Rapala Mini Digital Scale - Load Test Report

[Goose52]

I recently picked up a 3rd Rapala electronic scale. I will have one in my bank fishing gear, one in the boat, and the 3rd as a spare. As I always do with a new scale, I perform a pull test on a known weight to check the scale for accuracy and repeatability prior to use.  My first two scales have always been very accurate and close to each other during pull tests so I was very interested in how close the 3rd unit would be to the earlier units.  So, I tested all three scales at the same time and, for the amusement of BR members, photographed the process.

 

Test Results:

 

Measured weight:  The test weight was 9.804 pounds (more about how this weight was calculated later).

 

Unit 1 read:  9.81 pounds - .006 pounds heavy (~0.1 ounce)

Unit 2 read:  9.78 pounds - .024 pounds light (~0.4 ounce)

Unit 3 read:  9.87 pounds - .066 pounds heavy (~ 1.0 ounce)

 

Exteme spread between the three scales is .09 pounds (~1.5 ounce).

 

Repeatability:  The load was applied to each scale three times. Units 1 and 2 read identical weights each time. Unit 3 read 9.87 twice and 9.85 once.

 

Photos:

 

Unit 1 - 9.81 pounds

 

 

Unit 2 - 9.78 pounds

 

 

Unit 3 - 9.87 pounds

 

 

Unit 2 under load - showing the test load - 9.804 pounds

 

 

The test load:  420 lead bullets - .40cal/155gr nominal weight (157.63gr actual average weight). Plastic box weighs 2409.0gr. The white string weighs 17.2gr (.039 ounce).  I didn't weigh the white label...

 

Total weight = 68626.3 grains = 9.8037 pounds.

 

The stated weight of the test load is accurate to within a tiny fraction of an ounce. This is a bit more precise than some folks who have tested their scales using a gallon of water, a 10-pound weight from a bar bell set, or whatever.

 

NOTE:  The measurements are in "grains."  This is a somewhat archaic unit of measure used in the U.S. for ammunition components (primarily bullet weights) and for cartridge propellant charges. There are 7,000 grains in a pound, 437.5 grains in an ounce. Propellant charges are typically measured down to 0.1 grain (0.1 grain = ~0.0002 ounce). The scale used to measure the objects in the test weight is accurate and repeatable to within 0.1 grain.

 

 

Summary:

 

I am always amazed at how accurate these scales are; all three scales measure within one ounce of the test weight at the 10 pound range. Load cell technology has certainly improved and the price is now very reasonable for the capability that you get.

 

I am also amazed at how many people report poor results with this model of Rapala scale. My Unit 1 is now three years old, Unit 3 is brand new; there certainly seems to be consistency in the accuracy of units produced over the past 3 years.

 

I think knowing the weight of a 10-pound class fish within an ounce is close enough for me. It is extemely unlikely that I will ever come close to a record fish in my water so having a scale that is eligible for certification is unimportant. Compactness, and the ability to read to 50lbs IS important and these little scales work just perfect for me. Replace the battery once a year, don't drop the scale or dunk it in the lake, and you're good to go.

 

Note for Users:

 

This load test was conducted with the scales supported by a rigid bench, with the scales oriented vertical to assure that the chain is not rubbing on the scale housing, and with a static test load. When hand-weighing a fish on the water, it's difficult to keep the scale vertical, and to keep the fish immobile. I believe that these two factors are what contribute to variances in weight reading in the field.

[Darren.]

Nice review, Goose. Thanks.

[Long Mike]

Thank you for a very good report.  I would very much like to see a comparison of the units at say, one, five and twenty pounds to determine if the accuracy is linear between units.

[The Rooster]

I only tested mine with just a ten pound dumbbell, but I used two of the weights and switched back and forth multiple times between them. The unit told me one was dead on ten pounds while the other was not quite ten pounds. What was important to me is that the unit could tell the difference between them each time I switched weights, so that tells me it can measure with good accuracy and can also produce repeatable results well enough for me to rely on as a recreational fisherman.

[Scott F]

Although I don't weigh fish anymore, years ago I bought an early version of a digital fish weighing scale. Using certified test weights, my scale was off 3 ounces at 5 pounds and 5 ounces at 10 pounds. Nice to see today's models have gotten so much better.

[Goose52]

Thank you for a very good report.  I would very much like to see a comparison of the units at say, one, five and twenty pounds to determine if the accuracy is linear between units.

 

I did test Unit 1 a while back at several test weights.  Here's the results:

 

Actual   Measured

3.63      3.65

9.574    9.59

11.64    11.59

14.39    14.47

38.83    39.06

 

Note that Unit 1 read heavy at all weights except at 11.64. I don't have any immediate explanation for that, other than possible numerical rounding effects in either the measurement of the current change through the load cells, or in the algorithm that is used to convert that current change measurement into a weight.

 

Regarding this recent test, I selected a test weight in the 10 pound range since this is around my current LMB PB, and also around whatever my next PB is likely to be.  Weights under that PB level aren't as interesting to me. The only fish species in my water that are significantly above the 10-pound range are catfish and carp, and I'm not as concerned about the preciseness of the weight readings for those fish.

 

What I could do, though, is up my test load to about 12 pounds, with the bullets bagged into approx. 2, 4, and 6 pound bags. With different combinations of those weights, I could cover test weights from 2 to 12 pounds.  Sounds like a project for a rainy day...

[11justin22]

Have the same scale and mine is way way off. It is way under and the higher the weight the worse it gets off

[Comfortably Numb]

Thanks for the info.

 

I have one of these and turning it on sometimes takes 5 mins. I bought it new off ebay so could not easily return it. Anyone else have trouble with the switch or turning it on?

[Goose52]

I have no problems turning on my units - I press the button in (pressing from the side), hold for a few seconds, release the button, and it's on.  I've recorded the weights on almost 500 fish with these units - powering up and powering down with the switch each time.

 

I do have a problem switching between pounds and kilos however - that is a bit dodgy on this unit.  At this pricing point, the device doesn't have a separate switch for that function and you have to manipulate the power switch during power-on. Sometimes the scale will power-up in kilos and it can be a pain to get it back to pounds. In that case, I just record the weight in kilos and re-set the device to pounds later.

[bman310]

Very well done Goose, thanks!

 

-b

[QUAKEnSHAKE]

I have one too and it works fine. I weighed a small safe at work on a certified scale. The weight was 1415.63grams and on my RMS it reads 1.41kg thats good enogh for me.

[Goose52]

Yup - close enough for sure. Compact, you can always have it with you, and it's MUCH better than holding the fish up and guessing the weight or using length/girth measurements...

[gallowaypt]

 

I do have a problem switching between pounds and kilos however - that is a bit dodgy on this unit.  At this pricing point, the device doesn't have a separate switch for that function and you have to manipulate the power switch during power-on. Sometimes the scale will power-up in kilos and it can be a pain to get it back to pounds. In that case, I just record the weight in kilos and re-set the device to pounds later.

Hey goose, I just got one of these and figured out how to change from kilos to lbs. as you turn it on and it starts blinking repeatedly, hit the power button quickly, two times and it will change units

[gramps50]

Very nice review Goose, thanks for sharing

[Goose52]

Hey goose, I just got one of these and figured out how to change from kilos to lbs. as you turn it on and it starts blinking repeatedly, hit the power button quickly, two times and it will change units

 

Thanks - I know how to do it, but lakeside it can be a pain. It would be nice if there was a switch to set the units. Sometimes you have a wiggling bass in one hand, the scale in the other hand, and you look down and the unit is in kilos. So, instead of powering down, powering back up, and hitting the switch to toggle the units, I just record the weight in kilos and get the fish back in the water...

 

Still, at this price point, it's a pretty nifty scale...

[gallowaypt]

Yeah it is a pain. I caught a 4 lber today and it said 1.75 or something. I was thinking no way until I saw the kilos.

[00 mod]

Not weighing the white label is the main problem I see.    Other than that, FANTASTIC job!!!

 

Jeff

[jeb2]

Have the same scale and mine is way way off. It is way under and the higher the weight the worse it gets off

+1. Mine is usually way off and does a poor job at repeatability. I know others that have the same results with it. I did measure some static, known weights with mine and it was always several ounces off between pulls. Weather seems to impact its accuracy as well. Just not a trustworthy tool, in my experience.

[Goose52]

Not weighing the white label is the main problem I see.    Other than that, FANTASTIC job!!!

 

Jeff

 

Yeah - I got sloppy Jeff. Forgot all about weighing the label until after I finished the test - throws the whole test into question doesn't it.....................

[00 mod]

Yeah - I got sloppy Jeff. Forgot all about weighing the label until after I finished the test - throws the whole test into question doesn't it.....................

I literally LOL'ed!

 

Jeff

[Goose52]

An update to this report:

 

After 4 years of faithful service, my primary scale, Unit 1, has died.  It recorded over 500 weights, was turned on and off over 500 times, and was banged around the bank and boat all that time. It was never inaccurate, the failure is that it won't power-up - even with a fresh battery. I suspect the power switch (that was always a bit dodgy) finally failed. So, 4 years of service for under $5.00 a year. Not bad.

 

So, I purchased a replacement - now labeled Unit 4. AND, I finally got a "bad" scale - this one is off by a whopping .14 pounds (~2 ounces) on the 9.804 pound test weight.  Still, close enough for my purposes.  Unit 4 is now the back-up scale and won't typically be used much for now anyway. In any event, any scale I use to weigh a PB is checked against a test weight once I get home and I adjust my recorded fish weight based on any error I see in the scale.

 

$17 bucks for Unit 4 - within 2 ounces - good enough for me...

 

 

[BassinLou]

Thanks for the follow up. RIP unit 1.

[Comfortably Numb]

You can unscrew the scale and take the plastic switch button totally out and pitch it. This leaves the metal of the switch exposed. You then just touch that metal to the contact to turn on. Works better then.

[Goose52]

Good tip - thanks!