# Wireless power meter
**URL:** https://community.electricforum.com/t/wireless-power-meter/5887
**Category:** GEM Forum
**Created:** [March 29, 2016, 11:54am UTC](https://community.electricforum.com/t/wireless-power-meter/5887 "2016-03-29T11:54:53Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [March 29, 2016, 11:54am UTC](https://community.electricforum.com/t/wireless-power-meter/5887/1 "2016-03-29T11:54:53Z")
This is the meter I’m testing.
[Wireless Digital DC Voltmeter Ammeter Power Meter Capacity 0 120V 200A Shunt | eBay](http://www.ebay.com/itm/221969003046?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
Rated at only 200 amps.
Tested to \>290 amps.
Seems ok for most Gems.
Instructions are not clear. (to me)
Relay output for :
OVP volts
OPP power
OCP current (amps)
OFT time
OHA ah
It seems only one can be selected. Makes sense.
Just tested OVP for charging set to 69 volts. Worked OK. 🙂
Select either charging or discharging.
“out” is green (on) until limit is reached. Then grey. (off)
Just typing this is helping me understand it.
A little slow to learn new things:confused:!
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [March 29, 2016, 1:33pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/2 "2016-03-29T13:33:04Z")
Stuck.
I can read charge or discharge. Not both. ???
Conflicting diagrams.
Bringing meter to bench before getting frustrated. (smoke)
Study this please!
[http://www.mhinstek.com/pdf/MHF-120100S%20User’s%20manual%20.pdf](http://www.mhinstek.com/pdf/MHF-120100S%20User's%20manual%20.pdf)
Getting a headache!!!
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [March 29, 2016, 3:14pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/3 "2016-03-29T15:14:36Z")
Manual states charge and discharge readings.
Must mean, one or the other. ☹
Same price, same look. Bidirectional?
[New Wireless Bi Directional LCD Digital Voltmeter Ammeter Power Meter 200A V7X9 | eBay](http://www.ebay.com/itm/222007777404?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [March 29, 2016, 5:44pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/4 "2016-03-29T17:44:32Z")
I’m complaining to the seller.
Love it in any case.
Monitoring charging from my desk.
6ah in so-far.
When it gets to 72v I’ll know how many ah in my 5 mile test.
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [March 29, 2016, 5:52pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/5 "2016-03-29T17:52:45Z")
Crap, ah isn’t moving.
Forgot to reverse the leads. :lol:
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [March 29, 2016, 6:12pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/6 "2016-03-29T18:12:07Z")
Timer was working. 🙂
1.3 hrs @ 12 amps. ~15ah for my 5 mile trip.
About 1/3 of 47ah pack.
That should give me 15 miles of hard use.
If I go to my 42 cell pack, I’m up to 35 miles of hilly stop and go.
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### Author:  [@LithiumGods](https://community.electricforum.com/u/LithiumGods)
#### Post date: [March 29, 2016, 6:30pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/7 "2016-03-29T18:30:21Z")
i’ll bet over 40 mile usable range with 42 cells@ 4.1v.
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### Author:  [@Laslonimne](https://community.electricforum.com/u/Laslonimne)
#### Post date: [April 9, 2016, 12:01pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/8 "2016-04-09T12:01:10Z")
[quote=Inwo;29831]This is the meter I’m testing.
[Wireless Digital DC Voltmeter Ammeter Power Meter Capacity 0 120V 200A Shunt | eBay](http://www.ebay.com/itm/221969003046?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)[/quote]
OK, I bit and just received mine. It came with zero instructions.
Can I assume the display will run off a 9v battery?
What did you use as the 72v source?
Appreciate the help. While I’m a competent ICE mechanic, electronics are alien to me. I’m trying to learn but battling recurring synapse failure on this subject.
Don
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [April 9, 2016, 1:20pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/9 "2016-04-09T13:20:11Z")
[quote=Laslonimne;30041]OK, I bit and just received mine. It came with zero instructions.
Can I assume the display will run off a 9v battery?
What did you use as the 72v source?
Appreciate the help. While I’m a competent ICE mechanic, electronics are alien to me. I’m trying to learn but battling recurring synapse failure on this subject.
Don[/quote]
Yes, set it up with 9v battery. Won’t last long though. You will want to connect it to 12v.
Here is the manual…[http://www.mhinstek.com/pdf/MHF-120100S%20User’s%20manual%20.pdf](http://www.mhinstek.com/pdf/MHF-120100S%20User's%20manual%20.pdf)
Connect the free end of shunt to battery neg.
Connect the neg. lead that was removed from battery to other end of shunt.
Add one small wire. Battery + to VIN+ on board. +72v
The terminal strips are for controlling a relay.
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [April 9, 2016, 2:14pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/10 "2016-04-09T14:14:59Z")
I just remembered that diagram was for “charging” direction.
This is how I connected mine to show discharge.
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### Author:  [@Laslonimne](https://community.electricforum.com/u/Laslonimne)
#### Post date: [April 9, 2016, 2:30pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/11 "2016-04-09T14:30:22Z")
> [@Inwo;30043](#):
>
> This is how I connected mine to show discharge.
Even I should be able to pull this off.
Thank you very much,
Don
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [April 9, 2016, 3:06pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/12 "2016-04-09T15:06:47Z")
Let me know it it shows charge and discharge. As it should.
My seller was ignorant and offered me $2 back out of his salary.
Some are listed in the title as two way.
Other than that you’ll love it.😉
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### Author:  [@Old\_Houseboater](https://community.electricforum.com/u/Old_Houseboater)
#### Post date: [April 9, 2016, 4:18pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/13 "2016-04-09T16:18:05Z")
Will over amps damage the meter? High amps only exist during acceleration or climbing.
Rodney
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [April 9, 2016, 4:36pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/14 "2016-04-09T16:36:10Z")
They say it will. What are they going to say? 😃
I tested mine way over without incident.
Only talking a few millivolts going into the meter. 200A=75mv. 300A=112mv.
Volts are rated at 120v.
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [April 10, 2016, 10:10am UTC](https://community.electricforum.com/t/wireless-power-meter/5887/15 "2016-04-10T10:10:10Z")
Dust cover for shunt and electronics.
Make a wooden form proper size.
Shrink tubing with end pinched down while hot.
I slit the form and “swelled” it with a long “roof gutter” screw for easy removal.
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [April 10, 2016, 3:34pm UTC](https://community.electricforum.com/t/wireless-power-meter/5887/16 "2016-04-10T15:34:06Z")
This one specifically bi-directional.
[New Wireless Bi Directional LCD Digital Voltmeter Ammeter Power Meter 200A V7X9 | eBay](http://www.ebay.com/itm/New-Wireless-Bi-directional-LCD-Digital-Voltmeter-Ammeter-Power-Meter-200A-V7X9-/222007777404?hash=item33b0b1d87c:g:t9sAAOSw-zxWp103)
Ordered a few.
I’ll report when they come in.
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [April 15, 2016, 7:38am UTC](https://community.electricforum.com/t/wireless-power-meter/5887/17 "2016-04-15T07:38:12Z")
The more I use this the more I like it.
For those not wanting permanent installation, check this out.
Comes with charger and switch.
Velcro to wireless meter and done.
I keep it on my desk. Last night I flipped it on and noticed my batteries were getting low.
Plan to mount two meters to it for my two lithium cars.
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [April 24, 2016, 9:52am UTC](https://community.electricforum.com/t/wireless-power-meter/5887/18 "2016-04-24T09:52:32Z")
Meters come set to same address. Works good for me right now.
The voltage can be read from desk and from car at the same time.
To keep an eye on charging.
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### Author:  [@On\_the\_Fritz](https://community.electricforum.com/u/On_the_Fritz)
#### Post date: [May 28, 2016, 11:26am UTC](https://community.electricforum.com/t/wireless-power-meter/5887/19 "2016-05-28T11:26:33Z")
Thanks for all the work and data on these, Inwo. I’m ordering one to play with.
Did the battery you showed above for the display come from ebay?
Do you have a few data points on the current draw on a GEM while driving? I drive an e4 with a 7.5 hp motor.
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### Author:  [@Inwo](https://community.electricforum.com/u/Inwo)
#### Post date: [May 28, 2016, 11:37am UTC](https://community.electricforum.com/t/wireless-power-meter/5887/20 "2016-05-28T11:37:32Z")
Yes, but battery is over kill.
You could also connect to 12v from car.
I like to move it from car to car and in the house.
I’ll check amps next time I take out the lead Gem.
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