What conditions need to met for the Fastchargers to give me max KW Charging?

I googled the charging rate for a 2021 Kona and was surprised that Hyundai says charging 10% to 80% at 100 kW DC is only 1 minute quicker than at 50 kW! Sounds like the charging curve doesn't allow full 100 kW charging to proceed for very long.

KONA Electric's lithium-ion polymer battery only takes about 47 min to charge from 10% to 80 % state of charge (SOC) when using a 100 kW direct current (DC) fast-charger station. If connected to a 50 kW station, this charging time is 48 min.

 

As you stated, battery temp is a big factor; For the NMC battery chemistries like what the Kona uses, optimal battery temp should be between 70F (21C) and 80F (27C).

SOC is another major factor and most vehicles will peak between 40% and 50% SOC, except Tesla (maybe just older Teslas?) that peak at like 5% and decline steadily from there. Vehicles that have a low max charging speed like the Bolt of Kona can potentially sustain that peak for longer, to 70-80%.

But honestly the single biggest factor in practice is the CCS charger you're plugged into not being broken somehow. It is entirely possible your lower-than-expected charging speeds is because the charger(s) you are using have been power restricted or have some kind of fault. It's disgustingly common...

 

Sorry I didn't elaborate. I forged ahead with my answer without asking what your state-of-charge was at the beginning of your charging session. The "optimal conditions for high KW chargings" occur when your traction battery is at a low SOC.

I found that the info I copied is different in different places. On this Hyundai page, it says for the 64 kWh battery:
When using a 100 kW direct current (DC) fast-charger station, KONA Electric’s lithium-ion polymer battery only takes about 47 min to charge from 10% to 80 % state of charge (SOC). If connected to a 50 kW station, this charging time is 64 min [48 minutes for the 39.2 kW battery]. This page doesn't say what the max charging rate is.

I searched this forum for "temperature" and "charging" and found this post, which says: "I have found a strong dependence of range on the temperature of the car during charging."

 

Can only get 100 kW charge with a Kona during a hard braking regen. When DC plugged in, 77kW is max and most I ever saw was 76kW, very briefly.

 

My observed max was 78, maybe 79 kW briefly, at SoC less than 60% and my OBD2 widget said the
battery max temp was 98.6 degF (funny that). Summer roadtrips to FL and back, at 150 kW EAs.
Started ramping down around 68 - 70%.

_H*

 

FWIW: what I've gleaned from the net; applies to the 64kWh battery.

 

I have read on here were some chargers are not reliable ie. EVgo. Were you on Petro Can or Electrify Canada?

Have you checked the reviews of the station on plug share? The station you were at may be notorious for poor charging and the station being the problem and not the SOC or temperature.

 

Can you try a charging station that claims to deliver 350 kW? That would eliminate the charging station from the chain of suspicion.

 

The temperature on the graph is the battery temperature and not outside temperature. With a OBD2 reader, you can get these readings. There are 4 temperatures readings of the battery. When the lowest reading reaches the value in the table, you get the maximum power.

On 50kW charger, the maximum power is obtain when battery temperature reached 15C. In this case, you can maintain it up to 72%.

 

78kW can be maintain upto 55% if the maximum batterie temperature does not exceed 35C. When the maximum temperature reaches 35C, the charging current falls from 200A to 180A, which will give aroung 70kW like you show in your table.

 

With the conditions you described, the battery temperature was definitely optimal. The 50kW station had probably a problem. It should have maintained it's max amperage of 125A. At 8%, the battery charging voltage is around 330V, Power should have given you about 41kW. I don't think the car was limiting the power.