RCU Forums - View Single Post - LiPo overcharging (experiment, questions)
Old 04-17-2008 | 07:42 PM
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Default LiPo overcharging (experiment, questions)

I am planning on starting my next LiPo 'experiment' soon, but first I thought I would ask here for ideas.
I'll post the ongoing results here as I have for the previous experiments like the break-in one, but it is to be expected that the subject battery in this experiment will be sacrificed, or at least rendered useless, so I only get one shot at this.

My motivation for posting the results publically is twofold not to encourage the practice, but first to negate any IP concerns and then to avoid the 'sham of science' that happened with NIMH batteries, that is, 'secret' processes like 'zapping' that people insist work but no one will discuss in specifics or detail, or 'tricks' or 'marketing gimmicks' like pulse charging that have no scientific or real value whatsoever. If indeed overcharging produces no measurable results we don't want companies to push the myth and attempt to profit from it if it does produce measurable results then it should either be open to anyone, or better yet (IMO) racing bodies need to be made to understand this and either allow it or come up with an actual protocol to deny its use (like actually checking LiPo battery voltages immediately before the race).

Here is the background, basically with LiPo now being allowed in racing, and pro racing being what it is, the idea is to quantify the effects of overcharging. With NIMH overcharging was harmful and would not offer any kind of advantage whatsoever. Overcharging would depress the voltage and also cause cell damage. Now LiPo is another story, there just isn't a lot of information out there, at least not recent or useful information that I can find. There is some information about older Li-Ion tech but this is not really useful from my perspective.

From a racing perspective:
Starting voltage and voltage hold-up is of prime importance in the highly competitive stock and super stock class. Pro racers are always seeking and advantage over the competition, and like football, racing between experienced contenders can come down to a 'game of inches'. Anyone who has raced before knows the importance of being able to pull ahead of 'the pack' as early as possible in the race. For racers, overcharging may (or may not) provide an advantage in acceleration and speed at the beginning of the race, even if it means having to sacrifice a battery now and then or shortening the life of your batteries overall.

From a testing perspective:
I can't think of a simpler procedure here, basically charge the LiPo normally, then overcharge it slowly on a current-limited power supply, and finally do a discharge test similar to the discharge tests I did before with the LiPo break-in experiments (probably with a voltmeter for added precision). The big question is what voltages to use. I will be using a single cell and a small one as to minimize the safety hazard. I was thinking 4.2V, 4.23V, 4.25V, and end with 4.2V at first in order to see if any gain can be measured from these minimal overcharges.

And obviously "don't try this at home kids", stay safe, this is really of no value to bashers or club racers who race for their own recreation. Undoubtedly you will shorten the lives of your LiPos if you do this regularly, and extreme overcharging is a big safety hazard and should be avoided.