Description
The re-celling of a battery of the electric bike saves money and nature! Replacing the new battery cells is a cheaper way to get the wheels rolling again. The battery usually dies in winter because its voltage drops too low (less than 2.5V in the battery).
Batteries for use in electric wheels
In Finland, almost all e-bike batteries use li-ion or li-po battery cells. The advantage of lithium batteries is light weight and high capacity and power supply in relation to the size of the battery. The weakness of lithium batteries is sensitivity to overcharging or undercharging. For example, the battery cell 18650 li-ion, which is the most used battery cell for electric bikes, requires a charge of 2.5V to 4.2V. Therefore, aBMS (Battery Management System) (Battery Management System) has been added to the battery packs.
The function of the BMS is to monitor the cells in the battery pack and to interrupt the discharge or charge when the battery reaches the programmed voltage level. Due to bms, lithium batteries are quite simple because the cyclist does not have to measure the battery charge, but the BMS stops the power supply. Thus, the battery runs out before it reaches dangerously low voltage. So it's the same as on the phone. The phone reports a battery charge of 0%, but in reality the battery still has power to prevent deep discharge from damaging it.
Probattery tips for maintaining the battery of an electric bike:
- Do not disassemble the battery too empty! If possible, do not disassemble the battery in less than 20% of the charge. The lithium battery starts to oxidize in too low a charge. Keep the battery in a 60-80% charge, especially when storing. In winter, it is a good idea to charge the battery every three months.
- If the battery is hot, allow it to cool down before charging. The battery may warm up when discharged with high current. Heat is especially the enemy of the li-po battery. Battery chemistry stays smoother and in good condition for longer if you do not charge the battery when it is hot.
- Keep the battery close to room temperature. The frosty winter in Finland absorbs the juices from the batteries if the battery is left cold. Similarly, temperatures above 40ºC over time interfere with chemical reactions in the battery. Take the battery in for the winter and in the summer store in the shade.
How long does the e-bike battery last?
The cyclist's driving style affects the life of the battery. Hard accelerations require more power from the battery. The lithium battery can withstand about 500 recharges. This can be greatly reduced if the battery is constantly discharged with high currents. Some wheels prioritize the range and battery age by limiting the battery output.
Lithium battery performance is always a compromise between capacity and power supply. The maximum capacity of the 18650 battery is practically 3500mAh or 3.5Ah. The maximum power is approximately 35 amps from a battery cell of that size. However, these features can never be obtained in the same battery cell.
A high range is obtained by selecting a high-capacity battery sensor, such as samsung 35E or LG MJ1. These 18650 batteries offer 3.5 Ah capacity, but the maximum discharge current is only 10 amps. If you want more power off your bike, you can choose between high discharge battery cells such as the Sony VTC5A or Molicell P26. These batteries have only 2.6Ah capacity, but a wild 35A power supply.
Of course, by connecting the batteries in the chest and series, you can get more familiar readings, such as 36V and 418Wh. Well, what do we just talk about amps and now all of a sudden watt lessons?
The Shimano BT-E6000 e-bike battery is powered by 18650 li-ion cells with a rated voltage of 3.6V. It can therefore be calculated that the battery is connected in a series of 10 batteries. 36V / 3,6V = 10.
The amps are obtained by dividing the wattage hours by voltage, i.e. volts. 418Wh / 36V = 11,61 Ah. Then, when it is known that shimano's battery has 40 cells, 11.61Ah can be divided by four. Four because we already know that there are 10 batteries in a row, so in parallel 10 sticks there are four.
11,61Ah / 4 parallel connections = 2,9 Ah. So we know that the battery uses 40 pcs of 18650 batteries with a capacity of 2900mAh.
This is a good idea to know if you're wondering which battery cells you'd use to update your e-bike battery.
What should I take into account in the battery of an electric bike?
The e-bike battery package can be built according to the user's needs using high-capacity cells or high discharge cells. The most common need is to maximize travel, meaning we usually put LG MJ1 18650 cellsto provide 3.5Ah capacity per sensor. Another excellent, slightly cooler option is the Panasonic-Sanyo NCR18650GA 18650 battery cell,3.5Ah capacity and 10A discharge.
The lithium battery possible bms is also the hardest element in the battery. The BMS charge control circuits from the manufacturer have pre-programmed in-control. It involves not only monitoring battery performance, but also discussion sup with the bike management system. For example, the battery tells information about its charge to the bike's driving computer, which requires much more complex programming. Of course, e-bike manufacturers do not sell separately BMS circuits, but directly from new batteries.
BMS is the biggest challenge for the do-it-yourself construction. The battery pack may keep the battery dead if it has been empty for a long time. Even if the cells are loaded separately back into a good reserve, the programming of BMS cannot usually be changed at home. In this case, you will need to buy a new battery or put in a generic bulkkiBMS that monitors the battery cells, but does not know how to do anything else. Then the electric bike can run on an old battery, but it no longer knows the same tricks as the original.
Do-it-yourself e-bike battery
Only BMS status is an obstacle to those who are handy with their hands. If the BMS is very awake in the battery, but the battery cells are tired, the cells can be replaced.
Here's a good example for english speakers in the video:
The video makes 13S2P, or 13 cells in series, 2 parallel battery packs. It uses Samsung INR18650-25R 18650 battery cellsthat provide 20A continuous discharge current and 2.5Ah capacity. The parallel connection of two cell lines means 5Ah capacity and 40A discharge current in the battery pack. 13 cells in a stick, i.e. when connected in series, make the battery pack 13x 3.6V = 46 V.
What does it take to get a battery?
When building the battery pack, the battery cells must be as close as possible to each other. In the worst case, if the battery has a high voltage difference, you can build a battery that has not worked.
Connecting the batteries into a battery pack is done by spot welding. Spot welding is practically the only working way, as knocking heats the battery too much and at worst spoils the entire cell.
Spot welding supplies electrical current to the welding site, which provides the heat required by the weld. The result is a very neat welding result and the battery cell remains intact.
For more information on how to design and build your battery, see https://www.instructables.com/id/DIY-EBike-Battery-Pack/ Visit at least check out the images.
Custom-made e-bike battery
If your battery is running out of time, you can also send it to us. We're analyzing the potential for that condition and re-encapitsion. After the measurements, we agreed with the customer which direction to go with the project. We can order any battery cell from the battery pack, including the new 20700 and 21700 battery cells.
The cost of work consists of battery cells and work done. Depending on the complexity of the battery, the work can cost 150-200 euros. As a result, we'll send back a battery that probably has better features than original ones. (No need to use the most cheap cells, so you can maximize, for example, the capacity of the battery size within the limits allowed.)
The cells of the e-bike batteries depend a lot on the battery structure and desired features, so please contact us by email info @ proakku .fi
At least the battery model and preferably a picture of the battery should be attached to the message. Let's build the batteries that are right for you!
You can send the battery to:
- Jesi Verkkokaupat Oy
- Pääskynlento 13 B 43
- 20610 Turku, Finland
- FINLAND
- 045 263 8565
- Don't forget to bring the charger!
