QUALITY CONTROL:
Quality control is a joke in most China factories. Incoming material inspection, statistical process control, in-process measurements, Hi-Pot testing, six sigma etc are completely foreign concepts. In a lipo cell, the main source of failure is from internal shorts. In most cases, an internal short burns off a little material, creates a little gas, and you have a puffy cell with less capacity. Othertimes, the short can melt enough of the separator which causes shorts in other areas of the cell and the chain reaction causes a flame situation. These shorts may be prevented in manufacturing with good control over contaminants and manufacturing burrs. All the top tier manufacturers will have automated Hi-Pot testing where a large voltage is applied (200-300 volts) before the electrolyte is applied and the resultant current is measured - high current means that something is shorted out. The China factories don’t do this. The top tier factories will have specialized equipment to transfer material without exposing it to the environment thus reducing contaminants. The China factories literally use cooking pots and scoop them out manually. I could write a whole book about what the China manufacturers do wrong with respect to quality control, like how they measure coating thickness on a moving roll with a micrometer!!!, but I won’t bore you guys with that.
When asked about their failure rate after manufacturing – the China sales rep was proud to say that 0.3% of their cells swell up just sitting on a rack after manufacturing due to internal shorting – who knows how many cells are close to shorting out internally. Out of only 1 million cells – that’s 3000 failures. I asked a top tier manufacturer the same question – they produce 4 million cells a month – in 1 year, or 48 million cells later – they had a total of 0 cells swell up by themselves after manufacturing. 3000 cells out of 1 mil failure or 0 cells out of 48 million cells failure – that’s what you are paying for.

PERFORMANCE:

Current Rating – Most of the top tier manufacturers are fairly close to their published current rating. I find that most all the manufacturers are a little optimistic in their C-rating. Some of the China cells do live up to their C-rating, but I’ve tested some 20C rated cells from China that are virtually destroyed at a modest 10C discharge rate. Basically, there is no guarantee that a 20C cell from China can really do 20C. Some of the cells from China actually can do 20C and they hold a higher voltage than the top tier manufacturers - due to more volatile cathode chemistry, but at the expense of safety (see the safety section).

Cycle Life – the cycle life of the top tier manufacturers is stunning. I’ve tested many cells that perform just as good on their 400th cycle as they did their first. For whatever reason – every China cell has a degrading profile, where the capacity drops slightly every cycle. The rate of degradation varies depending on manufacturer. Some don’t last 100 cycles, while others are about 80% capacity at 300 cycles. The bottom line is that the cycle life is virtually guaranteed with a top tier manufacturer and it’s a crapshoot when you buy a cheap cell.

SAFETY:

The first step in safety is a top quality cell construction (see quality control). The elimination of contaminants and internal shorts is good prevention. I’ve tested enough cells to know that there is not a single Lipo cell on the market that can take an extreme overcharge condition without going up in flames. The distributors that show a little video about how the cells “can’t” be ignited through overcharging are sending the wrong message. Give the cell to me, I guarantee you that I can ignite it (except for the A123 Li-Ion cell). The next step in safety is the cell design itself. Most of the China cells use pure LiCo2 coating on the cathode which is the most volatile and also the most powerful molecule. That way, they have a great looking discharge curve for the first few cycles. Most of the top tier cells will have other additives that greatly reduce the volatility and also suppresses voltage slightly. This means that the cell can take a higher temperature before it reaches thermal runaway, and even if it does reach thermal runaway, the resultant flame is much less. I’ve purposely overcharged and ignited China Lipo’s and all of them turn into immense flamethrowers that burn for about 30 seconds. When I purposely ignited a Kokam cell, it’s chemistry self extinguished in about 2 seconds – the flame was an order of magnitude less than it’s China counterpart. Furthermore, the Kokam cells use the negative tab as a built in overcurrent fuse. If you short out the cell, the negative tab vaporizes and creates an open circuit.

I have yet to visit a “top tier” manufacturer in China, though I admit, I haven’t visited all of them, but I’ve visited enough to understand their pardigm. However, these Chinese factories are evolving at an accelerated pace. These low quality factories may equal the quality of top tier manufacturers in just a few years, but they definitely aren’t there yet. Just about every China factory I visited was in the process of building another newer, better factory. I’ve referenced Kokam as a top tier lipo manufacturer. There definitely are more top tier lipo manufacturers and some even have superior manufacturing quality vs Kokam, but their pricing is the same as Kokam – which is nearly 4x more than their equivalent China counterpart. The top tier manufacturers admit that the RC market rates price over quality and it’s obvious that the low price lipos are now dominating the RC marketplace. The good news is that some of these top tier lipo manufacturers are currently teaming up with top tier RC manufacturers to come out with high quality and high performance packs though I guarantee you that they won’t be able to touch MaxAmps pricing.

So there you have it. Other than the hard case – this is why the Peak/Team Orion Lipo is so much more expensive than their competitors.