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Charging the Roadster

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Anecdotally, many of us have found the sweet spot for the Roadster under normal conditions to be around 24A.

I finally got around to installing the Gen-2 HPWC's that I accumulated over the years (one as a referral bonus, one from a Canadian), so I can now charge at 70amps. Previously, my Roadster UMC would crap out over 30 amps, so I had it limited to that instead of the 40 of which it's capable.

So, tell me why I shouldn't just set it to charge as fast as it wants now? Sorry if I've missed some pinned post.
 
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Unless you need to have the charge finish more quickly, I've read that the "sweet spot" for charging is 240v at 24 to 32 amps. Higher wastes power with I2R heating, lower accumulates more of the base "overhead" load because of the longer charging time. 24 amps is plenty quick for fully recovering a day's use overnight.

I was initially limited to 24 amps for charging my car because I was using a clothes dryer 10-30 outlet. When I upgraded my panel to install a full 14-50 outlet (so, 40 amp capable), I kept the lower charge rate as an efficiency measure. The lower current is also kinder to the contactor in the charging station / UMC. The original Roadster UMC 240 is notorious for failures, and until I installed an OpenEVSE, I wanted to go easy on it.
 
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The max rate is way under the minimum C recharge rating so personally as long as it was not getting the PEM hot I would/do charge at max rate.

It used to be part of the Annual Service that they'd try charging the car at 70 amps. Several years ago, the local Service Center put a note in the report that since they no longer had a Roadster HPWC they couldn't test that out.
 
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My PEM was getting warm because of a tired fan so I can see why they would check, it was fine in lower amps, with the new fan it’s crazy cool all the time now. I think high amp charging has a worse effect on the PEM than the battery. We discharge at much higher rates.
 
...So, tell me why I shouldn't just set it to charge as fast as it wants now? Sorry if I've missed some pinned post.
There are lots of opinions on this subject, with some of the experts contradicting each other. I generally agree with the theory (suggested above by X.l.r.8, gregd and others) that it's best to strike a balance between efficiency and keeping heat generated to a minimum. Testing has revealed that the best efficiency is achieved between 24 and 48 amps depending on other conditions. Below 24A and the system overhead losses become a significant factor. Above 48A and thermal management starts reducing your efficiency. All of this depends on other factors. Is the car already hot from driving or high ambient temps? Is it so cold that the cooling efforts will be minimal and you might even save some energy from not having to heat the battery as much after charging? Apparently this can even apply to people in Texas this week!:(

Your question was probably not limited to matters of efficiency. As for what's best for cell life and PEM longevity, less heat is always better. That's an argument for lower amps. Maybe even lower than 24A. It depends on other environmental factors. Are you only adding 40 miles, it's a cool 50 - 60F in your garage, and the pack is not already hot from driving? In that case you're not going to hurt anything by charging at 70A. In fact charging at 70A every day would probably have very minimal impact in my opinion. You'll find lots of opinions on this. ymmv.

It used to be part of the Annual Service that they'd try charging the car at 70 amps. Several years ago, the local Service Center put a note in the report that since they no longer had a Roadster HPWC they couldn't test that out.
Yeah, it's disappointing they don't test that anymore. A few service centers purchased CAN SRs from me so they could continue this test using newer HPWCs after they lost their Roadster chargers. But now most of the 80A wall chargers are disappearing.

The lower current is also kinder to the contactor in the charging station / UMC.
If the charger is working properly the contactor only opens and closes when there's no current flowing. Having said that, you're probably still correct that it's kinder to the contacts to have less current flowing through them when they're closed.
 
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But now most of the 80A wall chargers are disappearing
This is kind of a lame excuse since Clipper Creek still sells their CS100. It is just the J-1772 version of the TS-100 which Tesla Sold as their Roadster High Powered Wall Charger.
It works fine with the J-1772 adapter (either the CAN JR or Tesla's OEM version).
I will note, however, that we've seen overheating issues with the CAN SR when charging at very high currents with an original 80 amp Model S HPWC so the advice to stay around 24 amps is probably still good. We tend to charge between 16 and 20 amps due to current capacity (ampacity?) in our garage.
 
Greetings all. My roadster recently stopped charging. I use the yellow 110v cable. The ring light is not lighting up. Current range is 35miles. I have been told it is a likely bad cell or two and I should send car from Michigan to west coast for rehab. Looking for any advice on trouble shooting I can do to get some charge on it so it doesn't go to zero range. Lot's of great info on this thread, just not sure where to start. Perhaps trying to charge at 220v would help?

 
Greetings all. My roadster recently stopped charging. I use the yellow 110v cable. The ring light is not lighting up. Current range is 35miles. I have been told it is a likely bad cell or two and I should send car from Michigan to west coast for rehab. Looking for any advice on trouble shooting I can do to get some charge on it so it doesn't go to zero range. Lot's of great info on this thread, just not sure where to start. Perhaps trying to charge at 220v would help?

I glanced at your debug photos, while not an expert, I don't see anything that makes me think you have a bad cell or bad brick. The yellow cable is somewhat infamous for failing, specifically the GCFI module which is part of the plug that goes into the wall. If you press the buttons on it does it cycle? If not that's likely the cause for the car not charging. You can also just swap to the 240 cable and see if the vehicle charges, again if it does, its probably the GCFI end on the low voltage cable. If that seems to be the issue, you can easily replace the plug end (either with a regular plug rated 15 amp, or a GCFI end rated the same) on the yellow cable and it should work fine again.

Again, not an expert, but that's all easy enough to check.
 
When you open the flap does the ring lite up white. And then nothing when you plug the charger in. If so then swap the gfci plug for a standard one and try again. The on board diagnostics will usually tell you if it’s not charging due to an ESS fault and give you a red ring. But if it’s not recognizing the cable is plugged in, then suspect the cable.
 
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+1 for the above and, the other options include but are not limited to...

1. Open and close your charge port at least ten times in quick succession to 'reset' the system.

2. If you have no reaction to the cord then, yes, it's likely the GFCI. I (and I stress I ) would cut the GFCI off and wire the cable into a regular 120V plug - I did that about 10 years ago, no issues since.

3. Phone a friend, try their cord.

4. Make sure that extended errors are enabled and search for the any code shown on the site here.

5. Call Grubber.

Good luck!
 
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