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Go Back   SailNet Community > On Board > Gear & Maintenance > Electrical Systems > Huge Voltage Drain Problem - Ideas?
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Thread: Huge Voltage Drain Problem - Ideas? Reply to Thread
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Topic Review (Newest First)
11-07-2013 10:13 PM
JohnZion
Re: Huge Voltage Drain Problem - Ideas?

As for the questions / answers regarding battery voltage, the voltage I gave was after the batteries were recharged.
Thanks everyone for the suggestions,. The problem has not occurred so far, but I am still working to figure it out.
11-07-2013 02:11 PM
chris_gee
Re: Huge Voltage Drain Problem - Ideas?

The Xantrex reads volts amps amp hours and time to discharge.
A discharge of 50 amps will show as -50. Over 2 hours it will subtract 100 amp hours from amp hours available rather more than the op recorded.
So you already have an ammeter in the unit. There is no need to install another particularly.
The question is was the apparent discharge real or not? The battery voltage suggests not.
The amps are measured via the voltage drop between the two sides of the shunt across a small fixed resistance. I believe they are the orange and brown wires from memory. The amps are then calculated by the device knowing the resistance i.e. 5 mv = 50 amps. The op may or may not have a voltmeter capable of that accuracy.
The unit would have reset when the new batteries were fitted. Capacity type and temp would be the only things needing to be entered. If the unit was wired incorrectly this would have been evident early on. When the batteries were disconnected if for more than 30 minutes the unit would have reset. That may have been what solved the problem.
11-06-2013 10:13 PM
Omatako
Re: Huge Voltage Drain Problem - Ideas?

Quote:
Originally Posted by JohnZion View Post
Erps - good thought, but it was actually -40 and -70 Amps that the Xantrex was registering. The Amp/hrs went from -275 to -335 Amp/hrs within two hours. I kept notes.

Dr Watson - thanks for the advice, I will get an ammeter. Fortunately for me there are forums like this to connect me to people with knowledge I don't yet possess.
That is the answer to the question. I wondered about the minus sign before the amp reading. Of course it is the outgoing consumption since the last charge diosplayed in negative amp hours.

Switch the Xantrex to Amps and it will give you a sensible reading of the actual consumption.

Well spotted ERPS
11-05-2013 12:06 PM
Bene505
Re: Huge Voltage Drain Problem - Ideas?

Quote:
Originally Posted by JohnZion View Post
Today I noticed (according to the Xantrex battery monitor) that the batteries were being drained at a rate of -40A. The Xantrex also said the batteries were at 37% of charge...
Quote:
Originally Posted by JohnZion View Post
I did check the batteries individually, they each read 6.22, they are 6 volt batteries. They are hooked together in a series. Would I check the individual cells with a hydrometer?
6.22 volts on a 6v battery is like 12.44 volts on my 12v battery. That seems high for a battery that is drained. Could it be that the Xantrex was not calibrated for zero current?

Suggestion you disconnect the house and starting ground wires from the shunt. (Keep the shunt connected to the negative terminal of your batteries, and keep the small power wire for the shunt connected to the positive terminal of the batteries.) Check the current reading and let us know what it was. Then calibrate the Xantrex to zero current.

Regards,
Brad
11-05-2013 09:41 AM
Maine Sail
Re: Huge Voltage Drain Problem - Ideas?

Quote:
Originally Posted by btrayfors View Post
A very nice clamp-on ammeter for very little $$$ is the Mastech MS2108 (NOT the MS2108A).

The 2108 is AC/DC, 600A capacity, in-rush current, etc., etc. I have two of them and often find myself reaching for them instead of my $350 Fluke 337.

Find 'em on eBay from US dealers in CA or NY/NJ for about $67.

Bill
Like you I also own the MS2108 but am not quite as happy over the long haul. I find the construction & long term durability pretty poor. My clamp lever is distorted and warped (from the factory), the case fit is very sloppy and my flashlight feature died in under a year. The meter hunts and floats pretty badly and does not zero out on either AC or DC. When I bought it a number of years ago it by far the best value on the market, today it has some competition..

Of course for the type of work the avergae DIY does, and this would be used for, it is still an EXCELLENT value in an AC / DC clamp meter. Be aware that the inrush feature does not work on DC but I would not expect a DIY to be using the inrush feature anyway...

When I first got mine I was pretty happy but the longer I have it the more the short comings begin to show up. Mastech does make some great stuff but the MS2108 could have been a tad better built in terms of durability IMHO..

A clamp meter I have been pretty impressed with for inexpensive boat DC work is this $50.00 Craftsman. My brother has one.. It is more robustly built and not as "floaty" as the MS2108. It also zeros out on clamp current where my Mastech won't any longer...

Craftsman 400A AC/DC Clamp Meter:
Sears.com

The UNI-T UT204A is also a decent little in-expensive AC/DC clamp meter. A friend has one and I was very skeptical but I honestly find the construction quality is better than my Mastech. I have not spent much time using it but it seems to performs admirably for the $40.00 +/- he paid...
11-05-2013 06:59 AM
btrayfors
Re: Huge Voltage Drain Problem - Ideas?

A very nice clamp-on ammeter for very little $$$ is the Mastech MS2108 (NOT the MS2108A).

The 2108 is AC/DC, 600A capacity, in-rush current, etc., etc. I have two of them and often find myself reaching for them instead of my $350 Fluke 337.

Find 'em on eBay from US dealers in CA or NY/NJ for about $67.

Bill
11-05-2013 01:48 AM
mitiempo
Re: Huge Voltage Drain Problem - Ideas?

Quote:
Originally Posted by btrayfors View Post
If you're going to play an electrical Sherlock Holmes then you need a proper magnifying glass.

You should have -- ALL boats should have -- an AC/DC clamp-on ammeter. Decent ones are cheap these days (around $60), and they'll save you hundreds of dollars of grief.

Wondering if you have a current leak? Just use the clamp-on ammeter to prove that you do (or don't), and to accurately measure the magnitude of the leak.

Did you really have a 40A current draw with all breakers off, or was the Xantrex lying to you?

No more will you have to say, "I think I have.....". With proper use of a clamp-on ammeter, you'll KNOW you have, or don't have....

You can also know very accurately:

- how much amperage you alternator is actually putting out
- how much amperage your battery charger is actually putting out
- how much amperage your solar panels are putting into the MPPT controller
- how much amperage your MPPT controller is putting into the batteries
- how much amperage your bilge pump draws
- how much amperage just about anything on your boat draws
- how much amperage is being drawn from your batteries
etc., etc.

You get the picture.

Sorry for the mini-rant. It just drives me crazy to watch the antics of folks trying to troubleshoot relatively simple electrical problems on their boats without having even the rudimentary tools required.

Bill
Bill beat me to this opinion and I agree. The list above could be completed to remove any doubt in under 30 minutes probably.
11-04-2013 10:38 PM
JohnZion
Re: Huge Voltage Drain Problem - Ideas?

Erps - good thought, but it was actually -40 and -70 Amps that the Xantrex was registering. The Amp/hrs went from -275 to -335 Amp/hrs within two hours. I kept notes.

Dr Watson - thanks for the advice, I will get an ammeter. Fortunately for me there are forums like this to connect me to people with knowledge I don't yet possess.
11-04-2013 08:39 PM
erps
Re: Huge Voltage Drain Problem - Ideas?

Quote:
I just don't feel any small wire to a bilge pump etc would have survived 40 amps.
The battery monitor gives three readings: Volts, Amps and Amp/hrs. I think in this case, it was a loss of 40 amp hrs that was experienced.
11-04-2013 08:02 PM
btrayfors
Re: Huge Voltage Drain Problem - Ideas?

If you're going to play an electrical Sherlock Holmes then you need a proper magnifying glass.

You should have -- ALL boats should have -- an AC/DC clamp-on ammeter. Decent ones are cheap these days (around $60), and they'll save you hundreds of dollars of grief.

Wondering if you have a current leak? Just use the clamp-on ammeter to prove that you do (or don't), and to accurately measure the magnitude of the leak.

Did you really have a 40A current draw with all breakers off, or was the Xantrex lying to you?

No more will you have to say, "I think I have.....". With proper use of a clamp-on ammeter, you'll KNOW you have, or don't have....

You can also know very accurately:

- how much amperage you alternator is actually putting out
- how much amperage your battery charger is actually putting out
- how much amperage your solar panels are putting into the MPPT controller
- how much amperage your MPPT controller is putting into the batteries
- how much amperage your bilge pump draws
- how much amperage just about anything on your boat draws
- how much amperage is being drawn from your batteries
etc., etc.

You get the picture.

Sorry for the mini-rant. It just drives me crazy to watch the antics of folks trying to troubleshoot relatively simple electrical problems on their boats without having even the rudimentary tools required.

Bill
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