My car is around 5 months old and done 8500 km till now.
BHPian anshumandhun recently shared this with other enthusiasts.
I’ve been facing “HV Critical Alert” on my Tiago EV since 1 month now. My car is around 5 months old and done 8500kms till now.
The first time I faced this issue was 6875 kms while coming back from office. I was at Regen 1 and I used brakes to slow down on a speed breaker and just as I approached the speed breaker, the car lost power and started beeping while giving HV Critical alert. Thankfully the car had enough momentum to keep rolling and be taken to the side of the road. I tried starting the car but it didn’t work for 5 minutes. Then I started calling Tata service guys to take their advice but no one knew what to do. So the last resort was to call the helpline and get a tow truck. All these calls took 15 minutes and I tried to start the car and this time it just started like normal!
Since the car had got the alert while slowing down, I made a random guess that maybe its related to regen so I switched regen to 0 and drove back 50 kms to home without any incident.
The next day I sent the car to service center (Prerana Motors, Yelahanka) for second service as well as to resolve the issue. They were not able to figure out the exact issue as they could not replicate the problem and gave the car back with a software check/update.
The car worked well for one week before the HV alert came back again. It again happened while slowing down for a speed breaker. This time I wasn’t very lucky with car’s momentum and the car stopped right in the middle of the road causing a huge traffic jam. I somehow pushed the car to the side and called helpline. By the time the helpline guys arranged for a call back from the towing company, it was 15-20 minutes and the car started again normally with no error. I cancelled the towing service and drove back home in 0 regen mode.
Next day I had to use the car for some urgent meeting so I used the car in 0 regen mode and it worked fine. That evening I forgot to change regen to 0 (car starts automatically in regen 1) and the HV alert came again. The car started after 10 minutes or so but the HV alert came once more and this time the car refused to start even after 20-30 minutes. So I called the helpline and tow truck was arranged which came after 2 hours. It was already 10:30pm by then. And guess what! The car started when the tow truck arrived. I anyway loaded the car on the tow truck and the car was taken to Adishakti Tata Service center near hebbal since that was the closest service center (although I asked them to take it to Yelahanka since my car had been there before for service as well as this complaint but their protocol asks them to take the car to nearest center only).
Next day the service center guys called me and said that they don’t know for sure the reason and since the car is starting normally, I should go and take back the car. So I went and saw the condition of the service center, it was so crowded with too many cars. I knew these guys will never have the time to take my car for test drive and spend time to find out the issue or resolve it. So I took back the car and in a couple of days the HV alert happened again.
So I used the car in 0 regen mode for a couple of days and then dropped the car to Prerana motors Yelahanka service center last Saturday (24th June). I went there personally and met the manager and explained the issue. They have informed me that one Tata engineer is visiting them on Monday to have a look at my car’s issue. I have also requested them to give me a loaner car if they have to keep my car for more than 1-2 days since the Tiago is my daily commute vehicle. Fingers crossed now! Hopefully there will be a quick and easy resolution. It’s not a good feeling at all to be stranded on the road so many times with a new car. If I did not love the Tiago EV as much as I do for the amazing product that it is, I would have been much more frustrated.
Here’s what BHPian electric_eel had to say on the matter:
I guess the summary is that if you set the regen to any level other than 0 then the HV critical error is poping up. Let me ask you a question. Suppose you charge your car to 100% SoC and keep regen at say 1 (or better 3), is the regen meter showing regeneration ? Nexon EVs when they are charged to 100% works as if regen is 0 till the SoC drops to something like 97 I think.
Why I ask this ? So far I have heard of people getting HV critical errors at certain fast chargers. The explanation seems to be that ziptron system is unable to tell those chargers to stop sending in current when the system has reached 100%SoC. May be there is something faulty in your regen limiting circuit which means charge goes to the battery
even when the battery is fully charged.In any case this looks like a serious error which I have not seen reported anywhere else.
Here’s what BHPian Venkat_KM had to say on the matter:
Looks like a BMS issue to me. This has to be confirmed from a Service Engineer dedicated for EV from TATA Motors. Please get in touch with the dealership and request for service engineer to check the vehicle for this particular issue, until then chances of fixing it in dealership level is minimal.
BHPian anshumandun had the following update to share on the matter:
The Yelahanka service station guys had asked me to send the car to their Peenya Service center as that is the main center where the Tata engineers visit often. So the car was with them for 1 week. I was told that the Tata engineer had come and spent 2 days to diagnose and the most probably culprit is the MCU (Motor Control Unit). The MCU has been replaced and a software update was done and I got the car back this weekend.
I’ve used the car for around 100kms after this and no issues so far. I am using 3rd level regeneration while driving now as a worst case scenario for testing since the issue was more prevalent during regeneration. I will update again after 500 km of driving.
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