LiPo Supply Quality

[Bravedan 106]

In the last year I have experienced a rising level of new LiPo reaching me in unsatisfactory condition. Since 1st Jan 18 EVERY new supply received has had some significant issues.

This from UK supplier/brands, Chinese supplier direct and from (different) Chinese supplier with UK warehouse, so it seems not to matter where the final supply comes from.

Purely as an example, yesterday I received four 1300mAh 3S. As usual I immediately tested with three differing testers for positive confirmation, but as one is an ISDT unit that has been proven to be reliably accurate, I will only quote its data here.

Pack 1 - 3.75v average per cell with a range of 8mV
Pack 2 - 3.76v average per cell with a range of 11mV
Pack 3 - 3.02v cell one, cells two and three below ability of tester to measure so 0v shown.
Pack 4 - 1.82v cell one with tester resistance causing it to slowly drop further, cells two and three 3.6*v

 

Pack 3 on a high quality multimeter gave 5.44v across the pack, with cells at 3.02v, 1.24v and 1.15v

I have charged packs 1 and 2 and they completed charge (on a verified good charger) as follows:-

Pack 1 - 4.191v average per cell dropping after an hour to 4.183v, at that time a 2mV range
Pack 2 - 4.18v average per cell with a range of 12mV, voltage has held overnight.

The previous new supply from a different source and brand were three 2200mAh 3S, and briefly one had a shorted cell 2 so pack indicated as 2S, and another was so unbalanced that there was no way I was about to use it. (These were not budget priced items)  When claimed within an hour of tracked delivery they were replaced under warranty, then one of the two sent was badly out of balance but did balance after a couple of cycles.

SO.............checking packs VERY carefully on supply is essential!

1. I hope you are carefully check new packs before charging for use?
2. In the light of above, you may like to review HOW accurately you check new packs?
3. What level of failures are you seeing?
4. Have you had issues getting warranty replacement?  (I have not, which suggests that the suppliers KNOW they are on dodgy ground!)

What does worry me is that in theory the possibility of a failure to thermal runaway (and poss fire) must also be increasing with such erratic supply quality.

Whatever, be careful, supply quality is definitely dropping!!!