Concerns over circuit protection with 2x160 34VDC Roboclaw
Posted: Tue Aug 13, 2019 2:34 pm
Hello All,
I'm inquiring as to recommendations on the fuse, power diode and pre-charged resistor for this circuit. I'd be using the 2x160A 34VDC Roboclaw Motor Controller
UPDATED CIRCUIT SCHEMATIC Motor Specs: MMP D40-675C-24V GP81-014
Rated DC Voltage -> 24VDC
Rated Continuous Current -> 23.1A
DC Armature Resistance -> 0.15Ohms
Stall Current -> 24V / 0.15Ohm = 160A
Battery Specs: Turnigy Graphene 5000mAh 6S 45C LiPo Pack w/ XT90 (Two of these in parallel)
Capacity -> 5000mAh
Voltage -> 6S1P / 6 Cell / 22.2V
Discharge -> 45C Constant / 90C Burst
I selected these batteries for safety, as the safe continuous current load would be 225A and the safe burst current would be 450A which is above the combined stall current of 320A for both motors.
I plan on using 10AWG wire for the entire circuit above since that is what the batteries and motors both come with by default, but if anyone thinks that could be an issue I'd like to address it before hand. My total travel length (one-way) won't be more than 2 feet, tops.
For the pre-charged resistor:
Based on what BasicMicro says in their resource page...
If I want a charge time of 1 second then (1/3) / (2820uF) = 118.2 ohm
Should I increase my charge time? Is a pre-charge resistor simply a resistor? Is it a power resistor?
Note: I really want to use these XT90-S connector that prevent sparking
https://hobbyking.com/en_us/xt90-s-anti ... s-bag.html
Would these be akin to a pre-charge resistor? I think they have about 8ohm resistance as you plug them in.
For the power diode:
I understand I need something with a reverse voltage of 22.2V and the forward current should be what exactly? Again, BasicMicro says that anywhere from 1A to 3A works for most cases.
For the fuse: I want a fast-blowing fuse, which I understand. So the current the fuse should blow at would be what exactly, the stall current of the combined motors, i.e. 320A? This would mean the fuse would be rated at a current much much less than 320A.
Note: I know I have two switches in the circuit, SW6 and SW5.
I'll be using these switches https://www.gigavac.com/catalog/power-p ... t-switches
Which range from a continuous current rating of 200A up to 400A.
(I know, overkill..)
Alternatively, I've used a voltage clamp circuit for another project because I was using a DC power supply. Could I use the voltage clamp that BasicMicro provides in place of the power diode? I'd still want the pre-charged resistor and fuse though wouldn't I?
I'm concerned about safety, so any advice is welcome!
I'm inquiring as to recommendations on the fuse, power diode and pre-charged resistor for this circuit. I'd be using the 2x160A 34VDC Roboclaw Motor Controller
UPDATED CIRCUIT SCHEMATIC Motor Specs: MMP D40-675C-24V GP81-014
Rated DC Voltage -> 24VDC
Rated Continuous Current -> 23.1A
DC Armature Resistance -> 0.15Ohms
Stall Current -> 24V / 0.15Ohm = 160A
Battery Specs: Turnigy Graphene 5000mAh 6S 45C LiPo Pack w/ XT90 (Two of these in parallel)
Capacity -> 5000mAh
Voltage -> 6S1P / 6 Cell / 22.2V
Discharge -> 45C Constant / 90C Burst
I selected these batteries for safety, as the safe continuous current load would be 225A and the safe burst current would be 450A which is above the combined stall current of 320A for both motors.
I plan on using 10AWG wire for the entire circuit above since that is what the batteries and motors both come with by default, but if anyone thinks that could be an issue I'd like to address it before hand. My total travel length (one-way) won't be more than 2 feet, tops.
For the pre-charged resistor:
Based on what BasicMicro says in their resource page...
If I want a charge time of 1 second then (1/3) / (2820uF) = 118.2 ohm
Should I increase my charge time? Is a pre-charge resistor simply a resistor? Is it a power resistor?
Note: I really want to use these XT90-S connector that prevent sparking
https://hobbyking.com/en_us/xt90-s-anti ... s-bag.html
Would these be akin to a pre-charge resistor? I think they have about 8ohm resistance as you plug them in.
For the power diode:
I understand I need something with a reverse voltage of 22.2V and the forward current should be what exactly? Again, BasicMicro says that anywhere from 1A to 3A works for most cases.
For the fuse: I want a fast-blowing fuse, which I understand. So the current the fuse should blow at would be what exactly, the stall current of the combined motors, i.e. 320A? This would mean the fuse would be rated at a current much much less than 320A.
Note: I know I have two switches in the circuit, SW6 and SW5.
I'll be using these switches https://www.gigavac.com/catalog/power-p ... t-switches
Which range from a continuous current rating of 200A up to 400A.
(I know, overkill..)
Alternatively, I've used a voltage clamp circuit for another project because I was using a DC power supply. Could I use the voltage clamp that BasicMicro provides in place of the power diode? I'd still want the pre-charged resistor and fuse though wouldn't I?
I'm concerned about safety, so any advice is welcome!