Battery Degradation: Why Your E-Bike's Batteries Aren't Holding the Charge They Used To
Have you ever noticed that after about a year your electric bike battery doesn't keep the charge it used to when you first got it? Why does this happen?
This phenomenon is known as battery degradation and it's in all battery's nature to degrade over time. It's what they do.
No matter if they're single-use or rechargeable batteries, car batteries, e-bike batteries, or the battery in your phone, eventually the battery will loose its ability to store energy as much as it use to when you first started using it.
Well, there are a lot of factors that contribute to a battery’s degradation. Over time you won’t be able to use your electronics for as long as you use when you first purchased it because of the way its charged, its use, and how it's stored when it's not being used.
But before we dive in to the factors leading to your battery's degradation, we think it’s important to look inside your battery to figure out what keeps your favorite e-bike or scooter running.
What’s a battery and what is it made of?
By definition, a battery is a container that holds one or more cells that store chemicals which create chemical energy that’s then converted into electric energy and used as a source of power. Simply put, it’s a container that holds smaller containers of chemicals (cells) that are used to turn those chemicals into electric energy a device can use.
Battery cells contain chemicals necessary to give your scooter or e-bike energy, and depending on the type of chemicals and material used in the battery, benefits and challenges will vary from battery to battery. For example, silicon batteries have silicon in their cells, whereas lithium batteries have lithium cells in them.
Types of batteries
When you see “lead acid” or “silicon” in the front of the word “battery” it’s an indication of what their cells contain. Depending on what type of cells your battery have inside, you’ll have different experiences.
We work with three different types of batteries: lead acid, silicon, and lithium batteries
- Lithium Batteries: 1000 charge cycles, usually lasts 3-5 years*
- These batteries are the lightest batteries on the market. They have high energy density which means they store much more energy than others and are significantly lighter than others
- Silicon Batteries: 600 charge cycles, usually lasts 3-5 years*
- These batteries tend to be heavier than lithium batteries, but still contain material that can hold the best charge outside of a lithium battery. It also has high energy density for long use and life
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Lead Acid batteries: 400-500 cycles, usually lasts 2-3 years*
- These batteries are heavy, as they contain- in addition to metals and chemicals- lead. These batteries are a low energy density, but do last a good amount of time before their lifespan degrades dramatically
A battery’s efficiency isn’t measured in time (like years or months), but in charge cycles. When a battery loses its energy and is charged to 100% the battery has completed a full charge cycle, and a battery can only complete so many charge cycles before it starts to lose its efficiency to hold energy.
So what the heck is lowering the efficiency of my battery?!
Now that you know what’s going on inside of that battery and what you should expect out of it, let’s talk about how your battery will lose its efficiency, both with and without use.
Battery life- It might sound like a no brainer, but you’d be surprised how many riders don’t know the maximum charge cycles allowed by their battery. If your battery’s not getting the charge it used to consider how many times you’ve charged the battery and how long you’ve been using it
- Tip: Always make sure to use the right charger for your battery. Let it the battery cool down before plugging it in to the charger, and let the battery sit for a couple of minutes before plugging it back in to your bike
Self discharging- This happens when stored energy gradually escapes from the battery when it’s not charged or in use for long periods of time. Though this happens naturally, it can have severe consequences on the rest of your battery because of chemical reactions that occur when left unattended
- Tip: If you plan on not using your battery for an extended period of time (say over the winter), charge the battery once a month
Improper charging- You know how your battery will be at 40 or 50% and you say, “You know, I might as well charge my battery so I can have energy”; or you think, “80% is good enough” and pull the battery off the charger? Don’t.
The power reading you see is a reflection of the charge in the total of all cells, but not of every individual one. Improper charging (i.e. charging/discharging before you have to) will cause uneven cell replenishment, which means your cells won’t charge to completion, which will degrade the life you get out of the battery
- Tip: When you want to charge your battery, make sure it’s no higher than 5% and charged to 100% as often as possible
Strain on the battery- Another seemingly no-brainer, but the more you use the battery the more times you’ll need to charge it. The more times you charge your battery the more charge cycles you use, which means it’ll lose its efficiency faster than the casual user
- Tip: To get an idea of how much energy you’re going to be using, get an idea of the max weight it can hold, how well it does on hills and inclines, and what sort of drive the bike uses.
For example, say you’re 250lbs and your bike can handle 200lbs. The battery efficiency will go down right out of the gate; then factor in any hills and what your bike has to do to keep you moving, and you can get an idea of how long a charge should last and prepare you for degradation outside of the rated charging cycles.
Storage & Operation Temperatures- The fastest way to degrade a battery is by keeping it in or operating an e-bike outside of recommended temperatures. Keeping a battery in an area where it’s too hot, too cool, or fluctuates in temperature will degrade the material in your battery cells, which will then lead to poor battery performance and a low threshold for energy storage.
- Tip: Keep batteries away from heat sources and out of areas of high temperatures. Keep batteries stored in temperatures of 32°F and 68°F (0-20°C)
