Bypass Diode on RC2x60 AHV 48v setup

[Mamosa]

I finnaly got my 2x60AHV controller and I want to protect it well from voltage spikes during regenerative braking.

My system is consist of:
1. 15Ah 48v li-ion battery (90A constant, 120peak) with BMS that will cutoff from overcharging,
2. 200A golf cart contactor with 10W 470ohm precharge resistor,
3. 2x60AHV controller
4. Very powerfull Ampflow a28 400-48v DC motor.

I also need bypass diode on contactor for protection of voltage spikes caused by regenerative braking.

I have doubt: 1N5400 or 1N5408 diode. Or maybe something completly different?

Thx!

[Basicmicro Support]

1. Warning: The 2x60AHV is undersized, by a large amount, for that motor. That motor has a stall current of approximately 560amps

2. Make sure your contactor has a flyback diode on the control input. Otherwise when the contactor is turned off it will produce a large voltage spike(this is just for the solenoid in the contactor).

3. You need a bypass diode on any point in your circuit that can break/open during operation. Fuse and Contactor usually. They should be rated for 1a to 3amps continuous. Peak current ratings will usually be hundreds of amps. THey only need to handle a case where the switch/fuse opens while the motor is in regen.

Either diode should be sufficient but I'd go with one that was 100v rated. The 5400 is only 50v rated which is really too close to the 48v operating voltage. Especially if you will be using 12v lead acid. Those full charged will be closer to 58v.

[Mamosa]

First of all, thank you for great and very useful answers...

1. It is a very powerful motor, but I expect max 60A (calculated 58A) in any condition. It is a 30 lbs cablecam driven on 1:5 gear ratio. But controller itself has a current limiter anyway, that is supouse to help, right?

2. I will do that ASAP

3. I will do that also. If I put parallel, on positive side of lead from contactor/solenoid to battery, before fuse, will it be ok?

I have spare 1N5408 diodes, will that do the job?

[Mamosa]

3. You need a bypass diode on any point in your circuit that can break/open during operation. Fuse and Contactor usually. They should be rated for 1a to 3amps continuous. Peak current ratings will usually be hundreds of amps. THey only need to handle a case where the switch/fuse opens while the motor is in regen.

Thinking about purchasing a v-clamp (Item#: IMC603) for that. Will the v-clamp do the job if I set the limit up to 58V in Studio?

[Basicmicro Support]

1. How do you plan on controlling that? It is not a linear function except when the motor is in a stead state. During acceleration/deceleration and changing loads you have no way of controlling the current that precisely. I highly recommend against it. You may think you have all the cases covered. In my experience that is never the case.

2. This is what a flyback diode on a contactor/relay is and how to wire it: https://resources.altium.com/p/using-fl ... r-circuits

3. Yes and No. A voltage clamp is for dissipating motor regen when you have no place to put it. Primarily when using a power supply but can also happen if you regen will be very high. The diodes across fuse and power switches is to provide a path for regen back to the battery + no matter what happens. Similar but not the same. The battery will almost always be able to take regen unless an external force is pushing more energy into the motor than is being pulled out of the battery. You can use a voltage clamp and proper power resistor with a battery as well but in general it isnt needed at these power levels.