[Ben Cole]

After someone raised performance loss in another thread I looked at it in my own car.

Reasonable ambient temperature (around 15c), SOC was low and when flooring the accelerator the car only read 130kw (power consumption)

SOC just above 50% and the car would consume
137kw.

So does anyone know the exact limits within which maximum performance is available?

Are all EVs as dependent on charge level for performance?

Due to the nature of battery behaviour I expected some variation but this is more than I thought it would be.

 

[stageshoot]

It’s a deep rabbit hole when you start getting into it, so many factors

one thing in the Konas favour is you will not normally notice it as the tyres will let go and traction cut in most times before the full power is down

I seems to be something Hyundai hide fairly well. Deemed to be a customer does not need to know item

in the Model 3. Every morning (bearing in mind we drove it from Sept to Feb). Anddid not normally charge overnight the power bar on the screen was up to 1/3 reduced and the regen bar up to 75% reduced

I think it bugged me more seeing the lack of power and regen rather than not knowing what was happing. What the eye can’t see the brain can’t worry about.

saying that there seems to be way way less restriction in low temps in the Kona than the Model 3. There would be power and regen restrictions in the Model 3 even after an hour on the motorway.

 

[Ben Cole]

Yeah, it's not something a person would notice normally, 130kw even at 20% SOC. Just nice to know.

Never really had massive issues with traction, mine came with Michelin and wouldn't floor it until well underway.

 

[stageshoot]

Yeah, it's not something a person would notice normally, 130kw even at 20% SOC. Just nice to know.

Never really had massive issues with traction, mine came with Michelin and wouldn't floor it until well underway.

the best way to get the full power down smoothly in the Kona is “launch control”

at the lights sport mode, foot on brake, and just bury the go pedal in the carpet. As lights change foot off the brake. Car gets all the power down smoothly. (The car senses the brake release and gets all the power down without having the reaction time of the go pedal press) Best and most reliable way I have found. The car gets the power on quickly without scrabble most of the time

 

[MarkyM]

Even in the wet?

 

[Ben Cole]

Even in the wet?

I doubt it 🤣.

I had a Saab 9-5 with similar (peak) torque through the front wheels and that was hilarious.

 

[KiwiME]

Reasonable ambient temperature (around 15c), SOC was low and when flooring the accelerator the car only read 130kw (power consumption)

Over 25°C would be a "reasonable temperature" for best Li-ion performance.

 

[i-s]

I had a Saab 9-5 with similar (peak) torque through the front wheels and that was hilarious.

We had a Volvo with 470Nm. That was frightening...

Are all EVs as dependent on charge level for performance?

Due to the nature of battery behaviour I expected some variation but this is more than I thought it would be.

It's fairly easy to calculate.

The kona has a maximum output of 150kW. The maximum pack voltage at 100% SoC is 412V, thus at full charge then full power is at 364A.

When the pack is at a lower state of charge and reaches its nominal voltage of 352V, then 364A will give you 129.6kW.

Probably the current limit is actually 400A, but the point stands that the voltage variation between full charge and discharged easily makes the difference between 150kW and 130kW.

Like @stageshoot I have noticed the model 3 to be more variable over SoC than my previous Nissan Leaf was, but given that the leaf only had 80kW then if it only had 70kW available at low SoC then it wasn't that noticeable of a difference. Dropping from 210kW to 150kW is a much more noticeable difference! It seems that Tesla have taken significant steps to limit charge/discharge rates at low temperatures (many model s owners were shocked by one update massively reducing charge rates at low temperatures) - whether this is a necessity of the chemistry of Tesla batteries or whether it's based on their greater data on battery degradation I do not know.

 

[Ben Cole]

Great post. Never even thought of applying a simple P=VI equation to it.

Drove my son to rugby this evening, pleased to see the full 150kw at 82% SOC.

 

[mikeselectricstuff]

Probably the current limit is actually 400A, but the point stands that the voltage variation between full charge and discharged easily makes the difference between 150kW and 130kW.

The main pack fuse rating is 400A

 

[KiwiME]

My docs show the main fuse rating is 600 A.

 

[mikeselectricstuff]

My docs show the main fuse rating is 600 A.

Maybe it's changed - 400A was from the online service manual, but this was download quite a while ago

 

[KiwiME]

Can you post a screenshot?
SD371-8

 

[mikeselectricstuff]

Can you post a screenshot?

Specs section in service manual, though this also shows 100kW DC charging, so probably out of date.