The battery for your electric bike is typically worth about a third of the value of the entire bicycle, so it’s important to find a good quality one and take care of it.
In the case of Pedego Canada, we offer a 2 Year Full Replacement Battery Warranty with all our electric bikes, which is one of the best in the business. Why we’re so confident in our batteries is the quality of the cells within them. If you take nothing else away from this post, remember this: do not buy an electric bike with anything less than a two year battery warranty and do your best to purchase a battery by one of the “big three” name-brand cells: Samsung, Panasonic or Sony. Cheap electric bicycles like the kind you find at Costco do not have the quality of manufacturing or warranty that will ensure you can enjoy the bike for years. It’s our recommendation that you spend a bit more money up front to save you from headaches (or worse – the garbage dump) later.
No matter what electric bike you buy nowadays, chances are it runs on a lithium-based battery. (There may be a few brands still using lead-acid batteries, but these tend to be heavier and their range isn’t as extensive.) Believe it or not lithium batteries have been around since 1912 but it’s only been in the last 15 years that they caught on and became economical in consumer applications. There are “lithium-ion” batteries and “lithium polymer” (aka “lithium-ion polymer”) batteries and the difference between them is the type of electrolyte used. Other than that, there isn’t a significant variance: Li-Polymer allows for a slight increase in energy density but is 10-30% more expensive and so manufacturers have yet to decide upon one over the other.
There is also a range of lithium chemistries available in different batteries and manufacturers might claim some are more robust than others but the single most important factor affecting the life of a battery is how well it is looked after. You should typically expect a battery to last between 3 and 5 years if it is well maintained. (A lithium battery will slowly lose its capacity over time, even if it’s not used.) Below are three things you can do to ensure you get the longest usage out of your electric bike battery.
#1. Keep The Battery Cool
Environmental conditions are an important factor affecting lithium batteries. For example, leaving one in your car in the hot sun will guarantee you lessen the life of your battery. In fact, that would be the worst situation: keeping a fully charged battery at elevated temperatures. It’s a good rule of thumb to store your bike out of the direct sunlight for long periods and when not in use, keep your battery in a cool place, preferably below 20°C (68°F). The chart below, provided by Battery University, shows the impacts of temperature upon recoverable capacity of a battery.
#2. Store A Battery Partially Charged – But Not Too Low!
You’ll also notice in the above chart that storing a fully-charged battery has an impact on the recoverable capacity. Even more important, storing a fully depleted battery may be disastrous because, as we mentioned above, a lithium-ion battery will slowly discharge over time even when you’re not using it. If the voltage drops below a certain point this may cause irreparable cell damage, depending on the time it’s left sitting. Ideally, when storing the battery for a long period ensure it has less than 100% charge (5 bars, if you have an indicator on your battery) but more than 40% (2 bars). Some chargers have a lower ‘storage’ voltage setting, so just switch to this before charging it for storage. An easy alternative is to take the bike for a short ride after you’ve charged it fully and before storing.
If you’re forced to store the battery for prolonged periods of time, make sure to check your battery every couple of months. If you notice that the battery indicator has dropped to one or two lights (out of five) give it a bit of a charge. If you don’t have a battery indicator, it’s probably a good idea to charge the battery for a half hour or so every few months. Again, try not to put the battery away fully charged (but it won’t be the end of the world if this happens.)
#3. Don’t Regularly Fully Discharge Your Battery
It’s amazing that we still see tech sites advising regular full discharge of your battery, even when this has been proven as detrimental. The chart below, again provided by Battery University, proves that regularly discharging lithium-ion batteries to 0% is harmful and partial discharges with regular top-ups are recommended to extend the recharge-cycle lifespan of the batteries. The occasional full discharge on that extra long ride is no problem! If you are doing very short rides on a regular basis, it is slightly better to charge it every few rides rather than every ride.
Correct maintenance and storage of your battery as detailed above will significantly increase its lifespan. A well-maintained lithium battery will last between three to five years, whereas a poorly maintained battery can be badly damaged over just one season or sooner. For more detailed, scientific information on batteries and how to care for them, check out the excellent online resource at Battery University, where the above charts came from.