Charging rate changing, going low/slow, then high ... ?

[Oldrocky]

Hi,
I was sitting in my Model X at a supercharger last night. The location has 10 spots and over 8 of
them were in use. I watched my charging rate - repeatedly - drop down to very low rate and then
pop back up to 'normal' (about 100 miles per charging hour). The low drop times were going
down to 20 and even 10 miles per charging hour. It would stay that way for a couple of minutes
and then pop back up. Vehicles were leaving and then someone would use that empty spot.
The low charging rates were not directly related to other Teslas leaving or plugging in to other
stations. I stopped my charging and then replugged. No difference. I've never seen this happen
before (owned car since July).

Is this normal? Is there a problem with my car? With that particular charging facility? With the
individual plug I was using?
- Jim in the PNW

 

[RTPEV]

With the individual plug I was using?

If you ruled out other vehicles as being the culprit (I'm not convinced you did, but let's go with that for a moment), then yes, it's the individual charger (not really the plug) that is the likely issue. In this case you should try to rule that out by moving to a different stall. Occasionally some of the charging cabinets will have individual chargers that go down (and then reset/restart), accounting for the kind of behavior you see.

I'm not sure how familiar you are with the different types of Superchargers (V2 vs V3 vs urban). You didn't say which Supercharger you were at, but if it was at a V2 station, with 8 out of 10 stalls in use, it's hard to imagine that the change in charging speed would not be caused by other vehicles using your shared stall. At a V2 site, the stalls are paired. So for example if you are at 2A, then you are sharing the same charger with 2B. That's really the only other stall you care about. It's possible you were distracted by all the other cars coming and going without any effect, but if stall 2B (in this example) had a car plug in, you are now sharing that single charger with that car. And it may not even be obvious when a car pulls into 2B--maybe it took them awhile to actually initiate a charge.

V3 sites have shared stalls (in groups of 4, not 2, so you would have 2A, 2B, 2C and 2D for example), but if need be, that group of 4 can pull more power from the rest of the site, so that it's very likely that all cars are going to get as much power as they demand.

One other thing is that it would be very useful if you expressed your charge rate in terms of kW instead of mph. When a particular charger inside a V2 cabinet drops out, it drops down by a relatively round number of kW (12kW I believe). Here's an example from a charging session I had once:

The charge started out fine, but after about 2 minutes it started to drop quickly (unfortunately after verifying it was charging at the expected speed, I went into the store). It had dropped down to 70-72 kW, which is 12kW * 5. There were no other cars at the site (or at least not paired with my stall). Once I noticed the slow charge rate I moved to a different stall (not the paired one, since it would have had the same problem).

Your case is a bit different due to the extremely low charge rate you got (I'm not sure what 10-20 mph on a Model X equates to, but it would certainly be 12kW or less), and you stated that your charge rate went back up. The charge rate going back up could be indicative of a charging unit inside the charger resetting (dropping out) and becoming available again (the V2 chargers have 12 12kW charging units inside them), but to drop by a factor of 5-10X would mean a significant number of them failed over and reset at the same time. So this is not the Occam's Razor explanation, but it is possible.

At any rate, as I said, the first thing to try is to try a different stall (just not a paired one at a V2 site). Also check on Plugshare to see if there have been any reported issues with the stall you used (and then put in your own entry to alert other drivers of the potential issue).

 

[Rocky_H]

Is this normal?
Is there a problem with my car?
With that particular charging facility?
With the individual plug I was using?

No.
No.
Yes.
Yes.

I've seen reports like this here on this forum sometimes, and it's just a defective stall or cable. It tries, but has a problem and drops really low for a minute or so and then tries again, but can't and drops really low again. Sometimes there is a bad one. It's rare, but equipment has problems sometimes.

 

[Oldrocky]

Thanks, RockyH ... so does anyone know if there is a way to report a faulty supercharger? I know where this
one was and which one of the 10 it was - just don't know how to tell the right person so it gets fixed ... Jim in the PNW

 

[RTPEV]

Thanks, RockyH ... so does anyone know if there is a way to report a faulty supercharger? I know where this
one was and which one of the 10 it was - just don't know how to tell the right person so it gets fixed ... Jim in the PNW

Supposedly Tesla monitors things like this (and in this kind of case, I would believe that to be the case--this kind of condition should be detectable by the Supercharger itself and it can phone home its status to Tesla). There should be no need to report this, but if it would make you feel better, there is a phone number listed on the stalls.

I would certainly report any physical damage to the connector or other types of outages (like something physically blocking a stall) that wouldn't be detectable by monitoring software.

 

[Oldrocky]

RTPEV - thanks, I'll look to see if I can figure out how to report it. - Jim in the PNW