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Battery question: sitting for days, and then...

Discussion in 'Pro/Adv Discussion' started by MikeyOnline, May 7, 2016.

  1. MikeyOnline

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    Now that I have two batteries, I sometimes find myself in the situation where I fully charge one and it'll sit for say 5 days before I fly with that one again. When I insert the battery, it still says 85% to 90%. Would you guys just fly with that to run it down... or charge it back up to 100% before you fly? In the back of my mind, I'm just wondering if the percentage is still accurate on a "stale" battery and if it says 86%, will I really get what I expect without topping it off. Interested on how you guys handle that and what's best for the battery. Related: wondering if I know I'm taking a longer flight, does it "hurt" the battery to top it from like 85% to 100% before a flight?

    TIA,
    Mike
     
  2. Fplvert

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    Top off the battery. There have been reports of erratic behavior if the battery has started auto discharging.
     
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  3. Jtrjr

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    Mike,

    This is just what I do, not necessarily what is proper. I always try to run my batteries (I have 10 for my P3's and 5 for my P2) down to 30-50% before I leave them laying around for several days or weeks. If I have a battery that was fully charged but I didn't use it and it sat around for more than a few days, I "top" it off before I fly with it. I put it back on the charger, if it doesn't start charging, I turn the battery on (while connected to the charger) that will usually initiate a final charge. I believe there is a balancing process that takes place at the end of the charge.

    Even if I can't fly and I'm not certain when I'll be able to do so again but I've already charged a few batteries, I'll run them back down to 50% or below before I leave them lay around for a while. I don't think leaving batteries fully charged is good for them. There is an "auto-discharge" process that takes place after so many days of sitting around. I think the default setting is 10 days. I just don't let them get to that point. I changed mine to start the auto discharge process at 5 days but I rarely leave them laying around fully charged for more than a couple of days. I haven't had a single battery issue (yet :)) using this process.

    I'm sure there are many people here that can provide better and more technical insight, this is just the way "I" choose to do it.

    Jerry
     
  4. ryantrax

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    What is your auto-discharge setting set to in the DJI Go app? It sounds like they have already started the discharge process. I normally top mine off before flying.
     
  5. alokbhargava

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    I usually top them off to 100% previous night. These percentage values are calculated values, actual values might differ.

    These batteries are rated for 4480 mAH. What you should do from time to time is to check how much battery capacity has degraded to. With the RC and AC on with fully charged battery, open up the DJI Go app and go to battery section and check the capacity of the battery. You will find it less than 4480. If you find it around 4000, it means that has come to go for deep charge discharge cycling to rebuild the lost capacity. DJI suggests to go for deep discharge cycles after 20 charges. I find it better to check the capacity of the battery and decide about it. As the batteries get older, you may have to go for deep discharging frequently. I follow a thumb rule that if capacity shown has degraded more than 10% of the fully developed capacity, i go for deep discharging.

    Hope this helps you.
     
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  6. alokbhargava

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    Setting Auto discharge number of days is an important setting. Three factors should be kept in mind:

    1. Keep batteries in fully charged state to minimum time
    2. Reduce number of charges
    3. Better to store batteries at 50-60% charge

    If you fly only on weekends, a setting of 3 days is good enough. If you fly everyday, you can leave the setting at 3 to 10, higher is better as you don't want to start unnecessary discharge cycle.

    Example:
    So if you are a weekend flier:
    1. Charge the batteries to 100% on Friday night
    2. Fly with fully charged batteries on Saturday and charge them back to 100% after use when batteries are not hot
    3. Fly with fully charged batteries on Sunday and charge them back to 60% after use when batteries are not hot
    4. Ensure you have set 3 days discharge cycle. This will ensure that even if you have not used a battery, it will be automatically discharged from 100% to 60% after 3 days.

    You can modify the charging/ discharging pattern based on your usage of batteries.
     
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  7. MikeyOnline

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    Thanks everyone for the useful info! That answers all my questions (and a few more).

    Mike
     
  8. piperjon

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    If you read up about Li-Po batteries you will under stand it is not good the have the sitting round fully charged. The rule is to only half charged to sit round for along time. Each cell should only be charged up to 3.8 per cell. This gives the battery a long life. If you continue to fully charge the battery and not use it for weeks you will see what the battery will do. They do swell up and are un safe you use.

    Read by googling "Getting to know Li-po batteries"
    John
     
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