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Well I just got new batteries for my RC glider and I'm thinking about what to do with its battery.

For those who aren't in the RC hobby the story goes something like this:

New kid buys a battery and hears that some people recommend breaking in the batteries. After that he asks the question on one of the popular RC forums.

Answers are usually something like "I have xxx batteries and always break them in." or "I never spend the time to break-in my batteries, it's a waste of time." and then threads move to the argue phase where each side tries shows numerous older posts which back one side or another and then they dig up PDFs hidden on manufacturers' sites can be interpreted to recommend breaking-in while the other side argues that many other manufacturers don't mention breaking-in and in the end no conclusion can be made as we have one side with no solid claims trying to refute other side with no solid claims and this all seems so unscientific to me.

One combination that seems to repeat often is to discharge the battery at 0.5 C and then charge it again at 0.5 C for first five times as that will cause chemicals which are supposed to keep the battery stable during shipping to dissolve and provide higher maximum output current.

Such threads are numerous and key word combination that seems to bring them up is "li-po break-in" for those who want the pleasure of reading endless arguments.

Also a bit about the battery requirements: Usually the battery is supposed to provide high current (10 C to 20 C is common, sometimes more), have low mass, low volume, charge quickly ( several C) and last for several hundred cycles.

So my question is: Do you know of any solid guidelines which explain if new batteries should be broken in, preferably backed by some research results or clear and unambiguous instructions provided by manufacturers.

UPDATE The particular type of batteries I'm using don't have electronics in them. They're just bare cells convected together and any electronics which sense battery status are external to the battery itself, so calibration of such electronics isn't the point here.

AndrejaKo
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    Surely this is something to look up in the manufacturer datasheet for the specific battery. If the manufacturer recommends it, do it. If not, then it's just superstition. – Olin Lathrop Oct 25 '11 at 18:14
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    perhaps you could apply some science to the matter, next time buy two packs from the same batch, break one in and not the other. Then alternative between charging and using each cell and store them together (same temperature) and same charge. see which one lasts longer! I would be surprised if there was a difference. – smashtastic Oct 25 '11 at 18:57
  • @Olin Lathrop That's the obvious solution of course, but in this case I'm the end user and don't get the datasheet. Also the batteries are often re-branded (sometimes numerous times) so it's difficult to track down the original manufacturer. Another problem with that approach is that major retailers don't seem to have the type of batteries I'm looking for, so I need to use shops which focus on hobbyists and that brings me back to my first point. – AndrejaKo Oct 25 '11 at 20:00
  • @smashtastic I'll definitely try that one time, but I'm not sure how good results I could get. There are many factors which make an impact on battery lifetime and it's not easy to reproduce the environment closely enough for my liking. – AndrejaKo Oct 25 '11 at 20:01

2 Answers2

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It is normal for a new Lithium (or any advanced type of rechargeable) batteries to require one or two full charge/discharge cycles. The main reason for this is because there are chips inside that control and monitor the status of the battery, and these chips do go through a sort of learning process. Once you do a couple of charge/discharge cycles the chip will learn the details about the battery and be able to give you a more reliable charge level indicator.

I see this a lot with cellphones, ipods, and other devices where the battery is integrated into the device. Most people charge their iPhones every night, even if it still has a 50% charge on it. Over time the battery controller chip will loose track of what a full discharge is (since it never sees a full discharge) and so the battery indicator will get progressively more inaccurate. Doing a couple of full charge/discharge cycles will force the chip to relearn how the battery behaves and the status indicator will be accurate again.

I know of no reason, other than what's stated above, for a battery pack to require a breaking in period.

Battery life is one of those things that tends to create a lot of myth, folklore, and urban legends. Googling for "battery myths" brings up 14,100 hits. It's possible that what I wrote above was generalized and mutated into something like, "Batteries don't reach their full charge capacity unless they have been broken in".

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    good answer - the chips are called gas gauges that are used to monitor the cells. – smashtastic Oct 25 '11 at 18:55
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    @David Kessner Interesting. This mad me aware of one problem with my question which I'll fix shortly. The batteries I'm referring to don't have any electronics in them at all. They just have two connectors: one which provides main power and from its point of view all cells are connected in series and another often called balance connector which gives access to each individual cell. It's up to charger to determine the state of the battery. – AndrejaKo Oct 25 '11 at 20:06
  • This answer states that the controller *learns* the maximum discharge by observing when the battery has run out, but [this answer](http://skeptics.stackexchange.com/questions/5102/does-recharging-a-battery-when-it-is-only-half-way-dead-decrease-its-life-span/5103#5103) states that the controller *sets* the maximum discharge to some arbitrary amount, because allowing the battery to discharge fully would kill it. You can't *both* be right... can you? Do you have any sources for this claim? – BlueRaja - Danny Pflughoeft Nov 02 '11 at 15:25
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    @BlueRaja-DannyPflughoeft You're confusing different issues. The max and min VOLTAGE are somewhat fixed in stone. But total energy capacity (Watt-Hours) can vary. What is learned is the capacity. If all you looked at was the battery voltage then you wouldn't know much, or what you did know wouldn't be that accurate. That's because the battery voltage vs. actual stored energy is not linear (or even consistent over the life of the battery). The controller learns what the battery voltage means in terms of the amount of energy stored. –  Nov 02 '11 at 20:59
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The text below allegedly comes from a few pages from a LiPo battery manufacturer

While I do not know if LiPo are usually provided in the "initial state" mentioned here it would make the advice received make considerable if not total sense. However, t seems unlikely that they would be shipped in this state BUT it may explain the "rumors".

  • When Lithium Polymer cells are first charged, lithium ions are transferred from the layers of the lithium cobaltite to the carbon material that forms the anode.

  • Subsequent discharge and charge reactions are based on the motion of lithium ions between anode and cathode.

Here's a data sheet for a Microchip charger IC that is specifically aimed at LiPo use (also LiIon). A quick read right through did not show any mention of first or early charge regimes. Even if these are not implemented, they are liable to be mentiond in such a document (Thy o mention several other things that it does not do).

In a look through several dozen documents referring to LiPo charging and use I saw NO mention of preconditioning. None of these were R/C hobby sites.

Russell McMahon
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  • Actually the text in the point 6.8 mentions the long term storage. One of the mentioned things is that it may take several cycles to restore full capacity. However it does not mention any negative long term effects on the battery itself and does not say anything specific on the load during those several cycles, which is an important point for the myth. – AndrejaKo Oct 25 '11 at 20:22