Mysterious battery drain... where to begin?

[OrangeCrush]

Originally Posted by Cadence

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.

For what it's worth, as OP I do have basic knowledge but I was a bit confused by twinboat's (correct) instructions before Jim Cate put it in slightly clearer terms. When it comes to electrical work, I need to be super sure I understand what I'm doing before I do it and I'd rather not have to assume anything, even if that means a less than efficient use of language. Having said that, nobody was wrong and you're all super helpful!

[Cadence]

Originally Posted by OrangeCrush

For what it's worth, as OP I do have basic knowledge but I was a bit confused by twinboat's (correct) instructions before Jim Cate put it in slightly clearer terms. When it comes to electrical work, I need to be super sure I understand what I'm doing before I do it and I'd rather not have to assume anything, even if that means a less than efficient use of language. Having said that, nobody was wrong and you're all super helpful!

I hope you find a leak. It could be just be batteries that have seen better days. If you can charge them, I would just leave them disconnected and check the voltage after a period of time. If they stay up good if not start hunting a leak.

Where on earth can you keep her being in Brooklyn?

[OrangeCrush]

Originally Posted by Cadence

I hope you find a leak. It could be just be batteries that have seen better days. If you can charge them, I would just leave them disconnected and check the voltage after a period of time. If they stay up good if not start hunting a leak.

Where on earth can you keep her being in Brooklyn?

Yep that's my plan, I'll report back when I have some results. At this point I think I'd rather just only bad batteries since if it's a leak I've probably damaged them pretty badly anyway before I realized what was going on. Having just read Stu's link to the "Gotcha Algorithm" that is a real possibility as well. I'll definitely report back!

As for Brooklyn, it's the best kept secret on the East Coast! Good breezes, 20 minutes to the open ocean, empty anchorages with skyline views, and lower marina fees than most other places I've been. Just don't plan on swimming...

[Littlechay]

Nobody has mentioned a Amp Clamp meter. A multimeter with an Amp clamp is so useful it should be in every on-board kit. Good ones are easy to calibrate to zero and sensitive enough to read the I that the OP mentioned.

Plenty of good suggestions above but think about adding a clamp meter to your kit.

Most will do up to 600A so no worries about the 10A limit when you put one in circuit.

[Cadence]

Originally Posted by OrangeCrush

Yep that's my plan, I'll report back when I have some results. At this point I think I'd rather just only bad batteries since if it's a leak I've probably damaged them pretty badly anyway before I realized what was going on. Having just read Stu's link to the "Gotcha Algorithm" that is a real possibility as well. I'll definitely report back!

As for Brooklyn, it's the best kept secret on the East Coast! Good breezes, 20 minutes to the open ocean, empty anchorages with skyline views, and lower marina fees than most other places I've been. Just don't plan on swimming...

I get that, don't swim. It probably helps on bottom growth, since nothing can live in it. I understand it is getting better? The foulest place I ever saw was New Town creek.

[ramblinrod]

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.

Using a voltmeter as described to determine if a load is connected to a battery is a proper and valid use of a voltmeter.

Measuring current may glean some insight into the size of load, which may or may not be of any additional trouble-shooting value, but definitely does introduce the risk that the current will exceed the DVM fuse and blow it, requiring replacement. Got fuses?

If one doesn't know what current to expect and they don't need to know the specific amount (as in this case, load presence or lack of presence will suffice), one should not connect an ammeter.

PS, Electronic Engineering Technician, 35 years experience, President of Sheen Marine - a total yacht care company, certified Raymarine Installer / Service provider, ABYC Member, and all around fart smucker. ;-)

[Bleemus]

10 amps limit? My ammeter (Blue Seas) autoranges from 0.01 to 400 amps. Covers everything you are going to find on a boat unless your cruising in a nuclear sub.

[Cadence]

Originally Posted by ramblinrod

Using a voltmeter as described to determine if a load is connected to a battery is a proper and valid use of a voltmeter.

Measuring current may glean some insight into the size of load, which may or may not be of any additional trouble-shooting value, but definitely does introduce the risk that the current will exceed the DVM fuse and blow it, requiring replacement. Got fuses?

If one doesn't know what current to expect and they don't need to know the specific amount (as in this case, load presence or lack of presence will suffice), one should not connect an ammeter.

PS, Electronic Engineering Technician, 35 years experience, President of Sheen Marine - a total yacht care company, certified Raymarine Installer / Service provider, ABYC Member, and all around fart smucker. ;-)

An ammeter my be useful for finding a faulty component, but that would not seem to be the OP's problem.

[barnakiel]

As others noted. Here is your drain.

Also battery fans if you have any. Gas sensor ... etc.

b.

[rwidman]

Originally Posted by ramblinrod

Using a voltmeter as described to determine if a load is connected to a battery is a proper and valid use of a voltmeter.

Measuring current may glean some insight into the size of load, which may or may not be of any additional trouble-shooting value, but definitely does introduce the risk that the current will exceed the DVM fuse and blow it, requiring replacement. Got fuses?

If one doesn't know what current to expect and they don't need to know the specific amount (as in this case, load presence or lack of presence will suffice), one should not connect an ammeter.

PS, Electronic Engineering Technician, 35 years experience, President of Sheen Marine - a total yacht care company, certified Raymarine Installer / Service provider, ABYC Member, and all around fart smucker. ;-)

Again, the spark from disconnecting a greater than ten amp current would be a hint that it might be greater than your meter's capacity but a greater than ten amp current would have the batteries depleted in hours.

I say an ammeter is what one would use to measure current flow.


Actually, if there's any spark at all you have your answer. There is current flowing and you are interrupting it.

[senormechanico]

Originally Posted by Cadence

I get that, don't swim. It probably helps on bottom growth, since nothing can live in it. I understand it is getting better? The foulest place I ever saw was New Town creek.

I haven't seen that spot, but I'd venture a guess that it can't be worse than the South anchorage in Mazatlan, Mexico.
The non treated sewage outfall for a HUUUGE city is right over the hill from the anchorage.
The wind clocks around generally coming from the direction of the sun once in 24 hours as a general rule.
You do NOT want to be aboard in that anchorage in the early afternoon !

[Jim Cate]

Originally Posted by rwidman

Again, the spark from disconnecting a greater than ten amp current would be a hint that it might be greater than your meter's capacity but a greater than ten amp current would have the batteries depleted in hours.

I say an ammeter is what one would use to measure current flow.


Actually, if there's any spark at all you have your answer. There is current flowing and you are interrupting it.

This makes sense to me, but I gotta wonder if a relatively naive DIY would understand the significance of the spark, or be able to judge the current by the magnitude of the spark. Any spark at all would be obvious to an old sparky!!

The VM in series with the pos lead will indeed show that there is some load on the circuit. If I was to do that, the next thing I would want to know is how large the current was, and then get out the ammeter. Seems an extra step, somehow, but each diagnostician to his own practice. I suspect that on many modern yachts, there will be enough parasitic loads all around the boat that many of the leads would show "current" with the voltmeter test. The ammeter showing that most or all of them are very small would help in determining if the battery was at fault or some significant load is doing the dirty deed.

The clamp ammeter is a great tool as well, but the inexpensive ones that I've looked at don't do too well at low (<1 amp) currents. Sounds like there are better ones available now, but perhaps not found in the DIY beginners kit.

Anyhow, I hope that the OP has had enough help to send him scurrying about, some sort of meter in hand, and soon discovering the source of his low batteries.

Jim

[ramblinrod]

Originally Posted by Bleemus

10 amps limit? My ammeter (Blue Seas) autoranges from 0.01 to 400 amps. Covers everything you are going to find on a boat unless your cruising in a nuclear sub.

Amp Clamp is a different beast. Most DVMs have a current limit. Many 10 A, some a little more for a short period.

[ramblinrod]

Originally Posted by rwidman

Again, the spark from disconnecting a greater than ten amp current would be a hint that it might be greater than your meter's capacity but a greater than ten amp current would have the batteries depleted in hours.

I say an ammeter is what one would use to measure current flow.


Actually, if there's any spark at all you have your answer. There is current flowing and you are interrupting it.

Of course one would use an ammeter function to measure current (if one needed to measure current).

So if one measures 3.72 A, what exactly does that tell them?

Answer: The load is more than 3.71A and less than 3.73 A +/- the accuracy of the meter. Little value. The load is greater than miniscule and less than a whopping amount.

What is the next step?

Start isolating circuits until the load is removed and discovered (or in other words, perform a load presence or lack of presence test).

But the main point is being lost in the details and rhetoric.

The claim was that a voltmeter used to determine load presence or absence was incorrect or invalid, and it clearly is not. It is a perfectly valid solution. Everyone's preference? Possibly not, but not the point at all.

[dlymn]

Originally Posted by Jim Cate

Umm... this does not make any sense. A voltmeter between the pos battery post and the positive cable should read zero, because there should be no voltage drop between them... even if there were a significant current flowing.

Perhaps you meant he should disconnect the cable from the battery and then, having set his multi meter to an AMPERE scale, connect it between the two points. That would indeed measure any current flowing. I'd start out on whatever the highest ampere scale the meter offers, and if nothing shows, work down to the most sensitive scale. Do be careful NOT to get the meter between a positive point and ground. The ammeter is essentially a short circuit, a large current will flow and the meter will be toast (some have a fuse in that circuit, and it may save the meter. Still not a good idea!).

Jim

Jim I would have thought that you should put a shunt in the line and then read across both sides of the shunt. I thought that reading amps in series with the power would blow up the meter. Disconnect any positive lead from the batteries and read voltage between the terminal and the disconnected lead. If it shows any voltage at all, you are getting a drain from the batteries.

Trace the big positive leads (red?) to the big switch (if you have one) Check if there are any leads coming off the switch on the same side as the big lead. If so and this leads to something switched on then it might be draining your battery. My PO put a flashing LED at the hatch wired directly to the battery to remind you that you had batteries. I used this power for the anemometer and have left this running for weeks because I forgot to look at the led.

Batteries will discharge if they have deteriorated badly. If you have a high load ammeter (with shunt) you can load up the battery and if this reading drops quickly, the batteries are having difficulty holding a charge.

Corrosion is a sign of a poor circuit. This might be a loose terminal but it might also be an indication of a circuit across the surface of the battery. I am having this trouble with corrosion around the top of my tank fuel guage.