Voltage differences between cells

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The_shansen

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Arrma RC's
Is there a rule of thumb for volatages between different cells in a pack? For example, I have an SMC 6s 4500 mah pack. My most recent run left 5 cells around 3.7v and one at 3.3v. The internal resistance for that one cell is 16 ohms compared to the 1-4 ohms of the other cells. Is the 0.4v difference between cells okay?
 
Is there a rule of thumb for volatages between different cells in a pack? For example, I have an SMC 6s 4500 mah pack. My most recent run left 5 cells around 3.7v and one at 3.3v. The internal resistance for that one cell is 16 ohms compared to the 1-4 ohms of the other cells. Is the 0.4v difference between cells okay?
Just looking at the internal resistance tells me that battery is bad. And I want to say the threshold is .02v per cell but I could be wrong.
 
Ya I heard that a .1 or .2 difference is all you want. People seem to be having a lot of issues with SMC batteries lately. :-(
 
I noticed this variation with many different cells and brands. I like gensacearespammers as of late and have several other brands. But Lipo's have similar characteristics. And yes you can get a bad pack from any brand no matter what price you pay! But generally you get what you pay for. 16 ohm seems high compared to the rest, but a quality balance charger should bring it back. Resistance in the the range of 1-8 ohms is normal for a new pack. I only care about the resistance when the battery is at rest and fully charged. And I always "Balance Charge" my batts. Resistance tends to stay lower. I don't cut corners/ time by doing a "Regular Charge". I also noticed that not putting the batt packs into storage charge mode "soon" after a bash increases that resistance. If you crash and burn/break something before you dump the pack, remember to remove the remaining power to storage level soon. Leaving a pack for even 4-5 days or more with more or less than 50% charge in them destroys them over time and they start to puff out. LVC on the BLX will generally trigger on average with 10% voltage remaining, which is acceptable, but soon after, I put a "storage charge" right back in. Both my chargers will charge/discharge to between 47-50% when in "Storage Charge" Mode. After a discharge, Lipos really like a storage voltage. They will be happy and live so much longer. And I spend much time on battery care. They are always half charged when not in use, so I'm half fully charged when I prepare for my next bash. And never do any charge if the cells are not at ambient temps. Let them cool/ rest first. This hobby and the fun that it offers is so dependent on Lipo's, so I spend much time caring for them and I notice the difference in performance. Hope some of this helps. Been doing RC of all types for 33 years. Enjoy.
 
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