Lipo interal resistance
03-09-2011, 08:35 PM
#2
Caveat, from what I’ve seen and read the measurements frequently vary a lot from device to device. Significantly temperature dependent, somewhat by charge state, etc. Probably need to get a device and keep records from new to really know.
Using a Hyp Duo3, name brand 45 to 50C 2S packs, I’m seeing 8 to 11 mOhms when new, dropping down to around 5 to 6 after many cycles (I strive to follow best care and storage rules).
Some older 25C packs (that I frequently stored fully charged) measure 20 to 40 mOhms. They are way noticeably different in power. (And run time)
Using a Hyp Duo3, name brand 45 to 50C 2S packs, I’m seeing 8 to 11 mOhms when new, dropping down to around 5 to 6 after many cycles (I strive to follow best care and storage rules).
Some older 25C packs (that I frequently stored fully charged) measure 20 to 40 mOhms. They are way noticeably different in power. (And run time)
03-09-2011, 08:55 PM
#3
Tech Master
iTrader: (3)
Only individual cell values are useful and need to be taken at a reference temperature
Use the following formula
12000 divided by size of cell in mah
Example
12000 / 5000mah = 2.4
Anything under 2.4 milliohms is a very good cell
Overall pack values will include connectors and wires which can vary a lot
A fella over at RCgroups sells a great device for measuring both cell and pack IR
Cheers
Use the following formula
12000 divided by size of cell in mah
Example
12000 / 5000mah = 2.4
Anything under 2.4 milliohms is a very good cell
Overall pack values will include connectors and wires which can vary a lot
A fella over at RCgroups sells a great device for measuring both cell and pack IR
Cheers
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