[Edd Beesley]

Observed something very strange in my Leaf yesterday! My GF had picked me up from work, after driving about 12 miles, possibly quite quickly. I parked the car up on the driveway, and went to reset the trip counter, noted that there were 5 bars of charge left, and 35 miles range. I then looked at my LeafDD which said 31.05 Ah remaining. Then it changed to 31.06Ah. OK, that's a tiny change I sho.... 31.07Ah. Hmm.

I sat for a couple of minutes just watching. What was actually happening is the reported capacity in Ah was fixed, but the reported SOC% was increasing. It started on 50.something percent and was creeping up. I was thinking "well, the LeafDD is an aftermarket device. It's reading the SOC from the canbus, but maybe the capacity number doesn't update. Still odd for the SOC to increase. Unless a downward calcualtion of capacity is happening, meaning my current actual charge level needs to go up because there's now a smaller battery to represent" and -then- I noticed

36 miles

On the GOM. Well that's mighty weird I think. but, maybe the climate control load changed or.... something. By this point, the LeafDD was reporting just over 33Ah, and eventually I saw 37 miles. Still that doesn't prove anything I....

6 battery bars. It added a bar in front of my eyes. So now the official instrumentation has shown me an increase in charge level -and- an increase in range, so I don't think it's a downdialling of capacity forcing an increase of reported SOC.

The car stopped making changes at just over 33.5Ah, at about 53% SOC.

Has anyone ever seen this before? What exactly does it mean?

 

[flipper]

Were you parked on a hill? Maybe the electrons were sloshing around and needed to settle. No, wait, I'm thinking of petrol...

I've honestly no idea! I've not seen this happen, but then I don't tend to sit in the car at the end of a journey.

 

[Paul_Moxhay]

When batteries are under load the voltage will drop but when they then come off load the voltage often "recovers".

This would be most noticeable when driving hard as voltage will drop more the harder it is driven.

I have not see it with car batteries but I have in other Li-Ion battery applications so this behaviour is not a surprise.

 

[Edd Beesley]

When batteries are under load the voltage will drop but when they then come off load the voltage often "recovers".

This would be most noticeable when driving hard as voltage will drop more the harder it is driven.

I have not see it with car batteries but I have in other Li-Ion battery applications so this behaviour is not a surprise.

You certainly do see voltage drop under load, but even when you're pulling 250 amps it's not a massive drop. The car also knows how the battery performs under load and does coulomb counting to know true amount of energy going in and out so it -should- remain accurate....

Maybe it is that though, the voltage at rest was higher than expected so it uprated the SOC level. If so, that's a big error for it to make, 2Ah is something around 700wh, not sure how it could have "mislaid" that much energy!

 

[hopbackguy]

You've installed wireless charging under your drive. Go on, fess up!

 

[Edd Beesley]

You've installed wireless charging under your drive. Go on, fess up!

..................

Totally forgot about that.

 

[Ian]

Thermal changes.

 

[Paul]

 

[GBEV]

I saw this on Leafspy pro recently. Parked up whilst waiting for passenger and thought I would monitor watt hrs used if car is left on. It started using watt hrs slowly then I noticed that there was a - minus sign in front as if it was regenning!

0.3 kWh remaining were added before I had to move off.

Could only assume warmer pack from recent drive was increasing the charge available figures to the Battery Control Unit. Never thought about voltage recovery but that makes sense too.

 

[Edd Beesley]

Strange behaviour from my Leaf again. I parked up last night with Low Battery Warning, and on checking I had 47 GIDs, so that's fine, 8 miles left on guess ometer, battery was about 33 degrees (driven~95 with a rapid in the middle).

Got in the car this morning, LBW was gone, GOM said 11 miles, battery had cooled down to 22 degrees, 58 GIDs.

I don't think there's neccesarily anything wrong, it's just an odd behaviour.

 

[Paul_Moxhay]

That is odd

Have you installed wireless charging without realising it

 

[Edd Beesley]

That is odd

Have you installed wireless charging without realising it

Beginning to think so Paul since both anomalies have occurred on my driveway...

 

[Paul]

I've yet to see anything to that 100% disproves my theory, so that's what I'm sticking to.

 

[Edd Beesley]

Hey if aliens have come all this way to wirelessly charge my car..... I'm cool with that

 

[Edd Beesley]

I'm actually starting to think it was something to do with the service/MOT I had done on the 24th, which included some "software updates". carwings has also stopped connecting in the car, but that doesn't necessarily mean anything either....

 

[Edd Beesley]

A somewhat boring video that shows my charge level increasing by itself while parked.

 

[GBEV]

I wonder if this happens because the shunts are still doing their balancing act as the car is switched on and the GOM range and Ah estimate are related to the lowest cell SOC which can be raised by the others during shunting therefore slowly improving the base line figure?
You can see the active shunts on Leafspy.

 

[Edd Beesley]

My understanding of the shunts is that they can pull cells down (remove charge) but can't push another cell up (could be wrong though!), and yeah you can see them on the LeafDD too on a different screen.

Overall my battery has been behaving oddly, it had 64ah capacity in March to May, dropped to 63 in June, dropped progressively down to 59.3 in July, and went back up to 60.2 yesterday.

 

[GBEV]

My understanding of the shunts is that they can pull cells down (remove charge) but can't push another cell up (could be wrong though!), and yeah you can see them on the LeafDD too on a different screen.

Overall my battery has been behaving oddly, it had 64ah capacity in March to May, dropped to 63 in June, dropped progressively down to 59.3 in July, and went back up to 60.2 yesterday.

Surely the point of removing charge is to to bring low cells up though or where does it go accessory battery? Assuming it is in the name shunt i.e. from one to another.
If they do just pull the cells down to heat in the battery control module maybe the mV spread reducing whilst shunts are open is helping increase the SOC figure. Will try to watch for this.

Our capacity is trending down but with the odd up too especially after a full charge to nearly empty when I can only assume the monitoring gets an update.