10 Amp charging

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Re: 10 Amp charging

Post by nuggetgalore » Wed, 22 Nov 2017, 18:55

Hi all iMiEV wizzards.
This is a duplicate post from the one in the iMiEV charge thread, to advertise it a bit more.....
I have another charging question . Because the 2010 iMiEV (at least mine) charges with 12.5 A, I use an Ampfibian when I charge at a friends place to legally plug it into a 10 A power point. It works but I have to reset the Ampfibian several times as it trips sometimes after ten minutes, sometimes 30 minutes.Not consistent (could be temp has an influence).
Is there a danger to hurt the battery (unlikely) or the charger (more likely) ,if the charger gets reconnected soon after it was disconnected? Soon after, how soon if it was the case?
Thanks for any advice.
tinker

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Re: 10 Amp charging

Post by coulomb » Thu, 23 Nov 2017, 06:45

nuggetgalore wrote:
Wed, 22 Nov 2017, 18:55
Hi all iMiEV wizzards.
I'm not an iMiEV wizard at all, but none seem to have answered so far.
Because the 2010 iMiEV (at least mine) charges with 12.5 A, I use an Ampfibian when I charge at a friends place to legally plug it into a 10 A power point. It works but I have to reset the Ampfibian several times as it trips sometimes after ten minutes, sometimes 30 minutes.Not consistent (could be temp has an influence).
The Ampfibian doesn't magically cause the car's charger to draw less than 12.5 A. So my understanding is that the Ampfibian is correctly disconnecting the excessive load. But because it's marginally excessive (it might not always be 12.5 A, especially with Australia's notoriously high mains voltage), it takes some time before the over-current breaker finally trips. This is safe, because house wiring can tolerate a slight overload for a period of time; it just isn't guaranteed to tolerate it continuously. I believe that a typical 10 A outlet can supply more than 10 A safely, as the active and neutral pins of a 10 A plug and socket are the same size as those of a 15 A plug and socket (only the size of the earth pin changes), so that's not an issue for occasional use.
Is there a danger to hurt the battery (unlikely)
No. The battery is used to seeing much more than 2.9 kW (12.5 A x 230 V) of charge power during regenerative braking, and of course it sees some 50 kW of discharge power during acceleration.
or the charger (more likely) ,if the charger gets reconnected soon after it was disconnected? Soon after, how soon if it was the case?
I don't know anything about the iMiEV charger, and I suspect that few people outside of Mitsubishi in Japan know either. However, it's reasonable to guess that the charger follows the same general principles as most high frequency power conversion equipment. In particular, there is sometimes an NTC (Negative Temperature Coefficient) resistor in series with the incoming mains. All that does is to make the initial current surge into the charger of less magnitude. That causes less stress on the components. The current through this resistor causes it to heat up, and this causes its resistance to decrease (most normal resistors would do the opposite). The lower resistance causes the NTC to have little influence after the first second or so of operation; by that time it's done its job. When you stop charging, the NTC cools down, ready to reduce the current surge the next time the charger is used.

But this assumes normal operation, where there would usually be many hours between uses of the charger. If you turn the power back on after only a few seconds, for example in the scenario you describe here, then the NTC may not have cooled down to near-ambient temperature, and so may still be rather low in resistance. This may cause the next turn-on surge to be of higher current than normal, which could stress the input capacitors and other components. My guess is that the NTC would have cooled down sufficiently after about 10 seconds, and certainly after a minute. These things are about the size of a five cent coin, except thicker, perhaps three coins stacked.

Having said all that, the iMiEV charger is likely to have a special input stage called a Power Factor Correction (PFC) circuit. These work a bit differently to the cheaper power supplies, and these typically don't have an NTC for surge protection. However, there are still large capacitors in such chargers, just that they are located after the PFC stage. Elcon and TC chargers for EVs are like this. Instead of the NTC, they have an input relay that shorts an ordinary resistor soon after power is applied. This allows the PFC stage to gently charge the large capacitors. So the operation is much the same. However, this time, the relay is powered by a small power supply that can operate over a wide range of voltages. What this means in practice is that the input relay won't drop out until some 30 seconds after the power is disconnected. It takes that long for the large capacitors, that are sized for powering multiple kilowatts for a fraction of a second, to discharge through the quiescent current drain in the charger (typically only control circuitry and the input relay). Until that input relay drops out, it's much like the situation with the NTC not having cooled down enough; the next connection could be quite hard on the input capacitors and a few other components, as the contacts of the input relay have essentially zero resistance.

Bottom line: there will be some sort of pre-charge circuit inside the charger, and the details vary widely. So it's difficult to put an exact time on how long to wait before re-applying power. However, it should be safe to re-connect after about a minute.

I'm sorry that the explanation ended up so long.

[ Edit: more 20A -> more than 20A.]
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Re: 10 Amp charging

Post by nuggetgalore » Fri, 24 Nov 2017, 19:33

coulomb wrote:
Thu, 23 Nov 2017, 06:45
nuggetgalore wrote:
Wed, 22 Nov 2017, 18:55
Hi all iMiEV wizzards.
I'm not an iMiEV wizard at all, but none seem to have answered so far.



Bottom line: there will be some sort of pre-charge circuit inside the charger, and the details vary widely. So it's difficult to put an exact time on how long to wait before re-applying power. However, it should be safe to re-connect after about a minute.

I'm sorry that the explanation ended up so long.
Thanks, you may not be a iMiEV wizard, but a wizard none the less.
Your explanations concur with my observation re the slow inrush current. I have not so far tried to reset the Ampfibian within less than several minutes.
I might try while observing (recording A at a few millisecond intervals ) the rise of current by interrupting the charge on my 16 A powerpoint with decreasing off times.
Any way thanks for assuring me that basically tripping and resetting an Ampfibian is a nuisance,but unlikely to cause harm (it is something that only happens once in a blue moon anyway).
tinker

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Re: 10 Amp charging

Post by reecho » Tue, 28 Nov 2017, 16:35

2010 I-Miev's pull 13 Amps all the time. that will explain the continuous tripping or the breaker in the Amphibian. Can't reduce it easily either as these models do not have PWM charge control.

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Re: 10 Amp charging

Post by bmscott » Mon, 04 Dec 2017, 20:39

reecho wrote:
Tue, 28 Nov 2017, 16:35
2010 I-Miev's pull 13 Amps all the time. that will explain the continuous tripping or the breaker in the Amphibian.
My 2010 iMiev charges with an Amphibian all the time and only pops the circuit breaker on days when the outdoor temp is in the high 30s or above - or if I leave it in direct sunlight. On cooler days it never triggers. It's rated for a temperature of up to 40C so I figured there was no mystery to this... I just wait 'til evenings on hot days, whenever possible.

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Re: 10 Amp charging

Post by nuggetgalore » Tue, 05 Dec 2017, 17:03

My 2010 iMiev charges with an Amphibian all the time and only pops the circuit breaker on days when the outdoor temp is in the high 30s or above - or if I leave it in direct sunlight. On cooler days it never triggers. It's rated for a temperature of up to 40C so I figured there was no mystery to this... I just wait 'til evenings on hot days, whenever possible.
[/quote]

If yours is the same as mine as i think it is, it draws 12.5 A +-0.2A. Because it ramps up very slowly to max draw, the Amphibian can handle that little over and above 10A until it gets too warm for too long then trips.
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Re: 10 Amp charging

Post by bmscott » Tue, 06 Mar 2018, 19:56

nuggetgalore wrote:
Tue, 05 Dec 2017, 17:03
If yours is the same as mine as i think it is, it draws 12.5 A +-0.2A. Because it ramps up very slowly to max draw, the Amphibian can handle that little over and above 10A until it gets too warm for too long then trips.
My Ampfibian has been getting steadily worse over the past couple of months and finally gave up the ghost the other day - the switch no longer moves properly and when I open it up, there's a distinct scent of fried important-thing...

We bought a new one yesterday and - it's doing the same thing! Not quite as bad, but it's tripping, even when the weather is cooler (like tonight).

I've ordered a replacement circuit breaker for the original Ampfibian, from the original manufacturer - we'll see how that goes.

But now I'm wondering if my car is somehow changing over time, drawing more power?? Because the original Ampfibian I had was 100% reliable, day or night. It never tripped the breaker until I'd had it at least a year.

And what alternatives are there, for charging from a 10-amp socket?

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Re: 10 Amp charging

Post by mikedufty » Tue, 06 Mar 2018, 22:24

Get a 15a socket? I think ours only cost about as much as 2 ampfibians.

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Re: 10 Amp charging

Post by antiscab » Tue, 06 Mar 2018, 23:43

Bypass the breaker and just let the car draw 13A from a 10A socket?
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Re: 10 Amp charging

Post by bmscott » Wed, 07 Mar 2018, 06:14

mikedufty wrote:
Tue, 06 Mar 2018, 22:24
Get a 15a socket? I think ours only cost about as much as 2 ampfibians.
We got a quote of more like $400, and haven't done it in the 2-1/2 years I've owned the car - at this point we're planning to put it up for sale soon, so I doubt we're gonna...

But yeah that would be the best way to go. I was just surprised to find that the Ampfibian wasn't really a current-limiting device after all - I suppose that would be more expensive? My bench power supply can limit current to a specific value, so I'd initially assumed that's what the Ampfibian did!
antiscab wrote:
Tue, 06 Mar 2018, 23:43
Bypass the breaker and just let the car draw 13A from a 10A socket?
What could go wrong? Hey wait, are you from my homeowners insurance company...?


I'm also starting to wonder if the original Ampfibian I had was actually faulty, and should NOT have been so reliable!

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Re: 10 Amp charging

Post by g4qber » Wed, 07 Mar 2018, 18:07

I have a Jaycar 15 to 10 amp adaptor that is out of spec
Ie allows 13 amp thru for imiev.
Wanted to get another but now they are in spec.
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Re: 10 Amp charging

Post by nuggetgalore » Thu, 08 Mar 2018, 07:35

g4qber wrote:
Wed, 07 Mar 2018, 18:07
I have a Jaycar 15 to 10 amp adaptor that is out of spec
Ie allows 13 amp thru for imiev.
Wanted to get another but now they are in spec.
I used the amphibian to charge at the electric vehicle expo. I needed top up charge because I gave visitors test rides.
What I noticed was that the Amphibian cord got rather hot at both ends. That had me a bit worried, any way I was able to put in enough until the CB tripped .
By the way, I use a 15 amp extension lead (from Bunnings ,yes I know ,should know better) for charging at home. I noticed there too that the plugs get fairly warm. It appeared it was caused by poor crimping of the wires to the pins and springs. I replaced the plugs,made sure of a good connection and bingo, no more warm plugs.
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Re: 10 Amp charging

Post by Peter C in Canberra » Thu, 08 Mar 2018, 09:00

I would use 15A cable for anything that pulls 10A continuously for an extended time. It's easy to remember: 15A rated cable has conductors that are 1.5mm2 cross-sectional area of copper and 10A rated cable is 1.0mm2. Look for the embossed 1.5mm2 on the side of the insulation. Some extension cords claim to be 'heavy duty' but this only refers to thicker or more robust insulation and they can still be 1.0mm2 inside. I am happy with my extension cord from Bunnings that has 1.5mm2 copper inside but 10A plugs on the ends.
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Re: 10 Amp charging

Post by antiscab » Thu, 08 Mar 2018, 14:52

I've seen heaps of 10A extension leads with 1.5mm2 wire. I get mine from bunnings

The wire in the wall is all 2.5mm2, with usually a 15A fuse, 16A or 20A circuit breaker.
The only difference between a 10A and a 15 A PowerPoint is the bigger earth pin.

If you've been charging fine from a 10A PowerPoint all this time with the amphibian, what's the worry?
If the circuit is overloaded the downstream cb will trip, but that's true even with charging with the amphibian.

All the amphibian does is protect your extension lead for over current. The solution here is a heavier extension lead
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Re: 10 Amp charging

Post by Chuq » Thu, 08 Mar 2018, 18:44

bmscott wrote:
Wed, 07 Mar 2018, 06:14

What could go wrong?
Rhetorical question of course, but ...

Image

Background: I bought my Leaf second hand, this 15A EVSE came with it from the previous owner, the plug had been chopped off and a 10A plug wired on. Was told "it was fine". And it was for many months, until this happened.

Note: It now has had the fried 10A plug removed and a new 15A plug put on. Has worked perfectly after many hours at caravan parks :)

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Re: 10 Amp charging

Post by mikedufty » Thu, 08 Mar 2018, 23:04

That is not much to do with it being a 10A plug, 15A plugs will do the same. Have a look at this thread for examples.

viewtopic.php?f=49&t=4413

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Re: 10 Amp charging

Post by antiscab » Fri, 09 Mar 2018, 00:34

Yeah the actual 15A plug on the evse supplied by Mitsubishi did the same thing.
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Re: 10 Amp charging

Post by Rusdy » Fri, 09 Mar 2018, 08:53

What I'm curious is why the burnt one is always 'Active' wire? Or has anyone has burnt the neutral wire instead? I'm at loss at the actual physics here. Must be pure coincidence that active wire is the one has weak connection?

Mine was the same (burnt active). After 3 years of good operation, the plug started has noticeable heat when I touch it, like a warm cup of coffee. When I dismantled the plug, the active wiring showed burnt insulation. Just replaced it last weekend and now all good again (no heat whatsoever). I used transparent plug now so I can visual check at all times.

[EDIT: My bad. After clicked the linked forum above, I've seen photos with burnt neutral. There you go... :roll: ]

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Re: 10 Amp charging

Post by bmscott » Fri, 09 Mar 2018, 10:06

g4qber wrote:
Wed, 07 Mar 2018, 18:07
I have a Jaycar 15 to 10 amp adaptor that is out of spec
Ie allows 13 amp thru for imiev.
Wanted to get another but now they are in spec.
I think that's the case with Ampfibian too - the new one we got uses a different circuit breaker which pops after a few mins charging an iMiev, but I ordered a replacement from the original manufacturer and it's now working reliably as my first Ampfibian did...

As for burnt plugs, I did notice this on the wiring inside the Ampfibian leading into the circuit breaker: Image
https://imgur.com/NEX575w

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Re: 10 Amp charging

Post by nuggetgalore » Sat, 10 Mar 2018, 20:18

[/quote]
I think that's the case with Ampfibian too - the new one we got uses a different circuit breaker which pops after a few mins charging an iMiev, but I ordered a replacement from the original manufacturer and it's now working reliably as my first Ampfibian did...

The new one that tripped every few minutes I think is working as it should because I am pretty sure you are charging with 12.5 amps and the idea of the amphibian is to make sure one does NOT draw more than 10 amps.
The fact that we are able to draw 12 or 13 is more because a device drawing 7 or 10 amps (anything in a caravan or small inverter welder etc) can peak at well over that for a few seconds at start up.
I recorded the rise in draw when the iMiEV charger fires up in milisecond steps , it is a very gentle rise,no spikes and therefore the amphibian (in my unscientific opinion) can handle a touch more than 10.
But that still puts a stress on the wire connections and after many hours of being marginally overloaded and getting hot ,the pressure on the wire reduces causing eventual fail.
tinker

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