Portable 120/240V KWH meter for your portable upgraded EVSE

[johnr]

Here is a kilowatt-hour energy meter I just finished putting together. It keeps track of the total KWH used, showing it on the digital display in 0.1 KWH increments - and with its L6-20 connectors it plugs right in to the modified EVSE. The meter works on 120 or 240 volts, just like the upgraded EVSE. There is also a small "impulse" light which flashes 800 times per KWH. At 240V that's almost one flash every second. At 120V it's about once every 3 seconds. So, you can get an idea of the current energy draw based on how fast it blinks. The meter is not resettable, and the memory is retained when unplugged.

The meter is small and easy to carry along. If you leave one at home and bring the other one in the car, you can know how much of your own electricity you use when recharging at home and also how much energy you use when charging away from home. If you need to borrow someone's outlet, you can plug in the meter while charging there and they will know exactly how much energy was used. The project is not quite finished yet - I need to do a little more testing and put it in a nice weatherproof box, and the cord connections will be much nicer - but hey, it works!

Here are some photos while testing:

Closeup photo. Display shows 0.6 KWH so far:



Here we are plugged in to 120 volts - and we're up to 1.8 KWH now:



Here we are plugged in to 240 volts:

[ericsf]

Where did you get the meter from ?

[TEG]

Nice!

[mitch672]

Yes, very nice. There are similar Meters on eBay, but I only seem to be able to find 50HZ models, search on "KWH meter". There is also one advertised for Teslas that uses CTs (Current Transformers), and can even measure up to 3 phases ($160 price, you'll find it)

[garygid]

Here are some similar kWh Meters:
http://kwhmeters.com/Meter_Types.html" onclick="window.open(this.href);return false;

This one is straight-through and $90, I believe:
http://kwhmeters.com/Basic_Pass-through_Meter_240V.html" onclick="window.open(this.href);return false;
This meter reads in 1/100 kWh instead of 1/10 kWh (the one pictured above).

Other models use current-transformer torroids.
Some are built for remote monitoring.
At least one model will monitor bi-directional flow, Net metering.

[DaveinOlyWA]

wow, too bad did not see this before i installed mine which only measures at home. a portable one would be awesome for shows, etc.

what is cost of all this? links to parts?

[mitch672]

Gary posted the link, its $90 + $2 for a DIN rail to mount it, just put it on a piece of plywood or a project box... you only need to add wire and the correct plugs for your application. The meter is a 100A model, with wiring "pass through" (wires don't have to be cut/spliced, just has a screw that tightens on it for the voltage tap)

http://kwhmeters.com/Basic_Pass-through_Meter_240V.html" onclick="window.open(this.href);return false;

[garygid]

1a. Three 10 or 12-gauge wires
1b. Male and Female connectors (maybe L6-30)
OR
1. One L6-20 extension cord (about $24 + shipping from http://www.StayOnline.com" onclick="window.open(this.href);return false; )

2. The meter linked to above, $90 + shipping from http://www.kwhmeters.com" onclick="window.open(this.href);return false;

3. Assemble:
The two "hot" leads go through the kWh meter.
The Green wire (Ground) bypasses the meter.

4. Package (optional):
The result is probably "safe" but not moisture-proof, so ...
You might want to "package" the meter in a protective box, similar to ones shown at http://www.kwhmeters.com" onclick="window.open(this.href);return false;

Cheers, Gary

[DaveinOlyWA]

interesting but beyond my price range (i debated over spending the $50 for my option) and i know my Leaf enough that i can probably predict within a kwh how much charge i got by using of all things, the gueessometer

[mitch672]

interesting but beyond my price range (i debated over spending the $50 for my option) and i know my Leaf enough that i can probably predict within a kwh how much charge i got by using of all things, the gueessometer

keep checking eBay, you might get lucky and find one for $20-$30 from one of the Chinese sellers, just make sure you get one that supports "60hz", most of them seem to be listed as "50hz"