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Thread: lipos

  1. #1
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    lipos

    What does it mean to cycle a lipo batteries every 5-6 weeks If i want to store them for a long time (6months)

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    Charge it and discharge it?

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    RC Turnbuckle Jr. Jimdog's Avatar
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    Yep. Just discharge, recharge, then return them to storage voltage again.
    This will TOTALLY work, saw a guy on YouTube do it

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    RC Qualifier Panamon Creel's Avatar
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    Quote Originally Posted by Jimdog View Post
    Yep. Just discharge, recharge, then return them to storage voltage again.
    I'd say other way around, first balance charge then discharge then charge back to storage level. Reason behind this is that cells may go out of balance during storage and discharging first may bring a cell into a critical low voltage if the means of discharge does not account for out of balance cells.

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    Depending on your brand of charger, you may have a low current storage charge setting. Mine does. For storage of a few weeks to a month or more, discharge your battery until it hits 3.85V per cell.
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  6. #6
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    Lipos can only catch on fire while being charged correct? They can Not catch on fire while sitting on a shelf at home? just got around to my toy (erevo)charged batteries it came with but it only lasted for about 10-15 minutes. Ordered 2 batteries from spc and 2 from scm for 4s and 5s configuration. Is it enough to keep them in a lipo bag at home or should I invest in fireproof safe? I don't want to scare my wife and kids by telling them it could be dangerous. My wife would never allow it in my house. Where do i keep it?any help would be appreciated. Just waiting for the batteries to arrive. I already bought hyperion 720i super duo plus power supply .i can't wait, but I'm a little worried

  7. #7
    Marshal ksb51rl's Avatar
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    lipos

    Quote Originally Posted by Panamon Creel View Post
    I'd say other way around, first balance charge then discharge then charge back to storage level. Reason behind this is that cells may go out of balance during storage and discharging first may bring a cell into a critical low voltage if the means of discharge does not account for out of balance cells.
    I'm sure I would not consider this bad advice, but I do have some thoughts on it...
    The cells of a healthy, balanced LiPo pack should not self-discharge more than a few dozen, maybe a couple hundred milliamp-hours in a month to a month and a half. I don't believe that amount of slow discharge can cause a noticeable imbalance.
    Secondly, there is certainly no reason to discharge past the point where we would stop if actually using the vehicles, nor even an 80% depth of discharge. Whether running normally or cycling, you should not get close to a critical low voltage level, and therefore there should be no danger either way you chose to cycle.
    I think I would advocate something slightly different, more rigorous, more time-consuming, and hopefully more effective.
    I would start with a balance charge. I would then discharge down below storage level, and then charge back up to storage level. I don't do this because I'm concerned with damaging my cells, but because I consider this method to be a more complete cycle.
    Still, I think any of the three methods would work acceptably.

    As for catching on fire just sitting on the shelf, I suppose it is possible for some sort of freak occurrences to cause this. Fire needs fuel, oxygen, and an ignition source. I am very skeptical that an ignition source can be created while in a static state. One may as well believe that tornados are able to drop sharks onto one's lap.
    Last edited by ksb51rl; 07-28-2015 at 09:40 PM.
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  8. #8
    RC Qualifier Panamon Creel's Avatar
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    Quote Originally Posted by ksb51rl View Post
    I'm sure I would not consider this bad advice, but I do have some thoughts on it...
    The cells of a healthy, balanced LiPo pack should not self-discharge more than a few dozen, maybe a couple hundred milliamp-hours in a month to a month and a half. I don't believe that amount of slow discharge can cause a noticeable imbalance.
    Secondly, there is certainly no reason to discharge past the point where we would stop if actually using the vehicles, nor even an 80% depth of discharge. Whether running normally or cycling, you should not get close to a critical low voltage level, and therefore there should be no danger either way you chose to cycle.
    I think I would advocate something slightly different, more rigorous, more time-consuming, and hopefully more effective.
    I would start with a balance charge. I would then discharge down below storage level, and then charge back up to storage level. I don't do this because I'm concerned with damaging my cells, but because I consider this method to be a more complete cycle.
    Still, I think any of the three methods would work acceptably.

    As for catching on fire just sitting on the shelf, I suppose it is possible for some sort of freak occurrences to cause this. Fire needs fuel, oxygen, and an ignition source. I am very skeptical that an ignition source can be created while in a static state. One may as well believe that tornados are able to drop sharks onto one's lap.
    True LiPo batteries have a very low self discharge rate and usually very little difference in internal resistance between the cells when they are new but as they get older/more used that perfect world may change.
    Personally I don't even cycle LiPo batteries that are in for longer storage, I check them occasionally and balance charge them back to storage Voltage if any of the cells is close to or falls below 3.5V but that's me.

    As for LiPo fires, well a healthy LiPo battery that's well cared for and is not getting overdischarged or severely overcharged should not go up in flames.
    Could a neglected and/or abused LiPo go up in flames while sitting on a shelf, low likelihood but it is possible thus some precautions are recommended (better safe then sorry)
    This danger comes from the electrolyte which contains organic compounds that can release flammable and caustic gases if the electrolyte disintegrates and ignition source can be a spark from a short between cells.

  9. #9
    Marshal ksb51rl's Avatar
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    ^^^ All very true. My office's safety manager would certainly approve that your recommendations stem from an abundance (but not over-abundance) of caution.
    FWIW, that's me.
    I just suppose I've become accustomed to explaining safety in a way that others will accept - "it's easier," or "it's faster," or "it's more thorough," or anything so that they don't tune out the underlying safety message. It can be hard to convince people to keep all of their fingers and toes.
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