Battery 30% / 43 V in 48 volt system...why sudden slowdown?

DonL

I have a scooter with a 600w motor 16 AH battery, peak 1250w. At 43 volts you’re supposed to have 30 % battery.

Why suddenly the motor slows down, even makes a grumbling or groveling sound, your speed is reduced, and the last bar flashes red when you push on the throttle too much.

I thought it could go down to 41, 40. I got 30 miles for today but I thought I’d get 40 since I had 18 at 48.5 volts. Which is supposed to be 60 % + battery.

What is that? Could I have gone a few more miles if needed?

Thanks!

justin

DonL

@duner nailed it. What scooter do you have?

duner

It’s common for scooters to slow down as the battery level drops. It’s more than just the expected drop in top speed due to voltage drop. They program in a safety cutoff where suddenly at a certain voltage the acceleration and top speed drops dramatically. To protect the battery.

For example, with my old Bird ES1-300 scooter, after it hits somewhere between 20-30% it puts you in ECO mode.

If you look at the Nami Burn-E video on this website, they talk about adjusting the settings to when the scooter puts your in ECO mode at the lower end of battery capacity, Though not all scooters have that. My Phantom has a controller cutoff voltage in the P-settings that does a similar thing and is adjustable.

DonL

Thanks but it’s not just a slowdown, the battery is almost out. Last bar is flashing red if you push the throttle too much, motor grinding, as if you were on your last mile or two. Even though at 43 V your’re supposed to be at 30% battery?

It behaves as if you’re about to stop.

I don’t have 10 miles remaining (even though I did 18.3 by the time it was at 48.5)

Thought I could get close to 40 in, with the same riding style….

duner

I still think what you’re noticing is by design. What scooter is it?

Range/power is not linear. So going from 54.6V (100%) down to 48.5V (60%) and 18.3miles, does not mean you’ll get another 18.3miles going down to 42V (20%).

When you draw 1200W peak, and your battery is full, that’s 1200W/54.6V = 22A draw from the battery.
When you’re at 48.5V, pulling that same 1200W means you’ll be drawing 1200W/48.5V = 25A from the battery.
At 43V, trying to pull 1200W means you’ll be drawing 1200W/43 = 28A from the battery.

So you can see that the lower the voltage, the faster your battery will drain if pulling the same watts. That’s why scooters limit output as the battery gets more depleted. Let’s say that your scooter has a 25A draw limit on the BMS and anything above that will cause it to throttle. So when you’re at 43V, you can travel slow, but as you push the throttle too much, the draw is too much and your BMS shuts down the output and your motor sounds like it’s dying.

There’s also the issue of voltage droop. The heavier the throttle, the more amps and drawn and the more the voltage droops. So at 43V, if you try and go full throttle, then the voltage might actually droop to 42 or 41V, at which point your BMS thinks the battery is dead.

Hope that makes sense.

Timotis

BMS - Everything you explain is a good thing - Its your BMS making sure you dont kill the battery!
Actually battery loose performace as the Volt decrease, you only notice it more as it drop below a certain % and also pending on what Watt output you have…..

Mandy

Think of the BMS as your scooter’s protective shield, protecting the battery from over-discharge. As the voltage starts to dip, it can result in diminishing power output, especially during those challenging climbs or when maximising the load of the scooter. The age and condition of your battery seriously impact its overall efficiency.

Plus the throttle response and your expected range are directly tied to these factors, which highlights how crucial it is to ride within safe limits.

Doing so not only prevents potential damage but also ensures your scooter remains reliable and ready for adventure for a long time to come. There are more things you need to know about charging your escooter.

Hiondsheings

As your battery discharges, the voltage decreases. At around 43 volts, your battery is likely at or near 30% capacity, which is a common threshold for many battery management systems (BMS) to start limiting performance to protect the battery.

Hiondsheings

If you had managed your throttle more conservatively as the voltage dropped, you might have eeked out a few more miles. However, pushing the throttle at lower voltages can lead to rapid performance degradation and potential battery damage.

Edited by slope game 1 day ago

charleswills