Wednesday, September 26, 2012

Quick Charging on a Cold Day

A lot of discussion going around between the disparate communication concerning the level of charge in an electric vehicle battery pack. the SOC (state of charge expressed in percentage of "fullness")  difference between the car and the charging station can be as much as 13%.

AV chargers will charge you to 89% per the station but my SOC meter says different. Now how different is also a question.  the first time I charged till it stopped which is rare, the SOC in the car was 76%.  Did it again a month later and it was a warmer day and it was 80%, so 9% off.

Well today, I plugged in to charge to check the Tumwater DCFC (direct current Fast Charge) station to check it status and it charged fine. I checked some email, sent some texts and then went into store to buy lottery tickets.  Now the AV station has circular lights at the top that tell you the level of charge so you can see from a distance when you might have to move your LEAF to let the next person charge.  pretty cool actually.

But when walking back to car after buying the lottery tickets, I noticed the lights were on but none were flashing which usually means the charge is complete. I checked the station and sure enough it said 89% but charge was still being applied.

"ok, no problem, be done in a minute" i thought. i took a phone call which lasted only 5-6 minutes and the car was still charging! very strange.

now, it was 44ยบ and foggy so I started remote climate control to warm up and it was running.  this made me curious, so I waited another 5 minutes making it about 10 minutes I had sit at 89% on the station meter and it kept going. Well, finally I decided enough was enough and manually turned off the station.

Got in my car, started up and was at 83% which is only 6% off. wondering if this was a way to get more of that last 20% without having to restart the charging session?

**Update Nov 19, 2012.  Just did a charge at the Tumwater DCFC and was a bit surprised that the rate of charge was much slower than expected. i had noticed that my charges were seeming to go a bit longer than before so pulling in with on 20 GID, I figured it was a good opp to check my charging rate.

Earlier in the Summer I was charging at the rate of 75-80 seconds per Kwh up to about 50-60% SOC.  So was expecting to get my first 8-10 Kwh in pretty quick fashion.  So away I went and the first Kwh was in at just under 80 seconds; so far so good. The 2nd right at 80 seconds but then the 3rd came in at 90 seconds. very concerning to see a slowdown in the charge this early.

#4 took 100 seconds, #5 took 104 seconds. I was only planning on charging 10-15 minutes but curiosity got the best of me so decided to let it run till it stopped. I was at 14.16 Kwh at 30 minutes which was still not a bad rate considering that the later  charge rate is much slower.

Well charge ended at 40 minutes and 10 seconds with 16.03 Kwh (77.5% per SOC meter 89% on the charger)  or a Kwh every 2½ minutes which was not bad really despite the last 2 Kwh coming in at just under 5 minutes each.

This rate is slower than I tracked this past Summer and since the heat related thing is unlikely to be the culprit, wondering if the power to the station has been reduced?

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