[electric_eel]

Concluding remarks

With the replacement of the gun locking actuator, I think we have managed to wiggle out of the niggle. It is worthwhile to summarize what has happened.

Symptoms

1. Charging gun refuses to unlock even after pressing the unlock gun switch

2. A more serious issue is the gun refusing to lock

3. In the worst case the charging itself is bad leading to unbalanced cells and sudden SoC drops.

The problem

Dirt and water gets into the charging port. Models like Nexon, Tiago and Tigor from TATAs and ec3 from Citroën, i.e. model which have their charging port located just above the wheel well (traditional fuel inlet position) are more vulnerable to this problem as the wheels kick in a lot of dirt and water during monsoon.

Temporary solution

1. Make use of the manual release to unlock the gun (see the reference video below). For nexon ev max it is a ring that you need to pull.

2. A couple of dry days would mean that the locking mechanism will start working and you will be able to slow charge the EV. Usually a couple of charging cycle with fix the battery out of balance issue.

Solution

The locking pin actuator needs to be replaced (costs approx Rs 6100/- as of today). This is a well known problem and the SC did not have any hesitation for replacing the part under warranty.

Unsolved Issues

The primary reason for this problem is a design flaw and cannot be rectified as it requires relocating the charging port. At best we can think of an aftermarket cover of sort, but this requires some care as one would still want access to the manual unlocking.

One might think that since the issue is primarily a cleaning issue, a through cleaning would help. However think again as pressure washing is not recommended (as per Manual). And recall that water getting into the locking pin can be even more problematic.

Unlocking the gun by hand (Nexon Prime)

https://youtu.be/HDHDTbB1CA8?si=kA5sq4IHNrKYqD54

MODS: You may want to edit the main title of the post to indicate that the problem has been solved.

[BlueGod]

Stupid questions

1. Won’t an additional mud flap covering the splash areas won’t help?

2. Xuv400’s charging port seems to be near front wheel. So how is Mahindra managing this?

[electric_eel]

Originally Posted by BlueGod

Stupid questions

1. Won’t an additional mud flap covering the splash areas won’t help?

The default mud flap that I got from the Dealer has a gap at that point. If you think about it completely covering it also is not a possibility if you want to exercise this manual override (you will have to unscrew the flap for this). It is another matter that the chances of having problem also reduces.

In any case I am in the look out for some after market jugad.

2. Xuv400’s charging port seems to be near front wheel. So how is Mahindra managing this?

Not sure because I am not familiar with the car. May be their manual overide is inside the bonnet and that way they can completely cover it off from the wheel well. I think in the Tata cars this is probably a design oversight.

[electric_eel]

This video is related and should be useful. I am not suggesting that you do it yourself but it gives you an insight on what the problem is.

https://youtu.be/2pS-FraY-0s?si=TggrHlJg4a6XxcVN

[electric_eel]

With some apprehension I am reporting our second niggle again related to Charging


1. The Cars SoC drops suddenly after 15 % SoC.

2. In the slow charging graph, the SoC rises faster than expected in the range 5% SoC to 18-20 % SoC then it become steady.


What is faster than expected ? With the 7.2 KW charger and a 40 KWH battery one expects that 18 % SoC increase in one hour or roughly 0.3 % SoC per minute. This is assuming no charging loss. In the 0% to 20% SoC it looks like the battery gains 1% SoC every minute. Clearly there is a problem here.


I have so far done two deep charging cycles 13-100 and 7-100. The behaviour seems to be predictable and I am expecting the worst this time (may be even a battery repalcement). It seems that the new BMS+VCU update which thankfully has eliminated HV-critical error but it has brought back a silent SoC drop issue. While I definitely prefer the latter, it has made the low SoC range a difficult proposition to trust on.


(MODS: I started this thread hoping that there will be only one serious niggle. It seems that I am bitten by the next one and will like to keep updating this thread with all the niggles that I have been facing. I hope this is fine)

[mally2]

Yes the new BMS VCU update has messed up low SOC in my Tiago EV too. TATA needs to fix this but they are not accepting there is an issue.

[electric_eel]

I am attaching the charging graphs of the last charging (done on a 7.2 KW home charger) . The first image shows the overall charging graph. Notice the change in slope of the graph which means the first 25 odd %SoC it is charging faster than normal



Here is the zoomed version of the charging graph in the normal charging region. Each dot in the graph can be seen as a 1 min worth of charging and as expected there is roughly 3 or 4 dots between each percent SoC increase (as expected). A 7.2 KW charger should be able to add 0.3 percent SoC per minute for a 40 KWH battery.



On the other hand in the abnormal charging region every soc increase is happening in less 1 min roughly. This means the energy content in 1% SoC in the abnormal region is about 1/3 of what is available in the normal region.




In practice the sudden SoC drop starts at 15 %SoC although the charging graph indicate some where around 25-26% SoC has a energy content issue. I will soon be taking the EV for its schedule service and will be raising this issue with them. As of now the SoC curve is predictable (although not desirable). I will be happy to get any suggestions.

[mally2]

Originally Posted by electric_eel

I am attaching the charging graphs of the last charging (done on a 7.2 KW home charger) . The first image shows the overall charging graph. Notice the change in slope of the graph which means the first 25 odd %SoC it is charging faster than normal

In practice the sudden SoC drop starts at 15 %SoC although the charging graph indicate some where around 25-26% SoC has a energy content issue. I will soon be taking the EV for its schedule service and will be raising this issue with them. As of now the SoC curve is predictable (although not desirable). I will be happy to get any suggestions.

Sending you a PM, I have similar analysis on my Tiago EV.