Spare UMC Availability

I considered that too but I never need to charge away from home for daily use and so far I have only needed to bring the UMC when I go on a trip to my cabin. I bought a HPWC to install at my cabin (when I get around to building a garage) and then I will only need to bring the UMC when going on trips elsewhere. So it seems unnecessary to buy one just to sit in the trunk. It's pretty easy to unplug it for the times when you go on trips. I guess, though, if you do a lot of regular long distant driving to visit relatives, camp, etc. it would make sense. You don't need it for Superchargers or J1772 plugs since you just use the adapter. The price is $650:

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I did - and very happy I did.
Always caring one UMC in the car and the other connected permanently in the garage. the one in the car is used when I visit my summerhouse.
also nice to have a spare if one should break.

Canuck said:

The price is $650:

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That's the price for the whole bundle. The OP is correct that some people have reported getting just the UMC (no adapters or case) for less, definitely less than $500, but I don't remember the exact price. Hopefully someone who has actually bought this can chime in.

markb1 said:

That's the price for the whole bundle. The OP is correct that some people have reported getting just the UMC (no adapters or case) for less, definitely less than $500, but I don't remember the exact price. Hopefully someone who has actually bought this can chime in.

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$480 for just the UMC.

For the record, and only because this has come up several times, you cannot put a J1772 plug on an a normal power cord and use your J1772 to Tesla adaptor to charge the car. It doesn't matter what the Service Center told you; it won't work.

I bought the whole adapter bundle just to have a spare 14-50 adapter too. I leave it in the trunk.

Just wondering if anyone here has directly wired the UMC up like the HPWC? I believe the UMC knows how much power it can draw based on the adapter that is attached. Direct wiring would provide the UMC without any info.

smsprague said:

Cosmacelf - have you ever used your spare UMC

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Yes, when I go on trips.

David99 said:

Just wondering if anyone here has directly wired the UMC up like the HPWC? I believe the UMC knows how much power it can draw based on the adapter that is attached. Direct wiring would provide the UMC without any info.

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Right, you would have to take care of the signal wire. But it is just a resistor between the signal wire and ground that tells the UMC the allowable amperage draw. So if you were hard wiring your UMC, it wouldn't be hard to do at all. I don't know anyone who has done it, but it is an interesting idea. It completely removes the adapter and plug as failure points.

Cosmacelf said:

Right, you would have to take care of the signal wire. But it is just a resistor between the signal wire and ground that tells the UMC the allowable amperage draw. So if you were hard wiring your UMC, it wouldn't be hard to do at all. I don't know anyone who has done it, but it is an interesting idea. It completely removes the adapter and plug as failure points.

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That makes sense. Adding the right resistor should be easy. Good to know!

I keep a spare UMC in the trunk and the other UMC semi-permanently affixed to a NEMA 14-50 in the garage. When I travel, I bring both because I don't want to be stranded in case of a UMC failure on the road. I also figured that I wanted an extra one at home because my car would quickly become inoperable if I had to wait for a replacement UMC. I'd like to believe that our local service center would always have an extra UMC for sale, but it's not a chance I'm willing to take.

TonyWilliams said:

For the record, and only because this has come up several times, you cannot put a J1772 plug on an a normal power cord and use your J1772 to Tesla adaptor to charge the car. It doesn't matter what the Service Center told you; it won't work.

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Interesting. For Europe, with the type 2 connector, there are actually two different connector shapes for 'mode 1' (dumb cable) vs. 'mode2/3' (EVSE signalling available power), such that you can't plug a mode 1 cable into a car that isn't built to accept it.

BUT - Tesla appear to have fitted the connector that accepts type1 cables to the euro-spec Model S.

Photo of Tesla inlet here, standard mode2/3-only inlet here.

I bought a second UMC bundle. One stays in the trunk. The other is left plugged into the 14-50 outlet in my garage. I did this so that I wouldn't go on a trip that would need the UMC only to discover that I had forgotten it in the garage. I've used the UMC in the trunk a couple of times when away from home.

arg said:

Interesting. For Europe, with the type 2 connector, there are actually two different connector shapes for 'mode 1' (dumb cable) vs. 'mode2/3' (EVSE signalling available power), such that you can't plug a mode 1 cable into a car that isn't built to accept it.

BUT - Tesla appear to have fitted the connector that accepts type1 cables to the euro-spec Model S.

Photo of Tesla inlet here, standard mode2/3-only inlet here.

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You've not shown a Type 2 Mode 1 inlet or plug yet you say the Tesla inlet is similar to it. The only difference I see is the triangle key above the PE pin. Presumably the Supercharger handle has a protrusion that fits in that triangle such that it is impossible to plug the Supercharger into a standard Type 2 inlet on another type of car.

I bought a second UMC just before I went on a long trip. There was a period of time where UMC's (not the adapters) were failing. The SC told me that they would FedEx a replacement UMC to me in the event my unit failed while on the trip, but it would take a day. Just for piece of mind, I ordered a spare unit, and took both with me. I still have not used the spare unit (have the car for a year now), but consider it my insurance policy so as not to get stranded due to a broken UMC.

BTW, I also ordered an extra 14-50 adapter with it.

David99 said:

That makes sense. Adding the right resistor should be easy. Good to know!

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40 amps - 9.08k ohms

24 amps - 33.16k ohms

16 amps - 75k ohms

12 amps - 140k ohms

I looked at a bunch of options a year ago and came to the conclusion that the HPWC is the cleanest, safest solution for my garage. No adapters to mess with and only one mechanical connection (at the car itself). I dislike the UMC because it has 3 mechanical connections (wall plug, adapter and car) plus the UMC module itself is on the cable. More points for stress and potentially failure. The experience with the 14-50 adapter recall kind of makes my point here. Sure the HPWC costs more but so does the car.