Battery too low to fast charge?

[TheLondonBroiler]

Got a little too close for comfort yesterday. Arrived at the intended DCFC with the battery gauge displaying "Low," Torque said the battery was at 2.7%, with the lowest cell voltages at 2.8 volts.... Total energy used was 15.7kwh (torque reports capacity being 15.1kwh.....). Distance traveled, 97 miles, just over 60ish miles were intrastate driving 60-65mph.


And now the fun part. It had started to rain on my way to the charger (not forecasted), which contributed to cutting it even closer. I arrived at the charger, (GreenlotsSignet/ plugged in, and received error 41(discovered 30 min later, according to signet charger manual pdf, it's a Pre-Charge Error - Requested to stop from vehicle during pre-charge operation. By this time it was pouring rain and I accepted my rate to charge for 2 hours at a level 2 charger across the street, so I could make it home. Fortunately made it across the street, charged to where the range was no longer a blinking orange bar, rather it was 2 solid orange bars with 12 miles of range (this took ~40 minutes), then out of curiosity, went back to the fast charger and had success.

I once arrived at a the same style Greenlots DCFC (my epic trip to the 350kw charger), with 6 miles remaining (unsure of SOC%), and was able to charge without issue. So what I'm wondering/thinking, did I go so low, that the Spark said no to fast charging? I suspect it's possible, but I don't foresee myself intentionally trying this again.

 

[Cephas2000]

Great that you have all that data. I've never reached "Low". The most drained I've been was with 4 miles of estimated range.

Not much help to you with this reply, but at least you know we're out here.

 

[JeremyW]

I’ve fast charged before when it said “low” on the GOM, I don’t know what the exact SOC was, but it did start and charge as normal.

I have had a failure to start charging from DCFC, the car was being towed on a dolly, with one of the safety chains slightly brushing the ground. I realized it was affecting the isolation resistance of the vehicle and moved it off the ground and the car then allowed charging. The Spark might be extra sensitive so, I would almost blame the heavy rain instead of your low SOC if I had to guess. At any rate, I would retry using the DCFC a few times before using the L2!

 

[TheLondonBroiler]

I have had a failure to start charging from DCFC, the car was being towed on a dolly, with one of the safety chains slightly brushing the ground. I realized it was affecting the isolation resistance of the vehicle and moved it then allowed charging.

I would almost blame the heavy rain instead of your low SOC if I had to guess.

Interesting. Definitely plausible.

 

[TheLondonBroiler]

Happened again, different station, same machine type (Signet/Greenlots 50kw), moderate rain, this time ~40%SOC. Went to another station (same machine), rain had all but let up, worked fine. Back at the machine that didn't work earlier, no rain, and now it works fine ( 3 attempts earlier, but this one worked on the first try).

I believe JeremyW is correct. There's an EVGo station minutes from work, so next time I have the opportunity, whether or not I need to charge, I'm trying it if there's moderate rain or a down pour.

 

[evolv]

The Spark might be extra sensitive

I’d love to know more about this.

I’ve only public charged twice so far. One was at an EVgo dcfc. Following the written directions wasn’t working, so I called them for live support. The rep was very helpful and patient, and seemed to know that making the connection could take some amount of finessing (seriously?). I recall it still took a couple tries, but I was able to get it going (and buy all of $1’s worth!).

Other instance was free L2 at the mall. Spot was open, so decided to try it but never got it to work. They didn’t have live support, just a number to call in and report the issue. The car in the adjacent spot soon left, so I moved over to it, and it worked on the first try.

When plugging in at home on 120V, the car often throws the (gfci) breaker. It might take me several trips between walking over to reset the breaker and plugging in, before the car is happy to accept the charge. I’ve always assumed this is due to the wiggly old outlet, which I should probably replace and cover in a proper outdoor box. Haven’t really worried too much about it, since I plan to install a 240V outlet soon (my charging cable does both).

 

[evolv]

Got a little too close for comfort yesterday. Arrived at the intended DCFC with the battery gauge displaying "Low,"

Having only been into the single digits on the GOM a couple times, curious to hear more about this. At what point does limp mode kick in (and how slow is it)? Did your GOM go to “LOW” right after “1”? And how much did you drive it in “LOW”?

I’m also suspect that the trouble was due to your SOC. Based on my limited experience, the Spark can be a finicky eater, even in good weather (and only gets worse when it’s wet out).

You’d think all this stuff would be well figured out by now, but when you hear the original Tesla guys talk about the differences between designing a car on paper vs. getting them to work (and keep working) out in the real world...

 

[TheLondonBroiler]

At what point does limp mode kick in (and how slow is it)?

I really hope my memory is correct, and apologize if I'm off a bit. "Propulsion reduced," is displayed around 10%, I believe. I used the Torque 0-60 tool one night coming home from work, low on juice with propulsion reduced, and I believe it was 11 seconds and change 0-60 (similar to a fully fueled, perfectly tuned gasoline spark :lol: ). It's very sluggish.

Did your GOM go to “LOW” right after “1”?

If memory serves me correctly, "Low" is displayed somewhere around 6-7% battery (torque figure, probably happens at 97% consumed, on the energy usage screen).

And how much did you drive it in “LOW”?

I believe I did about 2 miles. I really don't desire to have to do that again. I genuinely believe I was within a mile or two at the absolute most from being out of juice. Torque displayed the battery at 4%, however the Energy usage screen, to my recollection, stated I had used 99%.

 

[TheLondonBroiler]

Ok, so since I'm a gluten for punishment, I recreated my prior situation, using inefficient driving techniques, to arrive at the same DCFC w/ very low SOC (and I drove around more when I got there), and, add best I could while driving, I paid attention to what was going on with the car. Here's what I discovered:

-Propulsion is reduced at 10% SOC (via Torque Pro)
-Range resister estimator reads "Low" below 5% SOC (via Torque Pro. Energy usage screen will read 99% usage).
-Somewhere between propulsion reduction and "Low", use of the heater is disabled. The fan will just blow ambient air.
-No rain, no problem charging (it went straight to mid 30kw charge speed on a 50kw charger, and peaked at 45kw).

Charged for exactly 20 min and went from 4% to 87% SOC (via Torque). My latest battery capacity reading is 14.5667kwh.

Hope someone finds this useful and/or entertaining.

 

[NORTON]

....Hope someone finds this useful and/or entertaining.

Science !

Yes, thank you !!