The ones on the right are the high-voltage battery, while the ones on the left are from the charge port.
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The ones on the right are the high-voltage battery, while the ones on the left are from the charge port.
~400V DC battery capable of delivering >500A and they used black wires inside the PEM for both + and -? Interesting.
thefortunes
Active Member
Mine were designated +/- by a strip of electrical tape (red or black) around them
thefortunes
Active Member
Unfortunately, my Roadster is again down for the count (and I believe we caused it). I have messaged a couple people who have been helpful, but am throwing this out to the general population for two reasons:
In the diagnostics the ESS shows Vbatt 393V while the PEM shows Vbatt 253V (253V is apparently the normal resting state). The PEM climbs to around ~280V upon restart, but then drops back to 253V when the errors reappear. The car will not drive.
We started taking the phase boards out and noticed some arcing on the bolts at the back of the the 3rd phase board (closest to the access) where it attaches to the bus bar. It appears that we did not have that put together correctly (i.e. bus bar was not attached to the bolts) so when I went over the large bump the bus bar bounced and arced. Here is a picture of where I am describing:
We put things back together correctly and it is still throwing the same errors and only getting to ~280v before shutting down.
Is there a fuse somewhere that could have blown due to the arcing? We checked every visible fuse we could find.
Otherwise is there something else that needs to be reset, or replaced? Does anybody actually have a schematic of the PEM?
- If you are going to do this repair yourself, be SURE that you put everything back together properly (I would recommend that only one person is in charge of the disassembly and reassembly). We had too many (3-4) hands doing the reassembly.
- I'm hoping to get some additional knowledge of where to go next.
In the diagnostics the ESS shows Vbatt 393V while the PEM shows Vbatt 253V (253V is apparently the normal resting state). The PEM climbs to around ~280V upon restart, but then drops back to 253V when the errors reappear. The car will not drive.
We started taking the phase boards out and noticed some arcing on the bolts at the back of the the 3rd phase board (closest to the access) where it attaches to the bus bar. It appears that we did not have that put together correctly (i.e. bus bar was not attached to the bolts) so when I went over the large bump the bus bar bounced and arced. Here is a picture of where I am describing:
We put things back together correctly and it is still throwing the same errors and only getting to ~280v before shutting down.
Is there a fuse somewhere that could have blown due to the arcing? We checked every visible fuse we could find.
Otherwise is there something else that needs to be reset, or replaced? Does anybody actually have a schematic of the PEM?
Really sorry to hear of your troubles...I'm sorry I don't know enough to help you but I have found a little with the error message...
BSM: V_ess too low during precharge, t2 None
PEM - Internal Failure
"This indicates a short across the high voltage. Connect PEM and HVAC simulator. If fault clears, check PEM and HVAC. If not, open contactors and check for short across ESS J1 high voltage pins."
You being in the states...I guess Mr Gruber will be the man to contact (you have probably already done that...)
Good luck and let us know how you go. BTW that photo did not upload.
Jonathan
BSM: V_ess too low during precharge, t2 None
PEM - Internal Failure
"This indicates a short across the high voltage. Connect PEM and HVAC simulator. If fault clears, check PEM and HVAC. If not, open contactors and check for short across ESS J1 high voltage pins."
You being in the states...I guess Mr Gruber will be the man to contact (you have probably already done that...)
Good luck and let us know how you go. BTW that photo did not upload.
Jonathan
Last edited:
A bit of an update on my PEM...I took it apart yesterday in situ - quite easy with the rear wheels on ramps otherwise my back would have been a mess today...anyway, when I finally got it apart and checked on the Ceramic strips - every single one of the 12 x 0.63mm strips were cracked. There was no sign of arching or any problems and I think it would have been fine for a while - but ultimately it would have failed. I have now replaced them with 1mm strips and the torquing of these was a lot less dramatic. No noises whatsoever... If I were to give any advice I would probably suggest people go for a thicker strip say 1.5mm (if it exists?) Between 0.63 and 1.0mm there is no change in PEM temperatures - and likewise I would not expect any difference with the slightly thicker strips...temp of PEM at normal cruising speed is 37ºC or lower - when you hammer it - it goes to 40ºC and then quickly goes back down - outside temperature was 16ºC. So the takeaway - use at least 1mm or more thickness with your insulation ceramic strips...or if your a little more adventurous, have slightly deeper pockets, go for the Aluminium Nitrate...job took about 8 hours...any other questions just ask...
DanielFriederich
Member
Jonathan!
did you take pics of the damages stripes? would love to se how the damage looks like.
Used any thermal paste now with the AN stripes?
did you take pics of the damages stripes? would love to se how the damage looks like.
Used any thermal paste now with the AN stripes?
Yes just the finest smear of paste on the IGBT's...see attached photo... I have now re positioned the strips so the IPGT's are much more centrally mounted on the strips - but it seems the 1mm strips are going to give a better result - but I think 1.5mm would be better...
DanielFriederich
Member
Yes the torque was ok - that's for sure but 0.63mm was not a good idea...but this is part of the progress in getting it sorted. I think I dodged a bullet there...if everything is ok in 6 months when I pull out the PEM to clean - I'm so good at it now - I'll dive in and have a look and see how they look.
DanielFriederich
Member
might I suggest a heavy refurb like the one guy (Todd Wiersum) did in the Tesla Roadster Group on Facebook. PEM with Plexiglas Cover... so visual inspection would be easier ... (yeah I know you wont see them anyhow cause of the mounting side.. but anyway 
)
)
DanielFriederich
Member
maybe at the input side of the blower fans or somewhere in the main circuit board - there has to be a 12V source around there
Rotarypower
Member
@Jonathanm ....first off thanks to yourself and @DanielFriederich for sharing your experience with this difficult problem. I appreciate your openness in sharing in your success but more importantly your failures. That is the biggest benefit to those of us that will inevitably face these type failures in the near future.
But one thing I am perplexed by, and maybe I am showing my ignorance on this issue, if so, apologies up front....but how is this design implemented on the MS and MX? Is this an apples/oranges question? Is there something to learn from these later models?
DanielFriederich
Member
Apples and oranges....
1. power electronics are liquid cooled in the DUs of S and X (3 for sure too)
2. Power transistors (igbt) did develop in the last decade a lot (less thermal losses, less saturation voltage e.g.) and they are "higher integrated" in the meaning "one part - far more output power), also the driver boards responsible for the "driving" aka switching of the igbts have become better...
3. one can guess about the the software controlling the driver circuits for the power gen. probably far more sophisticated
4. Model 3 will use a different kind of motor! Still a 3 phase AC but with a permanent static rotor which gives some advantages concerning eddy current (hope I translated that well) but also needs more electronics in the power department...
roughly I would say the PEM is like from the age back where tubes were used and the S/X are up 2 date stuff
1. power electronics are liquid cooled in the DUs of S and X (3 for sure too)
2. Power transistors (igbt) did develop in the last decade a lot (less thermal losses, less saturation voltage e.g.) and they are "higher integrated" in the meaning "one part - far more output power), also the driver boards responsible for the "driving" aka switching of the igbts have become better...
3. one can guess about the the software controlling the driver circuits for the power gen. probably far more sophisticated
4. Model 3 will use a different kind of motor! Still a 3 phase AC but with a permanent static rotor which gives some advantages concerning eddy current (hope I translated that well) but also needs more electronics in the power department...
roughly I would say the PEM is like from the age back where tubes were used and the S/X are up 2 date stuff
Yes, but the S/X still have some high power semiconductor mounted on a cooling plate. What did they use for electrical insulation and thermal conduction?Apples and oranges....
1. power electronics are liquid cooled in the DUs of S and X (3 for sure too)
2. Power transistors (igbt) did develop in the last decade a lot (less thermal losses, less saturation voltage e.g.) and they are "higher integrated" in the meaning "one part - far more output power), also the driver boards responsible for the "driving" aka switching of the igbts have become better...
3. one can guess about the the software controlling the driver circuits for the power gen. probably far more sophisticated
4. Model 3 will use a different kind of motor! Still a 3 phase AC but with a permanent static rotor which gives some advantages concerning eddy current (hope I translated that well) but also needs more electronics in the power department...
roughly I would say the PEM is like from the age back where tubes were used and the S/X are up 2 date stuff
For those of you that are in the Facebook group this is no news, but I do also have a non functioning car now. The car has been to Tesla where they said that the PEM needed replacement and offered me to fix it for $9500. I am very happy about this group and the people here, since I now have a hope to have a friend of mine to fix it for me. I am in the process of getting the parts and was planning to get the PEM out today.
Before leaving Tesla the technician gave me some tips on how to start. he said three things:
1. Go to the service menu and disable the 12V system.
2. Open a panel in the drive whee larch and pull the lever to disconnect the battery.
3. Find the panel in the trunk and remember to take out the connectors.
What surprised me was nr.2
My plan was to follow the instructions from:
DIY: Roadster 2.5 PEM cleaning - step by step
and
But neither mention nr.2?
Before leaving Tesla the technician gave me some tips on how to start. he said three things:
1. Go to the service menu and disable the 12V system.
2. Open a panel in the drive whee larch and pull the lever to disconnect the battery.
3. Find the panel in the trunk and remember to take out the connectors.
What surprised me was nr.2
My plan was to follow the instructions from:
DIY: Roadster 2.5 PEM cleaning - step by step
and
But neither mention nr.2?
The reason for point number 2 is to provide some extra security for you so there is no possibility of stray currents, and secondly if your ESS is a little low and you cannot charge it will protect the charge in the ESS. So if you job is going to be more than a week or so I would pull the Service Disconnect...
That being said, on Saturday when I changed out my strips I just disabled the VMS...and I'm still here...
That being said, on Saturday when I changed out my strips I just disabled the VMS...and I'm still here...
There's a 12V supply coming in on the right side of the PEM through the Molex connector—RHC33—from the APS.
The reason for point number 2 is to provide some extra security for you so there is no possibility of stray currents, and secondly if your ESS is a little low and you cannot charge it will protect the charge in the ESS. So if you job is going to be more than a week or so I would pull the Service Disconnect...
That being said, on Saturday when I changed out my strips I just disabled the VMS...and I'm still here...
Ok, thanks for the reply. It will probably take more than a week, so I will probably pull it and stay safe
Now come the big question though. What kind of strips should I use :/
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