CHARGING AND CARING FOR YOUR LITHIUM-ION EBIKE BATTERY

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.
 

Radiant ebike battery in frame 

Ebike conversion battery

 
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:
  • The battery may be charged on or off the bike.
  • Plug the charger into the AC outlet first. If it has a switch, it should be switched on and then switched off.  Doing this will charge the charger’s internal capacitors and avoid an inrush of current from the battery.  
  • Next, plug the charger into the battery’s charge port and switch it on if it has a switch.  Most chargers will have a set of LED lights.  One of these will be red while charging and green when the battery is fully charged.  When the light is green, the charger is not charging the battery, and you should disconnect it.
  • The battery should not be near flammable items when charging.
  • Electrify Bike Co batteries with an on/off switch should be switched on before charging.
  • When the green light comes on, disconnect the charger.
  • Recharge your batteries when it has between 30% and 60% of its charge remaining.
  • A partial charge is better than a full charge for longevity
  • Do not charge below freezing or above 120°F (50°C)
  • Charge to 100% every 1–3 months

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.
 
Smart Charger with 80/90/100%             Advanced Charger with selectable charge
 
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.

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