Portable OpenEVSE at 40A

[dstjohn99]

I'm looking for a source for a NEMA 6-50P power cord. Stay Online has one for $87, which is awfully high, and high enough I would wire the plug onto some proper cable, or relent and use a NEMA 14-50 (but this is the wrong plug, as I don't need the neutral).

I agree the 6-50 is the best fit for EVSE use. Home Depot has the 6-50P for under $15 and 6-3 SOOW cable is about $4.42 per foot. Thats a 16 foot cord & plug for the same price you mention above.

 

[fooljoe]

You could get one of these, chop off the plug end, and use the receptacle end for a nice adapter/extension cord.

But I would just relent and go with a 14-50p. Saw off the neutral prong so you can plug it straight in to either RV park or modern dryer receptacles. How often are you going to find a welder socket to charge from in the wild?

 

[pchilds]

Here is a good quality 6-50, for $8.56 free shipping.
http://www.ktool.net/servlet/the-61800/Cooper-Wiring-Devices-S42-dsh-SP/Detail

 

[fooljoe]

Here is a good quality 6-50, for $8.56 free shipping.
http://www.ktool.net/servlet/the-61800/Cooper-Wiring-Devices-S42-dsh-SP/Detail

I believe he's looking for a molded power cord, not a plug. Although given the lack of availability of 6-50 cords just getting a screw-on plug and cable separately could be the best option.

 

[srl99]

Thankyou for the wisdom! Yes, I'm looking for a molded 6-50 cord, and surgery on that extension cord is a good and creative option. Relenting to the 14-50 probably does make the best sense as they are ubiquitous and cheap.

Great advice, thank you!

 

[fooljoe]

Here's another take on the welder extension cord that's $5 cheaper and a different color, if you decide to go the 6-50 route. Or just search for 'welder extension' on amazon to see a few others.

 

[Dsinned]

Have you checked welding supply companies? A NEMA6-50P power cord is generally associated with welding equipment.

Or, you could get this one footer and just cut off the other end. Currently on sale for only $6.67!

http://www.americord.com/6-50p-to-6-20r-locking.html?gclid=COzO1aaDxsACFZKBfgodQC4AIA

 

[ehelmholtz]

Or, you could get this one footer and just cut off the other end. Currently on sale for only $6.67!
http://www.americord.com/6-50p-to-6-20r-locking.html?gclid=COzO1aaDxsACFZKBfgodQC4AIA

This would not be a good idea; I have these adapters and the cable is only rated for 20A.

Most people who build OpenEVSEs use the NEMA 14-50 (without the neutral connected) because RV parks use these and they can be found at many homes. As such the NEMA 14-50 plug (and with the neutral off it could be used on a 14-30 outlet), is preferred over the 6-50 by many. I use NEMA 6-50 myself because that's what I have installed at home.

 

[fooljoe]

Or, you could get this one footer and just cut off the other end. Currently on sale for only $6.67!

http://www.americord.com/6-50p-to-6-20r-locking.html?gclid=COzO1aaDxsACFZKBfgodQC4AIA

That only uses #14 wire! Not a good idea assuming you're building a 40 amp (or even 30 amp) EVSE.

 

[Dsinned]

Oh, my bad! Good catch. No wonder it was so cheap! :mrgreen:

 

[dstjohn99]

So I verified my charging current and temperatures again today. My Rav4 is charging at 32 amps max. I drained the car today to less than 2 miles range. When I started charging it only draws 32 amps even though the EVSE is set at 40. I had the same readings last week with the JESLA also.

Today after 1 hour of charging, my range increased to 24 miles. The current was steady at 32 amps. Temperatures as follows:
50A breaker: 150°F
80A relay: 150
T1/2 connections: 170
J1772 cord: 115
Current at panel: 32A

Has anyone else verified their charging current and range increase during charging? Similar or different result? Recommendations?

 

[miimura]

I initially would have suspected the pilot signal on your OpenEVSE wasn't right. However, since the Jesla gives exactly the same result, the next most likely thing is your measurement tools. I would try a tool with a known calibration or something Revenue Grade. My digital utility meter shows voltage and instantaneous kW. If you cut the power to the rest of the house, that would be one way to get another reading.

 

[TonyWilliams]

Can you put a oscilloscope on the pilot signal? 30 amps is 50% modulation of the 1kHz square wave.

80 amps is 90+%

If not, I'd suggest your ammeter is out of calibration.

Another simple test. Drive to LO, then charge up. Tell us how long a complete 100% charge took.

5 hours is the result at 40 amps / 240-250 volts.

USING THE "Guess-O-Meter" TO AID YOU WITH DETERMINING CHARGING SPEED IS FOLLY !!!!

 

[srl99]

You could get one of these, chop off the plug end, and use the receptacle end for a nice adapter/extension cord.

But I would just relent and go with a 14-50p. Saw off the neutral prong so you can plug it straight in to either RV park or modern dryer receptacles. How often are you going to find a welder socket to charge from in the wild?

I also found this: http://airgas.com/product/Welding-Products/Welders-%26-Accessories/Machine-%26-Fixture-Repair-Parts/p/MIL254328?gclid=CLealuL-xcACFYhefgodqz4ANg#fo_c=306&fo_k=98d5bef5f759f1a1cdf6e9ac046a4d4f&fo_s=gplaus
I'm suspicious it has 50A wiring as it's a 30A "adapter". You can buy a 25' (40A) Welder extension cord as low as $75/shipped, which isn't bad. My local electronics heaven (where surplus electronics go after their initial life on earth) has a couple of foot 6-50 to some sort of round 50A Receptacle adapter for $25, but the 6-50 end wasn't molded. THIS had 50A (at least) wiring!

 

[fromport]

I initially would have suspected the pilot signal on your OpenEVSE wasn't right. However, since the Jesla gives exactly the same result, the next most likely thing is your measurement tools.

Or the on-board charger could be at fault.

for dstjohn99:

To verify your readout :

If you have a smart meter, most have a "current energy consumption" readout.

readout that setting before and after plugging in and you would know much power the car is pulling.

 

[Dsinned]

Since your EVSE is connected to a "split phase" 240V power source, just out of curiosity, what is your current meter reading when clamped around the other power line conductor? Is it also "32A", or a much higher reading?

Regardless of the GoM's inaccuracy, based on the statement that your range increased "24 miles" in 1 hour, the charging rate can be calculated, which suggests your EVSE must be charging at close to 9.6kW (i.e. 240V at 40A). The GoM's inaccuracy can be dismissed by comparing the same calculation for both cases (9.6 vs. 7.7kW) as follows.

Assumptions:

1. Avg mi/kWH: 3.0 mi/kWH (most recent reading on the center console)
2. EVSE charging eff: 85% (as measured at EV's onboard charger output)
3. EVSE pwr lvl: 9.6kW (same as 240V @ 40A) . . . case #1
4. EVSE pwr lvl: 7.7kW (same as 240V @ 32A) . . . case #2


To calculate miles of range gained per hour for case #1: (9.6 kW * 0.85) * 1 hr * 3.0 mi/kWH = 24.48 miles

To calculate miles of range gained per hour for case #2: (7.7 kW * 0.85) * 1 hr * 3.0 mi/kWH = 19.64 miles

 

[dstjohn99]

I love this forum! Great responses, thank you.

While not calibrated, my Amprobe is accurate to within 5%, and verified by other instruments. However, maybe there is some other error involved in the reading? The other leg of the 240 reads the same. I did not know about the smart meter reading, I will use that to verify.

Last night the Rav was at 0 bars (LO range). I charged from 7:51pm to 9:53pm to monitor amperage and temperatures. Then it charged per schedule during the night. Interestingly I received the email that it finished charging at 4:19am, but not the normal email notification that charging started. So I cant say for sure how long last night for a full charge. Of course, this is the time the Entune emails did not function normally.

Yes, I can check the pilot signal with the o-scope. I'll do that tonight. Also, I'll see if I can determine the charge time. If not, next time I go to LO will be my next opportunity. Based on previous charge times I also suspect there is an error in my ammeter readings. I'll keep you posted.

Thanks for the responses.

 

[Dsinned]

Certain types of clamp on ammeters can be error prone if the jaws are not making a good, direct contact, face to face connection. If there is even a slight gap between the two faces, this will throw off (lower) the reading.

 

[dstjohn99]

Certain types of clamp on ammeters can be error prone if the jaws are not making a good, direct contact, face to face connection. If there is even a slight gap between the two faces, this will throw off (lower) the reading.

I agree. I'm starting to suspect the way I have the ammeter hanging there may be causing a mis-alignment of the coil faces. That might explain why it checked okay in a different situation, but is not reading accurately for this measurement. I'll check that out too.

 

[srl99]

If you have a "SmartMeter" your utility may provide you N minute interval power use. And … you might get yourself a compatible display unit which would give you that resolution or greater inside the house.

We have a Zigbee gateway which sends our meter data to a web service provider who attempts to figure out what appliances/etc were running from the total power consumption - but I think this app is bad, so I won't glorify its name.