Battery capacity and kWh

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inphoenix

Well-known member
Joined
Aug 30, 2015
Messages
287
Location
Phoenix! AZ
I have a question about the battery capacity and kWh consumed. Fair warning ...... it is a noob question so it may provide a chuckle for some of those who know about this.

I wanted to try out the DC fast charging so I headed over to a charger nearby with 18% juice left in the battery (2014 S). I "pumped" almost 11kWh into the battery which brought the battery up to 85% in about 43 minutes.

So did it take 11 kWh to charge 67% (85%-18%) of a 24kWh battery? It was my assumption that 11kWh input would be equivalent to what battery would gain but it seems it gained 16kWh. What am I missing :?:
 
how did you get this 11 kwh? cause 43 mins at a "quick" charger and only getting 11 kwh is ahh... not very quick. is this 11 kwh what the station told you it doled out? if so and you are being billed by the kwh, you made out.
 
Most QC stations report SOC incorrectly. Where are you getting the 18% and 85% figures? A new battery is only about 21.5 kWh, if I recall. Of course, as the battery degrades the kWh that it takes to recharge is reduced.
 
keydiver said:
Most QC stations report SOC incorrectly. Where are you getting the 18% and 85% figures? A new battery is only about 21.5 kWh, if I recall. Of course, as the battery degrades the kWh that it takes to recharge is reduced.
Click to expand...

his will have had about 22½ when new. either way, the numbers are way off
 
DaveinOlyWA said:
how did you get this 11 kwh? cause 43 mins at a "quick" charger and only getting 11 kwh is ahh... not very quick. is this 11 kwh what the station told you it doled out? if so and you are being billed by the kwh, you made out.
Click to expand...

That's what the system told me and no I wasn't billed as this was a free charger at the dealer. I did take a pic of the screen that I will try to upload later. Should this have been more than 11kWh to charge the battery that much?


keydiver said:
Most QC stations report SOC incorrectly. Where are you getting the 18% and 85% figures? A new battery is only about 21.5 kWh, if I recall. Of course, as the battery degrades the kWh that it takes to recharge is reduced.
Click to expand...

18% is what the battery was showing when I parked in front of the charger.
85% is what the battery was showing after I unplugged the charger.
I assumed that the battery was 24 kWh as that's what Google shows. But if it is 21.5 kWh then 67% of 21.5 is 14.4 kWh which is still not 11 kWh.

:?

EDIT: I re-read your questions. The 18% and 85% were being shown by the car and the station both. I will repeat this "experiment" with LeafSpy when I get an opportunity and repost the numbers.
 
ok so your 18% to 85% was from the Nissan dash

FYI; it should take no more than 20 mins to get 11 kwh from a fast charger.

things that could change your ability to take a charge. By your location we have to start with heat. Your car has a gauge on the left that shows you temperature of your battery pack. Your charge rate could be slowed significantly if your battery temps were high but guessing it would have to be in the 10 bar range at least

Degradation can change what you can take. Imagine a 24 oz glass. you only put in 22 oz because you don't want to spill it. As degradation of your battery pack progresses, this is the same as putting sand into the glass. now your glass can't hold 22 oz any more because sand now takes up 5 oz of space so your fill is now 17 oz. As you can see, this can mean your battery pack is "used"

Your "gas gauge" has two sets of bars, big one on the left, little ones on the right. A new car has 12 little bars. do you still have 12?
 
Nissan's quick chargers may be lower capacity than some QC, I seem to remember a thread here or on the Tesla forums about it.

Also, charging over 80% usually slows way down as discussed here : http://www.mynissanleaf.com/viewtopic.php?t=12263...

When I was delivering the Leaf to inphoenix, I got stuck behind someone who had plugged in to a QC a few minutes before I arrived.

It took about 20-25 minutes for their car to charge from 30% or so to 80%, then another hour to charge from 80% to 97%

DaveinOlyWA said:
ok so your 18% to 85% was from the Nissan dash

FYI; it should take no more than 20 mins to get 11 kwh from a fast charger.

things that could change your ability to take a charge. By your location we have to start with heat. Your car has a gauge on the left that shows you temperature of your battery pack. Your charge rate could be slowed significantly if your battery temps were high but guessing it would have to be in the 10 bar range at least

Degradation can change what you can take. Imagine a 24 oz glass. you only put in 22 oz because you don't want to spill it. As degradation of your battery pack progresses, this is the same as putting sand into the glass. now your glass can't hold 22 oz any more because sand now takes up 5 oz of space so your fill is now 17 oz. As you can see, this can mean your battery pack is "used"

Your "gas gauge" has two sets of bars, big one on the left, little ones on the right. A new car has 12 little bars. do you still have 12?
Click to expand...
 
Going back to the original question, I would expect that it would take more than 11 kWh to charge a LEAF with a full-capacity battery from 18% to 85%.

Dave's question is key: how many capacity bars does you LEAF have? The image below shows the display for a LEAF with 12 capacity bars (2 red plus 10 white).

soc-display.jpg


The blue and white bars show the current state of charge (SOC), 10 bars bars in the sample image.
 
tomsax said:
Going back to the original question, I would expect that it would take more than 11 kWh to charge a LEAF with a full-capacity battery from 18% to 85%.

Dave's question is key: how many capacity bars does you LEAF have? The image below shows the display for a LEAF with 12 capacity bars (2 red plus 10 white).

soc-display.jpg


The blue and white bars show the current state of charge (SOC), 10 bars bars in the sample image.
Click to expand...

Sorry I missed that. I have 2 red plus 10 white bars for a total of 12.
 
I took a pic and some screen shots from LeafSpy this morning. The Leaf was set to have a full charge by 5 AM. I did not drive the car this morning and took the pics at 9.45 AM.

The pics are at http://imgur.com/a/rLwP2

At 100% batter capacity the GOM says 84 miles (past couple of days it has been saying 91 miles when I see at about 6 AM).
The SOH was 90% and SOC was 97%. Can someone help me understand what these numbers mean? Just trying to educate myself here. :)
 
inphoenix said:
At 100% batter capacity the GOM says 84 miles (past couple of days it has been saying 91 miles when I see at about 6 AM)
Click to expand...
Forget the GOM. It's worthless. See http://www.mynissanleaf.com/viewtopic.php?f=31&t=12899.
 
inphoenix said:
I took a pic and some screen shots from LeafSpy this morning. The Leaf was set to have a full charge by 5 AM. I did not drive the car this morning and took the pics at 9.45 AM.

The pics are at http://imgur.com/a/rLwP2

At 100% batter capacity the GOM says 84 miles (past couple of days it has been saying 91 miles when I see at about 6 AM).
The SOH was 90% and SOC was 97%. Can someone help me understand what these numbers mean? Just trying to educate myself here. :)
Click to expand...

The SOH is the capacity of original, i.e., the available capacity. So about 90% of what it had at 0 miles (actually what it had at delivery to the dealer, when I first checked SOH at around 3000 miles, it was at 95%).

The SOC is the current state of charge, and 100% is at max capacity, this is what the console displays when you cycle through and see the percentage view.

In summary, the SOH quantifies your degradation of capacity, and the SOC quantifies how much energy you have left right now, as a percentage of total available capacity.
 
SOH is your pack's capacity relative to a nominal new battery pack. Every pack is different, so some packs will start above 100% and some below 100%. I'm not sure if 100% is even the average, it's just a standard measure that allows us to compare packs in different cars and is a little easier to grasp than the amp-hours (AHr) number.

Keep in mind that these numbers are just the car's best estimates, approximations to the "true" values.
 

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