Q. How to check the string /individual row voltage of a SUMATOTEK Lithium Battery Pack?

A. Lets take an example of a 48.1V SUMATOTEK Lithium Battery. It has 13 Strings or 13 Rows connected in series. The BMS connector in the picture has 14 wires. You can access this connector by opening the Battery Box Cabinet Cover and after disconnecting it from the BMS. Remember to follow the Safety Instructions given at the end of this FAQ.

C0 : This is also the negative terminal terminal of the Battery Pack. It is also connected internally to the BMS at B- Terminal.

C14 : This is also the positive terminal of the Battery Pack. It goes straight to the output terminals & is also accessible via the Industrial & Charging Connectors. Note : The Main Red(+Ve wire : 4Sq mm ) is directly connected to the connectors. It is not connected to the BMS.

C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13 : These pins are connected to individual rows in the pack.

Our task is to measure the voltage between these pins. If you are using SUMATOTEK Service Battery Health Calculator to analyse your battery health report then you need to measure B0, B1, B2, B3, B4, B5, B6 ,…..B20.

B1 : Voltage Between C0 & C1. If you are using a multimeter (Set the Multimeter to 20V DC Setting) then the Negative Lead(Black Lead) will be placed on C0 & Positive Lead(Red Wire) will be placed on C1. Note down this Voltage, it should be within a range of 0-5V.

B2: Voltage Between C1 & C2. If you are using a multimeter (Set the Multimeter to 20V DC Setting) then the Negative Lead(Black Lead) will be placed on C1 & Positive Lead(Red Wire) will be placed on C2. Note down this Voltage, it should be within a range of 0-5V.

B3: Voltage Between C2 & C3. If you are using a multimeter (Set the Multimeter to 20V DC Setting) then the Negative Lead(Black Lead) will be placed on C2 & Positive Lead(Red Wire) will be placed on C3. Note down this Voltage, it should be within a range of 0-5V.

B4: Voltage Between C3 & C4. If you are using a multimeter (Set the Multimeter to 20V DC Setting) then the Negative Lead(Black Lead) will be placed on C3 & Positive Lead(Red Wire) will be placed on C4. Note down this Voltage, it should be within a range of 0-5V.

B5: Voltage Between C4 & C5. If you are using a multimeter (Set the Multimeter to 20V DC Setting) then the Negative Lead(Black Lead) will be placed on C4 & Positive Lead(Red Wire) will be placed on C5. Note down this Voltage, it should be within a range of 0-5V.

Keep repeating it until you reach ……………………….

B13: Voltage Between C12 & C13. If you are using a multimeter (Set the Multimeter to 20V DC Setting) then the Negative Lead(Black Lead) will be placed on C12 & Positive Lead(Red Wire) will be placed on C13. Note down this Voltage, it should be within a range of 0-5V.

SAFETY INSTRUCTIONS : Do not short the Connector Pins while measuring with the multimeter leads. If the leads touch each other while they are placed on the BMS Connector pins, it could short that particular string/row. Also do not press the Multimeter lead too hard while measuring the voltages, press gently or it might damage the connector. Do not bend or twist the connector in any way while taking it out from the BMS. Pull the connector out slowly in the direction of the connector.

Q. My Sumatotek Charger keeps on charging my Sumatotek Battery for hours and yet the Battery doesn’t full charge? What should I do?

A. First, of all check your average charging duration using our Charging Calculator on our website. You have to select the Ah (Capacity of the Battery) & the A(Ampere) of the Charger.
For eg for a 60V 6A Charger & a 60V 25Ah Battery, Ah value is 25 & A value is 6. When you select these 2, you get the expected charging duration.
Incase your charger is charging for more than the expected charging duration, then check your input supply voltage. In areas, with low input voltages, charging could be slow. Also make sure you don’t use very long extension cables to charge the scooter. It could result in a drop in current output & voltage output.

Even after following all these steps, the charging durations is more than the expected charging duration, you should visit your nearest service centre and look for a replacement. Your charger might be giving less current output than what is rated on the charger.

Q. What should I do if my Sumatotek Battery has been damaged by Liquid/Water?

A. If your SUMATOTEK Lithium Battery has come in contact with water, please take it immediately to your nearest dealer and inform him of the same. If you do not take action immediately and wish to delay or not report the incident to the dealer it may damage your SUMATOTEK Lithium Battery permanently. The dealer will take immediate action and ensure that the water doesn’t stay inside the battery. He will open the battery and dry it completely from inside out. He may also need to send the battery immediately to the SUMATOTEK Company Service Center for a thorough checkup. Keep in mind, Fast Action may save your battery. But if you do not report it then the damage due to water retained inside the battery will be permanent and your battery may not be repairable.

NOTE : Once water goes inside the battery by any means, intentional or accidental your battery will be out of warranty but note that we will try our level best to repair it at a nominal cost after the permission of the customer and all charges are to be borne by the customer in that case.

Q. How to fix a loose BMS Connector issue in a SUMATOTEK Lithium Battery?

A. If you are facing one or multiple of the issues mentioned below then follow the simple steps mentioned below. We strongly recommend that you keep an experienced technician by your side or get your battery checked at your point of purchase.

1. After I connect the charger to my battery, the charger FAN or Charging Indicator doesn’t turn on. To put it simply: The Battery doesn’t charge.
2. After the installation of SUMATOTEK Lithium Battery, the vehicle display turns on but when I sit on the vehicle the motor is unable to run.

Tools Required: A Multimeter, A Screw Driver, A Smartphone.

Note : In case you are unable to follow STEP 1 you can directly follow STEP 2.


STEP 1 [ Test ]: Measure the voltage of the SUMATOTEK Lithium Battery when not connected to the vehicle. Note down the reading. It should be within the range( Between the Lower Cutoff & Upper Cutoff) specified in the individual products’ technical description. Now connect the SUMATOTEK Lithium Battery to the vehicle and turn on the MCB and the key. Again measure the voltage of the battery. If the voltage reading drops to 0Volts or less than 10Volts or below the Lower Cutoff(as specified in the product’s technical description), then you need to follow the next step mentioned below.

STEP 2 [ Solution ]: The Battery Pack is managed by a BMS (Battery Management System). The BMS has multiple wires connected to a connector which is connected to each row of the battery. It is highly likely that during transportation the connector as shown in CASE A & CASE B might have gotten loose.
Under the supervision of an experienced technician open the battery and simply reconnect the connector as shown in CASE: C . Pull the connector out carefully without bending it. Bending the connector can damage the connector pins by breaking the soldering points.

Note : Always makes a full single video while opening the battery. Follow the safety instructions mentioned in a similar FAQ about how to safely open the battery in case the need arises. The video will act as proof that you have followed all the guidelines regarding opening the battery as mentioned on our website.

BMS Connector Scenario Diagram

NOTE : Always take prior written permission of authorized SUMATOTEK representative over mail/Whatsapp for opening of SUMATOTEK Lithium Batteries. In case of lack of video proof or without any written permission, you may loose your warranty.