Xiaomi M365 Battery


Xiaomi M365 Rechargeable Battery

Overview

The Xiaomi M365 comes equipped with an internal Lithium ion rechargeable battery that is capable of providing maximal travel distance of 30 km on a single charge.  

As is the case with claims of most manufacturers, these statements should be taken with a grain of salt when it comes to real life use.  In case of the Xiaomi M365, the 30 km is the distance traveled under ultimate conditions: flat road, 75 kg rider, average speed of 15 km/h, 25C air temperature, ideal tire pressure, etc.

For all practical purposes, a more realistic travel distance is 20-25 km on a single charge – this is based on my personal experience using two Xiaomi M365s interchangeably for over two years.  To be clear, I have owned one M365 for over 2 years, and the other for a year.

Xiaomi M365 Battery Specifications

  • Voltage output: 36V (max 42V)
  • Battery capacity: 7800 mAh
  • Weight: 1,500 g
  • Size (dimensions): 4 x 7 x 32 cm
  • Time to a complete charge: 5 hours

30 individual cells (18650mAh 10A each) connected in parallel and in series (10s3p)

3 wire connections between the battery and the electric scooter

Color of cells: purple (older models), blue (newer models)

On a photo, these battery cells may resemble standard AA batteries, but they are not.  These 18650 cells are about a third taller and thicker.  To be exact, an 18650 cell measures 19 x 66 mm and weighs 47 grams.

The 18650 cells are larger than a standard AA battery
Each one weights 47 grams

Note: based on my own experience, a brand new, fully charged battery will provide voltage of approximately 41.2V, while a two-year old battery in a relatively good working condition will deliver 36.6V when fully charged.

M365 Battery Life

Based on my own experience, I can honestly say that the battery in the Xiaomi M365 will last for at least 200 charge cycles. After this point, it will slowly start losing its capacity. You will still be able to charge it and use your M365 as previously, but eventually you will start noticing that the e-scooter does not go as far as it used to on a single charge.

There is a limited number of people reporting their batteries going bad at a certain point. However, based on Lithium ion batteries as a whole, I expect my M365 batteries to last for a total of about 500 charge cycles before they will need a replacement.

Maintenance

The Xiaomi M365 rechargeable battery requires little to no maintenance.

Calibration. Since the battery is made up of Lithium ion cells, it does not need calibration (full charge and full discharge) prior to initial use.

Memory effect. These batteries also do not have a memory effect, which was a common finding in the NiMH rechargeable batteries used in the past.

Depth of discharge (DoD). Understanding the concept of depth of discharge is important, because it requires the user to manage the battery quite differently from the rechargeable batteries used in the past.  DoD simply means how much of the initial full capacity is still left in the battery.  For example, if you were to take a 100% charged battery and used it a bit, you may have used a third of the power – the Depth of Discharge would be 30% (battery got discharged by 30%).  If you were to keep going, the battery would discharge further to 50%, 75%, 90% etc.  

What’s important about the Li ion batteries is that you should try to keep them from discharging completely.  I know that some of you will cringe, because this is exactly what we should not have been doing with older rechargeable batteries due to the memory effect.  But as I mentioned, Li ion batteries have no memory effect.  Not only that, discharging the battery to near 100% DoD will slowly but surely reduce the full capacity of the battery.

Water. This should come as no surprise, but you should keep the batteries away from water

Temperature. Avoid hot and freezing temperatures, all of which may damage the battery.  Hot temperatures in particular are detrimental to the overall longevity of Li ion batteries.

Overcharging. The problem of overcharging is not an issue in case of the Xiaomi M365.  The charging unit shuts off whenever the battery becomes fully charged.

Repairs

As a general safety measure, you should not attempt to open or to fix a malfunctioning battery yourself. Especially if you have no prior experience in the subject matter.  Li ion batteries can easily get damaged even further, or catch on fire in a matter of seconds.  

Having said that, please understand that these batteries can be dangerous if mishandled.

Also keep in mind that simply unscrewing and removing the bottom plate of your M365 will void the manufacturer’s warranty.

For those of you who may be interested, I will be publishing a lengthy post explaining some of the simpler repairs that some of you should be able to handle without any issues.

One of the simplest and common repairs involves reattaching a loose connector between the individual cells.  In this process all you have to do is find a loose connection and solder it.  Soldering is the hardest part because is should be done quickly to avoid overheating the neighboring cells.  If you have never soldered before, you may want to practice a bit to ensure you can do it quickly.

Another common problem with the battery is a malfunctioning or dead cell.  When this problem occurs your battery will not charge completely, it may even make your M365 inoperable.  Fixing this problem requires a multimeter, which is a tool used to check the voltage of batteries.  Once you’ve located the dead cell, replace it with a similar one, solder and you are done.  I would say the most difficult part of the entire process is removing the dead cell from the plastic battery enclosure.  I will be posting a detailed article on how to replace an old cell with a new one.

A Multimeter…

Other problems may involve the BMS.  If that’s the case, unless you are an electrician, I suggest you replace the entire BMS unit.

Replacing the M365 Battery

If your original battery is malfunctioning or not holding enough charge, but you do not feel comfortable attempting to repair it yourself, then the obvious choice for you is to replace the battery with a new one.

The process of replacing the entire battery is relatively simple.  It involves removing the bottom plate, removing a few screws that are holding the battery in place and disconnecting 3 wire connectors that are attached to the battery.  These connectors are all different so there is no chance of mixing them up and destroying the scooter’s circuitry.

M365 Battery-saving Tips

As I already mentioned, the two most important factors that can ruin your M365 battery are: Depth of Discharge (DoD) and temperature extremes, particularly hot temperatures.  This is not to say that if you keep your e-scooter out in the sun once or twice then your battery will get damaged.  Rather, exposing the battery to temperature extremes and not paying attention to the Depth of Discharge long-term will certainly have a detrimental impact on your Xiaomi M365 battery’s life in the months to come.

Conclusion

As is the case with most electronic devices, the Xiaomi M365 battery is a crucial component of the entire electric scooter.  No matter how well maintained, these batteries will eventually break.  Fortunately, fixing individual battery cells or even replacing the entire battery with a new one is a relatively simple task.  Although, it may not be a cheap one.  An entire battery will cost you approximately 30% of the entire scooter’s price tag.  An individual 18650 rechargeable cell will only set you back about $4 each.

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