Help testing my charging setup? N. Seattle area

[chriswood]

I'm currently charging a Prius Prime at L1, over an extension cord at home, and expecting my MYLR to arrive in the next month. Noticed that my breaker is 20A, so I've replaced the outlet and extension plug ends with NEMA 5-20, and bought the 5-20 adapter for the mobile connector. This should allow the MY to draw 16 amps, but obviously can't test it myself as the Prime only pulls 12. Was wondering if anyone here is an MY owner nearby who might be willing to plug in at my curb cut to test this out? I have the 5-20 adapter for the mobile charger, but need to test whether or not the voltage drop isn't too much to allow 16A - at 12A I'm losing 7V, which per ohm's law will result in a 9.3V drop at 16.

I'm in the northern part of Seattle; send me a PM and I can elaborate. Thanks!

 

[ATPMSD]

I'm losing 7V

This seem to indicate the extension cord is not suitable. If you plan to continue to use an extension cord be sure it is at least 14-AWG for up to 30’ and 12-AWG for 50. Any idea what other outlets use that same breaker? It really should only be used by the Tesla when charging.

 

[pkeller]

I'm currently charging a Prius Prime at L1, over an extension cord at home, and expecting my MYLR to arrive in the next month. Noticed that my breaker is 20A, so I've replaced the outlet and extension plug ends with NEMA 5-20, and bought the 5-20 adapter for the mobile connector. This should allow the MY to draw 16 amps, but obviously can't test it myself as the Prime only pulls 12. Was wondering if anyone here is an MY owner nearby who might be willing to plug in at my curb cut to test this out? I have the 5-20 adapter for the mobile charger, but need to test whether or not the voltage drop isn't too much to allow 16A - at 12A I'm losing 7V, which per ohm's law will result in a 9.3V drop at 16.

I'm in the northern part of Seattle; send me a PM and I can elaborate. Thanks!

As was mentioned the first thing to do is replace the extension cord with a 12ga (preferable) extension that is as short as possible. Then if you want to test the setup, go to you local Tesla Show room and take one for a test drive. Drive home and plug it in.

 

[chriswood]

This seem to indicate the extension cord is not suitable. If you plan to continue to use an extension cord be sure it is at least 14-AWG for up to 30’ and 12-AWG for 50. Any idea what other outlets use that same breaker? It really should only be used by the Tesla when charging.

The cable is 10 AWG - I'd had a 12/3 cord before, but swapped in a 10/3 to bring down the resistance - the drop was over 10V drop before, which could have made even 12A questionable. The outlet is on a dedicated breaker with 10AWG solid-core house wire. The main reason for the drop seems to be the overall cable length, currently 90' - Started with a 100' cord, and cut off about 10' to reduce excess slack, but I could take off probably about 5' more, albeit leaving virtually no remaining slack in the cord at all. Unclear how that would be enough to make a measurable difference in total resistance, however.

 

[ATPMSD]

A 100’ cord requires 8ga wire. You may find this site useful.

http://www.paigewire.com/pumpWireCalc.aspx

 

[chriswood]

A 100’ cord requires 8ga wire. You may find this site useful.

http://www.paigewire.com/pumpWireCalc.aspx

That calculator is showing 10AWG copper for me:

 

[Long Ranger]

The main reason for the drop seems to be the overall cable length, currently 90' - Started with a 100' cord, and cut off about 10' to reduce excess slack,

I'd check the connections. 10 AWG has a resistance of about 1 ohm per 1000'. That would only be about 1.1V @ 12A over 90'. So ~6V of your 7V drop is due to the connections plus your house wiring.

 

[ATPMSD]

Yes, but 17 amps puts it over, so 16 is boarderline. Also remember the wire run starts at the breaker. In any case I always use the circuit value to ensure adequate headroom. I am not an electrician so I cannot offer anything further. Good luck!

 

[DanL3]

Be sure you have a 20a female end on the extention cord. That female connector is what will overheat and fail first.

 

[pkeller]

Curious as to what you ended up doing.