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davidpm 05-28-2012 11:44 PM

Voltage tester idea
 
I do not have a wired in voltage meter. The Bene 32s5 has idiot lights on the panel for 11,12,13. Not sure how they are useful at all.

It is a bit of a hassle to get to the batteries.

If I would get a cigarette lighter plug and put a couple of alligator clips on it can I simply plug that into the 12 volt plug then to my meter and use the main battery switches to select the battery I want to check?

Will this work?

Frogwatch 05-28-2012 11:53 PM

Re: Voltage tester idea
 
Battery volt meters are nearly worthless as they do not really tell you much. A battery can read 12.5 V and still have almost no capacity. On liquid electrolyte batteries, I think the best way (maybe only way) is a hydrometer to measure spec grav of the stuff.

Classic30 05-29-2012 12:04 AM

Re: Voltage tester idea
 
Quote:

Originally Posted by davidpm (Post 876921)
Will this work?

Yes it will..but it won't tell you a lot more about the state of charge (SOC) of your battery than the current idiot(ic) lights do.

Time to fork out for a Battery Monitor - either the Victron or the Xantrex will tell you all you need to know, and much more. :)

asdf38 05-29-2012 12:56 PM

Voltage tester idea
 
It will work fine. One thing to remember is where the lighter plug is wired. Any load between the battery and the point where the lighter is wired will cause a small around of voltage drop. This is probably at your panel so turning off loads will give you the best measurement.

Also be careful with the exposed wires. You could easily blow a fuse if they touch. If you want to use this often you might wire a series resistor of 100 to 1k. Then it's no big deal if you short the alligator clips.

hellosailor 05-29-2012 06:34 PM

Re: Voltage tester idea
 
David, it will work but I'd suggest two other options.

One being a plug-in voltmeter, the display is on the "lighter" plug itself. Digital or LEd bars, both are available.

The other is to buy a pair of "pygmy" hippo clips from Rat Shack, crimp a run of duplex wire and a fuse onto them, and bring out the leads direct from the battey for a "cleaner" reading.

In either case the voltage will be a good reference for you, relative to the charge state of your batteries, but subject to all the usual ways to misread the information. Starting with the accuracy of the meter, no matter what kind you have, and whether it has been calibrated. I finally stopped wondering which meter was wrong and by how much, and built a little "10.00" voltager reference supply. That's all it puts out, and exactly what it puts out, accurate to a few thousandths of a volt. So when I need to know if my meter is on drugs, or just a little slow, I check to see if it says "10.00" when it is connected to the calibration source.
As the Wicked Queen said, "Meter meter on the wall, who's the foulest of them all?"

jorn85 11-08-2012 07:21 PM

Re: Voltage tester idea
 
Yes it will work but you will not get accurate reading from your meter because it is not directly connected into the batteries. You should remove the batteries for good readings because when you do this method you will get a small voltage drop from the batteries....

davidpm 11-13-2012 11:28 AM

Re: Voltage tester idea
 
Quote:

Originally Posted by hellosailor (Post 877305)
I finally stopped wondering which meter was wrong and by how much, and built a little "10.00" voltager reference supply.

How does one do that?. Seems like a good idea.

hellosailor 11-13-2012 03:40 PM

Re: Voltage tester idea
 
You chase down a handful of electronic parts that Radio Shack won't have, and then most important of all, buy some breathe mints because an (mini in this case) Altoids tin is the most effective way to put a case on anything. Small project boxes are incredibly expensive.<G> Of course the Altoids box doesn't LOOK very commercial, and I suppose the TSA would be closing down airports if they even saw it (good lord, a metal case with wires and a battery!) but if I wanted to keep it under a sawbuck, that was how it had to happen.

Or maybe I should have splurged on the fancy case and taken it to West Marine? (VBG)

Tim R. 11-13-2012 03:52 PM

Re: Voltage tester idea
 
I higher recommend the Victron 602.

SlowButSteady 11-13-2012 10:23 PM

Re: Voltage tester idea
 
I use one that plugs into a cigarette lighter socket. Like this:
http://www.girr.org/random_stuff/plug_in_voltmeter.jpg
The only problem is that the socket is a bit of a distance from my boat's batteries, so there is a bit of a voltage drop (even more so if I use the socket on the forward bulkhead).


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