trying to figure out why i'm not having consistent IR measurements with Liitokala Lii-500.
I did some simple tests to find the root of the inaccuracy:
Tested one fully charged, cold 18650 cell for IR, i got readings from 30 to 40 mOhm, some weird 50, 60 or so but most of them in that range.
Opened the case and found that springs are soldered to the pcb and hooked to the holder.
I soldered the spring to the holder, heated it good enought for the tin to stick very well.
Tested again with roughly the same readings.
So looks like the spring is not the main cause.
Then i soldered 20 cm of 2.5 mm2 new shiny cables to pcb.
Tested again pressing (hard) the cables to the cell with my fingers with bit more consistent readings.
Something like 30 to 37.
Then i went all the way and soldered the cable to the cell.
Tested pluging in and out the power source.
Got a bit more consistent results, but still 29 to 34 mOhm.
In Conclusion Lii-500 doesn't look to be very accurate (consistent) and holder contacts add some more inaccuracy.
May be accuracy could be improbed a bit with something like Crimp Daddy did: https://secondlifestorage.com/t-Int...g-Ultra-Low-Resistance-18650-holder-accessory
But Lii-500 is what it is.
I did some simple tests to find the root of the inaccuracy:
Tested one fully charged, cold 18650 cell for IR, i got readings from 30 to 40 mOhm, some weird 50, 60 or so but most of them in that range.
Opened the case and found that springs are soldered to the pcb and hooked to the holder.
I soldered the spring to the holder, heated it good enought for the tin to stick very well.
Tested again with roughly the same readings.
So looks like the spring is not the main cause.
Then i soldered 20 cm of 2.5 mm2 new shiny cables to pcb.
Tested again pressing (hard) the cables to the cell with my fingers with bit more consistent readings.
Something like 30 to 37.
Then i went all the way and soldered the cable to the cell.
Tested pluging in and out the power source.
Got a bit more consistent results, but still 29 to 34 mOhm.
In Conclusion Lii-500 doesn't look to be very accurate (consistent) and holder contacts add some more inaccuracy.
May be accuracy could be improbed a bit with something like Crimp Daddy did: https://secondlifestorage.com/t-Int...g-Ultra-Low-Resistance-18650-holder-accessory
But Lii-500 is what it is.