level 1 charging caused lost SOC

[flarend]

I was making a trip yesterday where my destination was very close to the range. So I stopped to charge with the handy level 1 plug along the way for 30 minutes. I pulled in at 50%, but when I left it was at 48% and quickly went to 46%. So I actually lost 3+% of the battery while charging for 30 minutes! I'm wondering if anyone can help explain what happened.

While charging for the 30 minutes, I had the car set in the ACC power mode so I could monitor the SOC. I didn't see the SOC increase any. After 25 minutes or so, I was getting ready to leave and so I turned the fan defroster on (fan only on low speed) to clear up all the fog on the inside. This is when I noticed the SOC drop to 49% within a minute or so. Puzzled, I checked to make sure the energy readout was zero for climate controls and accessories were very low (around 0.1 to 0.2 kW), and I unplugged the two phones that were charging.

Within a couple more minutes it dropped to 48%. At this time, I packed up the charger and left worried about what may happen if I stayed longer. Then as pulling out, it dropped to 47% and then to 46% within less than 1/2 mile of level driving speeding up to 50 mph.

Here are some details:
- 2013 model with 7500 miles.
- I tested the outlet before plugging in with a circuit tester, so I'm pretty sure it was wired correctly with no crossed wires or loose ground, etc.
- I kept an eye on the charger lights to make sure that no flashing error signals occurred. I've been burned before by a faulty ground wire.
- This was at night, and outside temp of 46 F.
- Battery temp stayed at 6 bars the whole time.
- I had just driven 40 miles, charged at level 2 for 2.5 hours, then drove for another 47 miles including several 1000' climbs and descents.


I ended up coming up short by 2.5 miles from my destination, so that 3% lost would have gotten me home. Fortunately, I coasted into a friend's house on turtle mode, and eventually got home nearly an hour later.

 

[adric22]

I can assure you that you did actually gain a couple of miles of range while charging. the main difference is simply the car changing its mind about the estimated power left in the battery.

 

[planet4ever]

While charging for the 30 minutes, I had the car set in the ACC power mode so I could monitor the SOC. I didn't see the SOC increase any.

You didn't have the car in ACC mode; you presumably had it in ON mode, or possibly READY mode. In ACC mode the dashboard is black, and you wouldn't be able to see the SOC meter. Phil tells us that the car uses a lot more power in ON or READY mode than it does in ACC mode, so that could be at least a partial explanation.

But I wonder if you were charging at all. If you were in ON (or READY) mode when you plugged in, it would not start charging. Page CH-4 of the Owner's Manual says:

When charging the Li-ion battery, place the power switch in the OFF position. When the power switch is in the ON position, the Li-ion battery will not start charging. If the charger is connected to the vehicle when it is in the READY to drive position, the power switch automatically changes to the ON position. Place the power switch in the OFF position to begin charging.

You can power back up (to ACC or ON, but not READY) after it starts charging.

Ray

 

[LeftieBiker]

I've had this happen as well, once. Since then I just don't charge at L-1 for less than an hour.

 

[flarend]

Sorry, planet4ever you correct me. The car was in 'on' mode (but not "Ready to drive" mode).

Based on some of the responses, I've tested a few things today. When in "ON" mode, the car did not loose any % SOC over 1 hour. When in "READY" (to drive) mode, the car didn't loose any %SOC over 30 minutes, nor any over the following 40 minutes with the fan turned on with two bars.

Thus I don't see how the %SOC would have been lost due to anything as simple as the dash or fan consuming energy. If Phil says the car uses more energy in the ready mode than acc or on mode, it is not of the order of magnitude that I saw.

As for the car just deciding that it really had 47% instead of 50% SOC, that may be plausible, but I've never seen any evidence of such randomness in the SOC readout before. Definitely the 'miles to go' is a guess-o-meter, but I have found that the %SOC readout is very reliable and extremely linear. I've been rather shocked at how good it is in-fact. So I'm back to my original believe that the charger caused some type of energy loss.

Richard

 

[smkettner]

If you are going to charge on L1 and expect max range... turn the car OFF.
And no climate control, none!

 

[Deleted member 9549]

L1 is called trickle charge for a reason. Running the AC can take tons of power. On the 2013 it can take as much as double the rate it charges from L1 (usually for a short while). Defrost can take even more because it can run AC as well as heat strips.

Charging for short time at L1 isn't usually worth it. If you do, don't have the car on and especially don't run the AC. On L2 it can be very useful to charge even for short periods, especially if you have the 6kw charger. Even on L2, running AC would reduce the charge rate but it would charge anyway.

 

[flarend]

I don't usually charge on Level 1 and expect to drive 90 miles! Unlike I suspect 99% of the folks on this forum, I have no 'public' Level 2 charging available anywhere within 45 miles. There are only 3 within 80 miles if I happen to be going in those directions. But there are several in key directions that are about 85-90 miles away hence the need to trickle charge for an hour or so while in-route. In fact there aren't many places in the country that have fewer charging stations. When I take a long trip in the Leaf, it is really an experiment more than a necessity. I could always take my Prius which is working just fine after 200,000 miles, but where's the fun in that??

As for climate control. The fan is not really climate control (In case I wasn't clear, I made sure the AC and Heat were OFF), when the outside temp is 46, and you have 4 people inside the car, you MUST have something to keep the windows unfogged in the humidity where I live! I was fortunate that I could keep the window clear with just fresh air. Come winter, I won't dare attempt that trip. But as I said before, the fan alone does not use much energy. Neither does the heated seats. Remember each %SOC is about 0.2 kWh or 200 Wh. That is enough to power a 50W seat for 4 hours which is far longer than needed to drive the max range at say 50 mph.

So this leads back to my original post, why would Level 1 charging have anything to do with power consumption on the order of 1000-2000W (3-4% loss in 30 minutes).

Richard

 

[Deleted member 9549]

Rereading your post, sounds like you said you weren't running the AC. If so, maybe it wasn't really charging because the car was on. I have had cases where I've arrived somewhere, left for 30-60 minutes, came back and had lost several percent battery power. Maybe the cells were leveling and it wasn't charging because it was sort of on.

 

[flarend]

There is a difference between "on" and "ready". The car does charge in the "on" mode (push button twice but keep your foot off the brake, and this mode is different from the the "ready" mode (put foot on pedal, and the car symbol shows up on the dash). Although I don't always do this, I've charged many times in the "on" mode, you just have to first turn off the car, plug it in, start the charging, and then turn the car on so you can monitor the charge. I started doing that when I found there is a huge variation in charging speeds at different locations.

Richard

 

[planet4ever]

So I'm back to my original believe that the charger caused some type of energy loss.

Well, the charger does indeed cause energy loss. It's only about 90% efficient itself, with the other 10% or so being turned into heat. Because of that it is water cooled, and I think someone here determined that the cooling system (pump + radiator fan) uses about 200-250 watts. However, if the car really was charging, and the battery was at 50%, it should have been feeding over 1400 watts to the car, and at least 1000 watts (1400 - 140 - 250) should have made it to the battery.

You didn't respond to my other suspicion. Did you watch the three lights on the top of the dash and verify that one was on solid and the second one blinking? That's what you should have seen with a battery that was half full. If that didn't happen, then the battery wasn't charging at all. Are you sure the car was completely powered down when you plugged in to start charging, and you only powered it up later to check the SOC? Another possibility is that you had a timer set which caused a charging delay. In that case you would, of course, have seen the three lights blink in a cycle when you plugged in. And a third possibility is that the EVSE detected a problem, such as a bad ground, with the power supply. Were the Ready and Charging lights on the EVSE both on solid?

Ray

 

[ERG4ALL]

My understanding is that when you are in the "ON" mode (i.e. double push button with foot off of the break) that you are using only the 12V battery to run all of the accessories. I wonder if after 30 minutes the 400V battery decided to recharge the 12V battery which led to squirrelly readings after the car was in the "Ready" mode?

 

[planet4ever]

My understanding is that when you are in the "ON" mode (i.e. double push button with foot off of the break) that you are using only the 12V battery to run all of the accessories. I wonder if after 30 minutes the 400V battery decided to recharge the 12V battery which led to squirrelly readings after the car was in the "Ready" mode?

It is my understanding that while you are charging the DC/DC converter is running full time to supply 12v to the coolant pump and fan. It should have enough excess capacity to supply 12v accessories without running the 12v battery down. The input to the DC/DC converter is, of course, the 400v battery, except that during charging it is effectively the output from the charger.

Ray

 

[ataman]

In my experience, after a long drive, if you charge for short period of time, using whatever method, and keep driving first few percentages drop very quickly. I think this is just the car adjusting. When charging battery voltages are higher, when you unplug, voltages drop causing and it takes a while for the computer to estimate the charge left.

I dont think you lost actual energy, its just car is having a hard time coming up with stable and accurate %.

 

[smkettner]

Just transitioning off the highway, getting parked, starting back up, accelerating back up to speed may have used more miles than the L1 provided in 30 minutes. Then you used the defrost? forgetaboutit.

 

[flarend]

In my experience, after a long drive, if you charge for short period of time, using whatever method, and keep driving first few percentages drop very quickly. I think this is just the car adjusting. When charging battery voltages are higher, when you unplug, voltages drop causing and it takes a while for the computer to estimate the charge left.

I dont think you lost actual energy, its just car is having a hard time coming up with stable and accurate %.

Attaman, I think you were correct. I've now seen this happen numerous times and in different Leafs, and even with level 2 charging. In each case, there was not much charging that had occurred for whatever reason, so I guess the batteries were just 'leveling'.