madscientist
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CHAdeMO power tapering question

Tue Oct 27, 2015 9:46 am

Does anyone have a handle on the Nissan Leaf DC charge cycle,


what is the max allowable constant current phase power allowable, i.e. what proportion of C is Nissan allowing

do they actually taper the power in the CC phase for safety ?

what cell voltage do they transition from CC full power to CV tapering power


thanks

GregH
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Re: CHAdeMO power tapering question

Tue Oct 27, 2015 3:07 pm

The Leaf can do the full 125A from standard CHAdeMo.. The Nissan chargers I think only put out 105A. (?)
Power only drops when the the highest cell gets to about 4.10-4.12V (around 394V on the pack.. same as a normal charge). The lizard packs might charge to a slightly higher voltage.

For me that's around 40% SOC :cry:
(due to my lower capacity and increased impedance)

This will be a big bonus for the 30kWh packs... I would imagine you could scoop up a lot more juice in 30 minutes.
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knightmb
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Re: CHAdeMO power tapering question

Tue Oct 27, 2015 11:39 pm

At Nissan HQ, the most I've seen (with mine and others) is 105 amps max or (400V x 105A) or 42kW I think? Once the charge hits over the 60% mark, it has a steady, slow decline down to around 45 amps (18kW) when nearing 80% SOC. As the previous posted said, it can probably do more, so it might be a limitation of the Nissan charger or max input power at that location.

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drees
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Re: CHAdeMO power tapering question

Wed Oct 28, 2015 12:02 am

GregH wrote:This will be a big bonus for the 30kWh packs... I would imagine you could scoop up a lot more juice in 30 minutes.

The Daily Kanban article on the 2nd gen LEAF has a slide that says this:

24 kWh LEAF - 100 km in < 30 min (50 kW CHAdeMO)
30 kWh LEAF - 100 km in ~15 min (50 kW CHAdeMO)
60 kWh LEAF - 100 km in ~8 min (100 kW CHAdeMO)

My LEAF on the other hand is like yours - due to increased impedance the charge rate really slows down above 50% SOC. Limiting cell voltage to 4.10V unlike the 2013+ LEAF which is limited to 4.12-4.13V makes a significant difference in charge rate.

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DNAinaGoodWay
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Re: CHAdeMO power tapering question

Wed Oct 28, 2015 1:48 am

60 kWh! Holy Smokes!
'12 SL last reading @ 2 yr, 22k, 260 GIDs, 62.35 Ahr

'15 SV w/QC, Mfd 5/14, Leased 8/14, 292 GIDs, 64.38 Ahr when new
@ 36 months, 34k, 270 GID, 57.49 Ahr

'17 Bolt LT



6.72 kW Array

knightmb
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Re: CHAdeMO power tapering question

Wed Oct 28, 2015 1:53 am

drees wrote:24 kWh LEAF - 100 km in < 30 min (50 kW CHAdeMO)
30 kWh LEAF - 100 km in ~15 min (50 kW CHAdeMO)
60 kWh LEAF - 100 km in ~8 min (100 kW CHAdeMO)

My LEAF on the other hand is like yours - due to increased impedance the charge rate really slows down above 50% SOC. Limiting cell voltage to 4.10V unlike the 2013+ LEAF which is limited to 4.12-4.13V makes a significant difference in charge rate.


Nice chart, I wonder why they leave such a large gap of "less than 30 minutes" for the 24kWh Leaf? I've brought my Leaf into a QC station at 3% SOC to see how long it takes to go from near empty to 80% SOC and getting enough power for 100 km (62 miles) took less than 13 minutes, it is the other top end (70%, 80%, etc.) that takes nearly another 10 minutes to reach when the power ramps down so much. If the chart was set for miles, then I could see it taking 30 minutes to hit a near 100% SOC on the 24kWh Leaf.

madscientist
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Re: CHAdeMO power tapering question

Wed Oct 28, 2015 10:43 am

Are people saying that Nissan will allow the chademo to put in whatever max it can , are Nissan allowing 4-5 C. Charging ? I find that hard to believe

GregH
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Re: CHAdeMO power tapering question

Wed Oct 28, 2015 10:58 am

4-5C? I've got a 50Ah pack now and can charge at 125A..
Nissan allows full speed as long as the cells remain below 4.1V.
Not sure how much it would allow on a 100kW CHAdeMO.. (do they even exist yet?)
'17 blue Volt Premier w/ACC
'12 SL black Leaf
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RegGuheert
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Re: CHAdeMO power tapering question

Wed Oct 28, 2015 11:14 am

madscientist wrote:Are people saying that Nissan will allow the chademo to put in whatever max it can , are Nissan allowing 4-5 C. Charging ?
The car CANNOT allow the quick charger free reign since the charger has NO WAY to know if it is overcharging any of the cells in the pack. Only the BMS can tell that since it is what measures the voltage of each cell.

GregH's description is the best one, and note that the cell with the HIGHEST voltage is the one which causes the BMS to limit the current. If you would put in 96 times 4.1V instead, you would get a MUCH higher current because all the other cells have lower resistance than this one. That would cause the AVERAGE voltage to be 4.1V, but would cause this one cell to have a much higher voltage.
madscientist wrote:I find that hard to believe
You should, since that is NOT what happens.
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 30K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
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TonyWilliams
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Re: CHAdeMO power tapering question

Thu Oct 29, 2015 10:03 am

The Nissan / Sumitomo chargers are 115 amps max. Most other stations are 120 amps. All the Fuji chargers are 63 amps. BTC chargers are 48 amps. Some Eaton units are restricted with 20 amp increments; either 120, 100 or 80 amps is typical. Blink units are generally 125 amps. Some ABB units are 125, also.

Next year, ABB will likely have a 200 amp charger.

Here's a taper profile with the 45kWh battery in the 2012-2014 Toyota RAV4 EV. The battery voltage is very similar to the LEAF (395 volt for LEAF, 382 volt for RAV4).

Because the CHAdeMO protocol is limited to 200 amps, any "100kW" stations would require a 500 volt battery (which no modern EV has). Therefore, even those future stations will be practically limited to 200a * 400v = 80kW maximum. The nominal charge rate rate would be closer to 200a * 350v = 70kW.

kW is simply volts multiplied by amps:


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