HV critical alert on my Tiago EV: Am I looking at a battery replacement

The limp home mode begins flashing first followed by the usual loss in power and AC shutting off.

BHPian AKINA recently shared this with other enthusiasts:

Hey guys.

Need some advice.

Tiago EV LR XZ+ Tech Plus bought in March 2023. It was one of the 1st cars manufactured as the vin shows December 2022.

After close to 14,000 kms I have encountered the dreaded HV Critical Error but not just that...

The limp home mode begins flashing first followed by the usual loss in power and AC shutting off.

As i keep driving the HV error rears it's head, the car is still driveable but this is highly disconcerting.

Moreover this has happened three times now;

1. 1st time when returning from Pune to Mumbai, about 2kms from my place at 7% charge. Limp home mode was already on but the HV error popped up suddenly at a traffic light. Luckily I managed to get home and charge as the car was still driveable and did not shut off. After charging the error dissapeared, so I thought it wasn't a big deal.
2. 2nd time during heavy rain and getting splashed a bit by other vehicles the flashing limp home mode came on for the first time at 21% charge followed shortly by the HV error. Again I managed to drive home safely and charge the vehicle. Now I was getting a little concerned but again after charging the errors dissapeared.
3. 3rd and last time it again started with limp home mode flashing and then the HV error, this time at 32% charge. Reached home and parked it and haven't driven it since.

When I spoke to a service technician they gave me the useless recommendation to unplug the LV battery for a few minutes and then see if the error symbol dissapears. I don't want to reset the light, i need a solution to why it's happening.

Diagnosing via ZConnect shows no issues.

P.S- The car has been charged at home via slow charging about 98% of its life, although it was charged twice via DC chargers on my trip to Pune after which this saga has ensued.

Any help or advice would be greatly appreciated. Thanks.

Here's what BHPian ferrarirules had to say on the matter:

If you have been charging to 100% regularly, there are high chances of this being a bad battery. Please report this to Tata.

Here's what BHPian vj_v3 had to say on the matter:

I don't know why there is not much noise in Social media and here in TBHP about the HV critical alert on TATA EV's but based on my exposure to various whatsapp groups and telegram channels for Tata EV's, i would straight away make the claim that more than 30-40% of Tata Ev's have a battery problem that causes HV critical errors and stalls the vehicle.

I know that Tata is very well aware of the issues with their battery packs but they continue to launch more and more vehicles with the same problem.

I see atleast 2 people report these issues on different whatsapp groups each day, some are able to get home or to the closest charger by disconnecting the 12v battery for a few minutes and reconnecting to be able to drive a few kms before the error returns again, while most others are just stranded.

The Tata EV veterans purely based on their experience have determined that this issue does not happen if people deep cycle the battery pack (soc 10% or lower) on a regular basis (once in 1-2 months). For people who cycle the battery to say upto 25% regularly, but on one instance during a trip they end up going way below, the error occurs and they get stranded on the highway with towing to nearest service center as the only option. Same scenario for different people based on how low they have been going in the past. I'd like to note here that i have been deep cycling my own tata ev to various SOC levels, sometimes close to 0 and i have not faced the issue in the last 1.5 yrs/15k kms. There are many people who do the same and have not faced issues but 100's of others who are scared of deep cycling and possibly degrading their battery packs and end up hitting the issue at some point.

Each time this is reported to Tata service centers, they just keep the car for 2-3 days each time, probably clear some errors and do some kind of software calibration/balancing and return the car and in almost all cases, the issue just returns almost immediately. after 2-3 instances of this drama, they replace they engage Tata engineer and he recommends a battery pack replacement. And then they recommend customer not to go below 20% SOC etc and give other lame suggestions. The advertised range of a tiago is 315, the real world range is 200 or less and then they recommend us not to go below 20%, what a joke.

Many customers with replaced battery pack have faced the same issue again and there are people who have had 2 or even 3 battery packs replaced so far to no avail.

Some unfortunate customer face this issue immediately after they get a new (not clear if they are brand new or refurbished batteries) pack as well. It definitely seems like some kind of memory effect of the cells that no one is able to explain or fix.

With the number of issues i have seen, i think that this is a total product failure and Tata knows that this is too big of a problem for them to go back to old customers, do a recall and fix. They probably have a huge shipment of these screwed up cells that they procured several years ago and they continue to shove them in more and more cars just continuing to magnify the problem they got themselves in. I wonder when this will blow up.

I heard the punch got a new battery pack from a new vendor but was shocked to hear that even punch customers are facing the same HV critical error issue.

One blogger has been making posts and tweets about his own ordeal with his tata Ev and also covering issues that various other people have been facing. It appears he has also exchanged court notices with Tata and the dealership related to the HV critical error incidents.

• HV Critical error 1
• Court notice
• His tips
• His HV critical incident blog post

Here's what BHPian anshumandun had to say on the matter:

My Tiago EV has done 40,000 kms now and I am facing the same issue. Limp mode activates when battery level reaches around 35% or lower and then HV alert kicks in. Will give it to the service center for diagnosis.

It's really sad that this car (and maybe other Tata EVs too) are plagued by the HV alert issue. Otherwise it's a wonderful city commute car.

Read BHPian comments for more insights and information.