Monday, January 8, 2018

DIY Charge Timer

The goal; Determine the reliability of using formulaic process for custom charging levels.  As we know, the LEAF has a timer that lists charging times for various EVSE speeds.

120 volts @ 12 amps.
240 Volts@ 16  amps
240 Volts @ 27.5 amps

Now the bottom one "could" be different but not likely.  Now I don't have the 27.5 amp version to test but the reality is there are several different EVSEs running at all different speeds and if  my experiments using my Clipper Creek running at 24 amps proves to be reliable and predictable, I might be tempted to test my 20 amp EVSE upgrade as well.

Background;  Using a Clipper Creek 24 amp charger running at 24 amps or 5.76 KW

Day One;  Happy Thanksgiving!  Starting the charge when I get up so I can monitor it. I want to charge to roughly 80%.   The issues I will be trying to figure out is how much of the estimated charge time is devoted to cell balancing. Initially, I was thinking about 90 mins plus 30 mins ramp down so my estimate would be the time estimate minus 2 hours to hit near full.

A full charge of say 90% DoD (for me) still being about 28 kwh @ 90% efficiency which takes 4.9 hours. So 80% would be just under 4 hours.  These are approximations since an 80% charge would experience no ramp down.

 Charge start;  6:34 AM

SOC  40% (41.6% LS)  Car timers  (6 KW, 3KW, L1) 6:00, 8:30, 24:30.
 With starting SOC of 40%, only 40% needs to be gained. with a 90% charge taking 4.9 hours, my charge should take  2.17 hours or roughly 2 hours and 10 mins.  Estimated time completion to 80%; 8:44 AM.

7:36 AM
SOC 62% (60.3 LS)  Car timer (only 6 KW is showing now) 4:30

8:44 AM Charge ended.  SOC on Car 84%, LEAF Spy 79.3 %  10 SOC bars.

Summary;  charged 130 mins gained 44% or  2.95 mins/%

Next to Check

40% SOC start good so check higher SOC starts and at least two low SOC starts of 20% or less if possible
granularity of 120 volt timer better to use?
Timer does not appear to update when car is powered off while charging

Day 2;  SOC  56%  Charge Start 0927    timers 5.30, 7.30, 19.30
Target  90% or 34% gain.  Estimated time  100 mins.  or  1107

time check; 10.24  time elapsed  57 mins  should be  19.3 % increase;  actual  75%  19% increase.

1115. elapsed   should be 92.6%  is 90%

1141   96%

Day 3;   10%   1718            timers 8/11.30/32.30

Target 90% or 80% gain   236 mins.

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