charging from 80% to 100% on L2 takes 3+ hours??

[JessEV]

Hi guys,

After 3 months on L1 only, I finally got around to installing my AV EVSE in the garage. Its sooo nice to charge faster.

Something strange though. It took 3 hours 15min to charge from 80% (where I had programmed it to stop earlier) to 100%. At 3.3kWh, that's over 10kWh. At 80% efficiency, that is still 8kWh. But 20% of a 24kWh battery is only 4.8kWh.

And I know it can take longer to charge the remaining few percent of a Li battery, more heat, etc... but it was still drawing 3.3kWh till the very end. You'd think if it had to trickle charge, it would reduce the kWh?

So is it that the charging process is only a ridiculously inefficient 50% at the last 20% or that Nissan is charging some reserver portion of the battery? There was earlier talk of a mysterious 10% held in reserve somewhere. I'm leaning a little more towards the latter... partially out of hope, partially that I think I noticed I'm getting a little more range on the car now when I charge it to full 100% with L2 in comparison to my earlier 100%'s with L1.

Thanks
Jess

 

[LEAFfan]

My Blink only takes a little over an hour to go from 80% (83%) to 100%.

 

[LEAFer]

Hi guys,

After 3 months on L1 only, I finally got around to installing my AV EVSE in the garage. Its sooo nice to charge faster.

Something strange though. It took 3 hours 15min to charge from 80% (where I had programmed it to stop earlier) to 100%. At 3.3kWh, that's over 10kWh. At 80% efficiency, that is still 8kWh. But 20% of a 24kWh battery is only 4.8kWh.

And I know it can take longer to charge the remaining few percent of a Li battery, more heat, etc... but it was still drawing 3.3kWh till the very end. You'd think if it had to trickle charge, it would reduce the kWh?

So is it that the charging process is only a ridiculously inefficient 50% at the last 20% or that Nissan is charging some reserver portion of the battery? There was earlier talk of a mysterious 10% held in reserve somewhere. I'm leaning a little more towards the latter... partially out of hope, partially that I think I noticed I'm getting a little more range on the car now when I charge it to full 100% with L2 in comparison to my earlier 100%'s with L1.

Thanks
Jess

First off ... when you talk about "draw" it's "kW" (not "kWh"), then you multiply by time to get "kWh" ... but ok ... let's get to the details.

How do you know it was drawing 3.3kW the entire time ? (And, BTW, it actually draws more than that from the wall. 3.3 is what goes into the battery.)

There may have been some battery balancing going on, which takes quite a bit longer, and does *NOT* draw 3.3 (or 3.8), but significantly less. Also, what was the ambient temp ? And how long had the LEAF been sitting at ambient ?

 

[JessEV]

I have a TED and it was reading 4+kW from 10:50pm to 2am last night. Normally I'm hovering in the sub 1kW range at that time. Checked that I didn't have any major appliances (oven, AC...) on at the time.

Ambient temp in the garage where it sat for most of the day was probably in the 70F-75F range.

I'll see if it continues to do that.

I also wondered about the balancing, but agree that it shouldn't have drawn that much... the kW has to go somewhere, or its wasted as heat. I'll use my thermal cam next time to see if the bottom of the car is warmer than usual during this last 20% charge.

 

[EVDRIVER]

I have a TED and it was reading 4+kW from 10:50pm to 2am last night. Normally I'm hovering in the sub 1kW range at that time. Checked that I didn't have any major appliances (oven, AC...) on at the time.

Ambient temp in the garage where it sat for most of the day was probably in the 70F-75F range.

I'll see if it continues to do that.

I also wondered about the balancing, but agree that it shouldn't have drawn that much... the kW has to go somewhere, or its wasted as heat. I'll use my thermal cam next time to see if the bottom of the car is warmer than usual during this last 20% charge.

You need to add a second MTU on that line to be accurate. If you have a 5000 it is easy.

 

[thankyouOB]

the experience here is 90 minutes to go from 80 to 100%

 

[DaveinOlyWA]

charge rate is not linear. even on 120 volts i see it start to trickle down for the last 30-45 mins.

 

[leafwing]

the experience here is 90 minutes to go from 80 to 100%

+1

 

[LEAFer]

charge rate is not linear. even on 120 volts i see it start to trickle down for the last 30-45 mins.

Yes, but he (?she) says it was 4+kW for more than 3 hours.
JessEV: have a graph from your TED for that time frame ?

(And like EVDriver says ... best to add an MTU.)

 

[garygid]

Had your LEAF decided to do about 1:30 for charging, then two 0:45
equalizing periods of about 0:40 no-draw and 0:05 of tapered charging?

 

[JessEV]

Here's a graph from Google Power meter (RIP). It is sent data from my ENVI (I said TED, I meant ENVI) unit that has its little hooks looped around the house mains. As an aside, it seems to consistently read 10% lower than actual (as seen from my Smartmeter directly).

You'll see from the graph the 2 markings. Start time and end time. Start time I know because that is when I hit the timer off button and watched it start charging. End time I know because I checked at 140am it was still going, and then sent me an email at 210am.

I'm going to charge again tonight from 80% (or wherever it really stops when it is programmed to stop at 80%) to 100% and see where it lands. Will update.

Thanks
Jess (could anyone this anal not be male?)
OceanBlue SL Leaf, 911 Cab S.

 

[JessEV]

Ok. Charged again from 80%. This time it only took 90min - just as predicted on the dash. Must have been balancing the other day, since I rarely charge to 100%.

 

[garygid]

Question:
Does the LEAF actually PERFORM its cell equalization ONLY when charging to 100%?

Others have graphed current draw and observed few-minute current "spikes" at about 50 minutes and 100 minutes after charging was otherwise "complete".

Presumably these are "topping up" the battery after about 45 minutes of discharging the "highest-voltage" cell-pairs.