Voltage levels for a meter project

[veewee77]

I am making a web page for my voltage monitoring system and I have a question on a meter. On a volt meter say in a motorhome or something, it shows the voltage being in a green band between say 12 and 15 Volts (these are guesses). Then it will show in a yellow band between say 11.5 and 12 and a red band for say 11.5 and lower.

What would be considered a "safe" set of these values for an analog meter.

I am building a graphic analog meter to display on a webage for my monitoring system and need to know these voltages so I can set the color bands on the meter. I used 11.5 for the top of the red, 12 for the top of the yellow and green up to 15. Once it goes over 15, the meter needle turns red and basically widens itself from 15 up to 15.5. In other words, the needle is black up to 15 volts, then it starts at 15 and fans out up to 15.5 so it gives you a wide needle the entire span between 15 and 15.5, varying in width from 15.1 to 15.5. For an example, look at http://dsjscrd.gotdns.com/~simpsond/solar/15.5.gif and http://dsjscrd.gotdns.com/~simpsond/solar.15.1.gif. And for an example of 12.7 volts look at http://dsjscrd.gotdns.com/~simpsond/solar/12.7.gif.

I need to know if the color bands are ok. I know for the best life of the batteries it is never a good idea to allow it to drop below 12V, but that meter will allow for heavy loads and etc. and still give a good reading if read after standing with minimal loads.

I should have asked this question before I built the meter, but that is OK. . . I can back up and punt and re-do it. . .

Thanks!

Doug

[wooferhound]

You talk about a battery in a motorhome

but if you have batteries in a renewable energy system you will need to be able to read voltages as high as 17 or 18 volts to cover the times that equalization charges are being made.

[Chagrin]

This question just came up in another topic:

http://www.fieldlines.com/story/2008/5/7/15112/17790

[wooferhound]

I personally would make

 0 to 10.5 volts = red for hard sulfation

 10.5 to 12.2 volts = yellow for soft sulfation

 12.2 to 14.4 volts = green for fully charged

 14.4 to 16 volts = yellow for equalization

 16 to 18 volts = red for over charged

[veewee77]

Thanks for the reply! I didn't think of eq charging. . .Guess I need to address that. Also, I don't ever plan on letting them get low enough to sulphate, and this will be on a continuously used system so if they get that low, there is something wrong. . .

Have a great day!

Doug

[TomW]

Doug;

How are you plotting the meter? Do you create each on the fly or simply overlay the voltage info on a meter face you created initially?

I thought the right script could get Gnuplot to do it all on the fly but haven't tried.

Tom

[wooferhound]

and don't forget this program to print the meter dial faces for you.

http://www.fieldlines.com/story/2004/2/3/191649/8833