What's up with 84% charge on L3??

[Canaussies]

Can anyone fill me in on why the onboard charger stops the battery from going beyond 84% on a L3 station? Is there a way to make it go to %100 instead? We have been traveling around BC and often stretch the limits of our range between charges, so it's really annoying to constantly have to restart the session 3 times to get to a %100 SOC.

Any insight would be appreciated!

Cheers!

 

[wrickcook]

The dealer in Renton, WA said quick chargers only take it to 80%. But then you can unplug it, and plug it back in and it takes it to 100%.

 

[mtndrew1]

The speed of quick charging drops off a cliff right at about 84%, which is probably why Kia chose to stop it at that point. As it closes in on 94% quick charging is roughly the same speed as L2 charging. From 94%-100% it's a total trickle of power, and if a car is charging from 0-100% on a DC QC it's generally at the detriment of whoever is waiting for the charger behind you.

I wish they'd offer a selection of 84% or 94% in the Soul's configuration menu, but I understand why they chose to implement the feature this way. It's generally accepted within the public charging community that it's rude to use a QC much beyond 80% as it often creates a bottleneck.

Edit: Apparently the second (and final) threshold is 94%. I've only done it once.

 

[GizmoEV]

The dealer in Renton, WA said quick chargers only take it to 80%. But then you can unplug it, and plug it back in and it takes it to 100%.

That isn't true with the Kia Soul EV. It routinely charges to just shy of 84% unless the charger it self is set to stop sooner, either via time or %. On Blink stations merely choose anything over the default of 80% and the Kia will charge to nearly 84%. With the AV chargers they stop when the car says to stop which is nearly 84%.

While I have not done a data collection on a fast charge but it appears that the 80% charge stop of the LEAF and the nearly 84% charge stop of the Kia is at the point that the charge rate begins to diminish to keep the battery pack voltage from going too high. If you charge to the 84% mark and then restart the QC and watch the rate or time how long it take to get to 94%, the next shut off point, you will see that it doesn't charge as fast. This is normal for battery charging. At some point it is not worth using a QC to reach 100% when the on board charger is ample. Switching to Level 2 opens up the Level 3 for someone else to use that needs it.

I do wish the Kia had the option to tell it to charge to more than 84% on Level 3. A leaf owner told me that the leaf actually stops at 80% and automatically starts up again and continues to 100%.

 

[irfca]

From 94%-100% it's a total trickle of power

I put a meter on my L2 charger, and have observed it charges at the full L2 charge rate (40A / 7.2kW/hr) right up to 98%. I was surprised that it charged that aggressively!

 

[mtndrew1]

From 94%-100% it's a total trickle of power

I put a meter on my L2 charger, and have observed it charges at the full L2 charge rate (40A / 7.2kW/hr) right up to 98%. I was surprised that it charged that aggressively!

Mine behaves the same way, but 7.2 kW out of 50 is trickle in my book! Nevertheless I'm thrilled that it goes full blast on L2 right up to the end.

 

[GizmoEV]

From 94%-100% it's a total trickle of power

I put a meter on my L2 charger, and have observed it charges at the full L2 charge rate (40A / 7.2kW/hr) right up to 98%. I was surprised that it charged that aggressively!

The Kia battery is a 360V nominal, 75Ah battery. Charging at 7.2kW (note it isn't kW/hr, a meaningless unit in this context) and ignoring any inefficiencies in the charging system this means that the charge current at the battery is at most 7200W/360V=20A. For a 75Ah battery this is a charge rate of 0.27C. Even cheap Li batteries have 0.3C as their standard charge rate. The batteries in the Kia can accept a charge easier (lower effective internal resistance) than the cheap Li batteries which means the peak battery voltage isn't reached until nearly 100%SOC. That is why the charge rate doesn't cut back until 98% or so.

I charged at an nrG/Evgo station one time and it displayed the voltage and current. Unfortunately the charger stopped after 30 min so I couldn't see what it did when the car reached 84% but all the way up to 78% when it shut off the charge current fluctuated between 99-100A and peaked at about 390V. I believe that the effective internal resistance of the cells Kia uses is lower than those in the Nissan Leaf which is why DCFC on the Kia goes to nearly 84%. I just don't have the data to back that up. Maybe I should take my clamp meter along some time and see if I can measure the current. I think the individual wires are available straight out of the CHAdeMO connector.

 

[johntox]

I talked to Kia and they say to protect the battery on fast charge, it's supposed to shut off at 86%. I got mine to 94% before it shuts off. Overcharging can kill the battery according to them so getting over 90% is not great for battery

 

[GizmoEV]

I talked to Kia and they say to protect the battery on fast charge, it's supposed to shut off at 86%. I got mine to 94% before it shuts off. Overcharging can kill the battery according to them so getting over 90% is not great for battery

The manual states and in testing, CHAdeMO charging first stops at just shy of 84%. The second shutoff is at 94%. Also, the battery pack in the Soul EV is 30.5kWh and only 27kWh is usable so even when charging to 100% as indicated by the meter in the car the battery pack is not at a true 100% SOC. While a higher SOC is a little harder on a battery it isn't as bad as your last sentence implies. Furthermore, there is evidence that the instrumentation of the battery gets calibrated when charging to 100% indicated so if one never does a 100% charge then the range calculation, among other things, will begin to deviate further from reality.

Look up voltage vs. SOC curves for different types of Lithium batteries and you will see that on most of them there is a big spike in voltage in the last few percentage points. Staying out of this region is typically best.

On another note, by transcribing from a video of a CHAdeMO charge to 84% and then on to 94% and the charge rate drops to around the 6.6kW rate at about 92%.

 

[jstack6]

First of all a DC Fast charge does not use any on board charger in the car. It goes direct DC to the battery.
The car communicates with the DC Fast Charger you plug into. It tells it to slow down at a little over 81%. It should continue until the battery is 100% full but depends on the equipment you plugged into.

NRG uses ABB equip and BTC http://www.btcpower.com/. The NRG starts at about 44 kW but drops to 4 kW after 81%. The BTC tapers from the start all the way t the end and I still got 12 kW after 90%. But latter they changed the charge plan so it ened up acting like the ABB equipment.

The car tells the DC Fast Charge to slow down to keep the battery from getting hot and allow it to charge more efficiently. So if you pay to charge unplug after 80% if you can make it to your destination. It will save you time and money.