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Spare Mobile Connector a waste?

Discussion in 'Roadster: Technical' started by smorgasbord, Jun 29, 2011.

  1. smorgasbord

    smorgasbord Active Member

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    I wish I had insisted that Tesla not deliver me the standard "Spare Mobile Connector" and instead sell me the NEMA 5-15 adapter for the UMC.

    Would I ever carry just the Spare Mobile Connector? No. But, if I'm traveling to unknown places, I want the ability to charge via either 220 or if 110 if that is the only thing available. So, now I'm carrying two cables instead of one cable with 2 adapters. It's a waste.

    Am I missing anything?
     
  2. Kevin Sharpe

    Kevin Sharpe Active Member

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    I think it's useful to carry both cables because if you have a failure in the UMC while traveling then you are completely stuffed... think of it as redundancy.
     
  3. S-2000 Roadster

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    I leave the UMC in my garage, connected to 240V/50A service, and carry the Spare Mobile Connector in the car at all times for unexpected emergency charging. In that sense I don't find it redundant at all.

    When I travel out of town, though, I bring the UMC. Thanks for pointing out that the NEMA 5-15 adapter might be a good purchase consideration. Now that you mention it, I might prefer to leave the Spare Mobile Connector at home if the trunk space is getting tight (as it is wont to do). I'm sure the UMC 5-15 adaptor is much smaller.
     
  4. tennis_trs

    tennis_trs 2010 2.0 Roadster Sport

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    Is there really a NEMA 5-15 for the UMC? It seems like some of the info on the Tesla site at least implicitly indicates that the UMC only supports 240V, even though it looks like they sell NEMA 5-15 and 5-20 adaptors.
    This page:
    Universal Mobile Connector - Available in North America Only Tesla Motors
    Says 208-240 or 240V everywhere. It only shows 8 instead of 10 adaptors in the one picture, but then it calls out 10 adaptors and shows the 5-15 and 5-20 in the list of charging times.
    This page:
    Universal Adapters - Available in North America Only (charging) Tesla Motors
    Also shows just 8 adaptors in the picture and indicates 240V in the text, but shows the 5-15 and 5-20 in the list of charging times and the pulldown seems to let you buy them.

    I expect that I'll eventually want the 5-15 adaptor, but haven't gotten around to determining if it really is available.
     
  5. Doug_G

    Doug_G Lead Moderator

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    I keep the Spare Connector in my trunk as an emergency backup. I never even took the cable ties off of it until recently, when I had an overnight stay in a hotel. Hotels can often accommodate you with 110V if you call ahead. My record so far is three hotels, three plugs, although in all three cases it took "special" parking arrangements. I'm 0 for 3 on 220V.

    Although it is slow as molasses, I have found 110V 12A does add usable range on an overnight stop. In a recent two-day stay it topped me all the way up! On my last road trip I encountered a defective NEMA 14-50 circuit, and I would have had a big problem except that I had accumulated an extra 50 ideal km at the hotel the night before.

    After this experience, I will always take the opportunity to plug into 110V even if I don't think I need it.
     
  6. Jaff

    Jaff Active Member

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    #6 Jaff, Jun 29, 2011
    Last edited: Jun 29, 2011
    A few weeks ago, I travelled around 240 kms to the cottage for a long weekend...I only had the Spare Connector to charge back up (as I had no access to any larger type of circuit).

    I was virtually plugged in all weekend, but I did make 3 small trips into the local "one horse town" to pick up supplies (and wow the locals) :biggrin::wink:

    Without the spare connector, I couldn't have made the trip.

    It is slow, but it is peace of mind!

    Besides, I use the Spare Connector to keep my battery pack warm when parked outside in the winter...that in itself (warm pack = no loss of regen braking) is worth the cost of admission for me.
     
  7. smorgasbord

    smorgasbord Active Member

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    Have Cables will Travel

    Here are the cables I think I need to travel with (L to R, T to B):
    J1772 Adapter
    UMC with NEMA 14-50 adapter plug
    Spare Mobile Connector with outlet cube for ChargePoint boxes
    Homemade NEMA 14-30 plug to NEMA 14-50 outlet
    Homemade NEMA 10-30 plug to NEMA 14-50 outlet

    [​IMG]

    Here they are not fitting into the bag:
    [​IMG]

    This collection must weigh at least 18 lbs. I could save some space/weight by getting Tesla 14-30 & 10-30 adapters, but the house I'm visiting in a couple of weeks has a dryer room across the hall from the garage, so I'm thinking I'll make good use of the extra length supplied by my homemade adapters. It was built around the time code changed from 3 wire dryers to 4 wire, so I'm needing both to be safe.
     
  8. S-2000 Roadster

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    Those are a bad idea, at least in the specific combination that you've chosen. It's perfectly fine to adapt from a NEMA 14-50 receptacle down to a 14-30 or 10-30 because you're pulling less current than the rating. But what you've done is made it possible to pull 40A from receptacles that are only designed for 24A!

    I recommend that you spend the measly $200 to get the two UMC adaptor cables from Tesla for 14-30 and 10-30. Then, when you plug in those adaptor cables to your UMC, the charging system will automatically limit the current to what is safe for all connectors. You probably spent more than $100 on the parts, not to mention your labor!

    All it takes is to forget one time to manually change your charge settings and you could either trip an inaccessible breaker and be stuck without any charging current at all, or worse you could start a fire.

    Well, there you have it: you could save weight and have a foolproof setup.

    Note that extension cords are not recommended, because sometimes there is a voltage loss.
     
  9. smorgasbord

    smorgasbord Active Member

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    Yeah, I should have stated that I'm fully prepared to set the appropriate amperage limit manually via the VDS.

    The wire in the UMC is heavy enough for 40/50 amps, so at 24/30 amps I'm not worried about voltage loss with the extension (which is also quite substantial). From the layout of the house, I'm going to need the extension, so if the foolproof setup doesn't reach the outlet that would be pretty foolish as well.

    The UMC is the heaviest component by far.

    The Spare Mobile Connector is just lame, IMHO. It should at least have an option to pull 16 amps on 20 amp circuits instead of only 12 amps on 15 amp circuits. But, you need the UMC for that. The Spare Mobile Connector makes sense if you're charging during a long period of time where you know 110 is the only option available (like at work). Then, it's good to not have to lug the entire UMC around, and risk getting it stolen.

    Hopefully, something like J1772 will appear in more and more places, so that on road trips I could confidently take just that. Someday, maybe.
     
  10. S-2000 Roadster

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    The Spare Mobile Connector pulls 15A by default. That's pretty damn close to the 16A limit of a 20A circuit. You have to manually drop that to 12A from the charging screen. I discovered this the hard way when charging my Roadster repeatedly tripped my 15A breaker. Manually lowering the charging current to 12A made me much less jumpy (i.e. I didn't have to keep checking that the car was still charging).
     
  11. smorgasbord

    smorgasbord Active Member

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    OK, so it's not quite as lame as I thought. Thanks for the info on amperage pull.

    At 110 volts and 15 amps, we're getting something like 6 or 7 Ideal Miles per hour?
     
  12. S-2000 Roadster

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    Granted, I pretty much only charged my Roadster with the Spare Mobile Connector on my first day. After that experience - and it didn't even reach a full charge before I woke up and wanted to drive again - my immediate decision was to install a NEMA 14-50 in my garage for faster charging. I availed myself of the free charging at the Tesla Store and then headed to the hardware store to buy everything I needed for the UMC. By the end of my second day with the Roadster I was charging at 40A!

    Still, it's nice to have the Spare Mobile Connector as a fallback. When I had to rework my 50A circuit wiring, I used the Spare Mobile Connector to charge the car while I worked on the high-capacity circuit. I've yet to use it away from home, though, even though it lives in the car just in case of an emergency.
     
  13. W.Petefish

    W.Petefish Active Member

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    Remember Ohm's law:
    I=V/R
    Where V is voltage potential drop, R is resistance, and I equals the current in amps.

    From what it looks like the resistance across, what appears to be, 12 gauge wire is 0.015880 ohms per 10'. That gives you a voltage drop of ~2-3 volts per 10' or 1%.

    I would be more concerned about the wire heating up. Which as you pointed out -is- a fire hazard.:scared:

    On a personal note: Has anyone else had a GFCI trip because you plug in the spare connector?
     
  14. S-2000 Roadster

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    Also, don't forget that the plug pins and receptacle sockets are not perfect conductors, and thus every plug in the path can drop the voltage. Since the Tesla Roadster pulls the same current regardless of voltage, it's not as bad as it could be - other electronics will heat the cable even more when the voltage drops.
     
  15. W.Petefish

    W.Petefish Active Member

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    #15 W.Petefish, Jun 29, 2011
    Last edited: Jun 29, 2011
    Too true.

    Even at those acceptable voltage drops, I would put a cap on an extension cord length of 25' at 6 AWG at 220v and only for short periods. (thats my welder's extension cord)

    For the Spare Connector, I limit my runs with heavy extension cords to 25' or less.
     
  16. S-2000 Roadster

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    On that note, the Tesla manual states that no extension cord should be used at all. My garage (rental) came with a really crappy 5-15 outlet that looks like it's about to fall off. With the default setting of 15A/16A, my Roadster actually canceled my first charge attempt claiming that an extension cord was detected. I think they noticed the voltage drop below 106V and flagged an error. I wasn't surprised considering the poor quality of the garage wiring. I re-seated the plug and had no further problems, but it tells me that a good connection is needed if you want to use an extension cord.
     
  17. W.Petefish

    W.Petefish Active Member

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    Right, I made my 120v extension cord with 10-3 wire. It also helps to have a local utility run just about exactly 120v.
     
  18. S-2000 Roadster

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    In my case I have 245V or 122.3V at the breaker box, so that 106V reading represented a very poor connection!
    My Tesla Roadster is perfectly happy with the 245V (via UMC). Just so long as it stays below 250V (249.992V if the VehicleLog format is any indication of the design limit).
     
  19. scott451

    scott451 KWH-PWR#1349Sprt,S Sig#96

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    #19 scott451, Jun 30, 2011
    Last edited: Jun 30, 2011
    Actually, (with a little help from Martin's blog) you can make really nice 24A NEMA 14-50 charger:

    attachment.php?attachmentid=2062&d=1309451228.jpg
    I use the above modified SMC for 95% of my charging. (The others? a MC240 modified for 40A and an AVCON modified for 36A at work)

    For most overnight trips, I just bring a small ziploc bag with a variety of plug pins. With this small collection I can charge @ 24A from NEMA 14-50, 14-30, 6-50, 6-30, 10-30, 10-50. The neutral pin is not used (therefore I removed it) so the Yellow NEMA 14-50 plug will work in a 30A or 50A outlet.

    PS I know someone who would gladly pay you $300+s/h for your SMC. sell your SMC, buy the $100 UMC->120V adapter and pocket $200 :)
     

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  20. W.Petefish

    W.Petefish Active Member

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    I need to, as probably the rest of us, make a kit like that.
     

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