Battery advice needed

[Jerry]

Hi.  I've just logged on for the first time and would like the accumulated wisdom of the Golden Motor devotees to help me with a simple problem.   I need a new 48v battery for my Magic Pie 3 and want to understand what wattage battery I should buy.   I'm seeing both 500w and 1000w 48v batteries for sale, but don't want to buy something that isn't suitable.  I looked on the Golden Motor store, but the wattage of the batteries isn't mentioned, so I'm even more confused.  Maybe this question has been asked before, but I couldnt find anything on the forum.   Thanks   

[Bikemad]

Hi Jerry and welcome back.

For a 48V battery you will need one that can supply at least 1000 Watts but ideally 1500 Watts or more would be even better.
If the battery is unable to supply sufficient current to the motor, it can result in the BMS suddenly cutting power to the motor under heavy load, and the sudden disconnection of power can result in failure of the motor's controller.

If you use a low power battery, you will need to adjust the maximum Amps in the controller settings to ensure that the motor will not overload the battery's BMS, which often causes it to disconnect the power completely.
Unfortunately, a lot of manufacturers do not specify the battery's maximum discharge current, which makes setting the current limit a bit more complicated.

Most "48V" batteries have a nominal voltage of between 48.1V and 51.8 with a fully charged voltage of between 54.6V and 58.8V depending upon their chemistry and the number of cells connected in series.

If your Magic Pie is set to its maximum 30A current setting it could easily draw between 1500 and 1700 Watts under heavy load with a freshly charged battery even though the motor is only rated as being 1000 Watts @ 48V.

The GM ebike batteries have a maximum discharge current that varies between 15A and 60A dependant upon the voltage, capacity and chemistry of each pack.

If you need to use full power on steep hills, you really need a battery that can supply the full 30A current for the Magic Pie. If you are happy to run the motor at a much reduced power output, you can probably use a less powerful battery without problem provided the controller's current has been properly set to safely limit the maximum load being placed upon the battery.

Alan

P.S. Did you ever get the noise generator to work with your Magic Pie?