Odd charging behavior (seen in logs)

[gregd]

Hi folks,

Only seen this once, but wonder if it was "normal" for the car, or the charger, or ? Seems wrong, and potentially battery-stressing.

I managed to snag the one charging spot at the city hall a week ago, and hooked up to the Clipper Creek unit installed there. I don't know the specific model, but it worked wonderfully via the CAN-JR adapter from hcsharp. After the meeting (about 9pm), I disconnected and drove home. Nothing seemed amiss.

Then today I looked back at the logs (a roughly-monthly ritual, highly recommended), and see that after the main charging, there were a whole bunch of very short charging events, almost like a "top off" was continually being requested (it wasn't).

What's going on here?

07/08/2016 18:48:13 - 07/08/2016 20:31:29 (01:43:16) Charge 68% -> 83% 236V 33A of 32A 12.3 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:32:06 - 07/08/2016 20:33:41 (00:01:35) Charge 83% -> 84% 235V 26A 0.1 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:33:51 - 07/08/2016 20:35:26 (00:01:35) Charge 84% -> 84% 241V 24A of 32A 0.1 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:35:35 - 07/08/2016 20:37:09 (00:01:34) Charge 84% -> 84% 241V 23A of 32A 0.1 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:37:18 - 07/08/2016 20:38:54 (00:01:36) Charge 84% -> 84% 238V 25A of 32A 0.1 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:39:03 - 07/08/2016 20:39:38 (00:00:35) Charge 84% -> 84% 241V 22A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:40:47 - 07/08/2016 20:41:21 (00:00:34) Charge 84% -> 84% 241V 22A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:42:25 - 07/08/2016 20:42:59 (00:00:34) Charge 84% -> 84% 241V 21A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:43:32 - 07/08/2016 20:44:07 (00:00:35) Charge 84% -> 84% 240V 22A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:44:40 - 07/08/2016 20:45:16 (00:00:36) Charge 84% -> 84% 233V 21A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:46:04 - 07/08/2016 20:46:38 (00:00:34) Charge 84% -> 84% 240V 21A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:46:59 - 07/08/2016 20:47:34 (00:00:35) Charge 84% -> 84% 240V 22A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:48:41 - 07/08/2016 20:49:17 (00:00:36) Charge 84% -> 84% 238V 19A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:49:46 - 07/08/2016 20:50:21 (00:00:35) Charge 84% -> 84% 236V 20A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:51:03 - 07/08/2016 20:52:22 (00:01:19) Charge 84% -> 85% 239V 21A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:52:39 - 07/08/2016 20:53:13 (00:00:34) Charge 85% -> 85% 242V 22A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:53:56 - 07/08/2016 20:54:30 (00:00:34) Charge 85% -> 85% 241V 20A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:54:52 - 07/08/2016 20:55:26 (00:00:34) Charge 85% -> 85% 242V 21A of 32A 0.0 kWh 0.0 Ah 0.0 Ah
07/08/2016 20:55:55 - 07/08/2016 20:56:30 (00:00:35) Charge 85% -> 85% 240V 20A of 32A 0.0 kWh 0.0 Ah 0.0 Ah

 

[wiztecy]

Seems normal to me, the amps taper down towards the end of a charge. Otherwise electrons overflow out of the battery in a sense, like a garden hose full blast on an almost full bucket. You get more water in as you reduce the input so less is wasted, also the cells can take in more voltage at a lower amperage.

 

[gregd]

Seems normal to me, the amps taper down towards the end of a charge. Otherwise electrons overflow out of the battery in a sense, like a garden hose full blast on an almost full bucket. You get more water in as you reduce the input so less is wasted, also the cells can take in more voltage at a lower amperage.

Yes, I saw that the general trend in the amps is going down, and that's expected. But why does the charging register as fully stopping and starting again, with 30 seconds to a minute or so gap in between? I've not seen that behavior before.

One thought... Is this some odd effect of cell balancing? All of my other charging has been at either 240v / 24 amps (home) or 208v / 30 amps (work). This was at 240v / 32 amps, if that matters...

Or, is it a behavior of Clipper Creek chargers? Maybe some auto-restart thing?

 

[hcsharp]

Interesting. A couple of weeks ago I heard from a Roadster owner who had just installed a new Clipper Creek charger in his garage. He described similar behavior. His car charged almost full (within a couple miles) and stopped. Then it repeatedly restarted for short periods before it finally stopped for good. He called Clipper Creek and they said they'd never heard of anything like that. His car does not have the same problem on any other charging station, including other Clipper Creeks. I'd never heard of it either so I wasn't sure what to tell him. I can't remember how he resolved it but if I can find his email I'll ask him.

I recommend you look at your event log and error logs. See if there's any messages associated with each stop and start. Try to find out if it was the charger that stopped each time? Or the car?

 

[BartJ]

Perhaps you had a (corrupted) ovms acc profile active ?
Happened to me before.

 

[wiztecy]

Yes, if your charger is registering a true on/off event that's not the normal charge tapering down and I'd follow Henry's logic on diagnosing it. If the car had a fault, you'd see that on the VMS screen, also I'd suspect the Roadster would abort charging especially if you were doing a std mode charge since the SOC was 84-85%.

Yes, quite odd if the charger is the source of the weirdness.

 

[gregd]

What I posted is all from the logs (per VMSParser.exe). Immediately before is a normal 26.6 mile drive home from work (there were a couple of error 1115 and 1116 errors, which are from a drive train sensor, apparently; now "normal" for this car), a 25 minute partial charge at home (while eating dinner), 5.1 miles drive from home into town, and then the charging log. I wasn't watching it do this - I was inside at the time - but when I got to the car, there were no errors on the VDS, and other than the 1115/1116 errors during the drive home, no errors in the log. Next charging was at home 3 days later, after running a few errands that day. I do not have an OVMS module installed, so this is all the car's or charger's doing.

Since Clipper Creek is right here in town, I am overdue making contact with them anyway... I'll give them a call.

Henry, is there a case # or some other identification that I can refer to, to link the two reports?

 

[hcsharp]

I wasn't able to find the email exchange. I'll look again when I have more time. I never got case numbers or anything like that and I'll have to ask the car owner if I can give you his name.

 

[gregd]

An update... I contacted Clipper Creek, and Charlie remembered the other customer's call, but didn't recall that they actually got to a conclusion about what was going on. Jason, who also has a Roadster, has also seen the behavior on occasion. Their active theory is that it's the car doing its ESS brick balancing, but he will do a bit of digging on the other case history to see if they have anything further to offer. (They had sent out a replacement unit, just in case, so will look at the return to see what was found, if anything.)

Will update here what they report.

 

[hjr]

I am the other Roadster owner who had trouble with Clipper Creek, as Henry recalled. Charging on their Model HCS-40, the car charges full, disconnects and then starts the charge process all over. The relay clicks in and out each time, each cycle lasts 1 minute. I spoke to Charlie at Clipper Creek who also noted that Jason drives a Roadster, and they gave me their theory that the Roadster battery is balancing and sends a signal each time. It is indeed the vehicle that controls the call for a charge and when to stop. For fun I let it go and counted 45 cycles before I got scared.... I do not want to wear out the relay contacts. Over the 45 cycles the car did take more charge - on standard mode it went from 178 miles to 200 miles over the 45 cycles.... so what would happen if you let it go all night - not worth the risk of over charging.

Let me say that Charlie and Jason have been terrific - they have sent a replacement charger to test if it is the charger... will let you know.

But I do not buy that the Roadster is the issue - as my car will charge to full and not cycle on other brands of chargers. Clipper Creek sent me a replacement charger to try but I have not had the electrician out yet to install it... will let you know how it goes tomorrow. I am doubtful that it is the car as the car will stop charging on several other brands I have tried.

it is strange that Clipper Creek made the first HPWC chargers for Tesla. My HPWC works perfectly but not the baby brother.

My theory is this : - the pilot signal of the Roadster does not go to zero after a charge - it stays at a low voltage to indicate that a car is plugged in. When the car calls for juice the pilot goes higher. I think the Clipper Creek is thinking the car is still calling for a charge - it needs to have a lower threshold set so it does not think the Roadster is still calling for a charge when its pilot goes low for an end of charge. maybe the pilot voltage goes low and drifts up a bit, or the charger senses the transition, but then thinks there is a call for charge coming after a bit.

I am not sure how to test this theory. Tech support at Tesla of course does not care about us anymore, and there seems to be nobody with knowledge of the charging protocol that they let us talk to. Our local Tesla techs are fabulous (Milford, CT) but they have no way to measure the pilot voltage when the car is in the charging cycle.

Maybe once I try out the replacement charger from Clipper Creek and report back then Jason and his great team of engineers can dig deeper.

 

[gregd]

Thanks for following up, and great timing! I had an opportunity last week to try charging again at this station, and the results repeated. After the initial charge was completed there were 27 short sessions (most lasting about 35 seconds) over the next half hour. They stopped on their own about a half hour before I returned to the car, suggesting that they really were done, but the number of cycles was very different than the first time I saw this which suggests that it's not a controlled process. It wouldn't surprise me that under slightly different conditions the cycling could terminate earlier or go on forever. Again, no alerts on the VDS, but the charge cycling is clearly shown in the logs. SOC at the end of the initial charge was 84% (usually about 167 miles), and after all the fussing it ended up at 85% (170 miles), so a different result there from what you saw. This was in standard mode. After driving home and charging, the car seems to have settled back to the 167-168 mile level after a 24A / 240V charge. It tends to charge every day or so for about 6 or 7 minutes to maintain that value.

I think you are right about the pilot. Seems like something is happening that causes the Clipper Creek unit to twitch its output, which makes the car think it just got unplugged and plugged in again, triggering another charge cycle. The car likely isn't asking for this, since it doesn't do so on other chargers (ChargePoint at work, or the Mobile 240 at home).

I verified the model of charger is the same - HCS-40 (placard picture, below). I've not heard back from Clipper Creek yet on my initial call, so will call them back and see what they think. One other variable to control for... Is your car a 1.5 or 2.x? I have a 2.0, and I believe Jason's is a 2.5.

 

[hjr]

Thanks Greg. My car is a 2.5 -
Tesla checked it all recently and said my car is fine - but they really have little to measure on this. Since I can charge fine everywhere else it is the Clipper Creek/Roadster interface for sure.

The cycling is clearly noted on my OVMS.

I bought the Clipper Creek with J1772 plug because I have the Roadster and a Model X. I already had Henry's CAN adapter (J to Roadster) the Model X comes with a J to new Tesla adapter so it made sense.

The charger works perfectly with the Model X. I suspect the Model X is more stable in its pilot signal, or its standard voltage for the not charging mode is a lower voltage.

 

[hcsharp]

Their active theory is that it's the car doing its ESS brick balancing,

and they gave me their theory that the Roadster battery is balancing and sends a signal each time. It is indeed the vehicle that controls the call for a charge and when to stop.

While in theory it is the vehicle that controls how many amps to pull and when to draw power and when to stop, it's highly unlikely that this behavior is being caused by the car. This is not how the ESS balancing takes place. Sometimes the Roadster needs more balancing than other times and it will charge a few miles higher than normal (for std mode) but then it will bleed down to something close to your usual std mode miles. When it does this it only charges once without restarting multiple times.

My theory is this : - the pilot signal of the Roadster does not go to zero after a charge - it stays at a low voltage to indicate that a car is plugged in. When the car calls for juice the pilot goes higher. I think the Clipper Creek is thinking the car is still calling for a charge - it needs to have a lower threshold set so it does not think the Roadster is still calling for a charge when its pilot goes low for an end of charge. maybe the pilot voltage goes low and drifts up a bit, or the charger senses the transition, but then thinks there is a call for charge coming after a bit.

I am not sure how to test this theory. Tech support at Tesla of course does not care about us anymore, and there seems to be nobody with knowledge of the charging protocol that they let us talk to. Our local Tesla techs are fabulous (Milford, CT) but they have no way to measure the pilot voltage when the car is in the charging cycle.

To some extent both the EVSE and the car control the pilot signal. The Roadster never pulls the pilot below 6v. If it's plugged in but not requesting power, it will pull the pilot down to 9v and then the EVSE will change the pilot to a square wave. If the Roadster wants to draw power, it will pull the pilot down to 6v on the high side of the square wave. At that point the contactors close and the car will draw an appropriate number of amps. When it's finished charging or heating its battery the Roadster will release the high side of the square wave back to 9v as long as it's plugged in.

I could write pages about the Roadster charging protocol. Especially the 2.x cars because I have one so it's easier to test. If the techs at Milford want to know how to get access to the pilot signal while charging I'd be happy to tell them, or possibly supply a CAN JR with the pilot and ground wires exposed. Same with Clipper Creek. I will only do this if they have an oscilloscope. You can't tell what's going on with a common volt/amp/ohm meter.

I have a theory what might be causing this but it's a long shot. @gregd can you remind me what version is your Roadster?

 

[hjr]

Henry:
Nobody has more experience with the plugs and handshaking than you do - so I am anxious for your evaluation. They would need your CAN J1772 to Roadster most probably since the charger is made with J1772 plug.

Greg said he has a 2.0

I would think Clipper Creek can solve this easily themselves if they decide to look at it. Just takes me and Greg and anybody else who has seen this to talk to Clipper Creek directly. I think this model charger is among their most popular as it is 240V/32A.

 

[gregd]

Yes, my car is a 2.0. I'll contact CCreek tomorrow (it was too close to closing time to call them today), and see what they propose. I think the key point of all this is that the behavior isn't normal, and the good new is that Jason's seen it too (so presumably they can reproduce it in-house). I live only a couple of miles from their shop, so can visit if they desire. The suspect charger is also here in town, just a few miles farther.

 

[hcsharp]

Henry:
Nobody has more experience with the plugs and handshaking than you do - so I am anxious for your evaluation. They would need your CAN J1772 to Roadster most probably since the charger is made with J1772 plug.

Greg said he has a 2.0

I would think Clipper Creek can solve this easily themselves if they decide to look at it. Just takes me and Greg and anybody else who has seen this to talk to Clipper Creek directly. I think this model charger is among their most popular as it is 240V/32A.

I agree ClipperCreek is in the best position to solve this. Jason has a CAN JR in case they need one. If they wanted to call me I have an idea what might be causing this.

 

[gregd]

I agree ClipperCreek is in the best position to solve this. Jason has a CAN JR in case they need one. If they wanted to call me I have an idea what might be causing this.

I'll relay the message. Fingers crossed...

 

[gregd]

I'll relay the message. Fingers crossed...

Called them just now, and Charlie will get with Jason and the engineering team to see what to do next.

Henry, I sent you a direct message with Charlie's email address, if you have any ideas to contribute.

 

[supersnoop]

I guess I'm m just confused how the charger can initiate the charge. Does it send some sort of signal to the car to engage the contractors?

 

[hjr]

Charlie contacted me too. My electrician arrived today and we switch out the original charger to the replacement charger they sent. I will report tonight when I get home and try to charge. I completely expect the same situation as they just sent another HCS-40. I will give Charlie Henry's email.