Terminal block melted on HPWC Gen 2

[gnuarm]

I almost never charge my EVs at full power for just this reason. I can get away with less than half power, which is what I do. For me there is no reason to stress the wiring and HPWC until I actually need to do so which is almost never.

As an extra step of redundancy, when I had the HPWC installed I also had my electrician install a 14-50 in the same spot. With the 14-50, I could use my UMC to charge the car too.

I don't mean to make light of people's concerns, but "stress the wiring and HPWC"??? The wiring could not care less what current you run through it. Unless the car is less efficient at higher currents the wire doesn't waste any more energy at high currents than low. The HPWC should be designed to take the full current it is rated for and should not wear any more at higher currents.

If the devices are not designed correctly or are not installed correctly, there can be problems at high currents. Otherwise it is good to go without concern. These are not mechanical devices which wear faster than proportionally when pushed hard. Even the relay in the HPWC is not impacted by the current since it only opens or closes when there is no current flowing. When statically closed the relay does not appreciably wear from the current flowing.

I'm not clear on how many circuits you can install in a panel. Is there any limit other than the mechanical issues? I already have a 60 amp breaker for the heat pump with electric backup, a 30 amp for the hot water heater, something for the stove, a 30 amp for the well, a 50 amp for the hot tub and maybe some others. If I add a 90 amp for an HPWC (or maybe 100 amp so I can have two at some point) as well as another 50 for a 14-50 outlet, will that be too much on a 200 amp service??? Can you branch off a 50 amp outlet from the 100 amp circuit if you use a 50 amp breaker in a box by the outlet? Would this require any sort of a switch to prevent the HPWC from being used at the same time?

 

[gnuarm]

May not have been torqued at all... Given the length difference between the red and black, it may only have been incidental spring contact (or gripping a strand or two on the end).

Isn't the yellow band itself a gauge? First, strip the insulation back the proper, measured, amount. Then, optionally, add a ferrule. Insert wire until insulation (or ferrule) contact the terminal block. Tighten to proper torque. Same setup as any outlet or breaker.

You can also gauge position by tightening the terminal without the wire. Then see check how far the wire will insert. Loosen the terminal and make sure the wire is a terminal depth further in before the final tightening.

Optionally, add a ferrule? I thought ferrules on this type of wire were required? This is the flexible cable to the car, right? It is made of a lot of tiny wires rather than a few fatter ones. When the screw is tightened the tiny wires can distort and even get into the screw threads messing up the connection. Using a ferrule keeps all the tiny wires together and prevents problems like this.

I don't think a ferrule is required for the much coarser wire from the circuit breaker box.

 

[mongo]

Optionally, add a ferrule? I thought ferrules on this type of wire were required? This is the flexible cable to the car, right? It is made of a lot of tiny wires rather than a few fatter ones. When the screw is tightened the tiny wires can distort and even get into the screw threads messing up the connection. Using a ferrule keeps all the tiny wires together and prevents problems like this.

I don't think a ferrule is required for the much coarser wire from the circuit breaker box.

I was speaking of wiring in general. These specific wires are premade high strand count flexible jumpers with ferrules specifically for the reasons you mention.

Fertules can be used (but aren't required) on coarse strand wire to keep the strands together. Industrial automation with lots of screw down terminal blocks will use ferrules for ease of wiring and service.

 

[mongo]

I don't mean to make light of people's concerns, but "stress the wiring and HPWC"??? The wiring could not care less what current you run through it. Unless the car is less efficient at higher currents the wire doesn't waste any more energy at high currents than low. The HPWC should be designed to take the full current it is rated for and should not wear any more at higher currents.

You are correct in that things should last their rated life at their rated current. However, wires (and most things in general) will run cooler at lower currents. For a given wire of resistance R, the heat generated is current×current×R (or I^2*R), so doubling the current quadruples the heat generation and power loss on the wire (71% more current doubles the power loss). If properly sized, this is not an issue.

Electronics in general fail due to time at temperature (metal atom migration forms dissimilar high resistance junctions at bond wires) and due to thermal cycles (different rates of expansion of different materials resulting in mechanical stress and eventual failure, Xbox red ring of death).

Running at the current level you need, instead of the max will make power deliver equipment run cooler and last longer (note overal efficiency is more complicated due to vehicle power usage (partly temperature dependent) while charging).

Max current may give 4 year service life (on an device with 3 year warranty) , whereas lower current gives 8.

I'm not clear on how many circuits you can install in a panel. Is there any limit other than the mechanical issues? I already have a 60 amp breaker for the heat pump with electric backup, a 30 amp for the hot water heater, something for the stove, a 30 amp for the well, a 50 amp for the hot tub and maybe some others. If I add a 90 amp for an HPWC (or maybe 100 amp so I can have two at some point) as well as another 50 for a 14-50 outlet, will that be too much on a 200 amp service??? Can you branch off a 50 amp outlet from the 100 amp circuit if you use a 50 amp breaker in a box by the outlet? Would this require any sort of a switch to prevent the HPWC from being used at the same time?

The proper method is to use make an NEC load calculation.
Dwelling Unit Calculations

A transfer switch (or breaker panel with generator kit) might be allowable to select between two loads. Depends on local code.

 

[mspohr]

I don't mean to make light of people's concerns, but "stress the wiring and HPWC"??? The wiring could not care less what current you run through it. Unless the car is less efficient at higher currents the wire doesn't waste any more energy at high currents than low. The HPWC should be designed to take the full current it is rated for and should not wear any more at higher currents.

If the devices are not designed correctly or are not installed correctly, there can be problems at high currents. Otherwise it is good to go without concern. These are not mechanical devices which wear faster than proportionally when pushed hard. Even the relay in the HPWC is not impacted by the current since it only opens or closes when there is no current flowing. When statically closed the relay does not appreciably wear from the current flowing.

I'm not clear on how many circuits you can install in a panel. Is there any limit other than the mechanical issues? I already have a 60 amp breaker for the heat pump with electric backup, a 30 amp for the hot water heater, something for the stove, a 30 amp for the well, a 50 amp for the hot tub and maybe some others. If I add a 90 amp for an HPWC (or maybe 100 amp so I can have two at some point) as well as another 50 for a 14-50 outlet, will that be too much on a 200 amp service??? Can you branch off a 50 amp outlet from the 100 amp circuit if you use a 50 amp breaker in a box by the outlet? Would this require any sort of a switch to prevent the HPWC from being used at the same time?

Basic electricity. I2R
Best consult an electrician. They are trained in these things and can give you good info.

 

[gnuarm]

You are correct in that things should last their rated life at their rated current. However, wires (and most things in general) will run cooler at lower currents. For a given wire of resistance R, the heat generated is current×current×R (or I^2*R), so doubling the current quadruples the heat generation and power loss on the wire (71% more current doubles the power loss). If properly sized, this is not an issue.

Electronics in general fail due to time at temperature (metal atom migration forms dissimilar high resistance junctions at bond wires) and due to thermal cycles (different rates of expansion of different materials resulting in mechanical stress and eventual failure, Xbox red ring of death).

As long as you are talking generalities this is all correct.

Running at the current level you need, instead of the max will make power deliver equipment run cooler and last longer (note overal efficiency is more complicated due to vehicle power usage (partly temperature dependent) while charging).

Now you are starting to draw conclusions which may not be accurate. "Last longer" is not meaningful unless put in context.

Max current may give 4 year service life (on an device with 3 year warranty) , whereas lower current gives 8.

Here you have provided numbers which you can not support. Properly designed electronic equipment will last a lifetime. The sort of equipment that self destructs just after the warranty expires was never going to last long no matter what you did within the stated usage of the device. I am pretty confident the Tesla HPWC is designed well and will last a lifetime even if used right up to the 80 amp design limit every day. The only thing that will mitigate this is installation. If the unit is not installed correctly it can fail very quickly as has been observed.

My understanding is that the HPWC is similar to a J1772 unit with a different connector. In this design nothing handles the current to the car other than the relay contacts. They will not be producing enough heat to matter and should not open while the car is charging. The relay contacts isolate the AC voltage from the connector when the car is not charging. The only parts of the HPWC that produce heat are the various high current wires and connections which should not be producing enough heat to matter... and the little bit of electronics in the box which also should only be drawing a watt or two (independent of load) which will not raise the temperature of the box enough to make a noticeable difference in lifespan.

The OpenEVSE J1772 device I've been looking at has a very low idle power and I believe is only about a watt when charging. I expect the main power drains are the relay coil current and the LEDs on the box.

The proper method is to use make an NEC load calculation.
Dwelling Unit Calculations

A transfer switch (or breaker panel with generator kit) might be allowable to select between two loads. Depends on local code.

Very useful info. Thanks

 

[gnuarm]

Basic electricity. I2R
Best consult an electrician. They are trained in these things and can give you good info.

Absolutely. But I can get a handle on what I can and can not do without paying an electrician to come out.

 

[mspohr]

Absolutely. But I can get a handle on what I can and can not do without paying an electrician to come out.

I'm not clear on how many circuits you can install in a panel. Is there any limit other than the mechanical issues? I already have a 60 amp breaker for the heat pump with electric backup, a 30 amp for the hot water heater, something for the stove, a 30 amp for the well, a 50 amp for the hot tub and maybe some others. If I add a 90 amp for an HPWC (or maybe 100 amp so I can have two at some point) as well as another 50 for a 14-50 outlet, will that be too much on a 200 amp service??? Can you branch off a 50 amp outlet from the 100 amp circuit if you use a 50 amp breaker in a box by the outlet? Would this require any sort of a switch to prevent the HPWC from being used at the same time?

The proper method is to use make an NEC load calculation.
Dwelling Unit Calculations

Here are a couple of worksheets where you can take a stab at load calculations. These should give you an idea of where you stand. I would have these reviewed by a professional before you do any wiring.
Electrical Load Calculator for Dwelling Units ~ Electrical Knowhow
http://www.sccoplanning.com/Portals...harging System .pdf?ver=2014-01-03-090850-683

 

[ajdelange]

I'm not clear on how many circuits you can install in a panel. Is there any limit other than the mechanical issues?

That's a good question. I think the only way you are going to get a meaningful answer is to sit down with an electrician that knows the local inspector(s) or with the inspector himself and ask. There is a limitation and that is what the manufacturer specifies. Recently manufactured equipment will have a number. Older (existing panels) will not. Just from looking at panels I've deduced that there was a rule of thumb that a panel could contain branch breakers labeled at about 2.2 times the label in the main breaker in the panel. Thus a panel with a 200 A main breaker could be loaded with approximately 440 phase amps (i.e. a double 20 amp breaker would count as 40 phase amps) of branch circuit breakers. I've had an electrician confirm that this is about right. But I've seen plenty of panels where that limit was well exceeded.

I just had a new panel installed. It has a 200 amp main breaker. By the rule of thumb, it could hold about 440 phase amps worth of breakers.The manufacturer's specification is no more than 220 A per stab (bus bar). That means 440 phase amps - right in line with the rule of thumb. But this panel has 655 phase amperes of breakers installed. And it passed inspection. IOW the inspector either overlooked this or was OK with it. . In newer equipment there may be a specified maximum number of amperes per 'stab' (bus bar). On older panels there is no such information. The best I can deduce is that there is a general rule of thumb to the effect that the amperage of branch breakers is about twice the main breaker in the panel. Thus a 200 amp main breaker would support 400 amps of branch service breakers. But this rule of thumb is certainly exceeded in all the panels I have ever looked at.

Now I have another panel with 200 amp main breakers and 1055 phase amps worth of branch circuits on it (one of which is 250 phase amp sub panel). That's 5 times the rule of thumb. This panel is old enough that it doesn't have a per stab sticker. Ostensibly this is way overloaded but in fact it isn't at all. The most current drawn by that panel in the last 12 months was 44.5 A (89 phase amps) which is 22% of the main breaker rating for that panel. Now clearly the inspector who signed off on that installation was aware, from the nature of the loads, that the distribution of actual current draw was such that the probablilty that the load would exceed 400 phase amps was vanishingly small. But an inspector who is a "book man" might very well not be aware and declare this panel well overloaded. I've had that happen too. I was forced to install 600 amp service in another house where the maximum recorded load was 156 amps. So I think it really depends on the climate in your jurisdiction.

Note that, up to this point, has nothing to do with the NEC load calculation. A WC isn't, most probably, like anything else in your house. It is, will certainly be the largest load on your service and is treated as a continuous load to boot. People with 150 A or 200 A service would, with the high amperage charging "upgrade" find that to be 48% or 36%, respectively, of their service and would doubtless require a service upgrade and probably a larger transformer as well. A conservative approach would be to do the load calculation normally and add the WC load to it in order to determine required service (and possibly, transformer) upgrade.

 

[BrokerDon]

I'm a DIY electrician who has done a lot of solar and EV charging work at my house. I have found that working with large diameter wires is challenging and difficult and requires a lot of patience as well as double and triple checking everything. I don't see how this HPWC could be made "foolproof" since they are making new and greater fools every day

SO true, especially in today's world of "personal responsibility denial" lawsuits.

I installed a 327W SunPower solar panel, 40A MPPT charge controller, plus 15A & 40A 12V DC circuit breakers, on our Winnebago View (Mercedes Sprinter) RV ourselves ("DIY") 6 years ago. Several weeks of researching the best materials & methods, several days gathering materials, and a full day to install the entire system... and RV dealerships

However when we bought our 2015 Tesla MS P85D I hired a Tesla approved electrician to install our HPWC on a 100A breaker because making this a DIY project could void my HPWC warranty and create a home insurance claim denial. "Juice not worth the Squeeze" for us (pun intended). Turned out to be a good decision since our HPWC cable & plug got VERY hot charging at 80A which a Tesla Ranger replaced the HPWC cable free of charge / no questions asked because we'd used their recommended electrician, breaker and wire. Paying a licensed electrician and getting an electrical permit & final inspection also should guarantee your home & auto insurers will cover any damage resulting from this installation.

Don't get me wrong, DIY installation of Tesla charging equipment like HPWCs can be DIY for experienced homeowners... but comes at a risk.

YMMV

 

[ajdelange]

Yes indeed. I am having a licensed electrician do this install for just this reason even though I will have to educate him on how to do it. Well, to be honest I also agree with earlier comments about working with anything bigger than No. 8.

I am also strengthened in my resolve to get some IR pictures before things are closed up.

 

[jboy210]

For my HPWC, I got everything permitted and had a licensed electrical contractor do all the work. In this day, people seem sue-happy. I want everything completely document. I have copies of the EV charger installation permit, all load calculations and assumptions for the panels, and the signed inspection report from the city. If some future calamity occurs, I want there to be no doubt they we did everything legally and proper.

We did not work all these decades to lose it in some lawsuit over shoddy workmanship.

 

[Thorsbane]

One thing I noticed on the gen2 that has me worried and is not addressed in the manual or installation video: The Line 1 and 2 wire ferrules are rectangular, not square. They seem to fit in the terminal regardless of orientation. What should the orientation be for recommended torque to be applied? Should the long edge be facing outwards or the short edge of the ferrule? I think I inserted mine with short edge facing out, and has me a bit concerned that it could slip out if the clamping mech slides of the edge of the ferrule. Also, I agree with those who stated that it is difficult to tell whether the ferrule is fully inserted. I had to use a needle nose and push up pretty hard and try several times before the ferrule would "catch" when I would torque down on the screw or clamp mechanism.

 

[mongo]

One thing I noticed on the gen2 that has me worried and is not addressed in the manual or installation video: The Line 1 and 2 wire ferrules are rectangular, not square. They seem to fit in the terminal regardless of orientation. What should the orientation be for recommended torque to be applied? Should the long edge be facing outwards or the short edge of the ferrule? I think I inserted mine with short edge facing out, and has me a bit concerned that it could slip out if the clamping mech slides of the edge of the ferrule. Also, I agree with those who stated that it is difficult to tell whether the ferrule is fully inserted. I had to use a needle nose and push up pretty hard and try several times before the ferrule would "catch" when I would torque down on the screw or clamp mechanism.

I would put it so the wider edge was being clamped, but I don't expect you will have any trouble. The clamp itself compresses the ferrule so it shouldn't tip over.
Now if you had it on a 45, that could be bad.

 

[Thorsbane]

I would put it so the wider edge was being clamped, but I don't expect you will have any trouble. The clamp itself compresses the ferrule so it shouldn't tip over.
Now if you had it on a 45, that could be bad.

This is sort of what I thought but I super appreciate someone else’s feedback.

 

[Oceanwolf]

Ouch. From experience, my first reaction is: "Oops. Someone forgot to torque to the proper number".
But it could be any one of a number of other reasons.

I did my own installation. When the inspector came, he asked if I used a torque screwdriver, I said what is it?
I bought one and used the torque instructions. In his next visit he asked did you use one, I showed him the torque driver and received my permit. I didn't know how important it is until my boss' HPWC burned at the terminals.

 

[spievak]

I love my Model X, but I'm starting to grow tired of little issues that I never experienced with ICE vehicles in the fist year of ownership. Last night my app popped up a message that stated the charging was interrupted. I immediately went outside to find that the vehicle had stopped charging and showed "Charge Cable Fault" and "No wall Power" messages on the digital dash. I can't tell you the particular light sequence on the charge port or the HPWC, but red was prevalent. I unhooked the charge head and placed it back in the HPWC receptacle. I reset the wall charger and hooked it back up to the vehicle. The vehicle wouldn't get pass 60 amps and then dropped to 30. I reset again. The charging sequence got up to the normal 72 amps and I went in the house thinking everything was good. A few seconds later I heard a pop in the garage. I went out to find the HPWC was dead. I checked the breakers which seemed fine and got around to popping the cover on the HPWC to find that a terminal block had melted. This charger has been installed since January and was done by a Tesla approved electrician. I've always charged at 72 amps without issue with voltage typically being in the 235-240 range. Maybe I just got a unit that bit the dust early, but I have to be honest when I say I'm tired of issues like this. It's not the end of the world, but it surely does change the family routine this week with the kids as we look to utilize Superchargers until this is remedied.

Similar problem. Full charger block meltdown in my HPWC. Tesla agreed to replace and is shipping out a new HPWC. Still need to pay an electrician again, but it was a quick and helpful response from Tesla support.

 

[mspohr]

Similar problem. Full charger block meltdown in my HPWC. Tesla agreed to replace and is shipping out a new HPWC. Still need to pay an electrician again, but it was a quick and helpful response from Tesla support.
View attachment 569580

Looks like the connections weren't torqued properly. Even a very small resistance at 72 amps generates a lot of heat.

 

[SYLotusElise]

Tl;dr. Thank you for such in-depth information! Can I get a new terminal block?

First of all, I want to thank everyone for such insight. I had never heard of a torque screwdriver until now. And thinking about it, it makes sense. . .very few wires are solid core and a torque screwdriver will prevent over torqueing which would spread the thread.

So, we got a Model Y in May. Got an electrician to run the wire, but I did the wall charger (long story. . .it made sense at the time).

One lead in the terminal block has melted. Not badly. When I cracked the WC open, it didn't look like the terminal block was damaged. . .until I tried to put the wires back in, and one of the leads would not secure. Took the WC off the wall and one of the two connectors has melted.

Where can I source a new terminal block? The charger seems fine otherwise. . .lights up green and initially charges at 48A for about 2 minutes before dropping to 16A then eventually to zero.

 

[GlowOwl]

Not sure what part you need but here is a link to ebay person who repairs terminal blocks for $85 Picture he shows should allow you to see if it is the same part you need.

Tesla Gen 2 A/C in Connector repair | eBay

I can repair the connector for you.

www.ebay.com