Care and Feeding of your E-Assist Battery

It’s starting to snow here in Upstate New York, so I thought a refresher in proper care of your e-bike battery was in order.  Batteries cost from $500 and up so I’ll also include some longevity tips that I’ve gleaned off the internet.

The first thing you can do is protect your battery from extreme heat and cold.  Remove the battery from your trike or bike and bring it somewhere heated and dry.  Best thing to do is keep it inside between 50-75°F at a charge level from 50% to 75%.  It should go around three months without you having to do a thing.  There is usually a button on the battery to push that shows charge level, push it after three months and if it’s still between half and ¾ then it’s fine. 

On some systems the battery goes into sleep mode and may need to be plugged into the charger to “wake” the battery up so you can get the charge level reading.  Something NOT to do is to take a battery that you left in the cold and connect it to a charger before letting it get to room temperature.  Same for a battery that accidentally was left in the sun on a hot day or in a car trunk, that’s a big no-no.  Like burn up the car kind of no-no.

I was surprised to learn that charging a lithium-ion battery to full charge and leaving it at full charge for an extended period (days) without using it decreases battery life over time.  I’m used to trickle charging my lead-acid motorcycle battery over winter by just leaving it plugged in.  I also leave my laptop plugged in and rarely take it off the charger and that IS a lithium-ion battery.  Same with a cell phone battery but they get used everyday so probably not a problem.  By longest life I mean how many charge cycles the battery can take without seriously shortening the run time of the gadget the battery is plugged into. 

After looking at the studies from battery companies and other resources, it looks like you can get up to a third more life by charging to 75% of max instead of going to 100% every time.  That just seems un-American not filling up the tank for maximum distance but if you look at it over time it will pay off in more overall distance per battery over its usable lifetime.

On a Bosch battery, there are five LED lights which equal a 20% charge per light.  When charging, the solid lights are the charge level and the blinking one is what it’s working on currently.  It takes two hours to get to 50% charge and 4.5 to get to 100%. 

A Shimano STEPS battery has five LED lights that work in the same manor and takes two hours to get to 80% and four hours to get to 100%.  Leaving it on the charger overnight probably isn’t the best idea for battery longevity.  What some people do is get an electrical cord with a timer built in that turns off the power so they can set it and forget it.  The really tricky people figure out about how much charge is left in their battery after a typical ride and then come up with a fudge factor for how long to charge the battery.  Say it’s showing one light on the battery, so a 20% charge is left.  One and a half or two hours should get them to around 75% which would give them a longer overall battery lifetime. 

Personally, I probably would just charge to 100% each time because I have other things to worry about than getting maximum life from my battery.  You are not doing anything wrong by charging to full each time, you just aren’t milking the battery for every last drop.  The big thing to take from this article is to get your battery inside somewhere room temperature that is dry (not the damp basement) and check the battery level in three months. 

Put it on the calendar for March, maybe bring your trike in for a tune up at that time to beat the first nice day rush.  If you want to go for a winter ride, pick a day in the 30’s and install the battery just when you are leaving.  You won’t get the range you would in the summer, but at least you got outside.  Just make sure to clean the road spray off your frame and chain so the salt doesn’t rust them and bring the battery back inside.  Then have some hot chocolate and a well deserved long winters nap.   

December 7, 2019 |