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Topic ClosedVoltmeter Install
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fwunder View Drop Down
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Posts: 1676 		Direct Link To This Post Topic: Voltmeter Install
    Posted: 04 Jan 2014 at 9:34am
I wanted to add a few things because this subject really interests me and because the Pod is still warming up so I can finish this mod. I shoveled a path to it yesterday!

OK, so I wanted to add a voltmeter. I go to my favorite bookmark and buy one - this one

*Then* I decided to really start studying. Sorta backwards, I know. It's the C in OCD.

Anyway, I get it, wire it to a 12v. sealed lead acid battery I have on my bench along with a very old RS multimeter. Multimeter reads 12.6v. New voltmeter reads 13.2v. Yikes! A 0.6v. difference! Referring to that chart above, that's huge. Now what?

Slowing down a bit, it became apparent that I needed some kind of reference voltage and/or a way to reasonably accurately measure and, ideally, calibrate the voltmeter to the reference. I didn't want to spend a lot of money on something like a TriMetric

Digging around the interwebs, I found this meter. It gets good reviews, has two decimal point readout and, most importantly, has a potentiometer so I can calibrate it to a reference voltage. When I got it and wired it to my reference battery it read 13.1v.! Watts up with that?! I borrowed a friend's multimeter which measured the reference @ 13.05v. Back to shopping. This time I ordered this multimeter. Can't afford a Fluke Multimeter.

While waiting for the new multimeter, I have finished the mounting plate (shown above) with a mini rocker switch so I can turn the meter off if I want to - it is pretty bright. I also made up a length of wires I will use wire to 12v. source on WFCO panel. With everything wired to reference battery, I find that I can use the potentiometer to adjust the output of the voltmeter to compensate for any voltage drop I may see from the hookup. The idea here is to get as accurate a 12v. system reading as I can.

Although, I'm pretty confident I will be able to dial the meter to closely match the chart I showed above, it's probably more important to note the battery voltage when fully charge using whatever you use to measure and to try not to let the voltage drop below -1.0 volt. That seems to be safe and probably about what the standard pod indicator lights read @ half full.

I hope that helps and please feel free to correct or comment!

-fred
2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6
Yes, those are wild ponies dining on grass while dumping tanks!
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fwunder View Drop Down
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Posts: 1676 		Direct Link To This Post Posted: 04 Jan 2014 at 9:43am
Originally posted by CharlieM

Exactly correct. The voltmeter is far better than the factory supplied system monitor. It is only good for telling you the battery is still there, maybe. To accurately assess the battery condition, short of a hydrometer, you need a digital voltmeter. I use a meter plugged into one of my added 12 volt outlets, which connect directly to the power converter.

http://www.amazon.com/Equus-3721-Battery-Charging-Monitor/dp/B000EVWDU0/ref=sr_1_1?s=automotive&ie=UTF8&qid=1352484368&sr=1-1&keywords=battery+monitor+12v

Charlie

That's a great option, Charlie. I considered that first, but use my one 12v. outlet for too many other things and that space to the left of the Jensen stereo seemed begging for a hole to be cut!

BTW, when I removed the Jensen head unit yesterday I found two of the four screws weren't screwed into anything. Jeesh, that kind of stuff bugs me when I find it.

-fred
2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6
Yes, those are wild ponies dining on grass while dumping tanks!
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Tars Tarkas View Drop Down
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Posts: 1454 		Direct Link To This Post Posted: 04 Jan 2014 at 10:04am
Originally posted by CharlieM

I use a meter plugged into one of my added 12 volt outlets, which connect directly to the power converter.

http://www.amazon.com/Equus-3721-Battery-Charging-Monitor/dp/B000EVWDU0/ref=sr_1_1?s=automotive&ie=UTF8&qid=1352484368&sr=1-1&keywords=battery+monitor+12v


  I have the same one but haven't gotten around to adding any 12v outlets yet. I clamp a cable with a power outlet on the end directly to the battery.  This seems much more versatile due to its innate portability.  We've always got our TVs, of course, and I usually carry this with me too:
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CharlieM View Drop Down
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Posts: 1797 		Direct Link To This Post Posted: 04 Jan 2014 at 11:10am
Fred,

Looks like you're on the right track. Re your multiple measurements on your "standard" battery: I'd suspect any reading near 13V if the battery has been sitting "at rest" for a while. It should be around 12.6-12.8 volts if fully charged. As far as calibrating the new meter, you will never be able to totally calibrate out hookup errors because they are load dependent. Just connect as close to the battery as you can, check the new meter against a trusted higher end meter connected in a similar manner, and sleep well.

Charlie
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PRESENT: 2014 Camplite 21RBS, 2013 Supercharged Tacoma 4L V6 4WD
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fwunder View Drop Down
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Posts: 1676 		Direct Link To This Post Posted: 04 Jan 2014 at 12:01pm
Thanks Charlie!

The battery I'm using for reference is a SLA 12v. 18ah in the enclosure shown below with the first meter I bought. I've replaced the battery and usually keep it on a Battery Tender. I'm pretty sure the resting voltage (not much of a rest) is around 13.2v. I could be wrong.

Funny you mention sleeping well, because I have used that rig to power my CPAP machine for a night when we've lost power @ home and didn't have the generator running. Thus, part of the reason I'm sensitive to battery storage. Probably over-sensitive.

Thanks for your comments!

-fred
2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6
Yes, those are wild ponies dining on grass while dumping tanks!
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techntrek View Drop Down
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Posts: 9062 		Direct Link To This Post Posted: 04 Jan 2014 at 12:48pm
I just want to jump in with a comment on letting the battery rest (no charging or discharging for at least 3 hours) for other readers.  Usually it is impossible to truly let it rest since the LP detector and the fridge's control board will still be running.  So even if those are the only things that have been running all night while boondocking and you check the voltage first thing in the morning before you turn on a light, the voltage you read will be slightly lower than the true resting voltage.
Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual
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fwunder View Drop Down
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Posts: 1676 		Direct Link To This Post Posted: 04 Jan 2014 at 2:12pm
OK, here's the install. Took hot to empty position on fuse block w/5 amp fuse. Took ground to 12v. grounding block on floor behind WFCO. Took a few hours to warm up the Pod today and still wore two pair of socks! :)

I'll check it with a reliable meter, when I have access to one.

Thanks for all the input guys! You people are great!

-fred

p.s. Yes, that measurement is while plugged it.
2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6
Yes, those are wild ponies dining on grass while dumping tanks!
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CharlieM View Drop Down
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Posts: 1797 		Direct Link To This Post Posted: 04 Jan 2014 at 7:20pm
Fred,

Looks great and ought to work great. Glad we were able to help.

Charlie
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OLD: 2013 RP-172, 2010 Honda Pilot 3.5L 4WD
PRESENT: 2014 Camplite 21RBS, 2013 Supercharged Tacoma 4L V6 4WD
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headcold View Drop Down
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Posts: 125 		Direct Link To This Post Posted: 06 Jan 2014 at 6:52pm
Pardon my complete ignorance, what and where is the "Jensen head unit"?    Embarrassed
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headcold View Drop Down
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Posts: 125 		Direct Link To This Post Posted: 06 Jan 2014 at 6:55pm
Oh, you're referring to your stereo unit. This must be a mod.
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