Custom internal battery for Xiaomi M365/1S/Essential/3

  • admin
  • Custom internal battery for Xiaomi M365/1S/Essential/3

Introduction

Xiaomi electric scooters were released  in 2017: 5+ years ago. The scooters have become very popular and makers created billions of upgrades for it. Just take a look, this is an original scooter:

..., and this is how geeks upgrade it:

Of course, a significant part of the mods is related to the scooter battery, because it determines such key characteristics of the scooter as range and maximum speed. There are many custom batteries projects in the Internet: sometimes they are really sloppy and you want to call firemen:

..., but sometimes they are fine, if created by someone  smart and skilled:

However, I did not find a project that would completely satisfy me. Therefore, I developed my own solution and I am proud to present it here. I'll show the detailed making process, including links to all the necessary parts, materials and 3D models, so you can make the same battery if you want.

I decided to create 2 different batteries: 13s3p(48V 14Ah) and 10s4p(36V 19Ah), based on 21700 cells. This is the batteries schematic, compared to original Xiaomi batteries:

Why 2 different batteries? Well, each of them has its own advantages and disadvantages:

The 13s battery provides + 30% to the scooter maximum speed due to its increased voltage, raising the speed from 30 km/h to 40 km/h. The disadvantage is the battery requires a new higher voltage charger and flashing of the scooter.

On the other hand, the 10s battery does not increase the scooter speed, but it works fine with the original Xiaomi charger and there is no need to flash the scooter. Literally, it is plug and ride.

Both batteries increase the range of the Xiaomi M365/1S/3 scooters by 2.5 times, and the M187/Essential scooters by 3.5 times.


48V 14000mAh battery


Let's start with 13s3p. First of all, I designed a 3D model of the battery. Here it is:

The main part is the cells cage, which is also the battery case. Sideway located grooves fit nickel stripes, connecting cells to each other. The BMS(a green part) is located at the front of the battery. Front and sides are covered by plastic covers.

So, we have to print 4 plastic parts: the cage, the front cover and two side covers. Just 20 hours of printing, and the parts are finished:

Now it’s time to put 21700 cells into the cage. Installation diagram:

I used LG M50LT cells:

Left side welding diagram:

Welded left side:

Right side welding diagram:

Welded right side:

Now let’s mount and solder the BMS. Pay your attention: you must connect wires in the sequence specified in the diagram, otherwise there is real risk to damage the BMS. Soldering diagram:

Mounted and soldered BMS:

Left side wiring:

Right side wiring:

The next step is mounting of the front cover, which secures wires sticking out of the battery. M2.5x10 countersink screws are used:

Now it’s time to glue side covers:

Covered left side:

Covered right side:

And this is how the battery looks now - very reliable, but still ugly and not waterproof:

Finally we wrap the battery into a heat shrinkable tube, securing wires output with a sealant:

That is, the 13s3p battery is finished! 


36V 19000mAh battery


The 10s4p battery is quite similar:

Cells layout and welding diagram. Left side:

Right side:

The plastic parts are printed, cells are installed and welded. Left side:

Right side:

Now let’s mount and solder the BMS. Pay your attention: you must connect wires in the sequence specified in the diagram, otherwise there is real risk to damage the BMS. Soldering diagram:

Mounted and soldered BMS:

Left side wiring:

Right side wiring:

Front and side covers are mounted:

Finally we wrap the battery into a heat shrinkable tube, securing wires output with a sealant. That is, the 10s4p battery is also finished!

Take a look at the batteries. They are almost the same, but the 10s one is 1cm longer. Let’s stick labels to distinguish the batteries:

Batteries installation


Let's install the 10s4p battery into the scooter:

No wonder the battery doesn't fit inside the scooter. A possible solution is to print a plastic spacer and screw the original cover through it. I designed the spacer and divided it into two parts so that they fit on the standard 3D printer bed. The spacer height it 25.5mm:

Print it:

And then glue the two parts. There is a small trick: you should glue them screwed to the scooter, then the correct connection is guaranteed:

After the glue hardens, we unscrew the part and finish it:

Checking how it fits:

Pay your attention, the spacer height decreases closer to the front of the scooter, because there is no battery in this part of the body, so increased height is not necessary. Such a shape reduces the chance of catching on something while riding. But the solution also has a disadvantage:  mounting holes of the original cover don't match the scooter body holes a little bit, so you have to correct their shape with a drill. And do not forget to stick the foam tape between the spacer and the scooter or cover these joints with sealant. Then we screw the cover on and get such a funny look:

Well, the spacer is a good option, but I will use a simpler solution - a ready-made extended cover:

The extended cover is mounted:

You can see that the extended cover keeps about 6mm of clearance, compared to the original cover + spacer solution:

By the way, the new battery is not screwed to the scooter body, like the original battery is. It is just fit inside and secured by the cover. Therefore it is necessary to stick a foamed PVC tape around the battery perimeter to achieve the best reliability:

Let's install the battery, connect all the connectors and try to start the scooter:

We press the power button on the scooter - but the scooter does not turn on. The thing is Happy BMS of a just assembled battery is in sleep mode, and you have to start it by connecting a charger:

Press the scooter power button again - and finally it works. It must be said that sometimes you have to wait a few minutes after starting the BMS before you are able to turn on the scooter. It happens because there is a high-capacity capacitor at the input of the main scooter controller, which creates a short high-current surge, which may cause the BMS short-circuit protection. But after several cycles of protection trip, the capacitor is charged, and everything starts to operate normally. As I told above, this may take 2-3 minutes.

Well, now everything is ready to close the cover and ride, but one more thing needs to be clarified. Generally, when you make a battery equipped with a smart BMS, you also need to adjust the capacity parameter. The default capacity value of the Happy BMS we used is 19000mAh. It is especially made for people who make a 10s4p battery of typical 5000mAh cells, so they don't need to configure anything. Why 19000mAh, not 20000mAh? Because the full capacity of the cell is achieved at the full range from 4.2V to 2.5V. We will not discharge cells below 3 volts, and we will not charge them above 4.15 volts: this extends the battery life, with a slight loss of capacity.

That's why we don't have to configure anything for the 10s4p battery. Let's just launch any app for the battery info monitoring, for example, m365tools by Peretti:

We see that the battery is recognized as an original one. All its parameters are dispayed, including voltages of cell groups. We plug in the charger and see that charging has begun and the charge current is displayed:

Try to spin the wheel - it also works:

Okay, it was easy to install the 10s4p battery. Let's try to connect the 13s3p:

As usual, we start the battery by plugging in a charger and press the scooter power button. The scooter gets turned on, but immediately starts beeping, reporting error 24 - “Wrong supply voltage”:

The error occurs because the scooter controller checks if the supply voltage is beyond of the original 10s battery range, so if the voltage exceeds the 43V limit, then the scooter beeps the error. A 13s battery voltage exceeds the limit.

Therefore we have to flash the scooter with a custom firmware without supply voltage limits . There are a few ways to flash the scooter, but the most popular and relevant in 2022 are XiaoDash and ScooterHacking. The first is paid: you have to pay about 10 euros to activate the application. The second option, ScooterHacking, does not require a payment and can be used for free, but the developers are open to donations via PayPal, so you can donate later if you are satisfied with the final result. Both development teams are great fellows and do a great job, continuously implementing new features and fighting against goverment and manufacturer obstructions, who are not happy when unlocked scooters fly at 50+ km/h speed.

I would say, XiaoDash is quite simpler for beginners, so I will use it - https://play.google.com/store/apps/details?id=m365.xiaodash.scooter . Let's install the app and launch it. We can see many parameters, which are not active yet, so the first thing to do is installing the XiaoDash firmware by pressing the “Perform scooter upgrade now” button:


Then we have to wait until the firmware is installed:

And finally, after a few minutes, we get a successful installation message:

That's it, the scooter has been successfully flashed, and the error 24 disappeared. Of course, this is just a tiny part of the XiaoDash functionality, and in the future you can still configure many  parameters, such as maximum power, speed, and there is even a secret combination to switch the scooter from stock mode to powerful and fast one(of course, for children protection purpose and for testing on your private land). But all these features are beyond the scope of this article. Now we open the m365tools application again, making sure that the battery is recognized well and all information is displayed, including voltages of each 13 cell groups:

Now we plug in the original charger - and nothing happens. The charger LED remains green and there is no charging current. What's the matter? We are faced with another 13s custom battery problem: voltage of the original charger is not enough to charge it, and we have to buy a new higher voltage charger:


We plug in the new charger and now it works fine. We can see the charging current in the app:

So, the charger issue was also solved. The last little thing to do is setting a correct battery capacity. As I wrote above, the default value is 19000mAh, which is suitable for typical 10s4p 21700 batteries. But the 10s3p capacity significantly differs, so we have to adjust it, otherwise there will be problems with remaining charge percentage calculating and displaying. I assume that a 10s3p battery assembled of 5000mAh cells operating in a range from 4.15 to 3 volts has a capacity of about 14000mAh. Let's set this value. You have to download and install the following application to configure the battery  - https://play.google.com/store/apps/details?id=embedden.m365.bms.tool

Connect to the scooter, go to the configuration tab and set the value to 14000 instead of 19000:

We have successfully overcome all the difficulties of the 13s battery installation: flashed the scooter, bought a new charger, adjusted the battery parameters. Now it's time to close the cover and tighten all the screws:

Final scooter view with the 13s3p battery installed:


Top speed


Let's pass to the most interesting: range and top speed tests with new batteries. I fully charged both batteries and took a ride, writing down the following results:

Top speed with the original battery is 30 km/h.

Top speed with the custom 10s4p battery is also 30 km/h. No wonder, because the maximum speed is determined by voltage, not capacity.

With a 13s3p battery I reached 39 km/h, which was expected: 30% more voltage gives about 30% more top speed. By the way, if you install 10-inch tires  instead of original 8.5-inch ones, this will give another 10 / 8.5 = x1.17 speed increase, for a total maximum speed of 45 km/h.


Range


Now it's time to test the range, and it's not too easy. Scooter's mileage depends on many factors: rider's weight and driving style, air temperature, wind, hills, pressure in tyres, etc. Thus, if 2 persons use similar scooters, one of them may cover 20 km, while another one drains the battery after 10 km.

I'll try to drive average style, avoiding hills and strong braking/acceleration. Actually, the most important thing right now is not to get an absolute mileage value, but to compare how many times the new batteries increase the range compared to the original battery. Then any scooter owner can easily figure out how much range he personally gets - just measure his mileage on the original battery, and then multiply by the number we're going  to get now.

So, I spent 3 days, riding a total of more than 100 kilometers, and here are the results I got:

This is the mileage for a quiet ride, but now any of you can easily calculate how much mileage your scooter will get with your weight onboard, your riding style and your terrain.

If you ride aggressively and cover just 10 km at the original battery - so at the custom one you will cover 24 km.

Or if you are a chinese girl from Xiaomi, you drive super-quiet and cover 30 km with the original battery, it means you will cover 70 km with the custom one.

The result of a custom battery installation looks much more epic for Xiaomi Essential scooter. This is the same scooter as Xiaomi M365, 1S or 3, but with a reduced battery:

Almost 4 times more range!

By the way, I would like to clarify something about the scooter range, especially for those who have never owned an electric vehicle.

You probably have a question: 40+ kilometers of range? Isn't it too much? My entire city is 10 kilometers in diameter. Who needs it? Delivery couriers only?

And here is the answer: if your combustion engine car is almost out of fuel, its acceleration and maximum speed is not reduced, it will just stop once the fuel is out. On the other hand, electric vehicles' power depends on its battery charge level. If your battery is full - you have full speed and acceleration. If the battery is half charged - your speed and acceleration is not perfect, but still fine. But when the battery is less than half charged - the scooter becomes really slow and boring. That's why you need 40km range to ride 20km with fun and joy.


Cost


Improving the scooter performance is really impressive, but how much does it cost? Let's do the calculation:

21700 cells - about 3-4 EUR per piece, 150 EUR total;

BMS - 65 EUR;

Filament for the battery case and spacer print, about 1 kg PETG - 10 EUR;

Nickel tape, screws, heat shrink, etc - 10 EUR.

You can see that it is absolutely possible to stay below 250 EUR. The only problem is cells welding: I bet you and your friends don't have a spot-welding machine in a garage. It is not worth it to buy a welding tool just for one battery, so I would say the best option is finding a local battery workshop to let them weld your battery: this is not too expensive.

In my opinion, it is quite possible to make everything except welding by yourself if you have at least basic engineering skills.


Is it worth it?


The cheapest Xiaomi Essential scooter costs 250 EUR. This scooter has a reduced battery, but the other parts - frame, electronics, motor - are the same as in the top models, so this cheap scooter is the best buy for the battery upgrade.

I think most people will not make the battery themselves, preferring to order a ready-made kit of battery and extended cover, which costs about 350 EUR.

So, we buy a 350 EUR kit for a 250 EUR scooter. Sounds epic! We get a scooter for 600 EUR, with a top speed of 40 km/h and about 45 km true range. I must say that this scooter is of the highest quality, with an excellent frame, ergonomics and electronics. It is very compact.

To understand if our 600 EUR scooter is worth its money or not, the easiest way is comparing it with another scooter models. What can be purchased for the same price? Is it possible to get the same features cheaper?

From my point of view, in 2022 no one has been able to compete with Xiaomi and Ninebot in the segment of compact city scooters. There is either garbage for a lower price, or just lower quality scooters for the same price, or there are crazy twin-engine monsters on lever suspensions that are closer to motorcycles than to scooters.

Thus, there are just 2 worthy alternatives:

1. Xiaomi PRO2.

2. Ninebot MAX G30.

Let's compare prices and features:            

Ninebot MAX looks worse by all characteristics: it has less range, less speed, more weight, and a higher price. But it must be said that Ninebot is very, very strong and reliable. You feel Xiaomi scooters like children's toys after you took a ride at a Ninebot MAX. If your work is related to the scooter and you are going to cover thousands of kilometers, it is probably the best choice. No matter how good the Xiaomi are, there is just less metal into them: they are lightweight scooters that can be folded and carried by hand without any problems. With Ninebot MAX you always feel pain if there are steps in your way. 

Now, as for the second competitor - Xiaomi PRO2. In terms of weight, it's almost equal, the PRO2 is a bit lighter. It is also a bit wider and longer, perhaps for some people this will be an advantage, and for some people it will be a disadvantage. The range is x1,5 less, but for me this range is quite comfortable for city riding, so I think it will be enough for many people. Top speed is lower, but who needs more than 35km/h in the city? The biggest advantage of our custom monster is not 40 km/h top speed with the fully charged battery, but a stable 30+ km/h speed even when the battery is almost empty.


Conclusion


I would say that the original Xiaomi PRO2 with no upgrades would be the best choice for most people - its speed and range is enough for trips around the city.

Custom battery option is mostly for geeks: you pay just 100 EUR more, getting x1.5 range and +10 km/h top speed. It's also really cool when your looking ordinary scooter overtakes all the bikes and scooters around.

Another case, if you already own a Xiaomi M365/1S/Essential/3 and you are looking for something more powerful, or your battery is exhausted - installing a custom battery could be a good choice to bring a second life to your scooter. Anyway, even if you sell the scooter, there is nothing better in this price segment, and in the segment above, as I said, there are just twin-engine monsters, not as compact and elegant as Xiaomi ones.


Afterword


I hope this post will not only promote my batteries and BMS, but also improve custom batteries manufacturing quality in the world. My dear rivals, today I shared many secrets from my workshop, but I am not worried about it, because I am pretty sure that there are enough customers for everybody. Hot glue, fishpaper and tape are obsolete, let's make cool things using modern technologies. =) 

Links to models and materials used:


Plastic parts for the 10s4p battery:

https://www.thingiverse.com/thing:5476722


Plastic parts for the 13s3p battery:

https://www.thingiverse.com/thing:5476800


Spacers for the original cover, 25.5mm:

https://www.thingiverse.com/thing:5476813

https://www.thingiverse.com/thing:5596327


Heat shrinkable tube:

https://eu.nkon.nl/accessories/packaccessoires/heat-shrinks-insulation-paper/krimpkous-hoogte-148mm.html


Nickel strip:

https://eu.nkon.nl/accessories/packaccessoires/battery-solder-strip/nikkel-weldingstrip-7mm-0-12mm.html


Sealant:

https://aliexpress.com/item/4000959632758.html


Cells 21700:

https://eu.nkon.nl/rechargeable/li-ion/21700-20700-size/lishen-lr2170sd-4800mah-9-6a.html

https://eu.nkon.nl/rechargeable/li-ion/21700-20700-size/lg-m50lt.html

https://eu.nkon.nl/rechargeable/li-ion/21700-20700-size/samsung-inr21700-50e.html


54.6V charger:

https://aliexpress.com/item/32696609629.html

https://m365.embedden.com/48v_2a_charger


Happy BMS:

https://m365.embedden.com/happy_bms_xiaomi


Extended cover:

https://m365.embedden.com/extended_cover_18mm_xiaomi


Ready-made 10s4p battery:

https://m365.embedden.com/36v_19000mah_internal_battery_xiaomi


Ready-made 13s3p battery:

https://m365.embedden.com/48v_14000mah_internal_battery_xiaomi


Complete 10s4p battery and extended cover set in my shop:

https://m365.embedden.com/36v_19000mah_internal_set_xiaomi


Complete 13s3p battery, extended cover and charger set in my shop:

https://m365.embedden.com/48v_14000mah_internal_set_xiaomi


If you like this post, please share it on your social networks and e-scooter communities you belong to. It will really help me to get more customers, grow my small business, and release new cool devices. =)


Russian edition of this post: https://m365.embedden.com/custom_internal_battery_for_xiaomi_m365_1s_essential_3_ru


Thanks for your attention!