I doubt it is a configs file. Probably hard coded in the code. Some SOFTWARE engineer didn't realize there are 120V sources that deliver greater than 20A. So he decided to hard code a limit for safety reasons. That's my guess anyways. Let me know if you're interested in building that TT-30 combiner.
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Tripple_T
Cincinnati Member
I would be interested in the combiner. How do you ensure you have two different poles and not the same one?
I would think that a hard coded setting in the software would be the same across all MS and would be more likely to have been updated with a software release. I could see a firmware in the chargers that could be hard coded. I was under the impression that the firmware was able to be updated over the air as well though.
I would think that a hard coded setting in the software would be the same across all MS and would be more likely to have been updated with a software release. I could see a firmware in the chargers that could be hard coded. I was under the impression that the firmware was able to be updated over the air as well though.
I'll track down my schematic, but basically I used three relays and a 240V indicator lamp. Two 120V relays are there to ensure that no power flows to the output unless both plugs are plugged in (otherwise you'd have a shock hazard since the Tesla and UMC completes a circuit), and the 240V relay ensures no power flows unless you are plugged into two separate legs of the electrical panel. It's pretty straightforward and works well.
snort
Member
I was able to get my 85D to take 24A @120V. So it's apparently been fixed in later versions. (I've been having a lot of fun building adapters and devising schemes to test them, starting out from Cosmac's article. Suggested improvement: be a little more clear on polarity issues where it matters. I suggest an actual picture of the inside of a NEMA 14-50r with black and whites in place. I'd also like to promote my amperage-limiting scheme (24A sources go only to 24A adapters (10-30) or less.))
I'm only slightly likely to build one but I'd like to see your combiner schematic. I'm very curious what the circumstances might be that would put two phases close enough to each other that such a thing would be useful, but not actually present them for access with a 6-, 10- or 14- receptacle. where does this happen? how long of a TT-30 extension do you need in these circumstances?
--Snortybartfast
Cottonwood
Roadster#433, Model S#S37
The limit is a little more than firmware. Older Model S's have the 20 Amp 120 Volt limit, but newer ones do not.
See "It IS possible to charge at 24A from a 120V TT-30 plug... - Page 5" for more info and examples...
In most cases, true; in some cases, there are failure scenarios in ground-handling that can leave certain parts of the device floating at line voltage. You're unlikely to encounter them if you use a plastic box for the combiner, rather than metal. It has to do with return path for current where the neutral is compromised (something I run across with reasonable frequency in campgrounds).
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Depends on how the campground's electrical system was designed and they're all over the place. I've seen some cases where 240V is run to a campground box, but the TT-30 runs from L1-N and they use L2-N to feed both line conductors on the 14-50 (you get 120V but not 240V in this case). I've seen some cases where a 3-wire 240V feed (L1/L2/N) is provided and every other pedestal alternates between L1/L2, not offering 240V. Newer campgrounds tend to get it right with a 4-wire feed to each pedestal, 240V on the 14-50, and TT-30 on L1 / 5-20 on L2.
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As I was reading this thread, I thought of another optional question you might try to ask as part of a future part of this poll...
"What percentage of your AC charging is done at the following currents: 120V/12A, 120V/16A, 240V/0-29A, 240V/30-39A, 240V/40-49A, 240V/50-79A, 240V/80A" Give them entry boxes that must add to 100% if possible. This might give you data for not only the mode (HPWC, etc.) but also the magnitude of charging...
You might also ask if dual chargers are equipped (can't remember if you have that or not).
Yes, my combiner box was built with two 25' cords in a plastic box. So the outlets could be about 50' away from each other. I put TT-30 ends on the cords, but also bought TT-30 to 5-15 converters so that I could use the box on regular 120V household circuits, and indeed I've charged a few times using the box that way (the condo had a non-GFI plug in the garage for a hot water recirc pump and then there was a plug in the nearby laundry room).
The non-GFCI circuits are getting less and less accessible to the garage now for new construction... 2014 code eliminated a lot of the exemptions, and now requires GFCI in laundry rooms too.
How'd you handle grounding? Only use one of the grounds? Or tie them together?
That's the safest way to do it, otherwise your box ends up becoming a return path for current through the pedestals, between the grounds (where the campground uses 3-wire feeders).
Thanks for the effort.
I'm curious, CHAdeMO is currently 7th in your rankings. Why did you choose to list it in second place?
Larry
Do-It-Yourself 240v from two separate 120v outlets:
Do It Yourself: 240v from two 120v sources - My Nissan Leaf Forum
Do It Yourself: 240v from two 120v sources - My Nissan Leaf Forum
CHG-ON
Still in love after all these miles
Poll is closed, so I can't vote. In the US, I use Superchargers most, regular 120V when at my sister's staying a few days, ChargePoint, in that order for now. I haven't gotten a Chademo because the plug is so ridiculously expensive. What gives with that?
Many reasons. The Chademo plug itself is huge, complex and expensive all by itself. I would bet that It costs Tesla $150 just to buy the Chademo receptacle. There are some fancy analog and digital electronics in the unit to do the conversion, and umpteen engineering man hours testing the unit for compatibility with about 20 different Chademo manufacturers worldwide. Frankly, I thought $1000 was a good price.
Hmm, I thought I had posted my home made 120V combiner schematic and pictures to another forum somewhere but now I can't find the link. Lost in the Internet. Ah well, here's how I rigged my 120V combiner. Inputs are on the left, output is on the right. As FlasherZ recommended, just use the ground from ONE of the 120V sources to connect to the output ground.
Also not shown, is a 240V indicator lamp I wired across the output 240V hots. Pictures to follow...
Also not shown, is a 240V indicator lamp I wired across the output 240V hots. Pictures to follow...
...and, please read the warnings about this in the FAQ (link available in my forum signature below, or at the following link):
FAQ: Home Tesla charging infrastructure QA
(Use it for emergencies only and recognize there are some failure scenarios that will make devices like this dangerous... do not use it daily. It may come with insurance and/or liability implications.)
FAQ: Home Tesla charging infrastructure QA
(Use it for emergencies only and recognize there are some failure scenarios that will make devices like this dangerous... do not use it daily. It may come with insurance and/or liability implications.)
I used a 4x4x4 plastic gray electrical box from Home Depot to house everything. I bought a 50' 10 gauge extension cord, cut it in half, and used that for the 120V inputs, ending in TT-30 plugs, which I can adapt to NEMA 5-15 plugs as shown. I used a NEMA 6-50 receptacle as the output since it fit in the box the best. And finally, you can see a small green indicator lamp that only lights up when I have plugged into two different legs.
Here's the back of the NEMA 6-50, showing how I used the ground from just one of the 120V inputs for the 6-50 output. I wired the 240V indicator lamp between the 6-50 hots.
And here's the inside. I screwed the three relays to the bottom of the box and used crimp on connectors to connect everything together.
Here's the back of the NEMA 6-50, showing how I used the ground from just one of the 120V inputs for the 6-50 output. I wired the 240V indicator lamp between the 6-50 hots.
And here's the inside. I screwed the three relays to the bottom of the box and used crimp on connectors to connect everything together.
snort
Member
Thanks Cosmac, that's just what I wanted to know.
What's the indicator you used? I see you've connected it between Gnd and one of the hots on the 6-50 so it must be ok if it sees >125.... not an LED, or maybe an LED with a resistor.
What's the indicator you used? I see you've connected it between Gnd and one of the hots on the 6-50 so it must be ok if it sees >125.... not an LED, or maybe an LED with a resistor.
snort
Member
I have a 14-50 at my condo, but I built an adapter that gives me both a 10-30 and a 5-15 from the 14-50. From the little one, I trickle charge an ICE that I've used 4 times since I got the Tesla and was surprised to find I'd drained a relatively new battery. About half of the joules the Tesla drinks are coming in at 216V24A. If I need to go faster for some reason I could unplug the ICE and go at 40A, but I haven't needed it yet, or even come close to it. the rest are coming from an 80A HPWC, occasional J1772s and superchargers.
I used to use a 5-15 that I shared with a bunch of fluorescent lights, but the car wouldn't take more than 7A from it and even then would panic and shut down now and then...most often around 6:30AM. I'm guessing when everybody else in greater seattle woke up and turned on their coffeepots, causing the voltage to drop faster than the grand coulee powerplant could spool up:wink:. So I paid to get the 14-50 put in. involved drilling a hole in a post-stressed concrete floor, so it was expensive.
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