E-bikes and Batteries – how to buy.
Consider the following topics for choosing a battery. (table of contents)
- Distances you can ride (click here)
- How long will the battery last? 1 or 4+ years? (Chemistry and care) (click here)
- Safety: avoid the fires. (click here)
- So… which do I choose? (click here)
- See the full graphic description.
Questions? Please email us firstname.lastname@example.org
Distance: the places you’ll see
Battery size is like the gas tank.
Watt-hours (Wh) is the key to how far you ride on a charge.
You’ve likely heard of volts and watts, but the Watt-hour is key.
The secret decoder ring: you will see Volts (V) and Amp-hours (Ah). Multiply these to get Wh.
Energy Watt-hours (Wh) = V x Ah (volts times Amp-hours)
How far will it go?
E-bikes range 2-6 miles/100Whrs. Most of the variation depends on how much the rider assists, the wind speed, hills, and tire pressure.
It is deceiving to say a 48V will go father. When a battery is advertised as “48Volts” or “24Volts”, you need Ah (amp-hours) to figure the distance.
Many advertise “50 mile range”. This can be a true number or based on a “gentle” assist on a smooth surface with no wind. Be sure to compare “apples to apples” by finding the volts and amp-hours to see the real capacity.
* Measurements show that riders with e-bikes go about 3 to 8 miles using 100 Watt-hours. These measurements are made with 24V, 36V, and 48V systems. The math-magic is that measured distances can be compared “apples to apples” with watt-hours, a common basis for all systems.
The 3 mile range is for high-performance acceleration and higher speed bikes. The 8 mile range is for cruising the city streets on well inflated tires. Data is from websites like: electricbike.com/forum/
* Based on hundreds of rides, a Ridekick trailer goes about 6 to 8 miles using 100 Watt-hours. This includes rides “into a stiff wind”, up and down hills, hauling 50 pounds of groceries, as well as cruising downtown for dinner. Range will change depending on many factors noted on this website.
Safety don’t get burned!
Do all lithium batteries catch on fire?
*** In a nutshell, no. Not only is LiFePO4 very safe, it has longer life and holds more energy per pound (capacity) than the SLA
Images of e-bikes on fire and garages with flaming batteries leave an impression! There are plenty of YouTube videos streaming these events, and safety events with flaming hoverboards reinforce the need for safety.
There are very good and safe alternatives!
There are many types of “Lithium ion” batteries, so be sure to look at the chemistry label. Some are safer, and also notice a distinct difference in battery life!
LiFePO4. There is a growing list of lithium battery chemistry with various “flammability”, density, and weight. It turns out that LiFePO4 is a great fit. As shown in the comparative table, LiFePO4 is very safe and well-suited for high power (500Watts) use. The comparatively “low capacity” means that the physical size of the battery is a bit larger than other lithium types, but still very good and much higher capacity than SLA, and they fit comfortably in a Ridekick trailer.
How long will it last?
1 year or over 4?
*** Some Li-Ion batteries will last much longer! LiFePO4 is one of those.
Lithium batteries are rated by “Number of charge cycles” (Number of times the battery is fully used and recharged).
Do you want to ride your bike 4 times a week? 400 charging cycles will take you 2 years.
LiFePO4 and NMC are among the best. (See the chart above: LiFePO4 is 2000 cycles!)
SLA batteries are generally rated for 400 cycles.
This chart shows that batteries will last for more charge cycles if they are not discharged to the lowest level. So if you use a 20Ah battery and use only 10 to 15Ah before charging, it should deliver more than 2000 charge cycles!
How intensely it is used: using a battery at max power for long distances also diminishes the life. Max power is generally on long hill climbs or continuous riding into the wind. A larger capacity battery will handle the higher power better. Therefore, if you plan to ride a lot of hills, then get the larger battery for longer life.
Long term storage is an important factor. When not riding for 2-3 months, keep the battery in a place that is between 30F and 90F temperature. Also, keep it charged between L4-L8 for best results. Check it every 2 months, and don’t recharge if it’s above L7.
Which battery should I choose?
(A) If you are on a budget, and ride less than 8 miles per trip, the SLA will work quite well! More than half of Ridekick riders use the SLA with great satisfaction.
(B) Love riding farther? Got a few hills to ride over? The 20Ah LiFePO4 is a very rewarding upgrade. 480 Wh propels you 20-30 miles depending on your power, and it works better than SLA in colder weather.
(C) Long distance with hills? The 30Ah LiFePO4 is awesome. A couple 89 year-young riders ride with their group on long tours with confidence. If that’s not enough, some riders get two LR30s and ride all day long.