I NEED AN URGENT ADVICE MY FRIENDS

[nemo micro chip]

guys do you know any web site with relatively cheap lithium batteries for any usage that ships internationally? i am from greece.

[TylerDurden]

A 48V 50ah battery might not really deliver 2400W for an hour. It depends on the battery chemistry. The cheap batteries deliver less power - the voltage will drop quickly, the battery will have a short life.

A motor may be rated to sustain 3000W output, but the claims may be exaggerated.

It is common to buy a motor and battery that are too small for the job - I estimate you will be unhappy with performance if you buy a motor less than 5kW for a scooter.

A larger motor will give you the power you want on the hills and will be more efficient overall. That will reduce the battery capacity you need.

[nemo micro chip]

higher motor you mean in watts for example 5000w or in volts? 60v or 72v for example? you mean i should have ordered the same motor of 3000w at 72 v??? look, now i have a 1000w motor and i go to my work daily with no problem. the distances here are small and not so many hills. i guess that with the 3000w motor it will be super for my case. do you think that this battery of 48v/50 ah lithium is enough for this motor?

[nemo micro chip]

tyler send me in pm message your mail so i can send you the characteristics of the motor to check it. thanxs.

[Arlo1]

The top speed of a motor is a somewhat mis-leading statistic. The more volts you feed into a motor, the faster it will turn.....until it burns up.

For example:



The top speed is dependent on it's Kv, the number of volts you are feeding it, and the size of the wheel the motor is put in. In other words, a motor in a 20" wheel at 48v will not produce as much speed as the same motor in a 26" wheel using the same voltage. On the flipside though, the motor in the 20" wheel will have more torque.

You can feed a lot of volts to a motor with no problem. It was the amps that burnt lukes motor. You can run that motor on 300v if you want!

[nemo micro chip]

are you sure? that is great news then. if i put a battery of 72v/50 ah then i will be al right i guess if your claims are true enough. show me efficient evidence to believe please.

[TylerDurden]

tyler send me in pm message your mail so i can send you the characteristics of the motor to check it. thanxs.

Better to discuss in public... Many people here understand much better than I do. Arlo1 is one of those people. He is a GURU !

Motors don't care much about volts: too low volts and they go too slow and get hot, too high volts and they can explode from the spinning force.

Here are some more basics to consider when you explore your options:

Current (amps) provides torque, but also heat.
Volts provide higher RPM, but also let more current flow.
Batteries provide energy (power * time) , but are limited by capacity and "C-rate".
Controllers reduce the voltage to the motor by switching current on/off quickly, but higher battery voltage controllers usually cost more.

[Arlo1]

are you sure? that is great news then. if i put a battery of 72v/50 ah then i will be al right i guess if your claims are true enough. show me efficient evidence to believe please.

Positive! In fact I built a bmx with a HS35 running on a 84v 15ah battery last summer for my youngest brother.
And I just road my bmx home which has a 100v 15ah battery running to a X5304!
Most if not all electric Motors work as buck converters converting hi voltage and low amperage into hi amperage and low voltage inside the windings themselves. So say you have a 100v battery and want to drive at 10% of the motors max speed and this requires say 10 amps from the battery. Then what happens is the controller will PWM (pulse the power to the motor) at a rate that allows for the 10% of the speed to be held. In side the motor you would see 10 volts and 100 amps (aprox).
Things to remember.
Voltage is your push (which is what determines the max rpm with most electric motors) (Not sure about AC motors)
Amperage is your current flow ( and with electric motors determines your torque out put)
Ohms are your resistance (which in the motor helps to determine how fast the current will flow)

[StudEbiker]

are you sure? that is great news then. if i put a battery of 72v/50 ah then i will be al right i guess if your claims are true enough. show me efficient evidence to believe please.

It looks like you are in more knowledgeable hands now. I was just trying to help as much as I could. If you go back and read the earlier posts I made, I never said you couldn't run your motor at 72v, in fact I specifically said you could, but it will get hotter faster. I think I am right about this but I'm sure Arlo or Tyler will correct me if I'm wrong. Best of luck, I'm going to sit back and watch now.

[nemo micro chip]

thanxs a lot all of you friends for your useful informations. i am so glad to be here in the forum with you. god bless you all.

i will post when i will receive the shipment of this 48v/3000w hub brushless drum brake rear motor and its 48v controller.

then i will buy the lifepo4 lithium battery of 48v/50 ah to complete the combination.

and then i will make tests and post them here. all this project i hope that it can not be worse than the existing one with the 1000w motor and the lead acid 48v/22 ah battery.....

[Arlo1]

thanxs a lot all of you friends for your useful informations. i am so glad to be here in the forum with you. god bless you all.

i will post when i will receive the shipment of this 48v/3000w hub brushless drum brake rear motor and its 48v controller.

then i will buy the lifepo4 lithium battery of 48v/50 ah to complete the combination.

and then i will make tests and post them here. all this project i hope that it can not be worse than the existing one with the 1000w motor and the lead acid 48v/22 ah battery.....

48v 50AH? thats a big battery do you have a link?

[nemo micro chip]

WHAT DO YOU MEAN BIG? BIG FOR MY MOTOR OR BIG IN DIMENSIONS?

[Arlo1]

WHAT DO YOU MEAN BIG? BIG FOR MY MOTOR OR BIG IN DIMENSIONS?

All caps is the = to Yelling. lol I'm sure you didn't mean it. But be careful you will find this to be a great forum without to much crap (yelling, arguing, bragging about private member sizes etc.) we leave all that for the other forums.

Ok so I have a feeling you don't quite understand the numbers on a battery.
AH is a way they label them to tell you how much energy is in the battery. eg. 10AH means it can run 10 amps for 1 hour But it can also run any combination of that as long as its not over stressed. This is where the C rating comes in 20 C means it can release all its energy in 1/20th of 1 hour so if its a 10 AH battery and needs to release its energy that fast it would be 10 x 20 which = 200 amps. So for 1/20th of an hour it would produce 200 amps.
The only reason you need to know that part is so you can make sure you do not over load your battery. And knowing the total AH of your pac will help you determine how far you can go on a charge.
What is really best is to learn how to calculate WH (watt hours) this is the most accurate way to know how far a battery will carry you.
So using the 10 ah pac lets say its 12s (12 cells) Now this is very important to know which battery you are using because all chemistry are different but we will use lipo for an example, Lipo has a nominal voltage per cell of 3.7v so for calculations we use that. So 10 Ah x 12 (12 cells) x 3.7v (each cell is 3.7v) = 444 Watt hours. This is the number you really want to know. Because a low power ebike will use a certain number of Watt hours per km and a high power ebike will use more but once you start riding if you use a Cycle Analyst (Awesome on-board display see link at end) it will tell you the Watt hours per KM you are consuming. My bike uses 60-90 WH per km depending how I ride and if I lower the top speed even less. So with my battery 24s 15 Ah Lipo its 24 x 3.7 x = 88.8 total nominal pac voltage x 15 Ah = 1332 wh so if I take it a little bit easy I can go 1332/60 = 22.2 km max.
The reason I said your battery is "BIG" is because I think the physical size might be big and this is why I asked for a link. Your motor doesn't care what you have for a battery because its up to the controller to limit the Amperage flowing out of the battery and into the motor. But your controller does care what voltage your battery is, and you need to make sure you select the right voltage and motor combination for a proper top speed.
Here is a link to the VERY RECOMENDED CA http://ebike.ca/store/store_accessories.php

[nemo micro chip]

arlo1 you are the best man friend! you help me so much with your knowledge. you are a really good man.sorry for the capitals.i dindt mean anything.

this cycle device is just for bikes or also for my e-scooter?? to solve your question about the big battery. i will buy this lifepo4 lithium battery of 48v/50 ah included bms and a charger of 48v/5 ah which means maximum 5 hours at full charge from a chinese manufacturer which will give me price as a wholesaler and will built this battery according to my custom desired dimensions. i have already tell them the exact dimensions i want to fit the slot under my seat space.

i understand that the most important is how many watts per 1 klm this 3000w motor will consume. then if i know this, i can estimate the autonomy distance that this battery will give me. arlo1 can you tell me from your experience, how many watts per 1 klm a 3000w hub motor like mine might consume???

the factory i bought it, send me the whole diagram specs for this motor but i cant get any meaning as they seem to me like chinese...i have no relation with electronics.

can i send it to you to check it and tell me? give me an email to send it friend.

[Arlo1]

Just post what ever info you can online on this thread.
What is the top speed you plan to ride at? And how much do you think the total package will weigh?

[TylerDurden]

the factory i bought it, send me the whole diagram specs for this motor but i cant get any meaning as they seem to me like chinese...i have no relation with electronics.

You can attach the diagram to the discussion. Check my signature below about adding pictures.

[Arlo1]

I should say one thing. If you up the voltage and keep the amperage the same then the motor will run hotter.
A motor generates heat based on the efficiency so say your motor is 95% efficient then you put 50v x 50 amps to it which = 2500 watts the motor will make 5% heat so 2500 x .05 = 125 watts heat. But if you double the voltage to 100v and keep the amps the same you will have 5000 watts going to the motor and make 250 watts heat.

But if all this is in the same motor it will spin 2 x as fast with 100v as 50v and because its spinning faster it might cool better. Not to mention You really need to make sure you have a controller for the higher voltage. Most controllers will work with a range of voltages. So you will have to see if yours is in the range you want.

And lastly if you run the same motor off of a 100v battery at the same speed as you were planing with the 50v battery the heat will be roughly the same.
Because in the motor its converting the voltage and amperage via buck converter.

[nemo micro chip]

the specs of my motor is in the excel file zipped with this message. please guys check it out and tell me what are my options. thanxs a lot all of you for your advises..

[TylerDurden]

Here is the data for all to enjoy:

[TylerDurden]

You may notice that the chart indicates peak power-out at ~600rpm, ~3000W and 81% efficiency. If true, you will only need to deal with 600W in heat - not too bad if you are cruising at 35mph.

But look at the efficiency when the motor is heavily loaded - like going up a steep hill. 30% efficiency means lots of heat - enough to cook your motor if the hill is too long.

So, it's vital to know the weight of your bike, battery and riders; plus the slope and length of the biggest hill. (Hottest day of the year too.) If you under-estimate the size of motor needed, the smell of burning wire will linger in your memory and your bank account.

[nemo micro chip]

so the weight is super important for this motor.....my weight is 65 kg.i am light weighted.the motor itself is 10kg. the scooter is around 70kg. and here it comes that for less weight i will need lithium battery than lead acid one. this lithium 48v/50 ah is 23 kg only.

so in total we have : 168kg with me on it full equipped with the lithium battery on it.

is it too much for this motor??

[TylerDurden]

Using this calculator (there are others around here) - http://www.kreuzotter.de/english/espeed.htm:

I entered the weight of rider, motor, bike, battery and used the MTB profile to estimate rolling resistance of big tires.

I found this searching google for "scooter drag coefficient":
"For more information see the simulated results when they are available at Vespa CFD/3D Model, here the calculated frontal area of scooter and rider is 0.81518 m^2"
from http://www.vespalabs.org/Vespa_101/Dyna ... rodynamics

So, I changed the rider height to 600cm in the calculator to get 0.8164 m^2 frontal area.

It looks like 3kW motor can get the bike about 65kph on a flat road. On a 10% hill, only 44kph ( 68% speed).

Looking at the motor chart, 68% speed (400rpm) is only about 74% efficient - ~1000W in waste heat. I don't know how long the motor will take the heat, short hills might be ok, but long hills might not (the heat will reduce the efficiency).

Adding a 50kg passenger (and 5kg handbag) : speed on flat = 68kph. On 10% hill = 37kph.
57% speed = 340rpm or 70% efficiency = more heat. Again, a short hill (or a few up/down hills) might be ok.... maybe.

The motor chart also shows that during peak load >3700W will be needed for input from the controller, a controller might be 75% efficient, so the battery would need to deliver >4600W... about 2C during peak load.

Are we getting the picture? The worst-case scenario needs to be estimated, to know if your equipment will be adequate.

It is hard to say if the motor will be adequate without knowing the hills and how loong the motor can take the heat. Bigger is almost always better. I like to have enough power to keep the speed the same going up a hill and use less throttle on the flat... (knowing I have more if I need it).

Many ES members use a temperature measuring device to know when to stop before heat damages the motor - magnets in the motor can suffer at 80C.

You can also get better efficiency with a bigger motor, so the motor runs cooler and the battery can be smaller.

[nemo micro chip]

WHAT ABOUT THE AUTONOMY? how many klm distance autonomy i will have with the 48v/50 ah lifepo4 battery? and at what optimal speed for me?

[nemo micro chip]

this is the list of all the motors they sell and their specs. this is from where i bought mine. i can give you name and contact if you interested guys.

[TylerDurden]

WHAT ABOUT THE AUTONOMY? how many klm distance autonomy i will have with the 48v/50 ah lifepo4 battery? and at what optimal speed for me?

The faster you go, the less range (autonomy) you get.

V*Ah=Wh (watt-hours). That battery has 2400Wh.

If you are using 3600W (~60kph), the battery will run for .66hr or 40km... but that would kill your battery quickly. It is common to only use ~80% of the battery capacity, so the battery will have a long life.

So imagine the battery only can use 2000Wh (83% Depth of Discharge). Then you only get .55hr or 33km.

But that's at top speed.


Reduce your speed and go farther: 55kph requires ~2000W at the wheel. You can do the math to calculate the battery power needed and the range you will get.