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[DonTom]

That's not how this works.

That is exactly how it works, depending on charger design.

Check the level two specs and compare to the level one spec on various electric  bikes and then perhaps you will understand.

IYO, what is wrong with these facts:

Zero (except SR/F )charges at around 1.4 KW on any voltage 90 to 240 VAC.


My Energica charges at 1.5 KW on 120 VAC but 3.0 KW on 240 VAC. So does the Zero SR/F. So does my Elcon Chargers (but more like 1.25 KW on 120 VAC but 2.5 KW on 240 VAC with the Elcons).

Do we agree on that much?

-Don-  Reno, NV

[DonTom]

It's not so much that the Energica is charging twice as fast on 240v, it's 120v that's cutting the charging rate in half.

I think we're saying the same thing. Half the wattage at 120 VAC is the same as saying twice the wattage at 240 VAC. But the Zero charger limits the current so it does not increase the wattage with the increased voltage. So with the increased voltage, the current is decreasing to keep the charger in it's safe low limit of 1.4 KW output.

The Energica lets the current rise with voltage so the wattage will double when the voltage is doubled. Just as it would on a fixed value resistor. A one ohm resistor will get twice as hot when the voltage across it is doubled. The Zero chargers lower the current as the voltage goes up to keep the power down to the safe level it can handle. IOW, cheap. And a cheap low wattage L2 charger is on the 30K$ Harley Livewire.


-Don-  Reno, NV

[TheRan]

That's not really down to charger design, in the sense that it's some sort of different architecture that allows it to increase wattage with voltage, it just the fact the charger is designed to output a higher wattage. Slap an aftermarket charger in a Zero designed to put out a higher wattage, or even the OEM charge tank, and it will behave the same as the Energica. It will still charge at the same rate on 120v, because that's what the infrastructure can support (in terms of current), but hook it up to 240v and it will charge faster. There's nothing special about the Energica, it just has a higher wattage charger.

EDIT: Think about it this way, would the Energica charge twice as fast again if you hooked it up to 480v? No, because it has a 3kw charger. It would just draw half the current (well, assuming it could handle 480v).

[DonTom]

That's not really down to charger design, in the sense that it's some sort of different architecture that allows it to increase wattage with voltage, it just the fact the charger is designed to output a higher wattage. Slap an aftermarket charger in a Zero designed to put out a higher wattage, or even the OEM charge tank, and it will behave the same as the Energica.

Of course if it safely lets the current stay the same as the voltage is doubled, you get twice the wattage. We are still saying the same thing.

It will still charge at the same rate on 120v, because that's what the infrastructure can support (in terms of current), but hook it up to 240v and it will charge faster. There's nothing special about the Energica, it just has a higher wattage charger.

Yes, but only higher on 240 VAC because it lets the current stay the same as the voltage is increased.

EDIT: Think about it this way, would the Energica charge twice as fast again if you hooked it up to 480v? No, because it has a 3kw charger. It would just draw half the current (well, assuming it could handle 480v).

I doubt that very much. I think the charger would be damaged. In the two seconds it takes to blow out, it probably will charge twice as fast for that two seconds. I doubt if there is any circuit to reduce the current in the Energica charger when the 240 VAC is doubled (unless it's a fuse of some type!).

No, I will not look for 480 VAC to prove my point!   But I would expect the charger to be toast.  There would be no practical reason to limit the current on the Energica charger for 480 VAC. But there is a practical reason to do such on a Zero from the operating range of 90 to 250 VAC.

-Don-  Reno, NV

[Crilly]

Dontom:  My SR/F came with a 3500 watt charger times 2.  When I plug in a j plug capable of 7 Kw at 240 volts it charges 5 times faster than at 120 volts.

[DonTom]

Dontom:  My SR/F came with a 3500 watt charger times 2.  When I plug in a j plug capable of 7 Kw at 240 volts it charges 5 times faster than at 120 volts.

As expected for the Zero SR/F. Your chargers are different than all the other Zeros as I have explained in several of the posts here where I added "except the SR/F".

-Don-  Reno, NV

[Crissa]

Don, a charger is not a resistor.

I don't know how to explain that to you.

The on-board charger has a certain wattage.  It cannot exceed that wattage.  If it's compatible with a J-plug, it can be told to operate below that wattage (within constraints of its design), that's why the J-plug has a signal line.

The charger on stock S and X Zeros is 1.4KW.  Hence, raising the voltage means less current draw because it cannot exceed that wattage.  Just as the 3KW one can't exceed 3KW, no matter how much voltage or current is available.

-Crissa

[TheRan]

Of course if it safely lets the current stay the same as the voltage is doubled, you get twice the wattage. We are still saying the same thing.

Not exactly. It gets twice the wattage because it's designed to have that much wattage, no more. The Zero chargers are simply designed to output less wattage and they're capable of that at a lower voltage.

EDIT: Think about it this way, would the Energica charge twice as fast again if you hooked it up to 480v? No, because it has a 3kw charger. It would just draw half the current (well, assuming it could handle 480v).

I doubt that very much. I think the charger would be damaged. In the two seconds it takes to blow out, it probably will charge twice as fast for that two seconds. I doubt if there is any circuit to reduce the current in the Energica charger when the 240 VAC is doubled (unless it's a fuse of some type!).

No, I will not look for 480 VAC to prove my point!   But I would expect the charger to be toast.  There would be no practical reason to limit the current on the Energica charger for 480 VAC. But there is a practical reason to do such on a Zero from the operating range of 90 to 250 VAC.

-Don-  Reno, NV

Like I said, let's assume it could handle 480v. By your reasoning it would keep the same current resulting it twice the wattage output and twice as fast charging. That wouldn't happen. Chargers are designed to put out a certain wattage and wattage is current times voltage. For the sake of simplicity let's say it's instead a 2400w charger. At 240v it will draw 10 amps, at 480v (again, assuming it is designed to accept that much voltage) it will draw 5 amps, and at 120v it would need to draw 20 amps. The thing is drawing 20 amps from a 120v outlet isn't very safe so it draws less, outputting less wattage. All chargers have a current limit inherent on the fact that they have a wattage limit.

[DonTom]

Don, a charger is not a resistor.

I don't know how to explain that to you.

-Crissa

Wrong! Any load has resistance (or impedance if AC). But that wasn't my point. Point is as voltage is increased on a steady load, the current will increase in proportion unless a special circuit is designed to lower it as the voltage is increased. As all the Zeros chargers do (except the SR/F).

If you increase the voltage on a 120 VAC lamp, the wattage (converted to heat and brightness energy) increases until the lamp burns itself out. But it is possible to build a circuit to drop the current as the voltage is increased so the lamp doesn't blow out and stays at the same brightness on 240 VAC as on 120 VAC.  And that is why your Zero on-board charger doesn't blow out on 240 VAC and has the same output in watts as on 120 VAC. It draws half the current on 240 VAC to drop the wattage on 240 VAC.

No doubt by Energica does  NOT have such a circuit (no need) and will blow out if I double the voltage from 240 to 480. So would your Zero, because it is only designed to handle 250 VAC max input. But from 120 VAC to 240, my current will double to get twice the wattage as your DC output wattage will stay the same from 120 to 240 VAC on the input.

-Don-  Reno, NV

[Crissa]

A charger is not a resistor, Don.

It's a charger.  Otherwise we'd just hook the battery up to mains, and we don't do that.

A lamp is a resistor.  Also, you put more voltage through it and it'll blow up.  You put more voltage through a PC power supply and... It consumes less current.

-Crissa

[DonTom]

  You put more voltage through a PC power supply and... It consumes less current.

That depends. If the PC power supply is 120 VAC max and you put in 240 VAC, you just blew out your PC power supply with the excessive voltage which caused excessive current and wattage (heat).

But if it is designed to run on 240 VAC as well as 120 VAC, then the current will drop as the voltage is increased because it was designed to do such, just as is your zero charger. Requires a special circuit. Is getting to be a norm because much of the world uses 240 VAC (most if not all of Europe), but the USA uses mostly 120 VAC, Japan uses 100 VAC, etc. So a lot of equipment these days are designed for  a world market of 90 to 250 VAC or so.

More than around 50 years ago, almost any 120 VAC item would instantly be damaged by 240 VAC. Just about any power supply or charger. Now the 120 VAC to 240 VAC input is rather common by design.

-Don-  Reno, NV

[Crissa]

If the PC power supply is 120 VAC max...

...And this has to do with what?

-Crissa

[TheRan]

But if it is designed to run on 240 VAC as well as 120 VAC, then the current will drop as the voltage is increased because it was designed to do such, just as is your zero charger. Requires a special circuit.

I still don't understand why you think the Energica charger is any different. It's not just some dumb constant current device, it's part of a machine costing tens of thousands of dollars with a massive battery that is liable to catch fire if handled incorrectly. It will be precisely and accurately monitoring the incoming and outgoing voltage and current (and by extension the wattage) and varying them when needed. There is absolutely no reason why it wouldn't have the capability to limit itself to the designed wattage.

[DonTom]

If the PC power supply is 120 VAC max...

...And this has to do with what?

-Crissa

The subject that you brought up, where you said:

"You put more voltage through a PC power supply and... It consumes less current."

-Don-  Reno, NV

[DonTom]

There is absolutely no reason why it wouldn't have the capability to limit itself to the designed wattage.

There is no reason to expect that  anybody to try to put 480 VAC on it. So why limit it outside of its expected ratings?

-Don-  Reno, NV