1500w rear hub motor

Parsons

Pedelecer
Jul 11, 2018
193
13
50
Hi people a friend of mine wonts to biuld a ebike. He's been given a new 1500w rear hub motor no controller etc etc. Should he us a 1500w controller or could he use one with more watts I think it will be 48v or 52
v battery
 

Benjahmin

Esteemed Pedelecer
Nov 10, 2014
2,485
1,699
69
West Wales
Controllers are not generally rated in watts but in amps. It is the controller that limits the power given to the motor.
A 48v controller rated at a maximum of 30 amps would give you 1440watts notional . In order to get this the battery must have a maximum delivery rating of at least 40amps so as to not be stressed and damaged by such a large draw. Such a battery will be very expensive and heavy.
A 1500w motor will be a direct drive. It will be large, obviously illegal and very innefficient at any thing other than high speed on the flat. Stop start riding or hill climbing will generate large amounts of heat, innefficiently using battery power and causing range to be very poor.
All the extra weight will require a serious upgrade of braking.
Your 'friend' has probably been given the motor because the previous owner realised that it's best use was to make it someone elses problem.
When the project is built, having spent a lot of money, to be legal the bike would have to be registered, plated, have proper lights fitted, be insured and the rider must wear a motorcycle helmet and the bike should be limited to either 25kph or 45 kph depending on what class it is registerd as.
So my advice is to either buy a motorbike or, if he really wants to build an electric bike, get a 250w geared hub.
 

wheeliepete

Esteemed Pedelecer
Feb 28, 2016
2,047
755
60
Devon
I would want to test the motor is working before spending any money out on controller, battery etc. as well as taking the info above into account.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,134
8,230
60
West Sx RH
What's the hub V rating ?
Any voltage higher then the V rating will increase the rpm of the hub so one will need to compensate with more current for the lost torque.
The issue will be how much can be spent on the battery to get the performance out of the hub, as mentioned it will need to be rated 40a + continuous otherwise the hub will underwhelmed and feel pretty gutless.
Those hubs are built for speed tbh in the UK there are users and followers of them but they bring there own problems for legality.

For 1500w one is better off with 60v and 30/35a on one of those over powered motorbike hubs or better still buy a legal moped/motor bike.
 

Parsons

Pedelecer
Jul 11, 2018
193
13
50
Thank you guys for the info I will pass it onto him the motor is brand new unused as for the v rating don't know but same brand as mine and I use a 52v battery