Originally Posted by linger
Stating that the main and only reason that Lipos puff from RC CAR applications is from the amperage demands is completely off target.
Stick a data logger on any RC car. Peak loads during max acceleration from a highly boosted 13.5 motor is a hair over 50 amps. This is a peak current and is never sustained. Average current over a 6 minute run is about 25 amps. For 17.5, the amp draws are much lower.
This is well under the capability of just about EVERY hard cased lipo, even those with inflated C rates. Even a 15C lipo will easily handle this current range.
Running a lipo over it's usable current results in very high temps. Over 180 deg and the electrolyte starts to break down and forms gas. Temp a lipo after run and it's nowhere near this temperature.
So what causes a lipo to puff?
Lot's of reasons and each has it's own specific failure modes. Here is a list - mostly likely incomplete.
- Immature Formation Process:
- Insufficient Hi-Pot testing during the electrode stacking process
- Insuficient or non-existant incoming material inspection
- Insufficient contaminant filtering of the slurry raw materials
- Bad pouch seal or badly designed pouch seal
My guess on why a bunch of lipos are puffing is due to the immature formation process. This process is highly proprietary to each manufacturer. This can take anywhere from 4 days to 2+ weeks depending on manufacturer. This process takes years to master. A lot of these lipo companies are very new and their formation process is immature. Combine this with a new untested chemistries and you have long term issues.
Sorry, for this tangent to a thread titled "Intellect 50C thread"
Dont be sorry this is very good information and keep it coming not all of us know everything and it is great to learn from different people so your opinion and advice means alot ot me and many others on the thread .
6 months ago i had mentioned contamination in another thread and man im so glad you brought it up as back then i was in a factory where they were mixing raw materials in a bucket and yes in a bucket in an uncontrolled environment and they were applying the electrolyte on the copper sheets with a paint brush in an open area with dust etc .I also saw a switch during producion from one chemistry being lipo to lifep04 within the same machine without being cleaned .I also saw air bubbles in the seal not just one but many small air bubbles .
so yes contamination is a large problem as is quality control .My info comes from extensive testing that we do week in week out and yes some puff and some dont with the same testing procedure.
keep the info coming and i sure we will come to a conclusion
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