E-bike & Battery FAQs

  • Posted on
  • By Ruda & Killian
  • 0

When you've spent as much time around E-bikes as we have, you answer all kinds of questions, from basic stuff to some real head-scratchers. We've gathered the greatest hits, including a bit of a down-the-rabbit-hole deep dive on Lithium Ion cells, including battery care and some common misconceptions.

How are eBikes regulated?  

 
The eBikes that we sell are categorized by Colorado state law into three classes. This categorization is the most common standard adopted by US States.
 
 

  • Class 1 eBikes, which are pedal-assist only (no throttle), and the electric assist stops at 20 miles per hour. 
  • Class 2 eBikes, which have a throttle (provides electrical power when the rider is pedaling or not), and are also governed at 20 mph.  
  • Class 3 ebikes, which provide power up to 28 mph. (Whether they have a throttle or not doesn’t matter).
  • Motors that provide assistance beyond 28 mph are not considered Electric Bicycles under Colorado law, and are treated as motor vehicles. 

 
 

Where are eBikes legal to ride? 

 
 

  • Class 1 and 2 eBikes can be ridden anywhere conventional bikes are legal, unless prohibited locally. Cities, counties, and other land owners have the last word. Always follow posted rules, but it’s also your responsibility to research and observe local ordinances, even if they’re not posted. 
  • Class 3 eBikes are limited to roads and bike lanes (referred to in the law as a ‘bike path within a street or highway’) or paths where permitted by local law.  
  • Just because eBikes are legal does not mean it’s OK to break laws that apply to everyone. The speed limit on Denver’s off-street multi-use paths is 15 mph. Always stay in control, and yield to other trail users (pedestrians and horses).  

 
 

What kind of range do eBikes have? 

 
 

Short answer: It varies, but anywhere from 20 to more than 60 miles on a full battery charge is common for batteries in the common 400 Wh size. 

 
Medium answer: The biggest factor is how much electric assist you’re using, and some systems (like STePS, Yamaha syncDrive, and Bosch) will change the estimated range that’s displayed when you switch between assist levels. The next-biggest factor is you--both the wattage you’re putting into the pedals and the terrain through which you ride the bike will significantly impact the amount of work the motor has to do. A number of smaller factors can also impact range, such as rider and cargo weight, operating temperature, headwinds, tire pressure, road surface, RPM (gear shifting), starts/stops, and battery condition. 

 
 

How do I take care of my eBike’s battery? 

 
 

Our most blunt advice is to get the most out of your eBike, whatever that means for you. You may have even purchased your bike specifically because of its range, so ride it and don’t sweat it. A quality lithium ion battery will prove reliable even if you regularly push its limits. That said, there are habits that, over hundreds and hundreds of charges, can extend or reduce your battery’s life. For more on this, please visit our Battery FAQs, which we gave their own page so that we could get a little geeky.  

 
 
 

Battery-Specific FAQs:

 
 

Why do bikes use Lithium Ion Batteries?

A few things make Lithium Ion batteries ideal for eBikes, until something better comes along: 

 
 

  • They have higher specific energy and energy density (energy per mass and volume, respectively) than other common battery types, both of which matter when it comes to making a sleek and lightweight eBike.  
  • They have a low self-discharge rate, so they’re ready when you are.  
  • They have no memory effect, meaning there’s no risk of losing capacity if the battery is repeatedly recharged after being only partially discharged. (More info on charging cycles and durability can be found below) 

 
 

 
 

Lithium Ion 

NiMH 

NiCd 

Lead Acid 

Specific Energy (Wh/kg) 

100-265 

60-120 

40-60 

33-42 

Energy density (Wh/L) 

250-700 

140-300 

50-150 

60-110 

Specific Power (W/kg) 

~250-340 

250-1000 

150 

180 

Cycle durability (cycles) 

400-1200 

180-2000 

2000 

<350 

Self-discharge (/month) 

2-4% 

30%  

15-20% 

4-6% 

 
  

 
 
 
 

How is my (Lithium Ion) Battery’s life affected by temperature: 

 
 

  • Temperature during use: Temperatures beyond the extremes of 15 to 140F (-10 to 60C) are very detrimental. Pushing a battery towards either temperature extreme is OK if you have to, but it will diminish a battery’s life more quickly than operating inside the optimal range of 40 to 70F (5 to 20C). Keep in mind that a dark battery case in direct sunlight can make a battery heat up to much more than the ambient air temperature.  

 
 

  • Temperature during storage: Optimal storage is 68F (20C), but 30 to 85F (0 to 30C) is OK, with one important exception, which is when the battery is at or near 100%. In this state of charge, increased battery temperature can cause excessive voltage, which  

 
 

  • Temperature during charging: This is a common question, and we’ve heard lots of misconceptions in this regard. Please see our answer to the next question: 

 
 
 

What’s the best way to charge (or not charge) my battery? 

 
 

Our most blunt advice is to get the most out of your eBike, whatever that means for you. You may have even purchased your bike specifically because of its range, so ride it and don’t sweat it. A quality lithium ion battery will prove reliable even if you regularly push its limits. That said, there are habits that, over hundreds and hundreds of charges, can extend or reduce your battery’s life: 

 
 

  • Partially charging a lithium ion battery between 20% and 80% is the best way to maintain its total capacity for as long as possible. This is different from the days of NiCad and NiMH batteries, when there was a risk of losing capacity if the battery was repeatedly recharged after being only partially discharged, but lithium ion batteries do not have a memory effect. Even though battery durability is often stated in terms of total charging cycles, it’s the stress of charging that degrades your battery’s capacity. When a battery is near the extremes of 0% or 100%, the charging process is far more lengthy and stressful than in the middle of its range. 

 
 

  • Running a battery all the way down (complete discharge) and recharging it fully will reduce your total amount of charge cycles, but will also mean that every charge cycle  goes through the two most stressful portions, which are 0 to 20% and 80 to 100%. It’s fine to do when you’re getting the most out of your bike and pushing the battery’s range, but if your routine allows it, partial charging will keep your battery’s stress levels low and capacity high. For example, if your commute is 20 miles one way, and your battery (on an average day) gets 40 miles on a complete charge, we’d recommend buying an extra charger to keep at work so that each one-way commute takes your battery between 80 and 30%. 

 
 

Some manufacturers recommend taking a battery through a complete charge and discharge cycle every 3 months or so. This is a method for recalibrating your estimated range, which your display unit calculates based on data that comes from the battery controller, and has nothing to do with resetting the battery’s memory effect (which is not an issue for lithium ion). 

 
 

  • Topping off a battery after each use has a couple of risks. The first is a reduced capacity over the life of the battery due to the repeated stress of charging past ~80%, which takes much longer than the rest of the charging cycle. The second is that batteries are much more vulnerable to heat damage when they are fully charged. In extreme cases, the excess voltage can be a battery killer. Topping off a battery when needed is always fine, especially if you’re careful with charging and storage temperatures. If, however, your situation allows you to take multiple short trips on a single charge, waiting until the battery is between 20 and 40% to top it back off can extend your battery’s life by reducing the overall number of charge cycles, and the amount of time spent charging near 100%.  

 
 
 

Can my battery's capacity be tested, and can cells be repaired if needed? 

 

Yep! If you have a Bosch, Shimano, Ebike Motion (Orbea and others) or Yamaha (Giant) system, we can check your battery's health through your bike's onboard diagnostics. If you have a battery from another brand, we can hook it up to our own diagnostic machine. This process takes 24-48 hours and requires a charger, but will also give a detailed analysis of your battery's condition. We can rebuild batteries if needed (we have the technology). Typical rebuilds run $300-500, and usually result in a battery that's better than new.  

Comments

Be the first to comment...

Leave a comment
* Your email address will not be published
* Required fields