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Load cell calibration

(@gasssed)
Member

I'm going to feel like I'm spamming the forum a little here of late, but I figure they are all valid questions. 

I'm experiencing some.. interesting HP and torque figures (my 150hp estimated car made 11500hp earlier today 🙂 ) 

I realised then that I had failed to calibrate the load cell. 

 

I have a 500kg load cell, supplied with my hardware blue box. 

I've zero calibrated it in its installed position (I originally took it out and desk calibrated like in the video from Jostein- before realising that was incorrect) 

I have a few issues- 

 

1) my load cell reading is "jumpy" 

Calibrated for zero, it then moves to -2 then +4 and jumps in between. 

 

I've ruled out interference from other cables and have isolated it as much as possible as suggested in other threads (unplugging laptop,moving away from everything etc) but no change. I'm not sure if such a minor "jitter" will impact on things? 

 

2) where do I place a known weight to calibrate and how heavy do I need? 

I've read 20% of Max load. 

So I need to stack 100kg of weights. 

 

But do I place them directly above the cell, at the end of the load arm? Or do I sit them further in board on top of the edge of the brake itself 

 

I'm assuming out on the load arm, above the cell is the best? 

 

 

Quote
Topic starter Posted : 10/02/2021 11:31 am
(@admin)
Member Admin

Hi,

The load cell will be jumpy before it is calibrated, that is normal. 

There is no fixed rule on the weight, but if you use a very small weight compared to the max rating, then a very small error will cause a large error at the end of the scale. 20% of full scale is good. 

You can place the load on top of the load cell, or further out (or in). If you don't put the load on top of the load cell, then you enter the distance to the load instead of to the load cell. Further out means you need a smaller weight, because of the load x arm. Note that you must include the weight of the arm too, and take into consideration the center of gravity of it. Think in terms of torque then it is easy to understand. 

ReplyQuote
Posted : 10/02/2021 6:22 pm
(@gasssed)
Member

excellent! 

 

Calibrated successfully with two 10kg plates, sat on the outer edge of the brake as far as I could. rough measurement from the centreline to the point of contact. 

 

PERFECT measure in yourdyno. removed a plate and reviewed, -10kg as expected. 

 

All done

ReplyQuote
Topic starter Posted : 15/02/2021 10:44 am
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