Uses more battery in the afternoon than in the morning?

[eappell]

I've been riding my Aventure (original) to work lately and I've found that it uses around 20% of the battery on the way in to work, but uses close to 40% on the way home. Same exact route, no major wind or changes to the weight on the bike. Any idea why it would use so much more battery in the afternoon? Thanks!

 

[Jeremy McCreary]

Welcome aboard!

Interesting correlation. Could it depend on the state of battery charge and only coincidentally on time of day?

Example: My display reports battery charge in percent with unknown accuracy. Generally keep the battery between 80% and 30%. But if I charge to, say, 95% before a long ride, I get many fewer miles out the first 20% (from 95% to 75%) than out of the next 20% (from 75% to 55%).

Consistently, and with 2 different 960 Wh Reention batteries on the same bike. Innate battery discharge behavior? Flawed charge level reporting? Who knows?

If you routinely leave work more charged than you leave home, could be a similar phenomenon. The correlation to time of day would then be spurious.

 

[Ben J]

I would guess that the battery management on the bike is just doing a poor job of reporting capacity. You probably use about the same watt hours each way.

 

[eappell]

Both interesting takes on what's happening. To clarify - I go from 100% (I charge each evening after I ride to work) to around 79% on the way to work. I do not charge at work. I then go from 79% to around 40% on the way home. Not sure about the time of day correlation...

 

[Art Deco]

Definitely different SOC (state of charge) not TOD ( time of day) as the kids say. Standard battery chemistry?
Some bikes use Lithium Iron with a more severe drop off.

 

[BlackHand]

2 things not addressed that affect battery usage a lot:

-How much climbing do you do each way? My battery usage is similar to yours and I have about twice as much climbing on my return route since my home is at a higher elevation than my work

-Starting and stopping. Do you deal with more traffic on the return? Constantly slowing down/stopping then accelerating can eat battery, so if you're dealing with rush hour one way but not the other way it can make a huge difference.

Also, what Jeremy said is correct. The % readout is not super accurate on most bikes

 

[eappell]

My entire route is fairly flat both ways. I would say my elevation in either direction is never more than about 10 feet. Most of the route is on bike paths, not in traffic or near cars. I spend about 60% of the ride on a canal next to a waterway that is completely empty, so I'm going full speed the whole time. I have no doubt the % readout is not accurate, but it's consistently the same to work and to home, and one is double the other. I'll probably never know the answer to this, but I thought I'd throw it out to see if anyone knew why. Thanks for the responses! Something to think about...

 

[rich c]

Lower end eBikes react differently when it has a full charge or partial. The controllers aren't high end computers and the curve they give you from the battery is not linear. Both the power feel and battery capacity are both non linear. Now a power system like Bosch does have a linear line. The first mile feels identical to the last mile.

 

[Roamers]

I've been riding my Aventure (original) to work lately and I've found that it uses around 20% of the battery on the way in to work, but uses close to 40% on the way home. Same exact route, no major wind or changes to the weight on the bike. Any idea why it would use so much more battery in the afternoon? Thanks!

Can you charge it at work and compare directions with full battery?

 

[eappell]

Can you charge it at work and compare directions with full battery?

Yeah, I can bring my charger to work with me tomorrow and charge it while I'm here. I'll post what the numbers are after my ride home tomorrow.

 

[keithj69]

Another questions/take.... What is the temp outside in the morning and what is the temp when you come home? Is the bike stored outside when it is at work?

 

[harryS]

Batteries are not linear. I've watched many differebnt lithium batteries discharge under load, either in "lab conditions" with load testers or riding on my ebikes. When they get halfway down on voltage, they've given more than half their capacity. I'd say getting another 30-35% before they shut off is typical,

 

[Jason Knight]

Batteries are not linear.

THIS. It's not like fuel in a gas tank. Was my first thought.

My second thought is temperature. If you've got extremes of 30F or more between AM and afternoon, that could be another 5-10% of difference. Batteries can deliver more power longer when kept cool. I know here in New Hampshire on a 55F morning I can go about 40 miles round trip on 60% of my charge in PAS3. That same afternoon in the mid '80's with a fresh battery the same trip uses closer to 70%.

Back when I was racing RC cars when everything was still using niCads, we used to keep the charged batteries in an ice chest to squeeze out a hair more performance.

My third thought is maybe it's NOT as level as you think. "fake horizon syndrome" and "gradual climbs you don't notice on foot or with power" are a thing.

There's a path near me where if you look at it, or walk it, you think it's level. It isn't. If you ride it on a normal bike, heading towards my home you get about halfway and your legs are burning and you start downshifting because it's a very gradual climb. But thanks to the trees and the fact that everything is slightly slanted (I'm in a valley), you can't SEE that you're going up a hill. It LOOKS flat. It isn't.

Kind of like the optical illusion that happens in some places where a car can look like it's on level terrain, but you leave it without the parking brake on it starts rolling away.

I'd pull up a USGS map or take some GPS altitude readings to see if it's really as flat or consistent as you think. It's very possible to climb two to three hundred feet or more over 20 miles or so and not FEEL like you've done so.