anyone ever extended their UMC?

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.

qwk said:

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.

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

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.

ajw said:

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.

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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.

ajw said:

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.

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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.

jrreno said:

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.

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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.

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tomas said:

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.

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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 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

tomas said:

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.

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+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.

qwk said:

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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.

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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 said:

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.

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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.

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.

Tony, slightly off topic but is there any reason the Leaf 110v charger would not work with the Model S, other than being very slow?

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.

jrreno said:

Tony, slightly off topic but is there any reason the Leaf 110v charger would not work with the Model S, other than being very slow?

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The 2011-2012 LEAF charge cords likely will NOT work.

The 2013 and newer cords will. Both are produced by Panasonic, however the later year ones are made by a different division.

TonyWilliams said:

The 2011-2012 LEAF charge cords likely will NOT work.

The 2013 and newer cords will. Both are produced by Panasonic, however the later year ones are made by a different division.

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Do you know why the 11-12 cords don't work? I thought J1772 was J1772...

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.

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.