How to use a 60v battery pack on 48v motor

[Ahmed-aomk2000]

Hello everyone ,
I have a 60v battery pack and I wanted to use it on a 48v motor without burning the motor. What options do i have? How can i step it down? will it burn the motor in the first place?
The motor I was looking at is this one https://www.ebay.com/p/48v-Rear-Wheel-Electric-Bicycle-E-Bike-Motor-Conversion-Kit-1000w-Hub-LCD-Meter/1680585473
Many thanks and much appreciated

 

[wesnewell]

The motor doesn't matter. It all depends on the controllers max voltage limit. Most with an lcd display are limited to 60V max by the display and 63V max by the controller. You need to know the max voltage charge of your 60V pack to determine if it will work with your setup. What's the specs on the pack? At worst, you will need a new controller, but if max charge is 60V, then it will work fine without a problem.

 

[fechter]

+1
It's the controller you need to worry about more than the motor. If the controller and battery are too big, yes there would be some chance of cooking the motor. The controller needs to handle the peak pack voltage and needs to have a current limit in the right range for the motor. Many are programmable.

 

[Sunder]

I'd like to add to this. While what they say above is true, cooking the motor still is a serious concern, because motors are usually most efficient just below their no-load speed. By increasing the voltage, you are increasing the no load speed.

So if the motor was wound to drive you at, (for ease of calculation), 48km/h @ 48v, then at 60v, the no load speed would be 60km/h. To most people, this would sound good so far.

But let's say your normal loaded speed is 40km/h, or 83% of your no load speed. This would be near the most efficient band of your motor, and you would be wasting about 10-15% of your energy as heat.

If you still cruised at 40km/h on a 60v battery, you could be at 66% of your no load speed. This is near the efficiency cliff, so you'd probably be burning up ~20-25% of your energy has heat. Below about 50% of no load speed, efficiency drops like a rock. This will raise the temperature of your motor. This means when you go up a hill and slow down even more, you have less buffer to sink the heat into (not to mention the decrease in efficiency is even higher at those loads).

Best bet is always to design properly. If you can't afford that, you'll want to do a lot of testing and monitoring when it's not critical (I.e. on weekends, not on your way to work). Push it 20-30% harder than you think you otherwise would in a daily situation. Carry extra weights, go up steeper hills, wait for a warmer day, etc.

 

[Ahmed-aomk2000]

Thanks for the replies appreciated it heaps

 

[tanstaafl]

I will start by admitting my ignorance, but this doesn't sound right. Doesn't a controller use PWM (through some decent sized capacitors) to vary the effective voltage sent to the motor? Unless you're actually going faster, seems there should be no effect of a higher voltage battery pack past the controller? Of course, you have to have a controller that can handle the input voltage.

I'd like to add to this. While what they say above is true, cooking the motor still is a serious concern, because motors are usually most efficient just below their no-load speed. By increasing the voltage, you are increasing the no load speed.

So if the motor was wound to drive you at, (for ease of calculation), 48km/h @ 48v, then at 60v, the no load speed would be 60km/h. To most people, this would sound good so far.

But let's say your normal loaded speed is 40km/h, or 83% of your no load speed. This would be near the most efficient band of your motor, and you would be wasting about 10-15% of your energy as heat.

If you still cruised at 40km/h on a 60v battery, you could be at 66% of your no load speed. This is near the efficiency cliff, so you'd probably be burning up ~20-25% of your energy has heat. Below about 50% of no load speed, efficiency drops like a rock. This will raise the temperature of your motor. This means when you go up a hill and slow down even more, you have less buffer to sink the heat into (not to mention the decrease in efficiency is even higher at those loads).

Best bet is always to design properly. If you can't afford that, you'll want to do a lot of testing and monitoring when it's not critical (I.e. on weekends, not on your way to work). Push it 20-30% harder than you think you otherwise would in a daily situation. Carry extra weights, go up steeper hills, wait for a warmer day, etc.

 

[Sunder]

When PWM is on 100% duty cycle, the effective voltage is the battery voltage.

If your cruising speed is limited by the power delivered to the wheel, and not by the no load speed or the throttle, then what I described is correct. Gowever you are right, if the cruising speed was arbitrarily self imposed by the throttle, then it won't be all that inefficient.

 

[tiny_n_terrible]

I changed the 63 volt caps in the controller to 100 volt caps.
I found out that I can only charge the 14 s nissan leaf cells to 15.20 volt . Any higher the overvolt protection in the 48 volt Yescoma controller shuts Down.
I felt so stupid when that happened the first time. I Full charged batteries and no Electric bicycle gooodness!!!

 

[dogman dan]

My experience is those type motors can handle a lot more than 1000w, 48v 20 amps controller. But about 3000w is the practical upper limit. At that point, you can and will melt the halls at least, if not the whole motor. But the motor can still stand it for a limited time. like about 30 min, or ten miles at full speed. Less time in the hottest summer weather of course, I used to run 1500w all summer, then switch to 3000w when it started to freeze at night. In the spring,, I tended to run 3000w till I melted a motor, then swap in a spare and turn it down. :lol:

If you end up going that far, vent the side covers. Lots of debate about how effective this is, but for sure, once you stop, a sealed motor will spike even hotter, while a vented one will cool off fairly quick.

Also, you can know when to stop on the vented motor, by the smell, if you pause long enough to take a whiff. Hot varnish smells semi sweet, while like toast, you can smell it when it gets to burning. Totally different aroma.

 

[999zip999]

What battery ? It must match the controller demands.

 

[AfdhalAtiffTan]

My experience is those type motors can handle a lot more than 1000w, 48v 20 amps controller. But about 3000w is the practical upper limit. At that point, you can and will melt the halls at least, if not the whole motor. But the motor can still stand it for a limited time. like about 30 min, or ten miles at full speed. Less time in the hottest summer weather of course, I used to run 1500w all summer, then switch to 3000w when it started to freeze at night. In the spring,, I tended to run 3000w till I melted a motor, then swap in a spare and turn it down. :lol:

If you end up going that far, vent the side covers. Lots of debate about how effective this is, but for sure, once you stop, a sealed motor will spike even hotter, while a vented one will cool off fairly quick.

Also, you can know when to stop on the vented motor, by the smell, if you pause long enough to take a whiff. Hot varnish smells semi sweet, while like toast, you can smell it when it gets to burning. Totally different aroma.

Wow, what controller did you used? I own a 1000W 48V hub motor kit too, but the included controller uses 70V mosfets.

 

[dogman dan]

At that time, I was running a 72v 40 amps controller, for 3000w. So I ran 72v year round.

 

[AfdhalAtiffTan]

At that time, I was running a 72v 40 amps controller, for 3000w. So I ran 72v year round.

Thank you for your reply

 

[999zip999]

We need to know the battery. ? Everthing.

 

[999zip999]

Here is a cheap controller and thead.https://endless-sphere.com/forums/viewtopic.php?f=2&t=71128. I haven't use these controller but is cheap. If your battery can support it ?

 

[cycleops612]

I'd like to add to this. While what they say above is true, cooking the motor still is a serious concern, because motors are usually most efficient just below their no-load speed. By increasing the voltage, you are increasing the no load speed.

So if the motor was wound to drive you at, (for ease of calculation), 48km/h @ 48v, then at 60v, the no load speed would be 60km/h. To most people, this would sound good so far.

But let's say your normal loaded speed is 40km/h, or 83% of your no load speed. This would be near the most efficient band of your motor, and you would be wasting about 10-15% of your energy as heat.

If you still cruised at 40km/h on a 60v battery, you could be at 66% of your no load speed. This is near the efficiency cliff, so you'd probably be burning up ~20-25% of your energy has heat. Below about 50% of no load speed, efficiency drops like a rock. This will raise the temperature of your motor. This means when you go up a hill and slow down even more, you have less buffer to sink the heat into (not to mention the decrease in efficiency is even higher at those loads).

Best bet is always to design properly. If you can't afford that, you'll want to do a lot of testing and monitoring when it's not critical (I.e. on weekends, not on your way to work). Push it 20-30% harder than you think you otherwise would in a daily situation. Carry extra weights, go up steeper hills, wait for a warmer day, etc.

You put powerful arguments for a mid-drive.

Why not a vehicle that fits my needs, whatever they may be, now and in the future, even if i move to denver? Its what most would expect of a car e.g.

The reality is, the other flipsides of poor efficiency, are also, bigger heavier dearer batteries for an equal result.

In this case, the OP can gear for optimum rpm, whatever the voltage.

 

[Ahmed-aomk2000]

Hi, So i bought a whole heap of cordless tool batteries from my local store. They are 20 volts each with 2.ah

 

[The Battery Doctor]

Install a new red discharge wire on the 13th positive cell and disconnect, remove or leave the remaining cells. Now you have 48V =)

The charging is trickier, you would have to charge them separately, maby even exchange the BMS in the long run.

If you want to use all the remaining cells a "dc to dc converter 60V to 48V" would do just that. However they are hard to get for that voltage and high amps.

 

[zackclark70]

if your controller can take 60v it will be fine just keep an eye on motor temps and avoid WOT if you find it gets hot

 

[999zip999]

It's. Best to have one big battery. A bunch of tool packs spaghetti string together ? A battery need to be balance all cells same voltage and capacity.

 

[alan0048]

When PWM is on 100% duty cycle, the effective voltage is the battery voltage.

If your cruising speed is limited by the power delivered to the wheel, and not by the no load speed or the throttle, then what I described is correct. Gowever you are right, if the cruising speed was arbitrarily self imposed by the throttle, then it won't be all that inefficient.

Old reply but still relevant for me. I just need you to clarify this bit for me.

Are you saying that if the cruising speed is limited by the throttle and not by some current limiter mode. Then there is no inefficiency ----> heat to worry about going from 48V to 60V?

Because most displays can both control the max speed and max current. Are there any difference between both modes when it comes to lower speeds and inefficiency?

 

[puddle]

Old reply but still relevant for me. I just need you to clarify this bit for me.

Are you saying that if the cruising speed is limited by the throttle and not by some current limiter mode. Then there is no inefficiency ----> heat to worry about going from 48V to 60V?

Because most displays can both control the max speed and max current. Are there any difference between both modes when it comes to lower speeds and inefficiency?

Yet again, reviving an old thread...
Generally speaking amperes affect the torque of the bike and voltage affects the speed. Sticking to the topic of this thread, the amount of voltage (and amperes) that a controller and/or a motor can handle is relative to the motor's coil and other components of the system. The copper magnet wire used to wind the motor's coil plays a major role. Usually, a heavier gauge coil wire can handle more current because it has less resistance and a thinner gauge coil wire can handle more voltage because the ratio of insulation to copper is greater. If the motor's coil is "tuned" to be most efficient within a certain voltage range then too many volts can cause arcing and result in a meltdown. Too many volts can also result in an RPM rate that is higher than what the axle bearings can handle. The hall sensor board might have electrical components that are not rated for higher voltages. Too much speed can cause things like nylon planetary gears to overheat and fail. Generally speaking when a bike is pushed past what it's rated for it's the current (amps) and not the voltage that cause things to overheat or fry. Heat is a motor's worst enemy. All that said there have been people finding ways to push motors beyond their rated capabilities for decades. It can be done (and sometimes is done successfully) but there are a lot of factors to consider. If you're gonna push your bike beyond what it's rated for you can expect things to break. Safety is the biggest concern. You don't want a lithium battery to burn - very dangerous. You don't want to push a bicycle frame that was built for casual riding to a speed or torque level of 40mph/64kmh - also very dangerous. Do research. Be diligent. Be safe. Push limits. Repair and repeat.

 

[puddle]

Hi, So i bought a whole heap of cordless tool batteries from my local store. They are 20 volts each with 2.ah

20v Lithium tool batteries have a nominal voltage of 18.5v. They are the same as 18v tool batteries. So 3 of them is series is an odd size ("55v" battery).