Replace 36 v battery by a 48v
- Thread starter Houbayida
- Start date
Making controller and display work across a wide range of voltages is cheap. Motors are different and their power output is maximised for running voltage. A 48V motor run at 36V will be less powerful, more expensive and heavier. Can't see why manufacturer would fit one to 36V bike.
Slaphappygamer
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The motor will operate at 48 volts. It may get hotter faster, which can create other issues. The bigger question is “Can the controller?”. You might want to check the capacitors of the controller. You mentioned 63 volts. In that case, a 48v will work. However, you’ll loose the low voltage cutoff feature, if the controller. LVC for a 36v controller is usually 30v. LVC for a 48 volt controller it is 40v. You wouldn’t want your 48v battery to be discharged to anything under 40v. With the 30v LVC of the current controller, you’d be relying on the LVC of the battery BMS. Hopefully the battery has a BMS. On the other side, max voltage for a 36v battery is about 42v. The max voltage for a 48v battery is around 54 volts. This means, having a higher voltage battery, you may induce an “Overcharge” error. So you’d have to play the game where you keep the 48 under 42v to avoid that situation. Very bad idea for a 48v battery. It will have a short life, and could be very dangerous.
If you want to use a 48v battery, it would be best to install a 48v controller/display combo. Be sure to get the controller and display as a bundle. They will be more likely to work with each other. Just know that if you go this route, you’ll be rewiring a few things at the controller, You are super lucky if you get anything plug and play. Truthfully, in the ebike world, not much is plug and play.
If you want to use a 48v battery, it would be best to install a 48v controller/display combo. Be sure to get the controller and display as a bundle. They will be more likely to work with each other. Just know that if you go this route, you’ll be rewiring a few things at the controller, You are super lucky if you get anything plug and play. Truthfully, in the ebike world, not much is plug and play.
harryS
Well-Known Member
Slaphappy covered all the tech issues. Little to add.
Let's see, a full charged 36V battery is 42V, which is right at the low voltage cutoff for a 48V battery. One downside is you will have no idea of your battery level, unless your display is dual voltage or shows voltage, While LVC for a 36V controller is 30-32V, your battery BMS will shut off well before this happens. While it still protects the battery, iI would rather not routinely run a battery til its LVC circuits trigger. Leads to unbalanced cells or shorter cell life.
Most of my bike controllers are dual voltage, so I find it convenient to mix batteries. You use lower current with higher voltage, and on a brushless motor, that's less heat in the connectors, wires, and motor provided you don't go nuts. If your bike doesn't have speed limiters, you typically get a 20% more speed boost at 48V over 36V. I never ride at max speed though.
Let's see, a full charged 36V battery is 42V, which is right at the low voltage cutoff for a 48V battery. One downside is you will have no idea of your battery level, unless your display is dual voltage or shows voltage, While LVC for a 36V controller is 30-32V, your battery BMS will shut off well before this happens. While it still protects the battery, iI would rather not routinely run a battery til its LVC circuits trigger. Leads to unbalanced cells or shorter cell life.
Most of my bike controllers are dual voltage, so I find it convenient to mix batteries. You use lower current with higher voltage, and on a brushless motor, that's less heat in the connectors, wires, and motor provided you don't go nuts. If your bike doesn't have speed limiters, you typically get a 20% more speed boost at 48V over 36V. I never ride at max speed though.
Houbayida
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- Europe
ok if I summarize:
- if I drive too quickly, I risk damaging the engine
- I won't know when my battery is discharged
- I risk damaging my battery
stevetug52
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I have a similar request. Mine is an older fat e-bike with 36V batt, controller and motor. I bought new battery and they shipped a 48V. Then bike shop said I needed a new controller/display kit which I purchased for about $40. Now the shop says the motor is not responding. They are trying a different motor "to make sure that is the problem." I am a novice e-bike owner. What say you more experienced guys out there?
stevetug52
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I followed your advice and purchased a 48V controller/display combo. Now bike shop says 36V 250W motor is not responding. Should I buy a new motor? If so, what do you recommend? And with 4" tires, do I need a "fat" motor?
Slaphappygamer
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Hi, I didn’t advise you to do anything to your bike. That post was not directed at you. You joined well after I posted that anyhow. It’s all good, though, just wanted to be clear.
So you have the bike now, or does the shop still have it? How are they engaging the motor? By throttle? You can also try walk mode. Usually you would hold the down arrow to activate walk mode. If you have the bike in hand, even better. Give walk mode a try?
Could also be a stuck brake sensor.
Was the bike running before you got the 48v battery?
So you have the bike now, or does the shop still have it? How are they engaging the motor? By throttle? You can also try walk mode. Usually you would hold the down arrow to activate walk mode. If you have the bike in hand, even better. Give walk mode a try?
Could also be a stuck brake sensor.
Was the bike running before you got the 48v battery?
stevetug52
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I understand and am not holding you accountable for the advice you gave someone else. It just seemed to be very similar to my problem and made sense to me. So no worries.
The bike is still at the shop. They haven't fully wired in the new controller, just the throttle. When they engage the new throttle, there is a sound inside the motor but it doesn't turn. Since the pedal assist isn't yet connected, I can't try walk mode. Should I ask them to complete all of the connections to the new controller and then try again before purchasing a replacement motor?
The bike is still at the shop. They haven't fully wired in the new controller, just the throttle. When they engage the new throttle, there is a sound inside the motor but it doesn't turn. Since the pedal assist isn't yet connected, I can't try walk mode. Should I ask them to complete all of the connections to the new controller and then try again before purchasing a replacement motor?
stevetug52
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Yes the bike was running well before the battery died.
Slaphappygamer
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There are many types/brands of controllers. Do you know what brand controller they installed? Or what model of display?
Depending on the controller, there MAY be a “self-learning” wire. The motor will make a sound if it is spinning in reverse. The wheel will stay in place. The self-learning wire will need to be connected LAST and can temporarily be connected so the controller can “learn” motor direction. Once everything has been connected, connect the “self-learning” wire. If the motor makes a sound, but no spinning wheel. Then, unplug the wire and reconnect. The wheel should now be spinning properly and you can disconnect the “self-learning” wire, as it is no longer needed.
If the controller does not have this “self-learning” wire, then trying to connect the motor hall phase wires will become a game. Not bad, just time consuming.
Please refer to the green, yellow, and blue phase wiring. Also note the diagram at the bottom right as that has more info on motor direction.
Depending on the controller, there MAY be a “self-learning” wire. The motor will make a sound if it is spinning in reverse. The wheel will stay in place. The self-learning wire will need to be connected LAST and can temporarily be connected so the controller can “learn” motor direction. Once everything has been connected, connect the “self-learning” wire. If the motor makes a sound, but no spinning wheel. Then, unplug the wire and reconnect. The wheel should now be spinning properly and you can disconnect the “self-learning” wire, as it is no longer needed.
If the controller does not have this “self-learning” wire, then trying to connect the motor hall phase wires will become a game. Not bad, just time consuming.
Please refer to the green, yellow, and blue phase wiring. Also note the diagram at the bottom right as that has more info on motor direction.
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stevetug52
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This is the controller I purchased. https://a.co/d/jfLQShc
stevetug52
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Thank you for this valuable information. I have sent your comments to the bike shop here. I'm in Mexico, so not sure how much they will understand.
Slaphappygamer
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That controller does have a “self-learning” wire. It’s the single green wire. One male side and one female end. Turn on the bike and try the throttle, if motor sounds but no movement, then connect the “self-learning” wire. Which seems to be the case with your bike.
CAUTION: The motor should start spinning when the “self-learning” wire is connected. Could be forwards or backwards. Be prepared for wheel AND pedal movement.
The “self-learning” works as an on off switch. Connect the wire and if no wheel movement, then unplug the “self-learning” wire and reconnect. The wheel should start to move in the proper direction. Then you disconnect the “self-learning” wire and tuck those wires away. This only need to be done once.
It could also be the default that throttle will only work AFTER pedal movement has been sensed. This is referred to as “non-zero start”. I would also try to pedal the bike and try the throttle again.
Regardless, the motor will be engaged when the “self-learning” wire is connected. Either forward or reverse.
CAUTION: The motor should start spinning when the “self-learning” wire is connected. Could be forwards or backwards. Be prepared for wheel AND pedal movement.
The “self-learning” works as an on off switch. Connect the wire and if no wheel movement, then unplug the “self-learning” wire and reconnect. The wheel should start to move in the proper direction. Then you disconnect the “self-learning” wire and tuck those wires away. This only need to be done once.
It could also be the default that throttle will only work AFTER pedal movement has been sensed. This is referred to as “non-zero start”. I would also try to pedal the bike and try the throttle again.
Regardless, the motor will be engaged when the “self-learning” wire is connected. Either forward or reverse.
stevetug52
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Wow! Thank you so much for sharing your time and knowledge. I translated your last message to Spanish and will do the same with this one. Hopefully Rogelio appreciates what he will have learned from you!
Slaphappygamer
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You’re welcome. I hope you get back in the saddle there soon.
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