Another battery question

Phildirt

New Member
I guess I wish I knew more about battery construction and design. I do read more about this all the time(Endless Sphere, etc.). My EM EVO 27.5 can be down to 1 bar of power and it takes about 4 to 5 hours to charge to full and I can ride it 10 miles and down 1 bar and it takes 3 to 4 hours for it to top off. I take it the performance of the battery is non linear, or is it that it just discharges at a different rate than it charges.
 

Ravi Kempaiah

Well-Known Member
I guess I wish I knew more about battery construction and design. I do read more about this all the time(Endless Sphere, etc.). My EM EVO 27.5 can be down to 1 bar of power and it takes about 4 to 5 hours to charge to full and I can ride it 10 miles and down 1 bar and it takes 3 to 4 hours for it to top off. I take it the performance of the battery is non linear, or is it that it just discharges at a different rate than it charges.

When it's down to 1 bar, the charger works based on voltage difference, it's called "Critical voltage- CV" charging.

When it reaches 90%, most chargers slow down and start "trickle charging" to avoid any damage. Its called " Critical current - CA" charging. Ideally, 90-95% charge will enhance your battery life.

Even then, it should only take 1-1.5 hours to charge back up from 1 bar down. (Although it's one bar down, it could mean 80% or 61% because each bar = 20%) 2.5 hours is reasonable if it was 61%
 

PowerMe

Well-Known Member
I experience the same charging time. If my battery is down to 1 bar (and just down to that bar from 2 bars) it takes up to 4+ hrs to charge the battery back up. This is why I don't think only having 1 battery is useful if the intent is to ride more than 35 mi at a time. Unless the rider is willing to wait in a coffee shop or can hang out somewhere for hours, waiting for that battery to get enough juice back to get home or the next destination does take longer than people realize.
 

Reddy Kilowatt

Well-Known Member
I'm with you PowerMe: two batteries ftw.
My Optibike Pioneer Allroad has two separate battery strength readouts: one is in the King LCD display on the dashboard and the second one is directly on the Battery. And for my money they're both wrong.
I fix Macs for a living and went to night school in electronics (a lifetime ago) so I know a thing or two about such matters, but the only way to learn a battery's behavior and performance is to spend time using it.
For example the bar-graph on the King Meter sags down to one bar on my commute back home from work. Then when I start pedaling above the motor's cutoff speed (and stop draining the battery) the display often jumps us to four (out of five) bars. Neither one is right.
But I have noticed that the bike will sink over 500 watts of current at the top of the battery's charge (riding in to work) and only makes the mid-400s (riding home from work. I think it's good for 25 miles but when I've gone 20, it feels pretty tuckered out
I could resolve this (non)issue by charging up at work; I do have a second charger there. Or, if I ever do a trip on the fat side of 20 miles, I could bring along my second, fully-charged battery.
That said, I have almost 1,000 miles on this whip and I'm still not really certain about the battery's personality. (Course I'm a little fuzzy about my own personality too, and I've got way over 1,000 miles on me.)
Allen
 

Ann M.

Well-Known Member
@Reddy Kilowatt , most battery gauges will display lower levels when under a load and thus are not actually providing battery level information unless riding on a flat surface or stopped. Even then, if that battery is aged it will still show 'full' but there's really less total amps, thus less range or power. That's where the more sophisticated consoles that display battery volts and amps are more accurate. With those types of readings it just takes some experience with the battery over time to recognize that a 36V Lithium pack sitting at 34V is really close to empty or fairly aged (just and example). A readout system like a Cycle Analyst or Watt's Up other similar data consoles really give a more complete picture of what's going on with the ebike's systems; however, those 1000 miles you talk about will give you pretty good picture just from experience (Kinda like life, no need to worry about being fuzzy!)