EV battery replacement fine print

More and more EVs (Electric Vehicles) are visible on the road as time is passing. On two-wheelers, it’s getting quite common. I don’t have sales stats but I can see as many as 1-2 scooters are electric out of 10 in the area. In cars, it’s still uncommon but one can see a few Tata Nexon EV and Toyota with green number plates when driving around in Delhi, besides many parked electric cars at terminal 3 in Delhi airport parking.

One mistake that many people do (including myself) is just calculating the running cost. If you compare the cost per Km of an electric vehicle with petrol powered, it will be easily 8-10x the difference. Electric scooters, for instance, can do 1 km for 0.12-0.15 INR when charged with domestically supplied electricity while petrol will be 2-3 INR depending on the age of the vehicle. Such calculation will make it an absolute no-brainer to go for an electric vehicle, especially in a two-wheeler where range anxiety is low (unlike a car). But this does not give the complete picture. The age of the battery is a critical aspect. Almost all vehicles are sold with battery warranty to give an impression that there is nothing to worry about the battery for that given period. It’s often hard (by design) to find the fine print of such policies and the devil is in the detail!

Battery replacement terms hidden in the warranty

Take e.g Hero Electric scooters, let’s read the fine print of their battery policy in their user manual (common for multiple models). Page 12 of the policy has the following:

So for a 30AH battery, i.e battery which can discharge at 30Amps in one hour (or 6A in 5hrs at C5 discharge rate) warranty cover for replacement is only when it’s below 22Ah in the first 6 months. So one can re-write this policy to give real meaning as follows:

Time Period AH of battery (for 30Ah @ C6 discharge rate) Acceptable loss of capacity with no warranty coverage
0 - 6 months Less than 22 Ah 26%
7th - 2nd year Less than 18 Ah 40%
2nd year - 3rd year Less than 14 Ah 53%

Thus in a three-year warranty period expectation is that even if the battery has lost 53% of its capacity, it’s OK and not eligible for warranty replacement. If it’s able to give at least 14Ah at C5. The likely initial peak is not 30Ah (due to electrical losses) but even if it is, one is looking at a loss of over 53% driving range within the first three years without replacement warranty cover. And lithium-ion batteries would cost anywhere from 40-60% of the actual vehicle itself!

It’s hard to find this sort of fine terms as all the landing web pages and brochures will simply claim 3 years warranty or 5 years warranty. For this post, I tried looking at Ola S1, Ather models, and Tata Nexon EV and all I can find is that in some cases warranty is linked to Km driven (like Nexon) while in some cases it’s not (like Ola S1). I cannot determine with 10mins of Google search whether a similar AH discharge policy exists for these.

If you are planning to buy an EV, check for following

  • Does the battery replacement cover has any discharge policy attached to it
  • What is the cost of battery replacement in absolute terms?
  • What is the cost of battery replacement in percentage terms w.r.t total pricing?
  • Be sure to verify the cost of the battery for the same capacity in lithium as well as lead acid. Some sales folks project the cost of lead acid while referring to a lithium variant
  • Find your average usage for three years, compare cost of petrol (with assumption that it will further increase) along with full battery replacement cost near to end of the warranty period
  • Is the tyre rim replaceable? (More on this below…)

The rim bend repair challenge

Often tyre rim of (electric as well as non-electric) vehicle bends over time. This has to do quality of roads and speed breakers. In cars, this is taken care of during wheel alignment and balancing. In scooters, it is often left until it becomes serious enough to cause issues like imbalance or short-term air pressure drop. And in those cases, it is either fixed or simply a tube is added to prevent air leakage from a bent area of these tubeless tyres. Both - fixing of bend and/or tube addition is possible in non-electric EVs because anyone can open the tyre.

But in the case of EVs often the back side wheel has integrated brushless DC motor. It cannot be removed without disconnecting all the wires connecting the motor. Brushless DC motors by design have three coils which are energised separately in a way that keeps pushing the permanent magnet (connected to the wheel rim). Thus three wires to energise each coil. plus two more for a sensor (which works on the hall effect to determine the motion). This means 3 thick wires (to carry high current) and 2 thin sensor wires. Now all this has to be removed to get the wheel off the EV. And after all this, the rim may or may not be disconnected physically from the motor. If not, all one can do is add a tube & hope for no punctures in future because each puncture repair would first require disconnection of the motor (a 15 mins process). It’s an early stage of this vehicle and a lot has to be fixed.

Well, there goes my two cents on EVs!