I am starting a project that will be using a 12V 8A motor. I would like to have complete control over the motor such as the capability of a L298N but that can do 8 amps. I'm not sure which control module would be best to buy for this use. Any suggestions would be greatly appreciated. Thank you so much.
If 8A is the "full load" current, then the start/stall current will be much higher, possibly in the range of 20-50A. Please post the full specs of the motor, or a link to the product page.
You will need a motor driver that can easily handle the start/stall current, which the motor briefly draws every time it starts moving. Pololu has a good selection.
This is the product page of it. Definitely calling it "repurposing".
You can estimate the start/stall current by measuring the winding resistance with a decent multimeter. Connect the multimeter to the motor leads, rotate the motor shaft very slowly and take the lowest reading. I would expect the winding resistance to be less than 1 Ohm.
Start/stall current in Amperes = 12V/R (R in Ohms).
Alternatively, you can lock the motor shaft, connect a fresh 1.5V alkaline D cell and measure the stall current at 1.5V (which should not damage the motor). Multiply by 8, to get the value for 12V.
Okay awesome thank you so much. I will do both of these.
From there, just use that number to spec what control module to use?
The start/stall current is usually the most critical specification for a motor driver.
The second most critical spec is the rated maximum continuous current, which must be at least 8A in this case. I suggest to be generous, and pick a motor driver rated for 12A or more continuous current draw.
Since many motor drivers have two channels, in some cases you can parallel them to double the rated maximum. But be sure to check.
This will do it
or any BTS7960 Dual H-Bridge driver
https://www.amazon.com/HiLetgo-BTS7960-Driver-Arduino-Current/dp/B00WSN98DC/ref=asc_df_B00WSN98DC
BTS7960 Motor Driver.pdf (1.1 MB)
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I think @jim-p is right. I've used similar radiator fans before for air-cooled motors and the starting current isn't that high. BTS7960 itself should be fine. However, I would derate the board a bit. The typical arduino breakout boards they use for that chip aren't well designed. I've had to remove the heatsink and sand off the soldermask on the vias that are supposed to be conducting heat away from the chip to help with power dissipation.
Hello, I'm writing to you regarding a comment on this post some time ago: LSM303DLHC - Calibration, Pitch, Roll and Tilt Compensated Heading - #7 by jremington.
I'm trying to calibrate my sensor (BNO085, I know that it probably still won't work and I will have to use ISM330DHCX and MMC5983MA with the magneto program but I want to try it). I'm wondering about this part of the manually calibration code:
// shift and scale magnetometer data
m.x = (m.x - m_min.x) / (m_max.x - m_min.x) * 2 - 1.0;
m.y = (m.y - m_min.y) / (m_max.y - m_min.y) * 2 - 1.0;
m.z = (m.z - m_min.z) / (m_max.z - m_min.z) * 2 - 1.0;
// same for accelerometer. Should also consider offsets and scale here...
a.x /= 16384.;
a.y /= 16384.;
a.z /= 16384.;
Why are you dividing the accelerometer values by 16384? From what I understood, the same actions should be taken here as with the values from the magnetometer.
I plan to test direct, automatically calibrated readings from this sensor, raw readings and manual calibration (as in the code you provided: smallest and largest values) and third manner is using a magneto to calibration with raw readings too. If they are still weak, I plan to use the previously mentioned ISM330DHCX and MMC5983MA sensors or use GPS. I want to determine the current course of a remotely controlled boat.
Unfortunately, thread with this shubject had to be closed, which is why I'm writing to you here.
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