Regarding my motors, stall current is 20A per motor.
My general switch is 20A...
My motors will turn freely in a normal use. The only duty they have is to send a ball that will be sent by friction with 2 wheels. Using a instrumented alimentation, current is lower than 1A even when the ball is launched (max normal current).
It could be a good idea to add a fusible (20A) before the motors maybe? A fusible that can be reingaged
So I search for a 50A diode now? Do you have an idea of the scheme with only one diode?
It won't protect your diodes or drivers. Silicon blows a lot faster than any fuse. Fuses are mainly for protecting against fires caused by overloaded cables. The battery you suggest is easily capable of starting a fire if shorted out; you should use fuses for that reason, but don't expect them to protect your silicon devices, they won't.
For the diode, I do not hide that it would be easier for me to control everything only with one transistor and one diode
Something I've not pointed put is that you can't put 2 diodes in parallel and expect them tocarry twice the current of 1 diode. Diodes conduct when the applied voltage reaches their Vf. This will vary between different diodes due to manufacturing differences and temperature. Whichever diode has the lowest Vf will carry most or all the current, the other one will get very little. The one carrying the current will warm up, lowering its Vf and thus making sure it gets still more of he current, until it dies.
It is mentioned on the datasheet the 20A. I did not measured it. What I measured is that my consumption during normal use was around 10W for 2 motors together (motors are not always at 12v).