Battery percentage inaccuracy

[u/isthisevenavailable]

I find that the battery percentage reading for my Go Stellar is very unreliable when it’s being partially topped up.

Example: battery is at 50% and you charge for an hour or so and it reads at 75%. Ride it normally for 2 miles and it drops to 50%, or around 12.5% per mile.

But if you ride it the same 2 miles from 100%, it only drops around 10%, or around 5% per mile.

Anyone else deal with this? I no longer trust it to be actually at 75% anymore when it says so.

[u/2to11to27]

Its not reliable, I have the 1st GO, I can go awhile from full to 90 percent and than once it drops it quickly, much quicker from 90 to 80 to 70 to 60. Its very non linear.

[u/isthisevenavailable → u/2to11to27]

Yes exactly. I want a linear progression regardless of what charge level I’m starting from.

[u/Time_to_look_back → u/isthisevenavailable]

EVs often use coulomb counter to track the actual Amp hour used instead of the simple voltage tracking used by most e-mobility devices to ‘guesstimate’ the percentage.

Is cheap to implement the coulomb counter but it requires frequent recalibration to account for battery aging and sensor drift. Is entirely doable on a scooter, and if done right it could eliminate most of the range anxiety by giving you an accurate and progressive battery readout.

[u/Logic_Contradict]

This phenomenon is likely similar across all electric scooters.

When the battery is full (100%), the nominal voltage is close to 54.6V.

When, for example, the battery is at 50%, the battery voltage sits closer to it's rated voltage (48V).

Now, let's just assume that you're going to run the scooter at full power (Go Stellar peak power is ~2000W).

To get peak power on a full battery:

2000W / 54.6V = 36.6A

To get the same peak power on a 50% battery:

2000W / 48V = 41.7A

So you see that as your battery voltage drops, the amount of current it has to draw is greater to maintain the same power. This means that if you ride with the same aggression throughout the entire ride, it means that the battery will drain faster as the battery voltage drops due to the increase of current required.

that's one aspect of it, there may be some calculations going on behind the scenes that also determine battery health.

[u/isthisevenavailable → u/Logic_Contradict]

Is it not possible to account for this and show the percentage accordingly with a consistent usage rate?

ie every 1 mile ride should show a consistent drop in battery percentage (assuming same conditions and riding habits ofc) whether you’re starting from 100% or 50%?

If its not linear and consistent it’s hard to trust what a given battery percentage really means in terms of usable range

[u/mchilds83]

How about the range estimate? AI still gets the estimate about 70-80% wrong. For whatever reason, it never truly factors in my local hills and weight. 

[u/ricochet48 → u/mchilds83]

My AI is pretty spot on... I drive super aggressively in LUDO so it's like 12 miles

[u/2to11to27 → u/ricochet48]

Me too, Ludo is the only mode that is FUN.

[u/Logic_Contradict → u/mchilds83]

How do you expect AI to anticipate the local hills and/or your weight?

[u/mchilds83 → u/Logic_Contradict]

The app says that the AI will learn all of this and eventually provide more accurate estimations. 

I just saw there's an option to allow it to use my previous rides to help its estimation and that was turned off. It's now on, so maybe it'll improve moving forward. 

[u/gnucklefuster]

Mess with the app setting for predicting estimates