working on a 120v fast charger. Good idea or waste of time?

[GigaGrunt]

3 things:

1. My thought is that it might be wiser to skip the conversion back to 240V AC and just go with a DC charger. Make a CHAdeMO charger out of it. This will save you the one out of 2 AC/DC DC/AC conversion losses. this adds to complexity and costs, but saves conversion losses.

2. Also keep in mind that Tesla specifically states you should not be charging the car from generators. The charger probably doesn't like nasty sinus or square waves either. So you need to be sure you have a high quality inverter with a true sinus output. Another reason is issue 4:

4. Tesla starts charging slow, and then slowly (in the course of a second or 10 or so) ramps up the amps. This allows your inverter to adapt. When charging is complete, it abruptly stops. In case of a generator or inverter this might cause a dangerous frequency peak. You should make sure there are no other appliances connected to the inverter when this happens and it might cause harm to the charging equipment (Tesla UMC)

When running a generator you can actually hear this happening. When you run a generator and you turn on eg. a coffee maker you will hear the generator adapt. It revs down for a second when you turn on the coffee maker, and it has to adapt and increase fuel injection. During that time the frequency of the output is off. Sensitive electronics don't like that.

5 . You need quite a few batteries to be able to draw a significant of power out of them. Don't know what your required charge rate would be, but to discharge 11 kW out of a battery pack you need quite a few batteries.

4. it is probably a lot cheaper to just get a 240V outlet at the location you want to use this.

@compu85's advise is risky. If the 2 outlets you are going to use are from the same leg you will:
1. Risk making a short circuit (if the polarity of the 2 sockets is reversed)
2. You break the functionality of the circuit breaker if the 2 sockets are behind different circuit breakers.

I would definitely not do compu85's advise on a property that is not yours or where there are other people. You risk lives by disabling circuit breakers or GFCI's and you increase risks of starting fires.

Is everyone going to skip over the fact that he started this off with '3 things:' and then numbered his items 1, 2, and 4. ?

 

[Tozz]

Haha, nice one

 

[mswlogo]

3 things:

1. My thought is that it might be wiser to skip the conversion back to 240V AC and just go with a DC charger. Make a CHAdeMO charger out of it. This will save you the one out of 2 AC/DC DC/AC conversion losses. this adds to complexity and costs, but saves conversion losses.

2. Also keep in mind that Tesla specifically states you should not be charging the car from generators. The charger probably doesn't like nasty sinus or square waves either. So you need to be sure you have a high quality inverter with a true sinus output. Another reason is issue 4:

4. Tesla starts charging slow, and then slowly (in the course of a second or 10 or so) ramps up the amps. This allows your inverter to adapt. When charging is complete, it abruptly stops. In case of a generator or inverter this might cause a dangerous frequency peak. You should make sure there are no other appliances connected to the inverter when this happens and it might cause harm to the charging equipment (Tesla UMC)

When running a generator you can actually hear this happening. When you run a generator and you turn on eg. a coffee maker you will hear the generator adapt. It revs down for a second when you turn on the coffee maker, and it has to adapt and increase fuel injection. During that time the frequency of the output is off. Sensitive electronics don't like that.

5 . You need quite a few batteries to be able to draw a significant of power out of them. Don't know what your required charge rate would be, but to discharge 11 kW out of a battery pack you need quite a few batteries.

4. it is probably a lot cheaper to just get a 240V outlet at the location you want to use this.

@compu85's advise is risky. If the 2 outlets you are going to use are from the same leg you will:
1. Risk making a short circuit (if the polarity of the 2 sockets is reversed)
2. You break the functionality of the circuit breaker if the 2 sockets are behind different circuit breakers.

I would definitely not do compu85's advise on a property that is not yours or where there are other people. You risk lives by disabling circuit breakers or GFCI's and you increase risks of starting fires.

Not that I’d recommend doing any of this. But if you did do the two circuit thing it would not defeat the breakers. What a 2 pole breaker does is if either side trips it forces the other side off. This is extra safety that if someone thinks the device is off but it can still be half hot. If you don’t have the bridge the circuit would still shutdown. But you have to realize it could be half live. If you’re doing these types of hacks, it’s probably the least if your safety concerns

You could also easily add a safety that the two outlets are not crossed.

BTW, there are third party 2 120V outlet to 240 conversion devices that already exist. I think they also add a secondary 2 pole breaker and probably checks polarity. But the outlets can’t be GFCI protected which is often the case on any outdoor outlet. Not exactly sure why GFCI would not work. Might depend on the load.

Quick 220 Systems: Model A220-15D For Equipment with US/Canadian Plugs

 

[mspohr]

Not that I’d recommend doing any of this. But if you did do the two circuit thing it would not defeat the breakers. What a 2 pole breaker does is if either side trips it forces the other side off. This is extra safety that if someone thinks the device is off but it can still be half hot. If you don’t have the bridge the circuit would still shutdown. But you have to realize it could be half live. If you’re doing these types of hacks, it’s probably the least if your safety concerns

You could also easily add a safety that the two outlets are not crossed.

BTW, there are third party 2 120V outlet to 240 conversion devices that already exist. I think they also add a secondary 2 pole breaker and probably checks polarity. But the outlets can’t be GFCI protected which is often the case on any outdoor outlet. Not exactly sure why GFCI would not work. Might depend on the load.

Quick 220 Systems: Model A220-15D For Equipment with US/Canadian Plugs

GFCI trips with the unbalanced load.

 

[davewill]

Quick220?

110-120 and 220-240 Voltage Converters & Accessories

Not in this case. You can't use one with GFI protected circuits and outdoor receptacles are required to be GFI protected.

 

[mswlogo]

GFCI trips with the unbalanced load.

How would the two individual 120V GFCI's know it's unbalanced?

And in the case of a 240V load (EV Charging) why wouldn't it be always balanced?

 

[Rocky_H]

How would the two individual 120V GFCI's know it's unbalanced?

It sounds like you're not getting what balanced means in context. A 120V circuit has the two lines that complete the circuit: a Hot and a Neutral. A GFCI is checking that the amount of current flowing in from one matches the amount of current flowing out the other. In the case of this Quick220 type of device, it is intentionally violating that Bigly(TM). It is taking the current in from the Hot and sending it elsewhere, so none of it is flowing back out through the Neutral of that outlet. So that outlet is completely imbalanced, with 100% from one wire and 0% on the other.

And in the case of a 240V load (EV Charging) why wouldn't it be always balanced?

Sure, the Hot1 and Hot2 from two different outlets are balanced with each other, but the GFCI is checking for balance at each outlet, with the Hot-Neutral circuit, which is way out of balance at that outlet.

I'm going to anthropomorphize a piece of hardware here, but basically, what the GFCI thinks it is seeing is that current is flowing in from the hot into someone's body being electrocuted, and going down to actual floor ground and none of the current is getting back to the Neutral wire. So it will cut that off to save someone's life.

 

[mspohr]

The Quick 220 hooks them together

 

[Sophias_dad]

What a 2 pole breaker does is if either side trips it forces the other side off.

Just to be clear... what you say is true if there's a single(usually small) handle for the two pole breaker. It is NOT true if you have two breakers that sit side by side and have a bridged handle. Up until about a week ago, I thought that the bridged handle would flip the other breaker when one side overloaded, and that's apparently not the case.

 

[Cosmacelf]

Has the Model 3 started working with the chademo adapter?

No.

 

[mswlogo]

Just to be clear... what you say is true if there's a single(usually small) handle for the two pole breaker. It is NOT true if you have two breakers that sit side by side and have a bridged handle. Up until about a week ago, I thought that the bridged handle would flip the other breaker when one side overloaded, and that's apparently not the case.

Both poles should trip if there is an overload on one side on any 2 pole 240v breaker. Whether it’s the single handle type or the dual handle that are bridged externally. If you have one that only half tripped, you should probably replace it.

 

[Sophias_dad]

Both poles should trip if there is an overload on one side on any 2 pole 240v breaker. Whether it’s the single handle type or the dual handle that are bridged externally. If you have one that only half tripped, you should probably replace it.

Note that I haven't actually tried it out, mainly because I don't want to intentionally trip a 20 or 30 amp breaker which might be somewhat dangerous or unpleasant. Also, I wonder if the rules are different for some breakers that look like they have a handle-tie, but maybe have an internal common-trip mechanism. I'm thinking in particular of my 200 amp main breaker, which looks like 4 handletied single breakers. I kinda hope that if it trips, it takes down both poles completely. I guess if only one of the breakers breaks, the other on the same pole is going to trip instantly anyway since its taking double its usual load. Still wouldn't guarantee the other pole is going down....




Common Misunderstandings in Overcurrent Protection

Misunderstanding #4: ...

It's important to understand the difference between the handle tie feature and the common trip feature. Handle ties fasten the handles of two or more single-pole circuit breakers together. With handle ties installed, all of the poles are switched on and off together. However, if one pole trips because of an overload or short circuit, the handle tie doesn't cause the connected poles to trip. The condition can leave one pole tripped and the other tied poles energized.

 

[mswlogo]

Note that I haven't actually tried it out, mainly because I don't want to intentionally trip a 20 or 30 amp breaker which might be somewhat dangerous or unpleasant. Also, I wonder if the rules are different for some breakers that look like they have a handle-tie, but maybe have an internal common-trip mechanism. I'm thinking in particular of my 200 amp main breaker, which looks like 4 handletied single breakers. I kinda hope that if it trips, it takes down both poles completely. I guess if only one of the breakers breaks, the other on the same pole is going to trip instantly anyway since its taking double its usual load. Still wouldn't guarantee the other pole is going down....




Common Misunderstandings in Overcurrent Protection

Misunderstanding #4: ...

It's important to understand the difference between the handle tie feature and the common trip feature. Handle ties fasten the handles of two or more single-pole circuit breakers together. With handle ties installed, all of the poles are switched on and off together. However, if one pole trips because of an overload or short circuit, the handle tie doesn't cause the connected poles to trip. The condition can leave one pole tripped and the other tied poles energized.

I stand corrected. The externally bridged ones are not required to trip both poles. They are only for the purpose of when the user turns it off or on they are switching both poles. But for safety/fault they don't trip both poles. It depends on the load on what is legal (common trip or common disconnect).

 

[diamond.g]

No.

That is what I thought as well, so I was confused when I saw folks talk about portable chademo charger. I don't know if I would consider L2 charging fast charging for track use, though I guess if your only other option is L1 then I guess you take what you get.

 

[Rocky_H]

That is what I thought as well, so I was confused when I saw folks talk about portable chademo charger.

Oh, whoops. I forgot this was in the Model 3 section, which can't use CHAdeMO yet.