Q. My SUMATOTEK Lithium Battery is giving less than rated mileage, what should I do ?

A. If your SUMATOTEK Lithium Battery is giving less than rated mileage then here are a few things you can do before you take your battery to the service centre. Keep in mind that degradation is a natural process and cannot be reversed by any means.

Answer these questions before you check the steps below :

  1. When did you purchase the battery
  2. How much old is your battery in months
  3. Do you use the complete capacity of the battery daily / Do you discharge the battery completely daily ?
  4. Do you ride alone or with 2 or more passengers on a regular basis?
  5. When was the last time you serviced/balanced your battery?
  6. Do you regularly accelerate the vehicle at higher speeds or driver roughly?

    Once you have answered these questions then you can proceed to reading the steps below.
  1. Tyres should be filled to the desired tyre pressure level. A lower tyre pressure will lower the mileage of a vehicle.
  2. The wheels of the vehicle should be able to run freely when no power is connected. If the brakes are constantly applied upon the wheels even without the user braking the vehicle, it can result in more than desired current draw from the battery which will lower the mileage.
  3. If any component of the vehicle, controller, converter or motor is faulty then it may consume extra current. This can be checked simply by checking whether they over heat during use, since any unused current will be translated to heat and will lower the vehicle’s mileage.
  4. Also remember than the rated mileage is stated for single rider at low speeds, so in case you are riding at a speed higher than the rated speed and with 2/3 passengers or with extra load then it is very normal to get a mileage that is lower than the rated mileage.
  5. Also if you are using the battery for a long period of time then you can expect a natural decrease in the battery overall mileage due to the natural detoriation of the battery health over time.
  6. If you haven’t used the battery for a long time or even when a new battery leaves from the factory, remember to use it for a few cycles before you can get the maximum mileage out of the vehicle. Storing a battery for a long time lower its output capacity which can easily be restored in cases of lithium batteries by charging & discharging it for a few cycles.
  7. In winter , you can expect a less than rated mileage since lithium batteries give less than rated output capacity at low temperatures. So if you are experiencing this then this is a normal experience & your battery could be absolutely fine provided it doesn’t have a damaged BMS or an internal faulty cell which can be checked by following the steps below.
  8. If the Battery is being charged to the optimum level or whether it reaches the upper cutoff voltage level of the battery as mentioned in the product specifications. Batteries may not full charge due to a lot of reasons including a faulty charger, faulty BMS or even a cell failure inside the battery. Try changing the charger to check whether a different charger solves our issue. If not then proceed to the next step.

    Upper Level Battery Cutoff Voltages are :
    1. 54.6V for a 48.1V (13S) Battery
    2. 67.2V for a 59.2V (16S) Battery
    3. 71.4V for a 62.9V (17S) Battery
    4. 84.0V for a 74.0V (20S) Battery
    Please note that the actual battery voltage could be a few millit-volts lower than the rated Upper Cutoff Battery Voltage.
  9. Discharge the battery completely to check the Lower Level Voltage Cutoff of the battery, the Lower level Voltage Cutoff of the battery should be as per the product specifications mentioned in the product description. If the battery cuts off at a voltage higher than the rated Lower Cutoff Voltage then there might be an issue with the BMS or an internal cell failure.

    Upper Level Battery Cutoff Voltages are :
    1. 39-41V for a 48.1V (13S) Battery
    2. 48-50V for a 59.2V (16S) Battery
    3. 51-53V for a 62.9V (17S) Battery
    4. 60-63V for a 74.0V (20S) Battery
    Please note that the actual battery voltage could be a few Volts higher(depending on the load applied) than the rated Lower Cutoff Battery Voltage.
  10. Finally measure the Individual row Voltage of a Battery Pack. If you dont know how to do so, you can learn on how to check individual row/string voltages of a battery pack by clicking on the link. Enter these values in the Battery Health Calculator and analyse the reports. A % of Unbalance below 1% indicates a good state of health & even if the mileage issue persists then the BMS could be at fault, but always remember to check whether the BMS is overheating or whether there is any difference in voltage before or after the BMS terminals, if the BMS also seems fine then recheck the steps above & re-analyse. Above 1% State of unbalance indicates a possible failure in any cells within the pack.