Hi MarK. Thanks for your help and usefull comments. Here most of the modifications that you suggested on your original schematic to make it work with my own motor. I modified the battery charger to accept the new 24V battery and change R4 to 1R2 (exact value still to confirm)
I'm on the road and I will need to validate the exact motor current when I'll be back. In the mean time, Mark can you validate my calculations for the L200C battery charger modified for the 24V battery?
L200C
Vout = Vref (1+R2/R1) where Vref = 2.770V
Io = Vpin5-Vpin2 / R3
Ver1.0 set for 12V Battery
values where R1=750R, R2=3K, R3=0.75
For 24V Battery
Typical float voltage (lead-acid) is 2.15 to 2.23V per cell, or 12.9 to 13.4V for a 12V Battery. So for a 24V battery, float voltage = 2.20 * 12 = 26.4V + 0.7V (D1 diode) = 27.1V
R2 = ((27.1V/2.770V) - 1) * 750R = 6587R (closest value 6.65K) = 27.3V
Q2 & Q8 are already mounted on a very good heatsink. I'll install small TO92 heatsinks on Q3 & Q4.
On my circuit, I will also to change the charger transformer and use an external 24V battery. My design already included the option to use an external battery, so I'm convered. My current transformer is a TE70033, 15V, 04A (parallel secondaries), or 30V, 0.233A (sec in serie). I'll keep the same transformer, but just modify the PCB to connect both secondaries in serie.
I guest I will also need to modify the LED's indicator Zener to accept the new 24V working voltage