warranty exchange ...
(the EVSE not the car :biggrin
This is the second MC240 that has not worked, so I thought it worthwhile to ask if anyone had any other ideas.
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Charging the Roadster
- Thread starter malcolm
- Start date
This is the second MC240 that has not worked, so I thought it worthwhile to ask if anyone had any other ideas.
Explain "not worked" ... did it work and then fail ? Did it behave oddly ? Did the two MC240s show the same symptopms or sequence of symptoms ( in your prior post you said "has never worked" for the current one ) ? What are you plugged into ? Are you sure the wire/breaker is properly rated ? Are other loads on that circuit ? Have you tried using the MC240 on a completely different circuit (even go to an RV park, for example) ? etc etc ...
Neither MC240 has ever worked. The car gives an "External charging error" message after a few seconds each time. The problem occurred even when I dialed the car down to 16 amps. Nothing else is on the same circuit at the same time as the MC240, but another high-draw device works fine on the circuit when the MC240 is unplugged and the other device is plugged in. The circuit breaker does not trip. I had an electrician check out the circuit.
I have asked some of my neighbors, but have not located any with a 14-50 socket. I guess I will have to go to an RV park
I don't have an MC240, but I do believe it has some indicator lights on it. Any unusual symptoms there ? Did the electrician who "check[ed] out the circuit" also install it ? It's possible neutral and ground are reversed ... which the other "high-draw device" may not care about ... what is that device ? ( Still best to try an RV Park. OR, depending on your location, there are some 14-50 locations listed at EVCN. )
samcarney
Sam C
I would check the ground circuit. Sometimes when the wires are run in conduit there is not a separate ground wire to the 14-50 outlet, the pipe becomes the ground. If this is the case a ground wire from the outlet back to the circuit breaker is needed (preferred), or at the least connect the ground blade of the plug to the conduit box with a suitable sized wire.
Agreed. we are too efficient here. :smile:Try finding that in 39 pages of messages!
Doug
30A at 240V is the charge time vs battery life happy point. I charge (for now) at 240 at 16 amp just fine for me except those times I come home late with a low charge. Just a bit more would be nice.
tomsax
Member
Tesla Roadster Charging Rates and Efficiency
I just posted the results from studying charging rates and efficiency with our Roadster. The study shows graphs of what charging looks like, how current tapers at the end, compares rates and efficiency at different amp limits, and shows both range mode and standard mode charge profiles. If other Roadster owners have done or want to do the same, I'd be interested to compare results.
As for battery longevity, Tesla's blog A Bit About Batteries (or the original version with Martin and JB on the by-line and much better formatting) explains Tesla's battery strategy and says that even at 70A, we're well below the threshold where charge rate harms battery longevity.
That battery blog explains what to expect from the battery pack and how to treat it well. It should be required reading for all current and potential Roadster owners.
Is there better data to support charging at lower rates? I've been charging at 40A because I think it should be better, but I don't have any data to support that.
I just posted the results from studying charging rates and efficiency with our Roadster. The study shows graphs of what charging looks like, how current tapers at the end, compares rates and efficiency at different amp limits, and shows both range mode and standard mode charge profiles. If other Roadster owners have done or want to do the same, I'd be interested to compare results.
As for battery longevity, Tesla's blog A Bit About Batteries (or the original version with Martin and JB on the by-line and much better formatting) explains Tesla's battery strategy and says that even at 70A, we're well below the threshold where charge rate harms battery longevity.
That battery blog explains what to expect from the battery pack and how to treat it well. It should be required reading for all current and potential Roadster owners.
Is there better data to support charging at lower rates? I've been charging at 40A because I think it should be better, but I don't have any data to support that.
MC240 update
SamCarney and ChargeIt, thank you for the input. The problem is in my household circuit, not in either of the MC240s.
I took the MC240s to an RV park and they both worked
I have not gotten to the bottom of what the wall plug problem is, but your suggestions that I check out the grounding looks promising.
SamCarney and ChargeIt, thank you for the input. The problem is in my household circuit, not in either of the MC240s.
I took the MC240s to an RV park and they both worked
I have not gotten to the bottom of what the wall plug problem is, but your suggestions that I check out the grounding looks promising.
I'm not 100% :biggrin: sure what that refers to, but it might be a "Storage Mode", which was initially meant to keep SOC around 50%. Remember the article is published late 2006 before any cars were ever delivered. Storage Mode with current firmware doesn't go that high, and so this mention of 50% is likely obsolete.I noticed in the blog Tom linked to that it says (emphasis added):
I thought the "Normal" mode charged it ~70% and the "Range" mode charged the battery to ~90%. Does the "normal" charge mode really only charge the batteries to 50%?
Normal mode (properly, "Standard Mode") is 90% (nominal) at the top, and hides the bottom 10% (giving you 195 miles or 80% of the advertised max. range of 244). Range Mode is 100% (nominal). Actual % depends on balancing and age/use. And remember, this 90%/100% is the already reduced/protected charge levels (i.e. 4.10v=90% and 4.15v=100% in the article). 4.20v is "verboten" and represents an over-charge (more than 100%).
tomsax
Member
I thought the "Normal" mode charged it ~70% and the "Range" mode charged the battery to ~90%. Does the "normal" charge mode really only charge the batteries to 50%?
The full charge is Range Mode, with safety buffers above and below. Standard mode charges to about 90% of Range Mode, and hides the bottom 10%. Storage Mode charges to about 50% of Standard Mode.
If you're going to leave the car for more than a few days, you can put it into Storage Mode and it won't charge until the charge level drops to 50%, then charges just enough to keep it around 50%. Last time we took a big trip, we left the car with a near full Standard Mode charge, set it to Storage Mode and plugged it in. When we got back 3 weeks later, it was just a bit above 50% and had never needed to charge.
I don't think it will start charging at 50%; I believe it will drop significantly lower before the charger kicks in. Also, if you start from a very low charge ... it won't go up to 50%. And again, as I said above, the article is older, and firmware updates (based on revised strategies ?) likely have superseded what is being described in Nov2006 regarding the "50% mode".
That's interesting. So over 3 weeks you lost about 90 miles of range? I wonder how that compares to the boil off rate of for HFCVs using liquid hydrogen. (In the lab, our 100 liter liquid helium dewars seem to lose about a liter a day.)
tomsax
Member
I should have looked up the facts before making that post. Over 25 days, the charge dropped from 75% (144 IM) to 58% (112 IM).
JRP3
Hyperactive Member
That must be due to the car still being "active" and using power, since self discharge of lithium is pretty low. Unless LiCo is higher than LiFePO4, I had LiFePO4 cells sitting in my basement for 6 months and they went from an average charge of 3.27 to 3.24.
Planning for my car, I think the NEMA 6-20 configuration has some nice properties. About 4kW, plug is as easy as a typical house plug. About 16 mi/h charging. Easy to install a receptacle, say at friends' or family houses. 12/3 gauge extension cords can be adapted easily.
Until on the road chargers are plentiful, this isn't a bad option.
tomsax
Member
It's probably obvious, but you do want to be cautious here. It's more than just replacing a receptical. The receptical is just the indication that the wiring and circuit can safely deliver 20A and thus is safe for supplying 16A for extended periods of time. You really don't want to be pushing 15A wiring to 16A for 10 to 12 hours per night for months or years.
Where did you get the 16 mi/h number? Charging from a NEMA 6-20 (drawing 120V/16A) will yield about 6 mi/h, assuming the ambient air temp isn't too high. That's still 60 miles if you charge 10 hours overnight, which is well above most people's average daily driving. I know some Roadster owners were unhappy with that setup, but I think others have made it work. It all depends on your daily driving, and how much joyriding and demo driving you'll want to do.
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