[Prabh]

We own the Nexon EV Dark Edition, bought in April 2022. However, within a year the battery started to misbehave where it went from 30% > 0% in a matter of few kilometers.

Now, with the battery replaced under warranty (which took 2 weeks). Firstly, on return the EV kept showing "Limited Performance Mode" activated. The car was sent to the service station again for a software update.

We put the car on charge on its return as it was completely drained. It was charging normally upto 30% and then it went up rather quickly. See attached gif.



The battery software is completely out of order. The service center folks have instructed to charge the battery from 20% > 100% for alteast 2 more cycles before the BMS re-calibrates.

The Tata Motors zApp has stopped tracking vehicle movements. So I have written to them to check what seems to the error.

Service Station - Auto Vikas Moti Nagar, New Delhi

Great to hear if any one else has experienced something similar with their Nexon EV.

[ferrarirules]

Originally Posted by Prabh

We put the car on charge on its return as it was completely drained. It was charging normally upto 30% and then it went up rather quickly. See attached gif.

Prabh - What happened with your charging post battery change is completely fine. I will try and explain the reason.

When you battery was replaced, the BMS software didn't know how much battery is present. During config, service center adds a low value for battery percentage in the BMS. There is no way for an BMS to accurately get the battery percentage from a current state of battery. Why this is so because this is a LFP battery, LFP battery has a very minimum nominal voltage variation (range from low to high is 3.2 to 3.6V). So you cannot say that it is at 3.3 v so it will be 50% full. And the BMS is designed to stop charging moment the cells touch 3.6V.

Now your battery would have carried more charge more than what your dash showed. When you put it on charge, the battery reached the max voltage and the graph showed 100%. Their recommendation is also correct, you should do minimum two charges from below 20% to 100% so that BMS can adapt to the new battery.

If the jump still happens post the two charge cycles then the battery still has a problem.

[Prabh]

Originally Posted by ferrarirules

Now your battery would have carried more charge more than what your dash showed. When you put it on charge, the battery reached the max voltage and the graph showed 100%. Their recommendation is also correct, you should do minimum two charges from below 20% to 100% so that BMS can adapt to the new battery.

If the jump still happens post the two charge cycles then the battery still has a problem.

Thanks. This is indeed insightful. Will it be safe to assume that the range that the BMS is reflecting is correct or should be taken with a pinch of caution. So far over the last few days - the drop has been linear.

Because when the car came back from the workshop and BMS not properly calibrated. The charge was not dropping it was stuck at 98%. And, after they fixed the BMS - it went from 71% > 0% in 20kms.

[ashokabs]

Like any of the new batteries the charging system or BMS must be properly calibrated to know correctly battery charge at 100% and of course at 0%, It takes a couple of cycles to do that. The same is true of the mobile phones. Especially the ones when we could remove and replace the battery with a new one. Laptops particularly on battery replacement need battery calibration.

[Atul Kolekar]

The explanation provided by ferrarirules is spot on. Tata motors should have explanied it to you instead of just giving instructions about charging.

[Prabh]

So its been a 3 weeks since we got the battery replaced and went thru the magic charge.

We choose to drive carefully till it reached 16%; especially having been stuck 3 times with a dead battery. So daily drive was about 4-6km; in total the car did 139km from 100% > 16%. Approximately 1% per 1km with the new battery.

This is the second charge after battery change and it seemed to have progressed fine.

Will update again on the 3rd recharge. So far it seems to be behaving as expected. Our Nexon doesn't do more than 150-170km on a full charge with AC usage in the city.

[extreme_torque]

Originally Posted by Prabh

We choose to drive carefully till it reached 16%; especially having been stuck 3 times with a dead battery. So daily drive was about 4-6km; in total the car did 139km from 100% > 16%. Approximately 1% per 1km with the new battery.

This is the second charge after battery change and it seemed to have progressed fine.

Will update again on the 3rd recharge. So far it seems to be behaving as expected. Our Nexon doesn't do more than 150-170km on a full charge with AC usage in the city.

What is the watt hour per km consumption reported by the car?

[electric_eel]

Originally Posted by Prabh

So its been a 3 weeks since we got the battery replaced and went thru the magic charge.

We choose to drive carefully till it reached 16%; especially having been stuck 3 times with a dead battery. So daily drive was about 4-6km; in total the car did 139km from 100% > 16%. Approximately 1% per 1km with the new battery.

This is the second charge after battery change and it seemed to have progressed fine.

Will update again on the 3rd recharge. So far it seems to be behaving as expected. Our Nexon doesn't do more than 150-170km on a full charge with AC usage in the city.

With the 30 kwh battern that means you are roughly doing 300 wh/km. Please confirm that you are seeing such high wh/km.

[Prabh]

The 6km it has run this morning it is showing 206 WH/km. Before charge, it was at 146wh/km.

[electric_eel]

Originally Posted by Prabh

The 6km it has run this morning it is showing 206 WH/km. Before charge, it was at 146wh/km.

Yeah 30000/206 = 145 Kms of range (I am assuming nexon EV not EV max) so that seems to be the kind of figure that you are getting. but 206 is quite high (it is understandable for 6 Kms) can you try driving a longer trip. In reasonable traffic with AC you can easily get 120-125 Wh/km on EV Max. EV prime should do better as the battery weight is lesser. With 130 WH/km you should get a total range of 230 at least for 100%-0 and about 18 for 100-20 %SOC.

[Prabh]

This is Nexon Prime. Bought it before Max was launched in April, 2022.

We did Delhi to Amritsar and back in this same EV in December 2022. So the effective distance was just around 200km at full charge and full load in the car.

The previous battery used to show 310km on a 100% charge. But then it would collapse at 30% due to a battery issue. Maybe as we drive it longer distances - the system calibrates and the WH numbers changes.

I'll update the thread; till I complete the 3 full cycles So the forum knows the drill - if they land up changing batteries for their EV under warranty. Though your experience might differ.

[extreme_torque]

Originally Posted by Prabh

The 6km it has run this morning it is showing 206 WH/km. Before charge, it was at 146wh/km.

I dont know how battery management works on a Nexon but if it works anything like Tesla, it would try and bring the battery upto optimum temperature and therefore uses a little more energy during the starting few kilometers.

206 wh/km is certainly very high for city driving. I have had my Tesla Model Y Performance for a month now and I am averaging approx 160 wh/km and that includes some very hard launches and its winters in Melbourne and quite cold. It will improve further as the weather warms up. To put it in perspective, Model Y Performance has more than 500 bhp and weighs 2 tonnes.

[advant]

Is the wH/km reported in a Nexon EV dependent on how well the battery is performing? In other words, isn't the wH/km just a product of the instantaneous or average current multiplied by the battery voltage while the odometer registers a 1Km increase? How well the battery is performing should not affect this number, correct? We can't blame a high wH/km on a poor battery, can we?

[aim120]

Originally Posted by advant

Is the wH/km reported in a Nexon EV dependent on how well the battery is performing? In other words, isn't the wH/km just a product of the instantaneous or average current multiplied by the battery voltage while the odometer registers a 1Km increase? How well the battery is performing should not affect this number, correct? We can't blame a high wH/km on a poor battery, can we?

Correct. The wh/km is calculated based on the power draw from the battery. Thats just translated to wh/km by the software taking in account the distance covered vs power draw. Since power draw varies based on road inclination, occupants and payload, head wind , air conditioning and user throttle input etc.

Motors will also have their sweet spot in terms of efficiency.

[Prabh]

So now we've done the 3 cycle charges after the battery change. And, here are the findings

> Avg. wh/km = 150 (continues to be very high, don't know why)
> Battery = at 20% has a max range of 6-8km and drop is reasonably fast.
> Charge from = 0-10% is equally fast.
> Max range 100% > 1% = 156km (100% city drive)

Will observe another few months - either will ask for replacement of battery or sell it off.