Holden Volt - Charging Cable Limited To Six Amps.

[weber]

Good in theory but in reality any resistance in the connection of the cable to the outlet makes the 20A capability of the cable meaningless.
I have a solar battery charger limited to 30A. I recently noticed charring on the insulation of an 8AWG cable where it enters a brass distribution bar. The cable is over 7mm^2 and is rated for 60A yet gets noticeable warm carrying less than 30A.

According to AS3008, under the same condition where 2.5 mm^2 is good for 20 A, 8 AWG (8.3 mm^2) is only good for 40 A. Those conditions include 75°C rated insulation and 3-core flat in conduit in air.

The only way 8 AWG cable could be rated for 60 A is if it has 110°C rated insulation. In which case you are only getting the higher rating because the insulation can take a higher temperature and so it _will_ run noticeably warm.

Let me guess. This 8 AWG 110°C cable is flexible. i.e. it has many fine strands. And it has been clamped under a screw in a brass distribution bar without first putting it in a ferrule?

The length of time involved in charging an EV increases the chance of a heavily loaded cable getting hot enough to start a fire.

Even if there is a high-R connection at the GPO, a 10 A load from an EV on a 10 A GPO is not going to overheat the 20 A cable in the wall cavity, apart from the few millimetres near the GPO. The GPO or plug will soften and droop or (as you mention) char, long before any fire occurs. If a person keeps using a GPO showing signs like that, and doesn't get it checked, ...

[Johny]

This extension cord (inherited from my elder brother) has been in use for over 40 years, has built a few cars and a house and has no doubt been misused and had many dirty plugs inserted into it. The thing that took it out however was just a loose connection. The Active wire did not appear to be clamped at all well. Note the copper plated (or zinc leached) pin on the plug. I had to prise them apart with a screwdriver.


The EV charged fine.
I can see reasons why GM defaulted the non-installed charger limit to 6 Amps.

Edit: This happened during this past weekend.

[weber]

I can see reasons why GM defaulted the non-installed charger limit to 6 Amps.

Thanks for showing us that, Johny. I note there was still no fire. The welding of pins or discolouration showed up the problem before that happened. But even if there had been a fire in this case, it would not be a reason to limit EV GPO charging to 6 amps. It would be a reason to get your extension lead inspected somewhat more often than every 40 years!

I can understand Holden, Nissan et. al. covering their arses by limiting it to 6 amps. But what I fear is that it will be made illegal for anyone to charge an EV from a GPO at more than 6 amps. That would play nicely into the hands of those who are doing their darndest to make money off EV charging over and above the normal (possibly time-of-use based) price of electricity, by intercepting our flow of electrons.

I understand the need for a new standard connector and control protocol for fast DC charging. But I see no reason why we need anything other than standard GPOs when charging off 240 Vac single phase or 415Vac 3-phase.

I was particularly impressed with the standard Aussie 32A single-phase GPOs I saw when I visited bladecar's garage. I've tried to find a photo of one online and failed. They have the usual arrangement of the 3 slots but the active and neutral slots are wider and the earth slot is shaped like a C-channel. So you can plug an ordinary 10 amp or 15 amp plug into it, but a 30 amp plug won't plug into anything else. They are of course wired on a dedicated circuit, presumably with 6 mm^2 cable or larger, and they don't come as double-GPOs.

There have of course been fires caused by EVs charging, but in all that I have heard about, the fire started in the car (specifically the batteries), not in the house wiring or charging lead. Does anyone know of any that are otherwise?

[Edit: Spelling. Changed 30A to 32A added link.]

[Johny]

I agree with all you have said. The reason whay I said I agree (GMs 6A) is exactly the point you made about checking cords more often than every 40 years. If I was them (GM) I'd be covering my a%$&e as well. Since most people driving cars have absolutely no idea how they work (John's lament), why should electrics be any different? We can't assume knowledge based decisions about power point limits and loading from EV users.

A dedicated 15A outlet solves the issue of routine charging from an outlet other than an expensive box on the wall (charge station).

Unfortunately if the folk who make decisions based on which advice they choose to listen to (read politicians), have anything to do with it - then it's just pot-luck what legislation comes out.

BTW I was pretty much expecting the extension cord to fail. It was a kind of "push until it breaks" experiment - monitored pretty closely.

[weber]

Since most people driving cars have absolutely no idea how they work (John's lament), why should electrics be any different? We can't assume knowledge based decisions about power point limits and loading from EV users.

Sorry Johny, but you (and others) are still missing something here. Nothing I said required EV owners to know anything about how their cars or power points work.

All I'm saying is that we should have the same right to pull 10 amps out of a 10 amp socket with our EVs as we do with any other appliance.

I find it very suspicious that some people are claiming EVs should be limited to pulling 6 amps out of a 10 amp socket when they aren't also claiming that plug-in space-heating appliances should be limited in the same way. These can pull 10 amps continuously for unlimited hours. At least an EV shuts off when it's full.

In fact there is no reason why either of them should be limited in that way. There are however good reasons why house wiring and extension leads should have to be professionally checked at intervals of somewhat less than 40 years.

So the worst that can happen is you'll trip a breaker. And Jeff Owen has been opportunity-charging his EV with 10 amps from any 10 amp GPO he can find for the past 15 years without ever once even doing that.

[Johny]

Sorry Johny, but you (and others) are still missing something here.

What! Splutter - missing something - me?
Yeah probably. I actually agree with you so I'm not sure why I keep posting other than it's more interesting than my current work project.

[weber]

What! Splutter - missing something - me?
Yeah probably. I actually agree with you so I'm not sure why I keep posting other than it's more interesting than my current work project.

Hey! You weren't supposed to let on that you were just playing devil's advocate so I could get on my soap-box.

[Edit: Oh darn! That was meant to be a private message.]

[jonescg]

When I eventually get my 37 kWh e-CRX on the road, I will need to get a dedicated circuit built into my house for charging. Even the most basic charging arrangement will still be a 4 kW affair. So I might get a dedicated 20 amp circuit with a 15 A socket. Alternatively I can use any 3-phase, 415 V 32 A plug made up and run a charger from each phase.

Still, it limits my opportunity charging to 15 A sockets.

[acmotor]

All I'm saying is that we should have the same right to pull 10 amps out of a 10 amp socket with our EVs as we do with any other appliance....

So the worst that can happen is you'll trip a breaker.....

A 20A MCB protecting a 10A socket is hardly protection, yet yes, that is what the standards allow. They do not expect long duration loads though (or multiples of these). Just add up the number of 10A GPO in your house. You cannot be free to draw 10A from each.
What if you have 2 EVs ? will you expect the same freedom or will you actually look for a separate circuit.

Sorry weber, I think you are missing the point !!!

**** If you plan to charge an EV it should be from a devoted circuit.****

**** The circuit should have an EVSE ****

If you are going to do oportunity charge from any GPO it should be at a very conservative current. Yes, you should be able to plug in anywhere, but I think the wisdom of the Volt outweighs our stubborn resistance. (no pun intended).

[Renard]

    
**** If you plan to charge an EV it should be from a devoted circuit.****

**** The circuit should have an EVSE ****

I'm going to make a rude noise here…

In my experience the electrical industry all too often uses 'safety' as an excuse to bring in rules that require buying more product. And to protect the electricians too -- just like the medicos keeping nurses from doing basic medical work, and plumbers, and so many other occupations. The same old protection rackets. Thank God we can still overload a domestic circuit (and trip the MCB) if we're careless enough to do so.
(Just imagine how much more money the industry would make if domestic power circuits were limited to one or two GPOs so they couldn't be overloaded. In the name of safety of course. Of course.)
There's a limit to how much one can protect people from themselves.
Ra ra ra. Go it Weber!

[jonescg]

**** If you plan to charge an EV it should be from a devoted circuit.****

**** If you plan on heating a room with a bar heater it should be from a devoted circuit*****


*** If you plan on cooling a home with an air conditioner, it should be on a devoted circuit***

...etcetera.


I can see the logic behind GMs decision; they don't want any pesky lawsuits at a time when commercial EVs are on tenterhooks. But by the same logic, why then does Harvey Norman stock appliances which can also be used at 10 A overnight?

[acmotor]

Ah yes Renard, I do get the "we don't want to be over-regulated bit".
And generally I agree.
It is just in this case (EV charging) I personally can see the need for good practice, not 'get away with' practice.

If, as part of NCOP14, EV conversions were required to include the safety of an EVSE for charging for instance, it would be a good thing IMHO.
Hoping here that everyone knows what an EVSE is and does for you ? surely nobody questions its value ? If this is what you call buying more product then I understand. So leave the seatbelts out on your next car. Fortunately safety standards say you can't.

The thing with safety and standards is that they are (almost) always in our favour.
I deal a lot with OH&S in my work and you know, apart from the annoyance at times of testing, complying, training etc. it is actually all for our safety. It is almost always impossible to mount a plausible case against doing things right.
Sometimes we cheat and sometimes we mock and there is always a '100 year old smoker' but that doesn't make it safe to smoke.

[acmotor]

**** If you plan on heating a room with a bar heater it should be from a devoted circuit*****

*** If you plan on cooling a home with an air conditioner, it should be on a devoted circuit***

Duh !
If you plan on heating a room with a bar heater you are quite energy irresponsible ! most likely it is 1000W anyway (4A) What, 2000W ? I guess you have a patio heater too !

If you plan on cooling a HOUSE with an airconditioner it will definitely be on its own circuit already. You are in Perth right ?

Sorry Chris, bad examples.

[jonescg]

I have a Noirot heater in the hallway. Mrs Wife loves it to pieces. It pulls 9 amps! We got a power bill shock one evening. In trying to work out where the bill came from, I asked how often she'd leave the heater on.   She sheepishly admitted to leaving it on overnight on a couple of occaisions. That was only part of the story - her iron is 2400 W and she'd leave it on all day during a sewing project! So yeah, multiple amps per circuit isn't that uncommon.

Anyway, my point is that if safety was the main concern in GMs decision, why then does it not apply to every other high energy appliance in the home? Oh, by the way, don't have AC and never will - we rent

[weber]

All I'm saying is that we should have the same right to pull 10 amps out of a 10 amp socket with our EVs as we do with any other appliance....

So the worst that can happen is you'll trip a breaker.....

A 20A MCB protecting a 10A socket is hardly protection, yet yes, that is what the standards allow.

Someone's missing something. By definition, a 10 amp socket doesn't need protection from 10 amps.

So long as we don't draw more than 10 amps from any GPO it's only the cable that needs protection. And a 20A MCB is perfectly good protection for the cable that 10A GPOs are wired with (2.5 mm^2).

They do not expect long duration loads though (or multiples of these).

Please show me where it says the 10 amp rating of a GPO, or the 20 amp rating of 2.5mm^2 cable, is not a continuous rating.

Just add up the number of 10A GPO in your house. You cannot be free to draw 10A from each.

Of course not. No-one suggested you could. But anyone is free to try. The consequence will not be a safety issue, only an inconvenience issue.

What if you have 2 EVs ? will you expect the same freedom or will you actually look for a separate circuit.

False dichotomy. I will expect the same freedom AND I will look for a separate circuit.

[weber]

If, as part of NCOP14, EV conversions were required to include the safety of an EVSE for charging for instance, it would be a good thing IMHO.
Hoping here that everyone knows what an EVSE is and does for you ? surely nobody questions its value ?

I think I know what an EVSE is and does. But I may be missing something, and there may be others who don't know. So please explain.

And based on what I know of them I certainly do question their value, compared to simply having a standard 3 pin plug of a kind that can only plug into a GPO that is rated for at least the maximum current the charger can pull, i.e. 10A in my case, or 15A in jonescg's case.

If this is what you call buying more product then I understand. So leave the seatbelts out on your next car. Fortunately safety standards say you can't.

False analogy.

The thing with safety and standards is that they are (almost) always in our favour.
I deal a lot with OH&S in my work and you know, apart from the annoyance at times of testing, complying, training etc. it is actually all for our safety. It is almost always impossible to mount a plausible case against doing things right.
Sometimes we cheat and sometimes we mock and there is always a '100 year old smoker' but that doesn't make it safe to smoke.

Ask jonescg if he thinks I'm the kind of guy who tries to make cases against doing things right, or cheats or mocks safety.

[jonescg]

Ask jonescg if he thinks I'm the kind of guy who tries to make cases against doing things right, or cheats or mocks safety.

Yeah - he's so mad about safety he doesn't even finish his conversions just in case!   

[acmotor]

OK, checked out the bosses sunbeam iron.
1200W
Warms to half setting on dial in <1 minute and then cycles about 20% of the time. So average power consumption 240W.
Even if an iron were 2400W it would most likely have a similar average power consumption just with lower duty cycle. i.e. typical of most appliances. Not on all the time like an EV charger.

What domestic loads >2000W are actually continuous (> 1 hour)?
HWS, but that is always on separate circuit.
Aircond > 1.5HP (7A) usually on separate circuit (if profesionally installed) but cycles load (usually !).
Ancient (hardly logical) 2400W bar heaters without temperature switch ?
Pool pumps ? Should be on separate circuit with RCD and probably TOD switch.
Clothes dryer, well ours can only be set to 30min. Even that is a waste !

Does the 9A heater have a temperature control ? It cycles ? Well at least it is only 9A. (don't plug your EV into the same circuit, wife might get cold if it is a 16A MCB or the iron as well if it is 20A MCB)

BTW, reduce your power bill. Buy a jumper, or a portable reverse cycle aircond if you are renting. Just don't plan to charge an EV on the same circuit...... Oh thats right, separate circuit, you indicated that.

Weber, that sums it up "AND I will look for a separate circuit"
At last an admission that a separate circuit would be a good idea.
So if you'd look for a separate circuit for a second EV then why not the first EV given that there may well be >10A load on the first circuit already.
Phew, I thought you'd never see the light !

Be happy that you have the skill to identify a 'separate circuit' and take pity on joe average who can't. I think GM is very concious of that.

BTW I wasn't suggesting at all that a 10A socket couldn't supply 10A continuous. You had me wrong. Just that if you had a planned 10A (or more) continuous load then don't share it with other General Purpose (GPO)loads on a circuit.

Re: EVSEs, Lets start another thread. It is a reasonable topic on its own.

[Johny]

I replaced the socket on my 40 year old extension cord and thought I'd better take a look at the end that is almost permanently plugged in above the garage door.

The plastic bit where the active wire wraps around appears to have plain melted away. I don't think that this happened with my use, I have a feeling that big brother used to run a single phase welder through it. The power point (fairly new) I plug into shows no sign of heat damage.

[weber]

I totally agree that continuous use of 2400 W plug-in heating or cooling appliances is wasteful and unnecessary. But that's irrelevant to this discussion. What's relevant is that (a) it's not a safety issue, and (b) you're allowed to do it.

Weber, that sums it up "AND I will look for a separate circuit"
At last an admission that a separate circuit would be a good idea.

Huh? I never denied it. I assumed it was obvious. And it's not what's at issue here.

So if you'd look for a separate circuit for a second EV then why not the first EV given that there may well be >10A load on the first circuit already.
Phew, I thought you'd never see the light !

Of course I'd prefer a separate or dedicated circuit for the first EV too. But this is a convenience issue, not a safety issue.

BTW I wasn't suggesting at all that a 10A socket couldn't supply 10A continuous. You had me wrong.

I'm glad to hear that, since you earlier wrote:

(we've all melted a 10A socket drawing 10A !)

and I was going to mention that I haven't, and ask you where you got your statistics?

Just that if you had a planned 10A (or more) continuous load then don't share it with other General Purpose (GPO)loads on a circuit.

That's a no-brainer. But we're also talking about unplanned charging here. See the thread title and first post.

If, as part of NCOP14, EV conversions were required to include the safety of an EVSE for charging for instance, it would be a good thing IMHO.

AND

I think the Volt's 'portable emergency use charging cord' limit of 6 Amps is quite wise.

So, are you in favour of NCOP14 mandating that all EV conversions should be limited to drawing no more than 6 amps from any 10 amp GPO that is not on a dedicated circuit? i.e. no more than 6 amps opportunity charging?

1. An installed EVSE is no safer than a GPO that's rated for the the maximum current the EV will draw. It just costs more.
2. Whether or not that GPO is on a dedicated circuit makes no difference to safety, only to convenience. For convenience I could have a control in the car to lower the current draw if the circuit breaker trips after first trying the full rated current of the GPO.

[Edit: Spelling]

[acmotor]

OK, got through the reply of quotes !

So you believe in separate circuits for EV charging at least.

You deny ever melting a 10A socket ? (not with an EV even)
OK, we'll believe you
That reminds me of the electrician talking to the electrionics guy
" if it doesn't blow a 5A fuse then it isn't there "

Hey, don't make up stories... I said NCOP14 should require conversions to use an EVSE for charging. Nothing to do with 6A or anything.
An EVSE is so much more than a GPO plugged to a charger.
I look at the J1772 and EVSE used with my imiev. Simply no comparision with the GPO/charger on my conv.

The idea with adjustable charge is good. The thing is that a GPO circuit might work one minute and trip the next when the kettle goes on. Cold coffee is not a convenience !
It might well be that you end up setting the current at 6A to be fairly confident the circuit won't trip.....

OH YEAH, GM ALREADY DID THAT ON THE VOLT !

We've gone full circle on this topic !

[weber]

Hi acmotor,

I didn't make up those quotes. And I didn't assume they were related. I asked the question.

The kettle also might not trip the breaker. GM have not "already did that on the Volt". GM have given their customers no choice. They are limited to 6 amps for opportunity charging. You still seem to think that's just fine. And since you didn't exactly answer the aforementioned question, I continue to wonder whether you think it would be just fine if DIY converters were limited to 6 amp opportunity charging too.

You've waved the safety flag on this, but failed to describe any specific safety problem apart from the dangers of cold coffee.

The reason I'm holding your hand to the fire on this, is that you are, quite deservedly, considered an authority on EVs. And you have in the past been a media spokesperson for the AEVA in your capacity as our president.

I hate to have to ask this, but do you have any industry affiliations that might be relevant to this discussion?

[acmotor]

GM HAVE gone for 6A on their occasional use charging lead.
The whole topic of this thread.
They still provide full charging rate as well via the much safer EVSE route. (and a dirty ICE) Sounds like real choice to me.
That may not suit you. So, don't buy a volt.

Their 6A on a 10A plug is the same ratio as Mitsi and Nissan ~9 A on a 15A plug. The 10A sockets are far more common than 15A of course. So the volt direction may offer more freedom and choice. That's what you are calling for isn't it ?
Do you have the same concern about Mitsi and Nissan with their current choice ?
Hey, take your crusade up with the EV manufacturers. I'll let you in on a reality.... you won't win.

I can see why they have gone for 6A and I have tried to pass that foresight on to you all. This is an informed opinion on my behalf and I see the world's leading EV manufacturers have gone this conservative direction.

EV conversions should be charging via an EVSE on a devoted circuit. I keep saying that. What you do when being mindfull of your own circuits is a choice that you are free to make. Can't see that changing. BUT it is not for the general public. I can only tell you that. You can choose to accept the advice or not.

Nope. No industry affiliations. But I have purchased a production EV and 2 EVSEs. One for home, one for work. (and the i has its own occasional (emergency use) EVSE lead as well). This, after building my own, fairly unique, EV conversion.
I guess you ask since I am so keen to see safe EV charging. Part of my history, as you point out, is to see the EV community adopt best safe practice. The worst thing for us would be to have regulations forced upon us coz we didn't adopt best practice ourselves.

[Rob M]

EV Works has done some work and research on the overheating charging lead issue. We have also involved "Clipsal" a major manufacturer of electrical equipment.
There are a lot of interesting comments made in the thread above.
We do understand the reasoning behind the cautionary attitude taken by the two EV makers mentioned and agree that it is probably a sensible move under the circumstances.
It does however sound a bit alarmist and does have a negative impact on the conversion industry and home charging from a standard outlet as an option.
An on board charger is an electrical appliance like any other and should be installed in a safe manner and earthed to the vehicle chassis which in turn should be earthed via the charging lead to "ground". This enables prevention of electrical shock providing the appropriate earth leakage protection devices are fitted to the home outlet.
It is important to note that electrical safety is related to the proper fitment of these devices and not the nature of the appliance connected, in this case an EV. In-cord devices should not be necessary and in some cases may give a false sense of safety.

Overheating of the connections is a different story.
In all cases that we have examined, the heat has not come from underrated wiring or pins(10 amp and 15 amp pins are identical). The heat has been generated by high resistance connections between the copper wire and the brass receptacle on the pin. This connection is usually made by a brass screw. Over time the copper oxidises and the resistance of the connection increases. The increased resistance causes higher temperatures which in turn accelerates the corrosion. Many leads only last a few months while others last a few years.
The problem is not as obvious with the use of high output home heaters because of the intermittant and generally shorter use time.
The longer lasting leads have better connections or are completely encapsulated so as to exclude air and moisture.

The possible solutions are:
1. Use good quality leads
2. Regularly inspect connections for corrosion and overheating
3. Use fully soldered or overspec connections like the commercial EV charging leads.(note it is not legal to solder the wire and then use a screw connection as the solder is soft and can yield over time).
4. Nickel or gold plate the copper wire before screwing it into the plug or socket to prevent corrosion.
5. Use a ferrule to encapsulate the fine copper strands found in most extension cords before screwing into the back of the plug/socket.

House outlets are usually wired with fewer and heavier copper strands so the problem is less common in these outlets.
As with all safety issues, it is better for those involved to be aware and proactive since regulations are often ignored and difficult to enforce properly.

[weber]

Thanks Rob M, for some real data on a real problem, and how to deal with it. Great stuff!

A couple more ideas which could be used in combination with some of those above:
6. Use marine cable, which has all strands individually tinned.
7. Use the same jointing paste we use on our battery terminals, both inside and outside the ferrule.

[Edit: Added corrosion prevention ideas.]