UNIVERSAL LIPO ESR METER INSTRUCTIONS January 2016 1
GENERAL Thank you purchasing your Universal ESR meter. This is the latest (and probably final) version of the meter which I first produced in 2010 and incorporates all the improvements and extra features introduced since then, also combining the capabilities of the standard 2S – 6S meter, the 1S – 6S meter and the now discontinued Single Cell meter.
This calculator has now been incorporated into the ESR meter together with several other additional features such as charge state, Low Cell voltage warning and Over Range warning. This means that the user can now input the capacity of the LiPo into the meter and read out the maximum safe current and the real practical “C” value of the pack directly. The new version of the meter reads:LiPo Pack Voltage. LiPo Pack ESR ( Includes the resistance of leads + connector) LiPo Cell Voltage for each individual cell.
OPERATION The unit is normally self powered by the pack under test, the only control being an operate button. ESR is measured at high current to simulate real operating levels. When connected to the pack, the display will read “Hold to set mAH” for approx. 3 seconds and then default to reading Pack voltage. If you wish to just read Pack and Cell voltage, Charge State and ESR you can do so by toggling the operate button for Pack Voltage and ESR without connecting the search lead.
Absolute Maximum Input Voltage: 30V. Protection: Unit is protected against reverse polarity on both main power and search wire inputs. Limit warnings: The meter will display “Cell voltage below 3.20V” for a low cell voltage. The display will read “ESR Over-range” for Pack ESR of >250mΩ or Cell ESR of >35mΩ Range: The unit can measure any LiPo pack of 1 – 6 cells in the range of 100mAh – 10,000mAh. Note: There is no upper limit to the capacity of a lipo pack or cell that the meter will read ESR.
OPERATING NOTES (a) Temperature The ESR of any LiPo is dependent on temperature; the lower the temperature, the higher will be the ESR. When comparing two packs therefore it is essential that you do so at the same temperature. Leave the two packs together for an hour or two to ensure this. To demonstrate this, take a cell reading of cell 1 on a pack. Hold the palm of your hand against the flat side of cell 1 for only 15 seconds and take another reading. You will see that the ESR has fallen slightly.
(d) Error Warnings (i) If you try to measure a pack which has an ESR >250milliohms or a cell of >35milliohms, the meter will display an “Over range” warning. (ii) If any cell is less than 3.20V, the meter will display “Cell Voltage Low” and the meter will not measure ESR. Pressing the button will display the actual cell voltage for 3 seconds and then default to the low cell warning. Note that the meter will only read cell voltages down to 1.
This will clearly demonstrate the self heating effect and consequent fall in ESR as the battery temperature rises. (g) The “LiPotool” The original ESR meter was designed and built as an aid to my testing of LiPo batteries several years ago as the IR of a cell tells more about its performance capabilities than any other parameter.
It is somewhat conservative; aiming at a max continuous current which should ensure that your LiPos have a good lifespan. In real flying the LiPo will be subjected to surges and a practical safe surge is probably about 40% greater than the safe continuous current for the region of 10 seconds or so. This represents doubling the heat dissipated within the pack for the duration of the surge.
(i) Measuring Single Cells The meter is capable of measuring cells as small as 100mAh but the 4 wire Kelvin measurement, and therefore the Lipotool calculation, cannot be made because there is no balance connector to plug the search lead into. In any case, such small cells have IR values outside of the Cell Mode measurement range 0f 0 – 35milliohms and can therefore only be measured in Pack mode where the range is 0 – 250millioums.
ESR METER ANALYSIS VERSION – OPERATING SEQUENCE Key: “PB” = Push Button Momentary “PBH” = Push button and hold >2Secs ACTION DISPLAY RESULT NOTES Connect Main Power Lead Option: PBH to set mAH* After 3 Seconds ESR Meter ver 2.0 Hold to set mAh Display lasts 3 secs only ESR Meter ver 2.0 Pack = XX.XXv Reading Pack voltage PB – Audible bleep. ESR Meter ver 2.0 Pack ESR = XX.X m.Ω ESR Meter ver 2.0 Pack = XX.
PB - Bleep Cell ESR = XX.XXm.Ω (“C” = XX max I = XXXA)* Reading Cell IR, Real “C” value and max safe current for Cell 2 Repeat last two steps for each cell * Setting the pack capacity in order to calculate Real “C” and maximum safe current. PBH – 2 secs – Set mAh hundreds Now ready to take Bleep – Release.
