>>>SIMPLE<<< 12V Battery Level Indicator

[absolutsnwbrdr]

Just wondering if anybody has used one of these in their builds. I know that it won't compare to a Doc Wattson, or other similar device, but it seems like it would at least provide an estimate of battery state of charge.



http://www.ebay.com/itm/12V-Battery-ind ... 99#vi-desc

Info:

Battery state-of-charge: 10-bar, tri-color LED

The battery meter has 10 LEDS that will light to show the battery condition. When fully charged, only the 10th LED will light shown a green LED.

12.47 volts Full; 10.5 volts Empty

As the battery discharges, successively lower LEDs will light; the 9th, 8th, 7th and so on lighting only 1 LED.
At approximately 30% battery life, the #3 LED will light and the color is Yellow as a caution indicator.
At approximately 20% battery life remaining, the #2 LED will light as a Flashing Yellow.
When the battery discharges to approximately ~10% remaining life, the #1 LED will start FLASHING RED with the #2 LED FLASHING Yellow alternately.

[parnold]

That will probably be fine if you just want a quick visual of an approximate level. Remember, the battery must be at rest for a while for it to be accurate, I think it's like several hours without charging or discharging. My doc wattson shows voltage, but I can never find my chart so that I know what the stupid voltage means. Build #2 is going to have a more simple indicator, something like what you're looking at.

[eamarquardt]

A digital volt meter, even a HF cheapie, would do pretty much the same thing by giving you the voltage which would be more accurate than a bar graph.

My 2 cents.

Cheers,

Gus

[parnold]

A digital volt meter, even a HF cheapie, would do pretty much the same thing by giving you the voltage which would be more accurate than a bar graph.

As long as you don't lose the piece of paper that tells you what the voltage levels are. With modern electronics there is no reason that this device can't be as accurate as a cheap voltmeter. The thing is to find out exactly what voltages trigger each stage.

[absolutsnwbrdr]

Well, I went ahead and got it. You both pretty much confirmed what I was thinking: something is better than nothing. I started eyeing this one up because its cheap and simple. No voltage charts needed. Just need to know that green means good, yellow means look out, and red means you're screwed.

I was looking at an identical meter on another site and it had voltages listed for each LED step. Now I'm trying to find it again, but it probably isn't that important as long as you know that yellow is getting low, and red = 10.5V

K.I.S.S.

[GuitarPhotog]

Here's a "state of charge" chart. Just print it and tape it next to your battery.



I got this from this thread here: http://www.tnttt.com/viewtopic.php?f=30&t=11173

I use Gus' solution since I carry a multimeter for troubleshooting anyway.

<Chas>

[parnold]

That's the chart that I can never find!!!! My meter is mounted inside my trailer, and I didn't want to tape the chart on my nicely varnished walls, so it floats around the cabin, usually only to be found when I get back home and I am cleaning out the insides.

[droid_ca]

I think its a good thing to have, if I were to get one I'd place it in a group of the barometric meters for temperature and what not. .an ounce of prevention is sure better then a pound of cure

[absolutsnwbrdr]

It seems that the colored LED indicators of the meter match up pretty close with the % state of charge in the chart that Chas posted. The meter specs at least agree with the chart that 10.5V is dead.

Saving that chart for future reference.

[GuitarPhotog]

That's the chart that I can never find!!!! My meter is mounted inside my trailer, and I didn't want to tape the chart on my nicely varnished walls, so it floats around the cabin, usually only to be found when I get back home and I am cleaning out the insides.

How about printing it, laminating it, and hanging it on some bead chain as an interior decoration

I have a door into the electrical compartment, so mine is on the back of the door. Of course you can't read it from outside the trailer, but that's a different story

<Chas>

[Shadow Catcher]

Having just gone through the exercise of deciding which battery monitor to buy and with my usual obsessive...
There are two problems with this meter, if you get to 0 you have killed the battery, you will probably not be able to recharge it. The other problem is that the full is not (should be around 13V) and not charging a battery to full degrades it.
The only accurate way to measure depth of discharge is to monitor the current going in and coming out based on the battery(s) them selves and I have settled on a Victron 600 S.

[absolutsnwbrdr]

Having just gone through the exercise of deciding which battery monitor to buy and with my usual obsessive...
There are two problems with this meter, if you get to 0 you have killed the battery, you will probably not be able to recharge it. The other problem is that the full is not (should be around 13V) and not charging a battery to full degrades it.
The only accurate way to measure depth of discharge is to monitor the current going in and coming out based on the battery(s) them selves and I have settled on a Victron 600 S.

Nice choice SC. That Victron is too rich for my blood. I'm not launching a space ship. I know, all the crazy LED's may make you think I am. But I'm not. All I need to know is when I'm getting close to a point where I need to stop using my gadgets. Nothing more, nothing less. As far as charging goes, I have one of them fancy smart chargers that'll charge yer battery until its full and then maintain it for ya. Oh, and I have a second hand el cheapo battery that I paid $40 for. When that one has passed its usable life, then I'll go by a brand new el cheapo battery. Then I'll slowly kill that one too.

[eamarquardt]

Then I'll slowly kill that one too.

Torturer!
Murderer!

Gus

[eamarquardt]

That's the chart that I can never find!!!! My meter is mounted inside my trailer, and I didn't want to tape the chart on my nicely varnished walls, so it floats around the cabin, usually only to be found when I get back home and I am cleaning out the insides.

How about printing it, laminating it, and hanging it on some bead chain as an interior decoration

I have a door into the electrical compartment, so mine is on the back of the door. Of course you can't read it from outside the trailer, but that's a different story

<Chas>

Nah, he'll still lose it. I agree he should print it, laminate it, and THEN hang it around his neck so it will always be handy. Problem solved. I love solving problems. I love creating problems even more.

Cheers,

Gus

[jabrobbins]

Zach, Thanks for the post. I don't want to carry a voltage meter around and my battery is mounted underneath the trailer where it's hard to get to. This is the kind of solution I'm considering. Are you going to wire it so that it automatically shuts off power to your 12v accessories? The wiring below is from the Ebay listing.

Pin 1 is for Positive Volts DC

Pin 2 is for Ground

Pin 3 and 4 are the connections to make use of the relay function. Connect a positive voltage supply to pin 3. Connect pin 4 to equipment that you wish to operate limited to 3 amps max. This connection provides an open switch. When the meter senses full voltage, it activates the relay allowing current to flow to operate accessories. When the battery becomes discharged, the relay will open and shut off the power supply to an accessory that is wired thru the meter to conserve battery life.