An aftermarket kit to improve charging to 6.6kW

[Ingineer]

A non-isolated power supply (aka non-galvanically isolated) has an electrical conduction path between the AC input and the output.

Let's use a cell phone charger for example. It is ALWAYS an isolated design. (except some of the cheap Chinese knockoffs that are electrocuting people!)

This means no part of the cell phone or the charging plug can pass current directly to/from the power line.

Now, let's say we use a non-isolated version. If you touch the bare metal on the charge connector and you are grounded or touch another product or fixture, current will flow, delivering an electric shock. It basically means the charger is "hot" and contains AC power in addition to the DC it's using to charge the phone. The AC part won't really have any bearing on the phone, it will still happily charge without issue, but it will have a disastrous effect on the people that use it!

Valery's argument is that the wiring and components in the LEAF are not directly connected to it's chassis, so there is reduced risk if you directly connect the AC power line to it's HV (High voltage) DC wiring. The problem is, the LEAF has a leakage detection system designed to disconnect all power to/from the battery if it detects any electrical relationship of it's HV DC to it's body. This is designed to detect a dangerous short circuit that could result in fire and/or electrocution. In order to "fool" this detector, you would have to disconnect the AC ground wire that is normally connecting the car body to the AC (earth) safety ground. Not only does this in itself present safety issues, and RFI radiation issues, you are risking your LEAF to generate a fault code if somehow it gets connected to ground. A simple barefoot touch of the body by a person could do this. You could receive a shock, and this would also then trip the leakage detection, disabling your LEAF until a trip to the dealer and a CONSULT III+ reset.

Years ago they used to make TV sets with a "hot chassis". This was due to the fact that it made the set simpler and cheaper to build. Problem was, you had to make sure all the knobs and exterior of the set was insulated, as anyone coming in contact with the metal chassis (or parts, such as a knob shaft) could be electrocuted. They designed the AC cord so it was attached to the back cover so that if you removed the cover, it automatically disconnected the AC power, so the set was "safe" to touch. The TV repairmen had to have a special "cheater" cord that they could power the set up for testing. Of course, when this was used, the set was then hot again.

They stopped doing live chassis because the liability was too great. It caused many fires and electrocuted thousands on a regular basis. I fully remember my first experience as a kid probing around in a live TV with the back off! :shock:

Every single one of the regulatory agencies around the globe will no longer permit such designs, and it would also be impossible to pass a UL test with such a design. Anytime you have a large appliance with a metal exterior, you are required to provide a ground bond that ties the metal of the device to the earth/electrical ground. Intentionally breaking this connection so you can get away with energizing the body of the car is insanity.

-Phil

 

[GregH]

In order to "fool" this detector, you would have to disconnect the AC ground wire that is normally connecting the car body to the AC (earth) safety ground. Not only does this in itself present safety issues, and RFI radiation issues, you are risking your LEAF to generate a fault code if somehow it gets connected to ground. A simple barefoot touch of the body by a person could do this. You could receive a shock, and this would also then trip the leakage detection, disabling your LEAF until a trip to the dealer and a CONSULT III+ reset.

I've been trying to avoid "touching" this discussion (as it is indeed hot)... but.. While on the most part I agree, I do raise an eyebrow at the "you could receive a shock" part of the last sentence. Am I missing something here? Touching earth ground to a metal part of the chassis would indeed trigger the iso detection and open the contactors.. but a shock? Unless something is terribly wrong with your Leaf (in which case the iso fault would have already been triggered long ago), I would not anticipate a "shock" other than, perhaps, the few micro-amps from the iso test itself. Not enough for any kind of shock you could feel. Although dragging your disabled Leaf to a dealer would suck...

 

[FairwoodRed]

I think what you missed is further up in the same paragraph - if you directly connect the AC power line to it's HV (High voltage) DC wiring *and* you would have to disconnect the AC ground wire that is normally connecting the car body to the AC (earth) safety ground.

So yes, there is something terribly wrong with that Leaf and it was modified it to be that way.

Valery's argument is that the wiring and components in the LEAF are not directly connected to it's chassis, so there is reduced risk if you directly connect the AC power line to it's HV (High voltage) DC wiring. The problem is, the LEAF has a leakage detection system designed to disconnect all power to/from the battery if it detects any electrical relationship of it's HV DC to it's body. This is designed to detect a dangerous short circuit that could result in fire and/or electrocution. In order to "fool" this detector, you would have to disconnect the AC ground wire that is normally connecting the car body to the AC (earth) safety ground. Not only does this in itself present safety issues, and RFI radiation issues, you are risking your LEAF to generate a fault code if somehow it gets connected to ground. A simple barefoot touch of the body by a person could do this. You could receive a shock, and this would also then trip the leakage detection, disabling your LEAF until a trip to the dealer and a CONSULT III+ reset.


-Phil

 

[GregH]

if you directly connect the AC power line to it's HV (High voltage) DC wiring *and* you would have to disconnect the AC ground wire that is normally connecting the car body to the AC (earth) safety ground.

Exactly. So the only way to get a "shock" would be if the Leaf was really messed up and had a short from HV+ to chassis. This would cause a shock if you were barefoot on the ground and touching some metal on the chassis (assuming the non-iso charger has earth ground tied to HV- internally). Of course if the Leaf detected such a short from chassis to HV+ it wouldn't leave the contactor closed for more than a fraction of a second.. ie the contactor wouldn't be closed at the time you happened to touch earth ground and vehicle chassis simultaneously. So while I do see how you could set off the iso detect and potentially brick your Leaf, I don't see how you could get shocked.

 

[Ingineer]

What you guys are missing is detailed knowledge of how the LEAF's leakage detection system works, how it's implemented, and the results of leakage. The LDS is NOT intended to directly protect a human from shock, and in fact, it could actually CAUSE one. Basically, It creates a galvanic path between body ground and either side of the traction pack (alternately) and measures the current. Depending on situation, it will not always open the contactor, and it will definitely not do it fast enough to prevent an electrocution. For instance, if you are driving and it detects a leakage, it will NOT disable the car right there on the road, as that could be dangerous. Also, there are times when contactor welding could occur, so the system will attempt to null the current before opening.

The LDS is there to detect a short or low-resistance of the HV to the body, which indicates damage of the integrity of the HV insulation system. It's designed to always have a fully isolated HV system, not one tied to the entire electrical grid! Since there is significant capacitance in these systems with complex interactions and we are dealing with high voltages, all kinds of things can happen!

Bottom line is that no competent engineer would ever consider something dangerous like connection to a HV system without a in-depth analysis of the complete system. It's clear to me that people here have not bothered to do this, and therefore have no business connecting to it, much less advocating other people do so!

Trying to save a few bucks to skirt around the safety systems is a very bad idea. An Isolated design will not add much cost to the system, but it more difficult to engineer, which is the main reason I suspect there are people trying to take shortcuts.

-Phil

 

[GregH]

Bottom line is that no competent engineer would ever consider something dangerous like connection to a HV system without a in-depth analysis of the complete system. It's clear to me that people here have not bothered to do this, and therefore have no business connecting to it, much less advocating other people do so!

Condescension likely won't improve your argument. I agree that an isolated system would be best but I still don't see how using a non-isolated charger creates any risk of shock given the safety systems built into the Leaf. Aside of course from the chance of a shock directly from a poorly designed charger.

Let me pose a slight variation on this question.. If you HAD to design a complete system with a non-isolated charger, which of these two flavors would be preferable:
A: The vehicle system checks isolation from chassis to HV+ and HV- prior to charging, then with the chassis earth grounded, charges without any further isolation checks.
or
B: The vehicle system checks isolation from chassis to HV+ and HV- constantly but the chassis is left floating relative to earth ground.
?

 

[Ingineer]

Condescension likely won't improve your argument. I agree that an isolated system would be best but I still don't see how using a non-isolated charger creates any risk of shock given the safety systems built into the Leaf. Aside of course from the chance of a shock directly from a poorly designed charger.

Let me pose a slight variation on this question.. If you HAD to design a complete system with a non-isolated charger, which of these two flavors would be preferable:
A: The vehicle system checks isolation from chassis to HV+ and HV- prior to charging, then with the chassis earth grounded, charges without any further isolation checks.
or
B: The vehicle system checks isolation from chassis to HV+ and HV- constantly but the chassis is left floating relative to earth ground.
?

It's not condescension unless you choose to interpret it that way. It's a simple fact.

I would answer "A" of course, because this would be the only possible solution from a regulatory and safety standpoint, (depending on country) but of course "A" cannot work on any production EV's currently on the market. I would also not accept "A" without continuous monitoring of leakage current, not just at the beginning of charge.

-Phil

 

[stevewest]

Hey guys, just wondering if there's still any appetite for a 6kW upgrade kit, as per the original post?

 

[TomT]

Personally, I believe that the 2011 and 2012 models are getting long enough of tooth that any interest has greatly dissipated...

Hey guys, just wondering if there's still any appetite for a 6kW upgrade kit, as per the original post?

 

[foolios]

First of all, the danger is hugely overblown. If the system does not have any electrically live components accessible to the user (which it doesn't in any of these cars), there is no possibility for a shock. Isolated or not. Furthermore, if protected by a proper GFI, non-isolated is nearly as safe as an isolated design - even if there are live components accessible (again, not in these cars). If that wasn't the case, we would still all have inductive charging...

It is not overblown. Clearly you do not possess enough engineering skills to even be qualified enough to make such a statement! If you did, you'd know that all common "GFI's" (GFCI) are NOT sensitive to DC leakage, and will NOT trip if you were to touch the EV's body (which is not grounded, as you don't seem to think it's needed, and in fact CANNOT be grounded if you are using a non-isolated design!) this could then conduct a large and fatal DC current through a person to something that is grounded. There would be no trip. Try it if you have doubts!

Secondly, if everyone thought like this, we wouldn't have automotive performance aftermarket industry at all. For example, increasing pressure by 2x in one's turbo engine has risks. Same for putting in a NOX system in your car. Some engines blow up. Yet hundreds of thousands of people do that. It's all about trade-offs. Learn about the potential risks, weigh them against the benefits, and make an informed decision. Not based on hearsay, ideally...

Risking some engine damage is not the same as risking LETHAL ELECTROCUTION!

EMI/RFI - I have a couple of problems with the related statements in your post:
1. To uninitiated (i.e. not EE types), saying 'radiation' and 'bad consequences' without explaining is fear mongering. We have a pretty paranoid society here as it is.

Paranoia starts because of people taking unreasonable risks.

2. 'A ton of RFI' is not a very scientific term. Have you measured it? Have you compared it with the background levels? Across the spectrum? We have measured radiated EMI from our non-grounded units - in a 0-10kHz band, at full 12kW power, at 3 feet, we measure less than 2 milli-gauss. Background level in my last 3 houses was 1.5-3 milli-gauss depending on how many lights are on...

If you use a non-isolated DC supply on the LEAF, you will have to intentionally NOT ground the LEAF's body to an RF sink (Earth ground) to make it not trip the leakage detection in the LEAF. This will turn the LEAF's body into a passive radiating antenna, re-radiating all the RFI from your poorly designed non-isolated converter. Note that I am more concerned about RFI, not EMI as you are claiming figures for. Apparently you don't know the difference, thus further proving your lack of qualifications to be working in this area. RFI is Radio-Frequency interference, EMI is Electo-Magnetic Interference. Milli-Gauss is measuring EMI NOT RFI!

3. Lastly, when your car moves, it's not grounded. Yet there is up to 80kW of AC power transferred around you (in a Leaf, up to 400kW in a Tesla S). And you are sitting IN the car (as opposed to you being in your HOUSE when you car charges). At freeway speeds, that AC also has much higher frequency than line - and radiated power is roughly proportional to the square of the frequency.

You also haven't directly connected the AC power lines to the car while you are driving, but when using a non-isolated converter, this is exactly what you are doing! All modern EV's use fully shielded equipment and transmission lines, everything is double-insulated and there always is a fault detection circuit that will cut power to the EV is a fault is detected. There is NO current path to ground or the car's body in normal operation, and during any connection to an external power source referenced to ground, there is always a bonded connection to the car's body to ground, as well as leakage detection that will cut power in the event of a fault. You will have to effectively disable all this protection in order to use your device and create a dangerous condition.

No regulatory agency on the planet would ever approve your device, and there are good reasons for that! It would be trivial to prove your negligence in a civil suit, and you'd be liable for damages if anything bad happened. The FCC would easily issue you a cease and desist as soon as your converter starts blasting RF interference all over.

So let's try to not generalize things into non-quantitative categorical statements. Especially if you decide to launch a direct assault on other people like you did.

If you want me to prove the danger and give you quantifiable measurements, I'll be happy to. Send me one of your converters and I'll give it a full and proper analysis for free and publish the results here. My concern is that people understand the risks before attempting dangerous scenarios. You are dangerously downplaying safety, and you clearly are not qualified to make such assessments. Your initial offering of your kit EVSE wasn't even going to include GFCI protection until you were called out on it! A $10 Chinese-made hair dryer even includes this essential safety device. That you could consider skimping on such a critical thing to save a few bucks shows where your sensibilities lie.

-Phil

This article is scaring the BEJESUS out of me!
I was looking up the keyword converter and saw this post.
Are we talking about any converter? Does this include the 1000 watt DC-AC inverters that are hooked up to the 12v battery positive and the negative to the DC-DC converter?

EDIT: nm, nothing to see here. I see you posted a reply in another thread that I'm sure you wouldn't answer with an explanation if that was the case.
Thanks!

 

[KillaWhat]

This article is scaring the BEJESUS out of me!
I was looking up the keyword converter and saw this post.
Are we talking about any converter? Does this include the 1000 watt DC-AC inverters that are hooked up to the 12v battery positive and the negative to the DC-DC converter?

Not sure what all the hubbub is about here.
We have "been there, done that" with both an add on charger (or two.. Or three),
http://www.mynissanleaf.com/viewtopic.php?f=37&t=12323" onclick="window.open(this.href);return false;


And adding the DC to AC inverter.
http://www.mynissanleaf.com/viewtopic.php?f=37&t=13097" onclick="window.open(this.href);return false;

 

[stevewest]

Not sure what all the hubbub is about here.
We have "been there, done that" with both an add on charger (or two.. Or three),
http://www.mynissanleaf.com/viewtopic.php?f=37&t=12323" onclick="window.open(this.href);return false;

Agree that it's no big deal. But no one offers a DIY kit, right? Would there be any interest in one, e.g. for $2k all in?

 

[KillaWhat]

Not sure what all the hubbub is about here.
We have "been there, done that" with both an add on charger (or two.. Or three),
http://www.mynissanleaf.com/viewtopic.php?f=37&t=12323" onclick="window.open(this.href);return false;

Agree that it's no big deal. But no one offers a DIY kit, right? Would there be any interest in one, e.g. for $2k all in?

The problem with a"Kit" is that's not the issue.
The "hard" parts are the interfaces to the vehicle.
You have to tap the Charging input in a very clean way, and attach to the HV pack just so.
Then there is the liquid cooling, and CAN bus tap.
It's kinda like - If you have the skills to install this, you don't need a kit.
I think the cleanest overall installs are the liquid cooled rear mounted ones.
Works for all years.
As in, wouldn't you like a 2014 that came with a 6.6Kw (6.0) to be able to charge at 12.6Kw.
From 50% to 100% in one hour..

That's what you get with a pair of 3.3 Brusa liquid cooled units in the back.

 

[foolios]

Not sure what all the hubbub is about here.
We have "been there, done that" with both an add on charger (or two.. Or three),
http://www.mynissanleaf.com/viewtopic.php?f=37&t=12323" onclick="window.open(this.href);return false;

Agree that it's no big deal. But no one offers a DIY kit, right? Would there be any interest in one, e.g. for $2k all in?

inverter kit?
http://www.evextend.com/Nissan-Leaf-Inverter-Kit.php

 

[JasonA]

Not sure what all the hubbub is about here.
We have "been there, done that" with both an add on charger (or two.. Or three),
http://www.mynissanleaf.com/viewtopic.php?f=37&t=12323" onclick="window.open(this.href);return false;

Agree that it's no big deal. But no one offers a DIY kit, right? Would there be any interest in one, e.g. for $2k all in?

you can't do it for $2k first of all..

Then I tried to push it.. a group buy of chargers and people said they were too expensive..

So there you go.. It was a DIY thing in the end.. with KillaWatt, Jeremy, myself, Victor and Allen in the end only doing it.

People talk the talk.. but then come up short when it's time to pony up the $$$'s

 

[KillaWhat]

Not sure what all the hubbub is about here.
We have "been there, done that" with both an add on charger (or two.. Or three),
http://www.mynissanleaf.com/viewtopic.php?f=37&t=12323" onclick="window.open(this.href);return false;

Agree that it's no big deal. But no one offers a DIY kit, right? Would there be any interest in one, e.g. for $2k all in?

you can't do it for $2k first of all..

Then I tried to push it.. a group buy of chargers and people said they were too expensive..

So there you go.. It was a DIY thing in the end.. with KillaWatt, Jeremy, myself, Victor and Allen in the end only doing it.

People talk the talk.. but then come up short when it's time to pony up the $$$'s

Well Said.

 

[EVDRIVER]

Not sure what all the hubbub is about here.
We have "been there, done that" with both an add on charger (or two.. Or three),
http://www.mynissanleaf.com/viewtopic.php?f=37&t=12323" onclick="window.open(this.href);return false;

Agree that it's no big deal. But no one offers a DIY kit, right? Would there be any interest in one, e.g. for $2k all in?

you can't do it for $2k first of all..

Then I tried to push it.. a group buy of chargers and people said they were too expensive..

So there you go.. It was a DIY thing in the end.. with KillaWatt, Jeremy, myself, Victor and Allen in the end only doing it.

People talk the talk.. but then come up short when it's time to pony up the $$$'s

Yes you can do it for under $2k. Many of us know why certain chargers are too expensive.

 

[TimLee]

... Years ago they used to make TV sets with a "hot chassis". This was due to the fact that it made the set simpler and cheaper to build. Problem was, you had to make sure all the knobs and exterior of the set was insulated, as anyone coming in contact with the metal chassis (or parts, such as a knob shaft) could be electrocuted. They designed the AC cord so it was attached to the back cover so that if you removed the cover, it automatically disconnected the AC power, so the set was "safe" to touch. The TV repairmen had to have a special "cheater" cord that they could power the set up for testing. Of course, when this was used, the set was then hot again.

They stopped doing live chassis because the liability was too great. It caused many fires and electrocuted thousands on a regular basis. I fully remember my first experience as a kid probing around in a live TV with the back off! :shock:

Every single one of the regulatory agencies around the globe will no longer permit such designs, and it would also be impossible to pass a UL test with such a design. Anytime you have a large appliance with a metal exterior, you are required to provide a ground bond that ties the metal of the device to the earth/electrical ground. Intentionally breaking this connection so you can get away with energizing the body of the car is insanity.

-Phil

I have some of those same memories from the 1960s :shock:
Never will forget the day I shorted that screw driver shaft and turned it into a welding rod.
Melted half way through that 3/16" shaft in probably less than 0.3 seconds before the arc flash cleared.

Thank you for the diligent clarity you provided explaining why non-isolated design is no longer allowed.

Theoretically the risk with non-isolated design was low.
But in real world experience it got people killed.

 

[DaveEV]

Yes you can do it for under $2k. Many of us know why certain chargers are too expensive.

Well spill the beans! Where can you get a charger that works as well as the Brusa for less money?

 

[Roadburner440]

I wanted to do this mod but more so than money the main thing that stopped me was the fact of having to cleanly tap the high voltage lines as said above. If I lived in CA where some of these guys were I would have gladly paid to have my car done and necessary kit. I just do not have the tools/skill set to do it myself. However with the recent rise of Chademo chargers in my area my want/need for 6.6 charging is a lot less than it was before the stations started proliferating. I know Phil said his installation was a plug and play with no splicing of wires. Maybe one day if something like that comes out on the open market I will do the install. Till then I will take the advice in this thread and keep my monkey paws off of the wiring.