AGM | SailboatOwners.com Forums

[tkeithlu]

Thou shalt not speak in absolutes. Deep cycling, I agree, but if their capacity is limited to a surface charge, or there's a bad cell in there, it'll show. If a battery reads 12.8, and a resistance across it causes the voltage to drop to 10.5 in seconds, it's bad. That's a crude measure. It could read OK by that means and not pass a 20 hr capacity test, because as you correctly imply, a resistance test better emulates starting than long slow draw. There were reasons to go to more sophisticated battery testers, but the old fashioned way has let me keep track of the health of my nine flooded size 27s adequately. Thank you for pointing out the difference.

[OrangeCrush]

I made the comment about sticking with AGMs because of the rapid charge they'll be getting from my alternators, plus the fact that they're pretty closed in and I think wet cells would need some additional venting and maybe spill protection. My comment was not very well informed though and I've got a lot of research to do, so I do welcome your opinions.

If any of you replaced your battery bank recently, what did you go with and why?


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[skipgundlach]

Originally Posted by OrangeCrush

I pulled off the large positive house cable and tested the gaps between the three positive cables on the terminal there. The biggest (house) cable showed nothing. The cable to the echo charger showed a draw of about 3mA and the charger started blinking when I did it. Then I tested the smaller cable marked "unswitched panel" and it showed a rhythmic fluctuation between 30 and 60 mA, like a metronome. This unswitched panel wire is going to be very difficult to follow, but obviously I need to figure out where it goes. Does this sound like a short circuit somewhere? What would do this? I don't know what else is on unswitched panel but I pulled the fuses from the bilge pumps so it shouldn't be that.

It sounds like good news for my battery bank but bad news for my overall understanding of what's going on.

As always, I really appreciate you taking the time to share any ideas or guidance.


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The solution to finding unknown wires is to go to a big box hardware or McMaster Carr or Grainger or the like. In the telephone and television bits and pieces section, get a "toner" - the one I have's transmitter has a telephone rj11 nipple and two alligator leads; they produce different tones on the wire.

The transmitter goes anywhere it's bare, and the receiver is a small AM antenna you point at a wire bundle. If you get a tweedle, the wire you want is in there. Pull the bundle apart and tone each one; some leakage will be present unless your other wires are shielded (they might be, so look for the strongest tone (much stronger than the bleed)). If your wire is shielded, put the alligator on the shield...

Depending on your area, you may get to hear some AM radio, too

[StuM]

Originally Posted by OrangeCrush

I made the comment about sticking with AGMs because of the rapid charge they'll be getting from my alternators, plus the fact that they're pretty closed in and I think wet cells would need some additional venting and maybe spill protection. My comment was not very well informed though and I've got a lot of research to do, so I do welcome your opinions.

AGM for me. Rapid charge, lower Peukert, maintenance free, no worries about hydrogen off-gassing/ventilation, less sensitive to occasional higher DOD, generally higher cycle life than FLA.

[ramblinrod]

Originally Posted by Jim Cate

The problem is that he neglected to mention disconnecting the battery cable. As you all state, with it disconnected, any load will generate a voltage reading between battery and cable. Not a very good analytical tool, IMO, but the ammeter, as he has now demonstrated, is. He's on the right track...

Jim

C'mon!

How can one put a voltmeter between a positive battery post and positive terminal UNLESS they are disconnected. (Answer: One can't).

There is no problem; he did not neglect to do anything.

There is no need to state the obvious.

And this is a great analytical tool.

Is there a load on this battery?

Disconnect the terminal and see if there is a voltage reading. If there is, YUP. If there isn't, NOPE. A perfect True / False test.

The PROBLEM with using an ammeter is that most DVMs are limited to 10 A, or you'll blow the fuse, and since the batteries are discharging so rapidly, one could expect a fairly significant load.

As a troubleshooting tool, with the voltmeter connected as stated, all one has to do (if it does read a voltage), is start disconnecting circuits until the load is indicated removed. That's it.

[ramblinrod]

Originally Posted by carambo46

The only unswitched thing I would have on my boat would be the bilge pump and the VHF radio good luck

Sniffers should not pass through the main battery switch either.

[Maine Sail]

Originally Posted by OrangeCrush

Hello,

My new-to-me boat is hauled out for the winter and it seems that the house battery is draining on its own somehow. The battery monitor shows zero amps of draw when the house switch is turned off, but after two weeks or so the voltage drops from 12.8 to 12.0 or lower. The only thing I know that is hard wired is the bilge pumps which are both off.

The previous owner said that the batteries would hold a charge through the winter without being disconnected. In general the wiring is in good shape and most of it was redone 3 years ago. The batteries are 4 AGMs for 440 amp hours total. I'm sure it's not good for them to get so low, but a month ago when I was sailing they were able to maintain their charge through pretty heavy usage over the course of a weekend, so I don't think they're shot (yet). The starter battery is charged with an echo charger and is staying full. The only switch I've been leaving on while the boat is unplugged is the Main AC double breaker because the PO said he never turned it off. Could that be a factor? The battery monitor itself seems to stay on but I can't imagine that draws much nor do I know how to turn it off.

I've got a multimeter and I'm ready to crawl into whatever nook I need to crawl into, but I don't know where to start. If the battery monitor shows zero draw, I don't see how pulling fuses or disconnecting wires will help me find the source of the draw.

Here is a picture of my panels (while on shore power) Any advice is most Attachment 136469greatly appreciated!


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#1 charge batteries to 100% SOC (equalize if Lifeline)
#2 disconnect batteries from vessel and each other
#3 in a week or so check voltage of each battery
#4 all batteries should be within .03 - .08V of each other
#5 if you have low batteries those are the bad ones that need further testing


When storing on the hard taking care of batteries is extremely simple;

Charge to 100%, equalize if applicable, DISCONNECT.

[Symphony]

Originally Posted by Stu Jackson

In addition, consider this:

For everyone installing a battery monitor: The "Gotcha Algorithm" thread, a "MUST READ"

Link-series Charging Algorithms -- The "Gotcha" Factor!

DEFAULTS are factory settings that are made to be modified to suit your setup.

Also read this one:

Programming a Battery Monitor (by Maine Sail)

Keeping Your Battery Monitor More Accurate Photo Gallery by Compass Marine How To at pbase.com

the links above are good info - I routinely get 10+ years from battery banks. I read the manuals for the Ah counter and knew it was really a guess. If you use expensive batteries you need to properly charge and maintain the bank to get your money's worth. If you are not into reading manuals and measuring/ calibrating then just get the cheapest batteries and replace often.

My gel batteries with 100A Balmor and smart regulator, plus Xantrex Freedom charger and link are great but require much more fiddling than my car's battery system.

The purchase price of complicated equipment is only part of the cost.

[OrangeCrush]

I've now read Maine Sail's articles on the reasons people have difficulties with AGMs, and I think there's a decent chance I will fall into one of those categories. My boat will be at a mooring during April, May, June, September and October. During July and August I will be cruising full time.

I'm installing 200 watts of solar and I'm thinking this will help keep the batteries topped off while I'm at the mooring. While cruising, periodic motoring will allow my two Balmar alternators (90amps each) to charge the bank much more rapidly. Based on what I read, these scenarios could be acceptable but not ideal for AGM batteries. For example, if I used the boat two consecutive weekends, the solar panels might not fully charge the AGMs between uses. While cruising over the summer, even with two alternators I might not get the voltage up high enough to keep them from sulfating. Considering these factors, it seems like AGMs are probably not worth the price difference simply for the lower maintenance and venting concerns, which I can address.

So it seems I may be a candidate for a new bank of Flooded Lead Acid batteries, maybe two pairs of 6v golf cart batteries in series since I had success with them on my last boat and they seem to be the most resilient of all.

My question is: if my boat is configured for AGMs right now with a Xantrex Freedom Inverter/Charger Model 20, Balmar Max Charge Regulator, and two Balmar Alternators, then what changes (if any) would I need to make to convert the boat to properly maintain a flooded lead acid house bank?

[Cadence]

Originally Posted by ramblinrod

C'mon!

How can one put a voltmeter between a positive battery post and positive terminal UNLESS they are disconnected. (Answer: One can't).

There is no problem; he did not neglect to do anything.

There is no need to state the obvious.

And this is a great analytical tool.

Is there a load on this battery?

Disconnect the terminal and see if there is a voltage reading. If there is, YUP. If there isn't, NOPE. A perfect True / False test.

The PROBLEM with using an ammeter is that most DVMs are limited to 10 A, or you'll blow the fuse, and since the batteries are discharging so rapidly, one could expect a fairly significant load.

As a troubleshooting tool, with the voltmeter connected as stated, all one has to do (if it does read a voltage), is start disconnecting circuits until the load is indicated removed. That's it.

You took more time than explaining than me. It is difficult to explain to people without basic knowledge. That was not meant to be demeaning. There are many subjects that could be said about me.

[rwidman]

Originally Posted by ramblinrod

.......... The PROBLEM with using an ammeter is that most DVMs are limited to 10 A, or you'll blow the fuse, and since the batteries are discharging so rapidly, one could expect a fairly significant load.

If there was a ten amp load, it would be pretty obvious. And the spark when disconnecting the cable would be a good hint.

When I'm trying to measure voltage, I use the voltage function. If I'm trying to measure current, I use the current (amps) function. Perhaps this comes naturally to me from my schooling and work as an electronics technician.

[Cadence]

Originally Posted by rwidman

If there was a ten amp load, it would be pretty obvious. And the spark when disconnecting the cable would be a good hint.

When I'm trying to measure voltage, I use the voltage function. If I'm trying to measure current, I use the current (amps) function. Perhaps this comes naturally to me from my schooling and work as an electronics technician.

That is called welding.