Batteries for electric bikes – The definitive guide.

Harley Davidson ebike
Harley Davidson ebike

Maintenance for your battery pack

Electric bike batteries can be more than 40% of the cost of your EV.  Care for your ebike  battery is an essential part of regular maintenance.  Extending the life of your battery by a year could be a huge saving in the running cost of the vehicle.

These notes are to help you get the best performance from your batteries and extend their useable life.

Managing the battery
All battery’s can be damaged easily.  Vibration, knocking, or dropping in some cases, can be fatal for an ebike battery.  Similarly, overheating (anything above 90o F) will degrade the life and performance of the battery.  Overcharging and an excessive discharge rates (such as a short circuit) are quick ways to reduce the life of a rechargeable battery.
ebike bottle battery
ebike bottle battery
Getting the best from your battery

To get the best from your battery pack you need to protect it from impact and vibration.  Literally handle them like eggs.  Keep your batteries as cool as possible. Charge the battery pack as often as you can, and keep it fully charged as much as possible.  All the above points are important while you also you need to ensure that your do not overcharge as this is a major factor in limiting battery life.

 

It sounds complex but a few useful tips and getting into a routine will make battery maintenance second nature.

Charging the battery

Remove the battery pack from the bike as little as possible. When charging the battery pack, follow the instructions that came with the charger, and turn the power off and remove the cord from the battery when the “battery charged” light comes on. Over-charging reduces battery capacity and shortens battery life.

Li-Ion battery on ebike
Li-Ion battery on ebike

Charge the battery pack immediately after each ride, the more you keep it “topped up” the better. If practical, take the charger with you and recharge the battery pack at your destination.

It does not matter if the pack is not fully charged, but it is good practice to keep it as ‘full’ as possible. 

Battery Myths

There is a myth that it is good for the batteries to be ‘fully discharged’ form time to time. This is incorrect. This concept comes from the early days of Nickel Cadmium batteries that required full discharging to help them maintain there capacity. The batteries in your power pack are not of this type. All modern batteries (including Lithium based batteries) are better off being topped up as often as possible, but remove from the charger once it is fully charged as over charging can cause over-heating.

Getting maximum performance from your Power Pack

A ‘smart’ charger is supplied with the battery.  Smart chargers reduce the current supplied to the pack as it approaches full. In addition, most Li-ION and NiMe batteries have protective circuitry inside which offers some protection to the battery from excessive or rapid discharge. Good battery maintenance, however, will extend the life of your battery.

Volt meter
Volt meter
Minimize power drain

Use as little power as possible, when riding the bike. It is far better to start off by pedaling and have the bike rolling before engaging the motor.  Pulling away from stationary without pedalling uses an enormous amount of power.

Note that this is not an option if a pedal sensor system is enable.  Electric bicycles with pedal sensors supply power a few seconds after you begin to pedal.

Charge the Power Pack as often as possible. Think of it as a water reservoir that will supply maximum pressure only when it is full.

Do not let the battery pack go flat. This is the worst thing you can do to your battery.

When the charger indicates the Power Pack is fully charged, switch off the charger as soon as you are able (see charging instructions below).

Over charging the batteries will cause overheating and, shorten the life of the Power Pack. 

Many riders put their battery on charge and leave it overnight or forget to remove the charger for several days.  A useful tip is to use an electric timer that will switch off after a pre set time.  8 hours is the maximum an ebike battery should be charged for.

CAUTION: If fitted with an “on/off switch, ensure that power is ‘off’ before connecting or disconnecting the charger. When connecting the Charger connect the Power Pack lead first. When disconnecting the Charger disconnect from the Power Point
How to extend battery life

First we should point out that batteries consist of multiple battery cells which are wired together to create the required voltage and power.  Proper maintenance will extend the life and charge of your battery.

Lead acid ebike battery
Lead acid ebike battery
Battery care process
  • 1. Connect the charging plug to the Power Pack then connect the other lead to the mains. Turn on the power.
  • 2. Once the charger indicates the batteries are charged, turn off the power.
  • 3. Let the battery rest for 20 minutes.
  • This is the part which is rarely explained by battery manufacturers or suppliers. To explain, let’s use an analogy: If you fill a bath with hot water, the temperature of the water near the tap is hotter than that at the far end of the bath.  If you don’t stir the bath, the water takes some time for the temperature to even out.  Of course the water near the tap eventually becomes cooler.   With batteries, something similar occurs. The charger is designed to sense when the correct Voltage of the batteries is reached.  The charger then switches to the ‘standby’ mode. (think of temperature in the analogy above).  Like the bath water, the Voltage of the batteries closest to the charger connections is higher than at the batteries furthest away. So, the battery (or batteries) needs to rest for a while to allow the charge to distribute evenly throughout the battery pack. This takes about 20 minutes.  
    • 4. After turning off the power, wait at least 20 minutes before turning the charger on again.
    NOTE: You will find the charger will indicate it is charging the battery pack again. Leave the charger on until it indicates the batteries are charged. Repeat this cycle until you get to a point where, after waiting 20 minutes and then turning the charger on, the charger indicates in only a few seconds that the power pack is fully charged. At this point, the batteries are now fully charged. Initially, this is a bit of a pain. I believe that this is why users are not made aware of the importance of this regime. By doing this, the life of the power pack is increased.  The capacity for the batteries to supply power will also increase. The good news is that you will find there is a pattern as to how the re-charging process behaves with your particular battery pack and charger so, once you get used to it, it becomes a matter of habit  
    • 5. Finally, connect the charger and go through the charging regime once a week when not using the bike. You actually need do this only once a month, but a weekly routine is easier to keep track of.
    Riding your ebike

    Plan your trip. You don’t want to run out of charge before you get home! Be aware that gauges presently available are inaccurate.

    ebike battery power indicator
    ebike battery power indicator
    Accurate battery guage

    Until you have an accurate battery gauge fitted to your bike you will need to rely on experience to know just how far you can go on one charge.

    Obviously the more you pedal, and by turning the power ‘off’ when rolling down hills, then the greater the travel distance will be. Hilly terrain and heavy rider can reduce distance.

    If you can, carry an extra battery pack or a charger with you so you can restore battery energy to extend your trip and battery life.
    When riding the bike, use only as much power as you need. Overpowering the motor causes excessive battery drain and more heat.

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    Steve
    Power Bicycle
    Power Bicycle
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