new electric go kart project questions//Size of pre charge resistor and fuse

[rengl34]

Alright so I bought a second hand electric go kart project online and my main intention now is doing it up.

It's rather DIY and quickly done with no contactor, undersized wiring, no fuse or precharge resistor and unmatched batteries etc that I plan to fix all the problems.

My question is What size ohm precharge resistor do I need inline with the contactor which will also be placed online from the battery positive to motor controller

Also What size fuse do I need from battery positive to motor controller....

all 5 of the batteries will soon all be rt12220Ev ritar batteries. 12v 22ah. 20hr

the motor is a 60-72 volt 1800w (BM1424ZXF)

the controller is undersized for some reason rated at 1.5kw so 1500w and 60volts 45 amps.

all of the yellow blocks are just terminal block connectors

 

[Functional Artist]

Sorry, somehow I missed this question

I posted this in my Excalibur thread, a few years ago.

"How to "do the math" to "size" a precharge resistor.

Let's use the 10W 1KJ resistor , that I installed on Excalibur, as an example

Current:
First, you have to figure out how much current will be flowing?
The basic equation is Volts = Amps x Resistance, V = I x R; In this case we know V and R, so we can calculate for current.
The basic equation is Current I = V/R= 60volts/1000 Ohms = 0.06 Amps. (the voltage divided by the resistance)
This will be the current flowing thru the resistor during inrush to fill the capacitors.

Power:
Next, is the resistor power rating adequately sized to handle this much current?
The basic equation is Power = I² x R , (the current squared, times the resistance)

Using the current as calculated above, and also, knowing the resistance, we come up with,
Power = (0.06 Amps) x (0.06 Amps) x 1000 Ohms = 3.6 Watts.

The numbers to precharge this 60V system would be
60V / 1,000 Ohms = 0.06A (current)
0.06A x 0.06A x 1,000 Ohms = 3.6W (power)

So, according to "the math", this 10W 1KJ resistor should be adequately sized to precharge this system."

I also did a video to help explain this concept.