1 whats the Lithium ion Battery 

                here we need to make clear the lithium ion Battery is for the single cell or the pack, normally when they are working on the vehicles or machines , it is lithium ion Battery pack,  we simply call it Lithium ion Battery , it is pack with BMS  ,Not the single cells 

2 What the fault of your Lithium ion Battery pack

we will repair or replace the lithium ion battery pack,  it is up to the cost . the cost will up to the problem. so firstly we need to know the main problem .

as below we simply list some problem for example :

1）Firstly No any Electric for the whole vehicle . even if  we connect the charger

2) secondly  the lasting time reduce too much ,speedy time electric reduces greatly  .the SOC always change.

3) Thirdly  the battery heating slightlly and when long time charge it,. the light  do not change into green .

4) fourthly charging and riding  the battery  heating heavily.

5) fifthly output is ok sometime it is not ok . the electric break when it jolts

3 Repair  cost  decide   solution 

1. )firstly BMS was locked and the voltage is light different .  you can just balance them  ,the lasting journey can recover 90% . you can just repair it . it is good, About the voltage difference . you can check the article as below https://ztekbri.com/blog/how-to-correctly-understand-the-voltage-difference-of-lithium-iron-phosphate-batteries/
2. ))Secondly the single series Battery is damaged . like some battery is meteorismed, you just changed some cells in this series. i it will be ok .  you can reapire
3. 3))Thirdly  beyond 3 series is damaged . and the box is huge broken. maybe you need to replace them, cant just repair them 

4 The daily maintenance reduce the repair

1. firstly prohibit to Deep discharge ,  then soc reach 20% pls charge your battery .about the deep discharge pls check the article as below  https://ztekbri.com/blog/deep-charge-deep-discharge-lithium-ion-battery/
2. secondly Long time no use it . every 30 days to charge it . make the soc between 40-60%
3. thirdly  Avoid long time directly on sunshine . raining 
4. fourthly check your charger . avoid to be heating .