18650 down to 2.3volts?

forcefed

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Oct 27, 2017
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I plan to use ridgid battery packs in my ebike, i decided to drain 2 battery packs in a drill until they stopped working just to see how low they'd go. To my surprise i measured 11.5 and 11.9volts in them, if you divide that by the number of cells inside which is 5 you get 2.3 and 2.4volts per cell.
Is ridgid using some magical battery that allows this low of a voltage? The charger easily charges them back up to 20.4volts or 4.1v each. They warranty these batteries for life so i'd imagine they'd want to stay on the safe side but 2.3v seems somewhat low, am i missing something or should i just not worry about it and set my low voltage limit to 12v for the battery pack?
 
anything under 3v is basically killing the cell. there is no energy below 3v anyway.

if the bms triggerd at low voltage is because udner load (driving) you pull the voltage down and they want to prevent false triggers so they put the LVC way to low. this also prevents people complaining about dying batteries before the warranty runs out. usually companies (apple turned this into a engeneering artform) make a battery lifespan basically 1 month after warranty.
 
I agree they set the low cutoff lower than you really would want to compensate for the voltage sag under full load. If it trips under full load, the cell voltage will immediately bounce back up to something that's hopefully in the healthy range.
 
Check with second meter or put a new battery in the meter you are using. After run to cutoff check voltage. Put on charger for 10 sec. Check voltage. Maybe just reset in the BMS because the Charger won't be able to charge it up to 16 volts in 10 seconds. It just my guess.
Now Im going to run down my porter cable 20v pack to see what happens. Nobody else ?
 
999zip999 said:
Check with second meter or put a new battery in the meter you are using. After run to cutoff check voltage. Put on charger for 10 sec. Check voltage. Maybe just reset in the BMS because the Charger won't be able to charge it up to 16 volts in 10 seconds. It just my guess.
Now Im going to run down my porter cable 20v pack to see what happens. Nobody else ?

Meter is fine, newly charged battery reads 20.9v.
I put the battery back into the charger for 10 seconds and it read 16.7 volts, but then dropped to 12.3 after a minute.
 
Just depends which cells are in your pack.
Many of the newer 18650 NMC cells are specified for capacity testing down to 2.5 volts,....
... though as others have said there is not much capacity or power to be gained below 3.0 v
Other tests (Tesla cells) have suggested that taking the voltage down to zero on some cells has no apparent harmful effect. ( other than making recharging tricky on a standard charger). Cell performance and life appear unaffected !
BUT.....all cells are not the same, and discharge abuse can instantly destroy some cells.
 
I found on net "Confidential" Technical informations from LG for their HG2 cells, where they test the cells down to 2V. But in "Confidential" datasheet for LG HG2, there is stated only 2.5V value as LVC :? . The same 2V LVC value I saw also in some document for SONY VTC cells. But as was said before, I do not see the benefit of doing that under normal operating conditions. Only in case, when operating cell under low temperatures, makes sometime sense to extend voltage range limits.
 
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