Motor draw on battery explained / amps

[powercartmen90]

Hi can someone please explain to me what type of battery I need for a 48v 500 watt low speed high torque gear hub motor. I don't understand what the battery discharge has to be for the motor to pull the energy it needs. How does it work? What does it need to be, or can it just be any battery with voltage matching alone.

 

[DanGT86]

Simple overview:
Just by the numbers 500watts / 48v = 10.5 amps.
So you will need a battery that can output 10.5 amps.

More complex overview:
"48v" can sometimes mean 13 lithium ion cells in series which are
48v nominal and
54v fully charged
36v empty

Some people call 14cells in series "48v" when in reality its
52v nominal
58v fully charged
39v empty

The reason this matters is that most controllers have a low voltage cut point that prevents you from overcharging the battery. A higher voltage pack has a higher voltage reading when empty.

Does the controller you are using have a tag that tells you the low voltage cut (LVC)? That is the best way to know what the ideal battery voltage is for you.

The good news is that almost all ebike battery packs can handle 10.5 amps so once you know what the LVC is on your controller you will have plenty of available packs to choose from.

Can you post a pic or link for what you are using and maybe we can give you a more definite answer?

 

[powercartmen90]

Awesome I'm doing that now. I get your explanation about what you said 10.5 amps and battery is matching 48v battery, controller and motor.. ( I don't know the LVC for sure) but my main thing is what battery would work with these low speed high torque hub wheels? I'll post . Also does the discharge rate have any play in this ? Or am I missing some other details that matter. I want to get a plain e bike 48v 30ah battery but if the other factors are right, the battery I get may only last 24 min. Instead of an hour... please thoughts. Wholesale High Power 6 inch 500W Golf Cart Electric Bicycle Motor Gear Hub Motor From m.alibaba.com

 

[Hillhater]

Also does the discharge rate have any play in this ?

i think dan covered that point..
discharge rate. IS output amps !

Just by the numbers 500watts / 48v = 10.5 amps.
So you will need a battery that can output 10.5 amps.

So, as long as you have a battery rated at 48v nominal, and able to discharge at 10.5 A or more,…..it can have a CAPACITY of anything from say, 5Ahrs to 30+ Ahrs,
The capacity will determine how long the battery can drive the motor for. …and how big/ heavy/ expensive, it is !

 

[richj8990]

I think if you are buying a geared hub drive from AliBaba, almost any decent 48V battery will do the job, assuming you have the right connectors on each side. Try to get at least 15Ah. I would not however buy the battery from there. At the bare minimum Amazon or EBay, but not AliBaba/AliExpress.