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Inaccurate voltage for cells 1 and 2 when charging #339

Closed intelligentpotato closed 1 year ago

intelligentpotato commented 1 year ago

Turnigy Accucell 6 50W running v2.00_20160613. Calibrated each cell to +/- 5 mV @ 3.96 V. Didn't do expert calibration. (upd: in the expert calibration menu I only have Vplus and Vminus) When I start charging, the voltage on cell 1 jumps to 4.2 V and on cell 2 to 4.1 V (@ 2.1 A current) according to the charger. In reality it doesn't exceed 4.0 V according to the voltmeter. Internal resistances are shown as 90/50/15/15 mOhm (4S pack). I've read about the hardware limitation that prevents accurate voltage measurement for cells 1 and 2, but 0.2 V error?! Is my unit faulty (it is indeed old) or am I doing something wrong? Previously I'd been blaming my old packs, but started digging deeper after buying new ones, and it turns out to be the problem with the charger itself. Additionally, please share the original firmware for my charger if you have one. I've lost mine after reinstalling the OS. Thanks!

RadioControl commented 1 year ago

Hi, i have a read out from my Accucell6 50W before the Atmega32L were blocked somehow (restore in progress with hvpp). I never tried to reflash the stock fw and i don't know if it is a valid read out. Maybe someone experienced can investigate it... accucel6-50w-oem.txt

intelligentpotato commented 1 year ago

@RadioControl according to this your dump is useless :(

intelligentpotato commented 1 year ago

@RadioControl I found a working backup. Not from this exact model, but it works. https://groups.google.com/g/cheali-charger/c/pz4mmbuzVj0

Unfortunately, it is also showing 4.16 V for cell 1 when charging while in reality it is 3.96 V. I guess my unit is faulty. Any comments are welcome. I will be closing this issue in a day or two.

RadioControl commented 1 year ago

Ok, thanks for the info!

stawel commented 1 year ago

@intelligentpotato

Turnigy Accucell 6 50W running v2.00_20160613.

What is the exact name of the hex file you used?

upd: in the expert calibration menu I only have Vplus and Vminus

if you don't have "Vb0pin", "Vb1pin", Vb2pin" you have flashed a version with "more advanced voltage measurement on first two cells", see: differences-between-versions that's a wrong one (or maybe the old versions didn't have one? I don't remember)

I would try this:

  1. flash you charger with: cheali-charger-Turnigy-Accucel-6-50W-5A_2.02-e10.3.12-[date]_atmega32.hex
  2. make sure you have "Vb0pin", "Vb1pin", Vb2pin" in "options"->"calibrate"->"expert DANGER!"
  3. reset charger: "options"->"reset default"
  4. calibrate charger normally (no need for "expert DANGER!" yet)
  5. check voltages during charge
  6. if voltages are still off: do "expert DANGER!"
  7. check voltages during charge
  8. if voltages are still off: hm... maybe your charger is damaged, repair charger: more info on that when 1.-7. fails
intelligentpotato commented 1 year ago

@stawel oh man, works like a charm! Internal resistance and cell voltage measurement are perfectly on point even without the expert calibration. So it turns out I'd been struggling for months due to my own indiscretion. upd: What's the difference between cheali-charger-Turnigy-Accucel-6-50W-5A and cheali-charger-Turnigy-Accucel-6-50W-6A firmwares? I believe I was running the 6A since that's what's written on my charger.

RadioControl commented 1 year ago

@stawel @diggit

can You confirm that my backup is locked?

diggit commented 1 year ago

Yes , your AVR was locked when you did this backup. You can see patternn in there (ignoring addressing columns). Compare it visually for exame with this hex file https://github.com/stawel/cheali-charger/blob/master/hex/unstable/cheali-charger-ADCKeyboardAnalyzer-150W_2.02-e10.3.12-20230523_atmega32.hex