These guidelines and instructions assume you bought your battery with your motor or ebike and that its power and charge capacity is matched to your motor and charger, respectively.
If you are buying them separately, there is a lot more you need to know to ensure you have the right battery and don’t have a potentially dangerous combination. Ideally, your battery can deliver more power than your motor can use and charge faster than your charger can charge. With headroom for both, your battery will not be stressed, will be safer, and will last longer.
Li-ion is virtually maintenance-free, and the battery lasts the longest when operating between 30 and 80 percent of a full charge. Unlike other battery chemistries, Lithium-Ion has no memory and can be topped off whenever needed
When your battery is new
Apply a topping charge before use. For this first charge, you should charge your battery to 100% full. If you have time, leave it on the charger for about 12 hours to ensure at that all of the cells have an even charge. After that, you can charge it to 80 or 90% to prolong battery life if you have a smart charger, and then every few months or so after a deep discharge, do a full 12-hour topping charge to level the cells.
Basic ebike battery charging guidelines:
Storing your Li-ion ebike battery
The two most important things to be aware of when storing your battery are charge percent and temperature. To store your battery longer than a few weeks you should target its charge to between 40% to 70% of full. Never store your battery at 100% charge. This will reduce its overall life. Also, never store your battery below 40% charge because the battery will lose capacity over time. If it falls below its low voltage which is around 2.6-2.8 volts per cell, it can become permanently damaged and the cells may not take a charge after that.
When storing for long periods of time the voltage should be periodically checked and when needed, charged to above 50% This could be as frequent as every 3 to 6 months.
Keep your battery at a moderate temperature. It will last longer if you store Li-ion at a partial charge in a cool place. The worst combination is high 100% voltage and elevated temperature. For long-term storage (several months or more), store Li-ion at approximately 50 percent charge. Ensure that you don’t leave the battery for any length of time where temperatures can climb above 120 degrees Fahrenheit, such as in a closed car or building without climate control.
If the temperature drops below 32 degrees Fahrenheit (0°C), do not charge the battery, or damage may occur. Bring the battery indoors and let it warm up before charging it. It is ok to discharge your battery (ride your bike) when it is cold, but it will reduce your range. It will not, however, harm your battery or reduce its life. Conversely, do not charge if the temperature is above 120 degrees Fahrenheit or damage will also occur.
Li-Ion and safety
Lithium-Ion batteries can be a fire hazard. If you buy quality batteries with name-brand cells from a reputable source, this hazard is extremely minimal. However, if any of the cells in the battery become damaged from dropping or by exceeding charge/discharge limits this risk will go up. It is a good idea to not leave a charging battery completely unattended and you should not charge the battery in close proximity to flammable items. If there is visible damage to the cells from dropping or water ingress, the battery should be recycled and replaced.
Extending the life of your battery
The easiest way to extend your battery’s life is only to charge it to 80% or 90% when not riding it for a few days. Most rides won’t require anywhere near a full charge anyway. Doing this will extend the life of your battery by 2 or 3 times. If you know that you are going for a long ride and want to make sure you have all the power your battery can store, top it off to 100%. Doing so just before a ride will not lessen your battery’s life. To control the charge to shut off at 80% or 90%, you will need an “advanced” or “smart” charger with this feature. Most chargers that come with an ebike do not have this feature.
Suppose you are using a smart charger to extend your battery life by charging to 80% or 90%, in that case, after a deep discharge, you should still occasionally charge your battery to 100% to give your battery’s internal electronics (BMS) a chance to rebalance the cells to get the maximum capacity.
Placing a high drain on your battery will reduce its life. If your battery is rated at 40 amps continuous power, you shouldn’t necessarily run it at that power for long. If your battery becomes warm to the touch while using it, you may be drawing too much current for too long. The battery’s BMS rating may allow you to draw more current when needed, but you should be aware that you shouldn’t abuse it.
Don’t charge your battery too fast too many times. Just like electric cars that have fast-charging stations, you can charge your ebike fast as well. Electric car manufacturers warn not to use the fast charging station all the time, or it will reduce the life of the car’s battery. Unlike fast chargers for cars, most ebike fast chargers are well within your battery’s safe charge limits that won’t decrease its life.
For example, all of the battery cells Electrify Bike Co. uses in their batteries can take a charge of 1.5 amps without reducing battery life. Our most popular battery, the Super Shark, has 14 cells in series and 4 of those series in parallel. Four times 1.5 amps is six amps so a charger to charge at six amps without any decrease of battery life. Our fastest chargers are just four and five amps, which is only two-thirds of the safe charge level. Each cell also has a fast charge rating that is safe but will reduce the battery life if used frequently. This rating is around 2.5 amps per cell which would be 10 amps for a 4p battery.
The Electrify Bike Co. mini-cube batteries have two series of cells in parallel and can be fast-charged at five amps. Since our fast charger is four amps which is right between the fast charge rating of five amps and the standard charge rating of 3 amps, it will have a nominal impact on battery life. For maximum battery life of a mini-cube battery, you should use a two or three amp charger.
Charging with a “Smart Charger”
Smart Chargers can automatically stop charging at 80%, 90%, or 100% charge. This is selectable with a rotary switch on the end of the charger. Electrify Bike Company has Smart Chargers in 2 amp and 4 amp sizes for 36v, 48v, 52v, and 72v batteries. We also have Advanced Smart Chargers in these same voltages that have an additional rotary switch for selecting from 1 to 6 amps. The Advanced Smart Chargers also have an on/off switch and a display that shows volts and amps.
We recommend that the best way to use a smart charger is to charge to 90% after every ride so your bike is always ready to go. Then if you are going for an extra-long ride and want to make sure you have maximum battery range you can top it off to 100%. Topping your battery off to 100% just before a ride does not negatively impact your battery life.
Ebike Battery - Frequently Asked Questions
How should I prepare a new battery?
Apply a topping charge before use.
Should I charge my ebike after every ride?
If your battery is below 40% you should charge it. If you will not be riding for a few weeks, you should only charge it to 50 to 80% to maximize battery life.
Can you overcharge an electric bike battery?
Most ebike chargers and batteries have protection circuits that make it impossible to overcharge the battery. However, batteries should not be left on a charger for extended periods of time at 100% as this lowers the life of the battery.
How long does it take to charge an electric bike?
Ebike batteries normally take 3-6 hours to charge. If the battery is not fully discharged, this can be a lot less. A 2 amp charger will take twice as long to charge as a 4 amp charger.
Do electric bikes charge when you pedal?
No. This would be like pedaling a generator. Some motors can charge the battery when braking or going downhill, but this usually only adds less than 5% to the battery charge while adding 20% to the weight of the bike. It is often better to just get a bigger battery.
How often should I charge my ebike battery?
It depends on how far you rode your bike and how far you will ride your next time out. If you are only going for short rides, you may go a week or more between charges. It is better for the battery to not be topped off to 100% all the time.
Can you ride an electric bike in the rain?
Yes, the components are ok in light rain. The bike should not be left out in a downpour or on a car with water drenching it from the car’s wheels. Never submerge a motor, battery, or electronic components or wash or rinse with a pressure washer.
How long do batteries last on electric bikes?
Batteries typically last many years. If charged to 100% they can take 300 to 500 full charge cycles before the capacity is reduced to 85% of its original capacity. If you charge it twice a week that will be 3 to 5 years. However, you get more partial charges than full charges and when your 3-500 full charges are used up the battery still has 85% capacity. If you have a smart charger that can charge to 80/90/100% you can extend that life to 1000 to 2000 full charge cycles.
Can I charge my ebike battery overnight?
It is not recommended to charge your battery unattended. If you charge to 100% you should ride your ebike right away to maximize battery life.
How much does it cost to charge an electric bike battery?
A typical 500-900 watt-hour battery will cost 10-20 cents to charge. (Compare that to a tank of gas!)
Can I damage a battery with incorrect use?
Keep partially charged. A low charge can damage cells. Full charge reduces life. Extreme temperatures reduce life.
Do I need to always charge it full?
A partial charge is better than a full charge for longevity.
Can I disrupt the charge cycle?
A partial charge causes no harm.
Should I use up all battery energy before charging?
No. Deep discharging wears the battery down.
Do I have to worry about battery “memory”?
No, There is no memory with Lithium-Ion.
How do I calibrate or balance the cells with a “smart” battery?
Charge to 100%. Repeat every 1–3 months.
How do I store my battery?
Store in a cool place partially charged.
Does the battery heat up on charge?
No, it should stay cool or slightly warm. If it gets hotter, you are charging too fast or it may be damaged and can be dangerous.
How do I charge when cold?
Do not charge below freezing. If it is below 32 degrees Fahrenheit take it indoors to charge.
Can I charge at hot temperatures?
Do not charge above 120°F (50°C).