Lithium-ion battery packs are built using many cylindrical cells that are configured in parallel sets of rows called series. All the series work together as one unit in order to provide the voltage and current that your e-bike needs to run properly.

The BMS (battery management system) is a device in each pack that acts as the “brain.†The BMS is wired into each series of cells, and is directly wired inline with the negative charge and discharge leads. Everything that comes in and out of your battery pack will run through the BMS, that serves to protect and control your battery. These features include:

• Current Output
• Temperature Protection
• High Voltage Cutoff
• Low Voltage Cutoff
• Cell Balancing

Every battery on this planet has a limited life span. Battery cells will lose capacity after every FULL charge and discharge, which is called a “Cycleâ€. In other words, the more cycles a battery completes, the less capacity your battery will hold. Over time, your battery will slowly degenerate and your range will decrease. If you avoid full cycles by properly charging and discharging,  you shouldn’t see a decrease in performance for years.

You must ONLY use a compatible voltage Lithium-ion battery charger for your lithium-ion battery pack. Using any other types of chargers can damage your pack and/or cause a fire/explosion!

Unlike other battery chemistries, Lithium-ion cells have no memory. This means that you can charge a li-ion pack while it’s at any voltage level without damaging it or reducing capacity. For example, if you have a pack that’s at 60% capacity and want to go for a long ride, you can plug it into the charger to top it off. However, if you are at 50% capacity and want to go for a short ride, you will be good to go and use it as-is.

When it’s time to charge your pack here are a few tips to keep your battery pack in the best possible shape for a long, healthy life:

• Allow your pack to cool down for at least an hour after a ride before charging.
• Charge your pack to 80%, 90% or somewhere below full charge level majority of the times. Why? Remember what happens when you put your battery through a full cycle?
• BUT, make sure to charge your pack at 100% every 5-10 charges. This is important to do, because charging your battery at 100% will allow your BMS to balance all of the cells in your pack. To ensure your battery is balanced, allow your pack to stay connected to the charger for 1/2 to 1 hour after the charge is complete. Then, unplug after fully charged for safety precautions.
• Never charge your ebike battery when it is not attended. Always charge your ebike battery when you are awake and nearby, as there is always a chance your ebike battery could start a fire.
• Never charge your ebike battery outdoors or in extreme heat or cold conditions.
• Never leave your ebike battery on the charger, as this very dangerous and could cause a fire.
• Never interfere with the wires or connectors while charging.
• When charging your ebike battery, always be cautious of a potential fire or explosion.
• Do not store a fully charged pack any longer than a week. Although this is not dangerous, it will degrade the cell life.
• Do not store a fully discharged pack any length of time either. The cells will degrade at a much faster rate in this state as well.
• When storing your pack for anything longer than 2 weeks, your pack’s ideal voltage level should be a couple of volts within nominal voltage. Nominal voltage is what your pack is listed at (52v, 72v, etc.) Therefore, if you are going to store your 52v 8ah pack for the winter, charge it up (or drain it down) to about 52v.

Summary for Charging eBike Battery:

• WARNING: Be attentive when charging your ebike battery at all times. eBike Batteries can be dangerous and may cause a fire or explosion. Bicycle Motor Works will not be held responsible for damages, injury or loss caused by use of our products, as stated in our Terms and Conditions, Store Policies.
• Every 5 cycles, charge your ebike battery 100%. After reaching 100% leave your ebike battery charging for additional 30 minutes in order to balance. Then, unplug your ebike battery from the charging station.
• Only charge your ebike battery 90% for all other cycles, unplug your ebike battery from the charging station when reached 90%.
• NEVER leave your ebike battery on the charger, as it could cause a fire or explosion. ALWAYS be cautious.

Lithium-ion batteries will over heat by being exposed to the sun or high temperatures over extended periods of time. When a battery over heats, the cells’ chemical composition begin to change thereby decreasing the capacity of any number of cells in the pack. This can greatly reduce the pack’s cycle life, and worse, it can cause some cells to become weaker. If some cells become too weak, or die, then the BMS may not be able to balance the pack properly. At this point the BMS may shut down any input or output from the pack to protect it from an overcharging situation that could result in fire or explosion.

The BMS is an important factor in an e-bike battery, because it ultimately creates a safe environment for the battery to function. Naturally your battery cells will slowly degrade, but overheating the cells will speed up this process. A functional BMS will shut down your battery completely when the cells are too badly damaged and are unable to balance. Similarly, extreme cold weather is also not an ideal environment for your lithium-ion battery. When your battery becomes frozen, the pack’s performance and capacity will decrease. Your battery may still operate, but it could lose the capacity to hold a full charge or it will begin to lag in performance. Unlike heat damage, this loss of performance is temporary when dealing with the cold.

Over time your pack will slowly start to lost capacity. This means that the same pack that used to take you on a 30 mile trip may only get you the 25 mile point. This is normal, and it will happen with all types of batteries, regardless of its chemical composition. Using the tips that Bicycle Motor Works provided can help you get the longest life out of your pack.

Batteries are sensitive. It is important to take great care of it.