Cost of L2 charging at ($1/hr) vs L1 trickle charging

I recently purchased a new Nissan Leaf (S with quick-charge package) and have a 6.6kW ChargePoint charger at my work available to me at a cost of $1/hr. I'm not sure if I'll qualify for the No-charge-to-charge program on this charger, so lets assume not for the purposes of this discussion.

My question is whether is will be cheaper (per kWh received) to charge at this station vs trickle charging with L1 at home (with a cost of $0.13/kWh).

At the surface, L1 charging appears cheaper at $0.13/kWh as L2 would cost $1/6.6kW = $0.15/kWhr. Or is the actual maxiumum transfered only 6.0kW, so $1/6.0kW = $0.17/kWh. But L1 is less efficient than L2 charging due to the lower voltages involved (110V vs 220V). I've seen different efficiency ratings of L1 (66-75%) and L2 (75-87%) quoted.

Also -- I'm not sure if ChargePoint charges for actual time used or increments (in 15min etc...).

Also -- I'm not sure if ChargePoint continues to charge even when the battery is full.

While I know that many ChargePoint chargers are free, this really wouldn't be convenient for me on a daily basis, so let's restrict the discussion to a cost of $1/hr to use the charger.

Any thoughts would be appreciated. Certainly L2 is much faster which is great, but I'm primarily interested in the comparing the final cost charged vs. energy received.

glaurent said:

Also -- I'm not sure if ChargePoint continues to charge even when the battery is full.

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That is the important question, if you cannot time the disconnect.

L1 is about 80% efficient
L2 is about 90% efficient

So...
At work, presuming optimal use, you pay $1 for 6 kWh into the battery
At home you pay $(6 * 0.13 * 1.25) for the same 6 kWh into the battery

Also note while you might be getting 6kw into the battery up to ~90% SOC above that the charging rate drops to half or even more as balancing takes place. You really need to know how Chargepoint is billing to know which is more economical. I know when I use free Chargepoint chargers they tell me exactly how long I was plugged in and how many Kwh's were consumed.

Do you have the 80% charge option? (What year and country?) If you're being charged per hour (instead of per kWh, which would make more sense) you don't want to keep charging up above 80% or 90% when the charging rate slows down.

OK -- So it sounds like the conclusion is that charging at $1/hr on a 6.6kW L2 charger until I get to 80% charge will cost essentially identical to home charging. Anything after that will end up costing substantially more.

IssacZachary said:

Do you have the 80% charge option? (What year and country?) If you're being charged per hour (instead of per kWh, which would make more sense) you don't want to keep charging up above 80% or 90% when the charging rate slows down.

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I'm actually from Lakewood, CO. I'm just in the initial stages and am not sure if the ChargePoint has any charge limits. It appears to charge per hour rather than per kWh, so removing it from the charger before 80% will be necessary.

glaurent said:

OK -- So it sounds like the conclusion is that charging at $1/hr on a 6.6kW L2 charger until I get to 80% charge will cost essentially identical to home charging.

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Huh.

And here I thought you were counting pennies. The difference could easily be a nickel a day! :lol: