My bike: 26” fat tire converted from 36v to 48v. 2 batteries connected with a 30A balancer, 22A 500W controller, 750w peak motor. The controller and motor were bought off Amazon, and it’s understood that you get what you get. There are some steep hills where I ride, including one lung burner. I have watched bikes and a skateboard fly up this thing seemingly effortlessly and they no doubt have more robust setups than I do. It takes some effort for me, which is understandable. As far as my bike, PAS 4 and 5 really do nothing for me except add some speed on level surfaces. It’s almost like I lose power on hills in PAS 4 and 5. Like putting your car in 5th gear on a hill. If I do try to use 4 or 5 on a hill, the bike will lose power, even if I go to a lower PAS. It has a little recovery period, then I regain normal power. I suspect that either a temp sensor or amp fail safe gets triggered in the batteries, controller, or motor. However, nothing seems overly warm. I have read that batteries have such a fail safe and if you disconnect the batteries from the controller it will reset. I haven’t tried that, it kind of defeats the purpose of the odometer because it will reset. I do not think this is correctable, but I don’t want to smoke my bike either, so any insight is appreciated. Does this happen to you?
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Bike temporarily loses power, and so do I
- Thread starter Scott000
- Start date
docw009
Minor legend
Description suggests weak or old batteries. Maybe they are too small. Can you give details?
Good point, thanks. Batteries are fairly new, 48v 14ah X2. They charge up fine, and take nearly the same amount of time. But again, sometimes you get what you get. These are the standard frame mount type. I have the second one in a rack pack. I have read where the load takes the battery voltage down to a point where a safety kicks in. And some say that they need to be balanced by leaving them on the charger for long periods. Frankly, I’m not sure all BMSs will balance.
This is true. And that brings up the need to get more information on the batteries. Where from? What cost (not always the only good indicator of quality but usually a good clue)? What cells are they made of? Any more info from the vendor? (They might have described cell balancing sessions in the users manual?)
Does or can the display show battery voltage? Can you observe the voltage when under heavy load? Is it sagging badly?
docw009
Minor legend
Got a link to the batteries? Some sellers will lie about specs, but a 48V14AH battery is probably a 52 cell pack that uses 3500 mah cells. The arrangement would be 13 groups with 4 cells per group, Full throttle would pull 20-22 amps, and that works out to 5 amps per cell. which is not hard to do with average cells.
The battery's protection circuit is called a BMS for battery management. It monitors atthe cell voltage level, and is typically set to shut off the battery under 3V/cell, With 13 series groups, that would mean the total battery voltage is 39 volts. Your ebike controller will shut off the bike based on the total battery voltage. That's usually set around 40-42 volts,
How about you run the bike on one battery and take off the blender. The blender is basically two power diodes, or two big transistors if they spend a little nore money. I could see where they degrade with heat and start dropping a few volts inside the blender. Fools your bike into shutting off early. It doesn't make sense that two batteries go bad at the same time.
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The battery's protection circuit is called a BMS for battery management. It monitors atthe cell voltage level, and is typically set to shut off the battery under 3V/cell, With 13 series groups, that would mean the total battery voltage is 39 volts. Your ebike controller will shut off the bike based on the total battery voltage. That's usually set around 40-42 volts,
How about you run the bike on one battery and take off the blender. The blender is basically two power diodes, or two big transistors if they spend a little nore money. I could see where they degrade with heat and start dropping a few volts inside the blender. Fools your bike into shutting off early. It doesn't make sense that two batteries go bad at the same time.
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Here are the batteries, they are 15ah: LGECOLFP 48v 15ah 30amp BMS for 250-1000w motor. They were about $200 each. I’m sure they aren’t top notch but frame mounts are somewhat cheaper than specialty. They are one year old and I have about 400 miles on them. There wasn’t a users manual other than for the charger. I put a new display on the bike and it shows voltage. I need to go see what kind of drop I get. I didn’t think of that…
I have wondered about the blender. Not that it’s doing anything, but just how it does what it does. I can take it off. I basically use it so I can go the whole trip on the odometer.
I have wondered about the blender. Not that it’s doing anything, but just how it does what it does. I can take it off. I basically use it so I can go the whole trip on the odometer.
Figured as such.
If you cannot detect any significant heat in your motor or battery after the hardest of use cases, this is your limiting factor.
These cheap amazon controllers have no documentation and typically no tunability. No company stays in business long enough for anyone to document them or bother learning them.
You should buy a programmable controller so that you can adjust the power to your use case because factory controller programming is impossible to get right when the user could put whatever motor on it they like. The controller must be tuned around the motor's capabilities and your use case.
Diagnosing battery performance problems involves a numerical readout of the battery voltage instead of a set of bars. This can show you precisely how much voltage the battery is dropping under load. You could also use a better screen that allows you this view.
If you cannot detect any significant heat in your motor or battery after the hardest of use cases, this is your limiting factor.
These cheap amazon controllers have no documentation and typically no tunability. No company stays in business long enough for anyone to document them or bother learning them.
You should buy a programmable controller so that you can adjust the power to your use case because factory controller programming is impossible to get right when the user could put whatever motor on it they like. The controller must be tuned around the motor's capabilities and your use case.
Diagnosing battery performance problems involves a numerical readout of the battery voltage instead of a set of bars. This can show you precisely how much voltage the battery is dropping under load. You could also use a better screen that allows you this view.
Nix Liou
Regular
Batteries at that price point have an expected lifespan of 6 months to a year often, because of sub par cells and often no balancing. Sometimes they can last longer though, and I don't know this one specifically.
Yeah, I know this isn’t a hard core bike. It does have a numerical voltage readout so I can at least check that. It could well be that I have more than one component contributing. If I knew it was the batteries or the motor, I wouldn’t even bother. But I wouldn’t mind trying a programmable controller. Do you have any links for one that may work?
Okay, if you have a numerical display of the voltage then..
You could tell if it's the battery if the voltage drop is proportional to the amount of speed lost.
If you are getting weak power and your battery is dropping voltage a a lot, then we could probably blame the battery. More than 4 volts of drop is considered bad.
If that's not the case, the controller is not feeding enough battery or phase amps to the motor for your liking, and the battery can handle more.
For programmable controllers, i like VESCs but they're pretty nerdy. Phaserunners are nice because they're more newbie friendly. But i'm not a fan of hteir low power limits.
Here's some suggestions for programmable controllers:
Successor to 1-3kw programmable infineon clone controllers?
You could tell if it's the battery if the voltage drop is proportional to the amount of speed lost.
If you are getting weak power and your battery is dropping voltage a a lot, then we could probably blame the battery. More than 4 volts of drop is considered bad.
If that's not the case, the controller is not feeding enough battery or phase amps to the motor for your liking, and the battery can handle more.
For programmable controllers, i like VESCs but they're pretty nerdy. Phaserunners are nice because they're more newbie friendly. But i'm not a fan of hteir low power limits.
Here's some suggestions for programmable controllers:
Successor to 1-3kw programmable infineon clone controllers?
docw009
Minor legend
LGECOLFP is a cheap battery, If the battery can sell for $189 with free shipping, a rule of thumb is the seller paid around 90 bucks.
Even though it's cheap, when new, the battery should still move the bike along at 24 mph on flat ground.What's top speed on the display with the rear wheel off the ground?
Even though it's cheap, when new, the battery should still move the bike along at 24 mph on flat ground.What's top speed on the display with the rear wheel off the ground?
docw009
Minor legend
How about you talk about the motor you bought on amazon.
I assumed it was the typical bafang type geared G60 or a clone, Good hill climbing, in my opinion. Maybe you bought a direct drive motor, since your unloaded speeds are over 30 mph. I believe the direct drives need big battery amps to climb.
I assumed it was the typical bafang type geared G60 or a clone, Good hill climbing, in my opinion. Maybe you bought a direct drive motor, since your unloaded speeds are over 30 mph. I believe the direct drives need big battery amps to climb.
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