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anyone ever extended their UMC?

ajw

Member
Apr 29, 2014
84
0
Richmond, VA
I'm thinking about having this done....and just wanted to see if others have tried.
I'm planning on having 30 feet added,,,making 50 feet total. The extra length has amperage/volt loss issues, so it was recommended that the extended cord should not charge above 24A.
I have 2 cords BTW.....the extended version would be largely for destination charging...and should solve lots of problem for using dryer outlets etc.

So...has anyone tried this as a solution (rather than fabricating your own extension cords)?

Thanks.
 

qwk

P130DL
Dec 19, 2008
3,024
766
I thought about doing something like that in the beginning(almost two years ago), but not anymore. The current UMC design isn't even enough to make them last unmodified(I've been through too many to count), let alone modified. Tesla went bare minimum on pretty much every aspect of the Model S UMC. If you want to put money into something, you are better off making your own portable UMC with better cables and connections.
 

islandbayy

Active Member
Feb 25, 2013
2,644
1,015
Greendale, Wisconsin
I thought about doing something like that in the beginning(almost two years ago), but not anymore. The current UMC design isn't even enough to make them last unmodified(I've been through too many to count), let alone modified. Tesla went bare minimum on pretty much every aspect of the Model S UMC. If you want to put money into something, you are better off making your own portable UMC with better cables and connections.

I agree, I'm on 8 or 9 of them now :( And I carry a brand new spare.
 

jrreno

Nothin' left to do but smile, smile, smile
Jul 21, 2013
962
232
Sarasota , Florida
What failed on these units? If you were going to make a replacement I assume you would still have to use the plug for the charge port.
 

tomas

Out of warranty...
Oct 22, 2012
4,233
3,804
Chicago/Montecito
I'm thinking about having this done....and just wanted to see if others have tried.
I'm planning on having 30 feet added,,,making 50 feet total. The extra length has amperage/volt loss issues, so it was recommended that the extended cord should not charge above 24A.
I have 2 cords BTW.....the extended version would be largely for destination charging...and should solve lots of problem for using dryer outlets etc.

So...has anyone tried this as a solution (rather than fabricating your own extension cords)?

Thanks.

I just don't understand why you would do this -or- why anybody would fabricate an extension cord. You can buy this for $100. There is no degradation of current, I've used one at my second house for 18 months and it charges at 240/40 with nary a blip.
 

roblab

Active Member
Jul 15, 2008
3,348
2,407
Angwin (Napa Valley) CA
I'm thinking about having this done....and just wanted to see if others have tried.
I'm planning on having 30 feet added,,,making 50 feet total. The extra length has amperage/volt loss issues, so it was recommended that the extended cord should not charge above 24A.
I have 2 cords BTW.....the extended version would be largely for destination charging...and should solve lots of problem for using dryer outlets etc.

So...has anyone tried this as a solution (rather than fabricating your own extension cords)?

Thanks.

I bought two 15' 220 volt 50 amp RV extension cords with molded connections. I have used them both when I was unable to reach a 14-50 outlet at a hotel, and charged without incident at 40 amps. I normally charge only in my garage, and take the cords along only on long vacations where outlet availability might be questionable, so I have used them maybe three times; it's not like they get worn out.

They are priceless if you need them, but I'm glad I don't have to haul them around all the time. Maybe if I had an outlet that was too far from where I'd park my car, I would think about it, but would probably just run conduit and put in a closer outlet.
 

qwk

P130DL
Dec 19, 2008
3,024
766
What failed on these units? If you were going to make a replacement I assume you would still have to use the plug for the charge port.
The early UMC's would just stop working(problem with the electronics). Now, Tesla has updated those, but the adapter end connection is prone to getting too hot/melting. Tesla has since updated the 40A adapters, but I don't think that the adapters were at fault to begin with. I imagine that it was much cheaper to send out adapters than newly designed UMC's. Somebody dropped the ball bigtime, and I guarantee that this problem isn't going away as long as the current UMC design stays. The longest I have had a UMC last is 8 months.

- - - Updated - - -

I just don't understand why you would do this -or- why anybody would fabricate an extension cord. You can buy this for $100. There is no degradation of current, I've used one at my second house for 18 months and it charges at 240/40 with nary a blip.
I have one of those extension cords, and they absolutely suck. Very cheaply made, and very hard to coil back up when it's cold. For the same price one could make a much better/longer extension cord.
 

mitch672

Active Member
Jul 1, 2012
1,861
13
Stoughton, MA
I bought one of Tony Williams cut off UMC ends, then bought the EVSE cable he has, and built an OpenEVSE with it.
Has a much beefier 40A relay, I haven't had any issues with it. The biggest pain is soldering the cable together, I used the heat shrink with the solder in it, then put a piece of heat shrink over all of the individual but splices.

Thread: 40A OpenEVSE UMC replacement
 
Last edited:

Btrflyl8e

Supporting Member
Mar 24, 2013
2,582
1,264
Seminole, Florida, United States
I just don't understand why you would do this -or- why anybody would fabricate an extension cord. You can buy this for $100. There is no degradation of current, I've used one at my second house for 18 months and it charges at 240/40 with nary a blip.
+1
I used this exact extension cable for my daily charging at home for the first few months, no problems charging at full 40 amps.
 

islandbayy

Active Member
Feb 25, 2013
2,644
1,015
Greendale, Wisconsin
- - - Updated - - -

I have one of those extension cords, and they absolutely suck. Very cheaply made, and very hard to coil back up when it's cold. For the same price one could make a much better/longer extension cord.

I did went this route, made my own 15ft cord. Their was a cord remnant left at Home Depot at half price. Snatched that sucker up (90cents/ft!!!), got both ends, total cord cost was $20 and much "beefier" then those premades.
 

ajw

Member
Apr 29, 2014
84
0
Richmond, VA
+1
I used this exact extension cable for my daily charging at home for the first few months, no problems charging at full 40 amps.
That cord seems to work fine, if you need an extension for 50 amp charging....but I'm looking for a flexible solution that fits multiple outlets. For me, it seems that an extended umc would fill those gaps for destination charging. If you have that cord, and come across a 10-30,,then you're out of luck.
nevertheless, it doesn't sound like anyone has done this. Also it stinks to hear that the cables break down so quickly! Yikes.
 

Btrflyl8e

Supporting Member
Mar 24, 2013
2,582
1,264
Seminole, Florida, United States
That cord seems to work fine, if you need an extension for 50 amp charging....but I'm looking for a flexible solution that fits multiple outlets. For me, it seems that an extended umc would fill those gaps for destination charging. If you have that cord, and come across a 10-30,,then you're out of luck.
nevertheless, it doesn't sound like anyone has done this. Also it stinks to hear that the cables break down so quickly! Yikes.
Gotcha. I have not had any issues with my UMC. The SC replaced it once when I had an issue charging on a 110, but really it was an issue of ambient temp. I'm sure I'd still be on my original one if not for that.
 

TonyWilliams

Active Member
Jun 11, 2012
1,438
758
San Diego - Tesla powered Rav4 EV
I don't know of anybody who has actually cut open every piece of both normal and FAILED UMC's besides me (virtually everybody else just exchanges the failed ones under warranty, and only crazies like me cut open perfectly good ones), but the failures seem to be manufacturing flaws (failed ultrasonic welding).

So, while the UMC isn't overbuilt by any degree, it's not inherently a bad design. They are built in Mexico by Jabil, and shipped to Fremont for distribution. Tesla doesn't build them at all.



TeslaUMC1450cutopen2.jpg



TeslaUMC1450cutopen3.jpg
 
Last edited:

Cosmacelf

Well-Known Member
Mar 6, 2013
8,295
19,579
San Diego
I agree. Don't bother extending the UMC since they are so prone to fail. Get a 50A RV extension cord and use adapters. Frankly, I can't believe Tesla hasn't redesigned the the UMC/adapter connection mechanism since that is where the problems lie. It needs to be much more robust.
 

ajw

Member
Apr 29, 2014
84
0
Richmond, VA
I agree. Don't bother extending the UMC since they are so prone to fail. Get a 50A RV extension cord and use adapters. Frankly, I can't believe Tesla hasn't redesigned the the UMC/adapter connection mechanism since that is where the problems lie. It needs to be much more robust.
This was my first inclination a few months back....but whenever I think I've got a decent extension cord solution, I find out that I've got to cut the cord open and do some minor electrical surgery.
I'm looking to avoid this. The basic stuff seems pretty easy, but I'm also well aware that I have no business fabricating electrical wiring.

So, Cosmacelf...you are suggesting the 50 amp extension cord route. For adapters, I supposed I'd just get 50amp receptacles, with an assortment of plugs (ex: from evseadapters.com)? Then I'd dial down the amperage to 24, if I was charging off, say a 10-30,,,correct?
 

bevguy

Member
Jan 24, 2014
81
16
Tennessee
I use extension cords with no problem. But I use appropriate size wire in the. With 14-50 these cables are heavy and not very flexible.Dial down the amps a bit to be safer.
On line calculators are available for sizing, get one with less than 1% current drop at the distance you need and you will be fine. Keep in mind that connectors have resistance too.
 

jrreno

Nothin' left to do but smile, smile, smile
Jul 21, 2013
962
232
Sarasota , Florida
I just verified that my 2012 Leaf 110 charger does NOT work with my 85.
I also have a J1772 Wattstation in my garage that works fine at 240v/30a.
 

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