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Discussion Starter #1
I assume there is a post somewhere, but I cannot find it. Does anyone know what the official max DC charge rate is for the Clarity Electric (2019 specifically, not sure if it changed from year to year)? I've seen mine top out at about 30 kW, but I wasn't sure if that's what the limit is or if it's just the chargers I've been using.
 

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6.6KWh, which translates to 4 hours to charge using a 28 amp EVSE. (Source for max charging rate: www.clippercreek.com)
 

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6.6KWh, which translates to 4 hours to charge using a 28 amp EVSE. (Source for max charging rate: www.clippercreek.com)
He was asking about the DCFC rate, which bypasses the charger in the car (which will draw up to 32A but typically 7.2 kW @ 240V even thought the specs say 6.6).

The max DCFC rate is going to depend on the amperage of the charger.
The nominal Voltage of the Clarity pack is 311, so on a 100A charger it will be close to the 30 kWh you are seeing (at low SOC%). If you connect to a charger that supports 125A, you will see up to 39 kWh. The taper starts at about 70% SOC.

Li-Ion DCFC starts at constant current, then switches to constant voltage, so as the battery charge increases you'll see the charging voltage increase and the amperage drop (at some point the voltage remains constant at ~ 348).
 

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Thanks for the info. I hadn't looked at the intricacies of how DCFC worked, that's good to know.
Do you know if there is an upper limit the batteries can support, assuming the charger can support any amperage?
 

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Based on the battery size and the ChargePoint article on the Clarity Electric stating 80% charge in 30 minutes, I'm estimating the peak DCFC charge rate is between 30 and 40 KWh. The reason for this range vs. a single number is the ChargePoint article doesn't say the starting SOC when charging to 80% in 30 minutes.

Battery size: 25.5KWh
Charging 10% to 80% in 30 minutes => 40KW
Charging 20% to 80% in 30 minutes => 30KW
 

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Thanks for the info. I hadn't looked at the intricacies of how DCFC worked, that's good to know.
Do you know if there is an upper limit the batteries can support, assuming the charger can support any amperage?
The limit is 125A. Charging at an Electrify America 300A/150 kW charger doesn't yield anything more than a 125A unit.

Honda has determined that 125A (~40 kW) is the upper limit and the Battery Management system will not pull anything more than that from a charger.

Note: A "50 kW" charger can get there by a rating of 100A @ 500V, or 125A @ 400V. Since the Clarity (and most other EVs) will not draw more than 400V, the 125A units will charge faster (higher kW).
 

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6.6KWh, which translates to 4 hours to charge using a 28 amp EVSE. (Source for max charging rate: www.clippercreek.com)
Keep in mind that kWh is a measurement of quantity of energy, not a rate. You could say that a battery charges at a rate of 6.6kW **per** hour (rate). If it could charge at that rate for four hours then it would have received 26.4kWh of energy (amount).
 

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Keep in mind that kWh is a measurement of quantity of energy, not a rate. You could say that a battery charges at a rate of 6.6kW **per** hour (rate). If it could charge at that rate for four hours then it would have received 26.4kWh of energy (amount).
KWh is shorthand for KW per hour, which is a rate.
 

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KWh is shorthand for KW per hour, which is a rate.
kWh is a unit of energy (capacity)

kW is a measure of power (rate)

kW per hour is something else entirely that is roughly equivalent to saying "gallons per minute per hour" when talking about pumping gas.
 

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kWh is a unit of energy (capacity)

kW is a measure of power (rate)

kW per hour is something else entirely that is roughly equivalent to saying "gallons per minute per hour" when talking about pumping gas.
Exactly. When I get my electric bill at the end of the month stating that I used 1300 kWh, it has nothing to do with the rate at which I used the electricity. It has to do with the amount of energy, in total, that I used.
 

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KWh is shorthand for KW per hour, which is a rate.
It’s not shorthand for kilowatts per hour. A kilowatt-hour is the amount of energy consumed when one draws a kilowatt for one hour. It also happens to be the amount of energy consumed when one draws 500 watts for two hours or 2,000 watts for a half-hour.
 

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It’s not shorthand for kilowatts per hour. A kilowatt-hour is the amount of energy consumed when one draws a kilowatt for one hour. It also happens to be the amount of energy consumed when one draws 500 watts for two hours or 2,000 watts for a half-hour.
Drawing one Kilowatt for an hour is mathematically represented as

1 KW
------
1 Hr

or KW per Hour.

This is how you can estimate how long it will take to charge an EV once you know the battery size and the supply rate. Rates are always expressed as amount divided by time.
 

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Drawing one Kilowatt for an hour is mathematically represented as

1 KW
------
1 Hr

or KW per Hour.

This is how you can estimate how long it will take to charge an EV once you know the battery size and the supply rate. Rates are always expressed as amount divided by time.
No, drawing one kW for one hour would be 1 kW times 1 hour which is 1 kWh
Drawing 1 kW for 2 hours would not be 1 kW per 2 hours or .5 kWh

5 gpm x 5 minutes = 25 gallons
7.2 kW x 2 hours = 14.4 kWh

5 gpm/5 minutes = 1 gallon per minute per minute

To estimate time, you divide kWh by KW. To add 13 kWh to a battery with a 7 .2 kW EVSE would take about 1.8 hours

It can be confusing to have a time measure associated with the capacity and not the rate, but that's how it works
 

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Drawing one Kilowatt for an hour is mathematically represented as

1 KW
------
1 Hr

or KW per Hour.

This is how you can estimate how long it will take to charge an EV once you know the battery size and the supply rate. Rates are always expressed as amount divided by time.
Let’s see then. If I draw 10 kW for a hundred hours (that’s a long time!) then that’s equivalent to (10 / 100) .1 kWh?

Sorry, Charlie! You need to go do some research on this. DucRider explains it correctly.
 

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Google says:

A kilowatt is simply 1,000 watts. A watt measures the rate at which electrical power is used or generated. In comparison, a kilowatt-hour is a unit of energy equivalent to one kilowatt of power expended for one hour of time.

A KW is a rate of discharge or charge.

A KWh is a unit of energy that last 1 hour at a rate of 1KW draw.
 
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