I have an electric scooter running the following setup…3000W hub motor and ND72680 controller. If I open the throttle too much, the controller “shuts down” and output no power. I have to stop, turn off the scooter and start again. Also, some times, it is almost acting like a car with fuel starvation, where the scooter first have a “hiccup” before it goes. Any ideas as what could cause this?
Fardriver shut down when accelerating
- Thread starter NanFeiJsn
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Dui ni shuo de dui
100 kW
Switch on your lights. When the scooter cuts during acceleration do the lights stay on or does everything just shuts down?
If everything shuts down, which I assume is the case, it means that the battery is the cause, and more precisely the BMS.
What it means is that the BMS has cut power to protect your cells because they are not capable of delivering more current safely. So basically you are limited by your battery cells, the BMS is simply doing its job which is to cut power in order to save the battery.
Now you got two options:
-lower the power settings on your controller.
-buy a more powerful battery.
Another possible option is to cut down the weight drastically, but that's impractical most of the time.
@all Thanks for the advice...Regrettably, I didnt give you all the info, sorry! I am sure it is the batteries, since it is still the 72v 20Ah lead acid setup (but with new batteries) that the scooter came with. If I accelerate slowly and evenly, I can get +- 60km/h in 1st gear, 100km/h in 2nd gear, but as soon as I go to 3rd, the controller shuts off immediately. I suppose I can live with this, it was just a for fun project anyway and 100 km/h is really fast enough for me.
I recently saw these lithium batteries somewhere online. In size it is a one on one replacement for the lead acid ones I currently use...but I am a bit skeptical if it is real and I am not sure how they are managed. Not to mention the price...it would be nice though if it could work, then I dont need to modify the scooter frame.
Recently, another problem showed up, when the scooter is fully charged, and you brake hard (front or rear), the controller also shuts off. But after a while the problem goes away...so I am not sure I want to invest more time and money...which is a pity though, because the scooter is really pretty after the mods and paint job...
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E-Moto Tuner
10 W
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- Mar 20, 2022
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I saw those type of 12v lithium packs the other day as well and they were being used in a set of 6 for a 72v pack like the lead acids. Think they have a bms in each battery from what I read but not 100% sure as it wasn't clear from the info.
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When you still have regenerative bracking active, the controller tries to charge the battery during braking , the voltage of your lead accid battery rises and the over voltage protection from the controller is activated and you can only drive again after you came to a full stop.
You can shut off regenerative braking in the app.
You can shut off regenerative braking in the app.
Can you post a link for this battery? Thanks!
Dui ni shuo de dui
100 kW
Ok so the reason why your bike shuts off during acceleration is likely because your batteries are a bit too weak. When you accelerate the motor needs a lot of current from the battery. But due to the battery's internal resistance the total voltage will go down suddenly. Let's just take some random figures in order to illustrate: at rest, your battery voltage is around 78V, during light acceleration it sits around 72V and under full acceleration or close to max speed the voltage drops even further to 65V.
The problem is that your controller has a lower voltage limit, meaning it will cut power in case it sees the battery voltage going too low. This is usually set up in order to make sure you don't damage your battery by discharging it too much. In some case it's even a physical property of the controller, like some internal voltage regulators can't work properly under a given voltage. I will assume it's the first case as the second one usually occurs at much lower voltages.
Anyway, let's say that the minimum voltage set up in your controller is 67V. Then as you can see, it will run fine most of the time, but since the voltage will go down to 65V during full acceleration the controller will cut, because 65V is lower than the 67V limit.
Once it cuts power the battery voltage will instantly rise again back to 78V, so the controller sees that and re establish power back again.
This just keeps repeating until you lower your power requirement.
In order to confirm this, you can go in your controller's settings and try to set up the minimum voltage limit lower, to see how it affects the power cuts. If this solves the problem, then you should consider changing your battery.
I suggest not using these battery modules you've posted above. They do work, but they are quite low power and I really wouldn't trust them for long term reliability. I suggest you get a battery pack that is custom made for your purpose, this way it should last a whole lot longer and offer much better performance. There are plenty of battery manufacturers all around China so it shouldn't really be a problem to find one. It will be more expensive, but you'd rather spend more at first in order to get something reliable so you won't have to buy a new battery every year.
Dui ni shuo de dui
100 kW
This is the opposite issue of the one I described just above: this time it is the maximum voltage limit of your controller.
When you're braking, the motor is used as an alternator to recharge your battery. So this creates a voltage spike.
Let's use the same figures I used in the post above: at rest, with a battery 50% charged, your battery sits at 78V. But during braking, the voltage will increase to maybe 82V. Your controller maximum voltage limit has been set up to 84V (again, random figures to illustrate as I don't know your actual set up).
Now let's say you've just fully charged your bike to 100%. Now your battery resting voltage is not 78V but let's say 81V. You're using the brakes, the motor generates voltage and suddently the total voltage rises to 86V. Since 86V is higher than the 84V limit, the controller cuts the power in order to protect the battery and the other components. Now that the power is cut, the voltage goes back again to its resting voltage and the controller switches power back up again.
This keeps happening until your battery has been discharged a little further, then the battery voltage gets too low to trigger the limit.
Here you can change this setting in your controller to allow for a higher limit so it won't keep cutting. But don't put it too high as this is intended to protect the electronics from overvoltage. An overvoltage event can damage the controller, the dashboard or the 12V voltage converter.
Maybe you could share screenshots of what parameters are currently set up in the controller's app so we can check for you.
Mainly 72V20Ah battery too weak for the 3KW system, and if you have a bluetooth adapter and you can login Fardriver's APP to read out what happen,when the controller shut down, mostly should be like Dui said the voltage problems,then you can adjust the APP>Pro mode>Protect> Volt protect parameters. And suggest to limit the max line current and the Ratios in speed to run in a right speed range. And the life of the battery can be longer.
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