24 V motor on Lower voltage supply

[TaoBaiBai]

Hi,

Due to weight limitation,I want to use a 15V lipo battery to supply  two 24V  motors and two 15V motor.Beside the changes in torque and speed,will the low voltage make any negative impact(over heat or damage on the  coil and winding )on the 24V motor or motor controller(different motor use different controller)?

[newInRobotics]

No 

[TaoBaiBai]

That means there's no any negative impact? Alternatively,Is there any way to step down the 24 voltage to 15v with a big current(normal voltage regulator can only allow a small current and transformer is too heavy)?

[waltr]

big current?? What is that in Numbers?

[TaoBaiBai]

40A

[waltr]

I assume the 24V is DC. that means there are two way to regulate this down to 15V.

1- A linear regulator. The maximum rating for a 3-pin regulator is about 3Amp. But it can be used with pass transistors to increase the current rating. See any of the National Semiconductor 3-terminal regulator's data sheets for circuits using pass transistor. The down side in the amount of heat that needs to be dissipated. In this case its: (24-15)*40 = 360 Watts so a large heat sink is required but no transformer.

2- Is to use a DC-DC switching power supply. This can be fairly small (compared to #1) since to efficiency can be much higher. The down side is the design is not trivial. If the switch frequency is high then a fairly small transformer can be used. This is the type of power supply used in PCs.
Google for more info.