Socond hand lip04 battery test

spacebass

Here in Thailand there are a lot of smallish lirthium batteries for sale with pictures of. boxes of them tempting one.
At the moment I am looking at 200 ah 3.2 v lipO4 at 2000 thb each about $65US each , accompanied by a car battery meter photo that I know is meaningless thanks to this board.
Is there any  reasonable test that can evaluate a second hand  lithium battery ? 

mcgivor

Are those 200Ah cells, they look more like 100Ah judging by the physical size though it hard to do so by a picture without reference. To test them a capacity test by fully charging then dischargeing at a constant current whilst monitoring the voltage and measuring the time it takes to approach the lower knee of the curve ~3.000 volts. Care must be taken not to go below the knee as the voltage will collapse rapidly resulting in damage, the same applies when charging the voltage will Spike after 3.650 volts.

One could check the cell voltages they should be ~ 3.300 V and all cells should be within 10 mV if properly stored, they should definitely not be higher or lower, not an ideal method as it has nothing to do with the residual capacity, but will give an indication if they were stored correctly.

My supplier has new CALB 200AH cells for $135, the 100Ah I purchased were $65 in September 2018 not CALB, personally I wouldn't buy used especially In Thailand unless a farang who knew what he/she was doing, was the seller.

spacebass

I think I agree with no buy 2nd hand they butare advertised as 200 ah 3.2 v  new twist as just translated Thai text seller says they are new and weigh 6 kgs each if that says anything .
This is the weight of a 200 ah 12v comprising 4 x lip04 battery pack on amazon : 'size:278*180*280mm | weight:25kgs' includes some fittings.

mcgivor

With a weight of 6 Kg each, that would be consistent with 200Ah, CALB are listed at 5.7kg, would be an OK deal if there were some assurance they are in fact new, if local it may be worth checking out...... but then again it involves taking a chance. 

spacebass

Thanks for your input K..Mcgivor , I am edging towards taking a chance , then he will be sold out !!

Battery_Man

mcgivor said:

Are those 200Ah cells, they look more like 100Ah judging by the physical size though it hard to do so by a picture without reference. To test them a capacity test by fully charging then dischargeing at a constant current whilst monitoring the voltage and measuring the time it takes to approach the lower knee of the curve ~3.000 volts. Care must be taken not to go below the knee as the voltage will collapse rapidly resulting in damage, the same applies when charging the voltage will Spike after 3.650 volts.

One could check the cell voltages they should be ~ 3.300 V and all cells should be within 10 mV if properly stored, they should definitely not be higher or lower, not an ideal method as it has nothing to do with the residual capacity, but will give an indication if they were stored correctly.

My supplier has new CALB 200AH cells for $135, the 100Ah I purchased were $65 in September 2018 not CALB, personally I wouldn't buy used especially In Thailand unless a farang who knew what he/she was doing, was the seller.

Hi, where did you buy CALB cells? CALB has set up official agent and only one in China since end of 2019. Price with USD135, should be ok, but from official channel? If price with USD65, it's definitely used cells.