nikwax
Posts: 567
Joined: Sun Apr 26, 2015 3:27 pm
Location: Portland, Oregon

Two battery questions

Fri Jul 19, 2019 1:53 pm

Hi all, two questions:


1) When I pull into work, the car will say I have consumed 2.7 kWh, I plug into the ChargePoint charger, and it takes 4.4 kWh to recharge. Why the diff?


2) If I use 50% of my battery capacity per the dash, and that represents 5 kWh, does that indicate that my battery pack only has 10 kWh of capacity?


Are any of these useful numbers?
2015 Spark EV 1LT DCFC
BF Goodrich g-Force Super Sport A/S
ClipperCreek EVSE

SparkE
Posts: 326
Joined: Tue Sep 06, 2016 1:18 am
Location: SF Bay Area (San Jose, CA)

Re: Two battery questions

Sat Jul 20, 2019 1:11 am

nikwax wrote:
Fri Jul 19, 2019 1:53 pm
Hi all, two questions:


1) When I pull into work, the car will say I have consumed 2.7 kWh, I plug into the ChargePoint charger, and it takes 4.4 kWh to recharge. Why the diff?


2) If I use 50% of my battery capacity per the dash, and that represents 5 kWh, does that indicate that my battery pack only has 10 kWh of capacity?


Are any of these useful numbers?
1) the amount of energy displayed by the chargepoint unit shows total energy pulled from the grid, not *necessarily* how much goes into the battery. First, there is a conversion loss (AC to DC, 240V to around 370V, maybe around 85-90%). Also, if the battery cooling system, or the AC, or the heater, is/are running, part of the 'pull' from the EVSE is used for heating/cooling and isn't going to refill the battery. As an example, during the summer I often 'remote start' the vehicle while plugged in about 5 minutes before leaving to run the A/C to cool the interior while not using much (if any) battery electricity.

2), theoretically, yes. However, the 'counter' on the energy screen is only reset after a full charge. So *directly after a full charge* drive down the battery to 15-25% and then do the calculation of battery capacity:

- You must START at 100% (after a full charge).

- Say you drive for a while and the battery is down to a 20% charge (drive the battery down to a low % in order to get a more accurate calculation : under 40% at least)

- Your energy consumption screen - NOT the "guess-o-meter / speedometer area, the screen in the middle of the console (press the 'LEAF' button under the middle screen) says that you used 12 kWh since last full charge (AND YOU MUST NOT CHARGE IN THE MEAN TIME). This screen tells you the kWh consumed, and the % of the battery you have consumed. (for this example, you consumed 80% of the battery and 12 kWh.)

- the calculation is :

(kWh consumed) / (% of battery consumed) = total battery capacity

( 12 kWh ) / (.80) = 15 kWh total battery capacity


2a) If you really only have 10 kWh (or 12 kWh) capacity, you qualify for a free battery replacement under warranty (the Spark EV has an Eight-year/100,000-mile drive battery warranty). If you think you really only have that much, bring it to an EV-certified GM dealer to have the propulsion battery tested.

- I suggest driving the car down to (about) 10 miles of range at some point (while staying close to a plug, just in case, and with the EVSE in the car for emergencies), and then filling up to 100% (and leaving plugged in for 30-45 minutes after 'full' is shown). If there is a problem with the "guestimate" of range, this should reset the car's idea of how much range the battery has.

- I would also suggest not charging to 100% all of the time (unless you need the range - and if you really only have 10 kWh available in the battery, you need the range!). If you have range over (say) 60, and you routinely only use (say) 15, then fill it up to 80% most of the time, and fill it up to 100% once a month or so (or when you know you need more range).

NORTON
Posts: 1230
Joined: Fri May 01, 2015 5:52 am
Location: KC,MO

Re: Two battery questions

Sun Jul 21, 2019 7:18 am

This time of year when it is close to 100° F the Thermal Management System runs to keep the HV pack in a happy temp range.
This takes away from the 3.3kW going to the pack. The car will draw a max of 3.3kW.
TMS and BMS are using power during charge sessions. I believe BMS only runs after the pack is at 100%. This function is needed routinely.

I had a record setting charge on Friday. It was a hot one! 8-)
Charged for 7:32 and used 21.54kWh of Free Electrons, as in zero $$, not the other kind.... ;)

This was arriving with:
5 mi. on the GOM.
On the Energy Detail page:
Driving and Acc- 82%
Climate - - - - - - 9%
Battery Cond. - 3%
Total - - - - - 94%
Energy Used - 17.0 kWh
__________________________________
Which calculates to _ 18.09kWh for the current Pack Capacity.
Which is 93% of Original Capacity.
( I use 19.5 kWh as the original cap. for a '14 Spark EV. Getting this spec from GM is not clear....)

I charge 5 days a week to 100% and then the car sits for ~ 4-5 hrs before I drive it home. Sometimes I'll charge in the PM if I don't beat the Volt and M3 that also uses this 2 place free L2.
That's my work week charging. :)
Used '14 2LT w/ DCFC. +71 K miles.
Mostly free charging! Only one LONG visit to the shop....
GM needs Modern Troubleshooting tools for Modern EV's.
3 step Trouble Tree, 2nd guess not covered by warranty and cost $800. 3rd guess fixed the problem.

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