Battery Questions…

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I just purchased a Phantom 4 Pro from a woman who’s husband recently passed. She said he flew it a couple of times before he got sick, but that was four or five years ago. So, I buy this drone, which looks like new, but the battery wont charge. After reading on the internet it appears it can be reset (maybe) by getting into the case, but it hasn’t had a charge in a very long time. At this point, would the cells be dead? My question…. Is it a waste of my time to open this battery up and see if a reset would work, or should I just get a new battery? Thanks for any advice you might have.
 
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Lithium batteries are pretty explosive if you don’t know what you’re doing. I’d opt for new or good used battery myself.
 
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I‘ll go with a new battery! It looks like the controller battery is working. I get four white lights, but being that old maybe I should replace it as well? I’d hate for it to stop working mid flight!
 
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It's likely that the original battery self-discharged to zero volts, or to below the voltage threshold that the built-in smart battery circuitry will let you recharge it. This can happen to any LiPo-based smart battery that isn't properly maintained, which is why I call them "pet batteries" since they need "proper care and feeding" to survive/not burn down your house or car.

DJI smart batteries (and other smart batteries) are "smart" because they have built-in microprocessors/circuitry that, after a time, discharges the batteries to a safe storage voltage to reduce the risk of the battery bursting into flames in storage, which is relatively rare but a real risk. Typically, the proper storage voltage for LiPo-based batteries is about 3.8-volts/cell. So for a smart battery in long-term storage, the smart circuitry automatically reduces the voltage to 3.8-volts per cell and then normal self-discharging will continue to discharge the battery to zero volts unless the battery's owner intervenes to maintain the battery properly.

All chemical-based batteries self-discharge at some rate, even when not in service like when "sitting on a shelf" in storage. This is normal and why chemical batteries have a "shelf life." According to online sources, LiPos have a low self-discharge rate of approximately 5% per month, which may be a bit higher for smart batteries since the battery powers the battery’s internal microprocessor/circuitry.

Once a LiPo battery is discharged during use or self-discharges below 3.2-volts/cell, it's junk and shouldn't be recharged. This is because crystals begin to form within the battery that can short it out internally, which is one reason a LiPo battery can heat up, melt the Mylar shell exposing the internal chemicals to the atmosphere, and burst into flames. If not properly stored in away that can contain the heat and flames of a LiPo meltdown, the battery can burn down your house or car.

So, I think it will take a neglected LiPo that was put into storage at 3.8-volts/cell to self-discharge to below 3.2-volts/cell about (3.8 - 3.2) / (0.05 x (3.8 - 3.2) = 20 months or about 1.67-years to junk itself by dropping below 3.2-volts/cell. Again, the time will be a bit shorter for a smart battery. Somebody should check my math.

There are probably billions of LiPo batteries stored properly and improperly all over the world, but fires from LiPo meltdowns seem to be rare or not news worthy, but they do happen.

I store my LiPo batteries in metal 50-cal ammo boxes. I “vent” the boxes by cutting about 1-inch of the rubber gasket out of the lid at the hinge line, so if the batteries within meltdown, the boxes are less likely to trap rapidly expanding gases and explode. The ammo boxes also help to contain the heat and flames, venting hot gases and smoke in a known direction (out the “vent”). If and when LiPo batteries do light-off, it's safe to assume the smoke is toxic and may injure or kill you.

The bottom line is, be careful with LiPo batteries. Know how to care for and store them safely.
 
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I just purchased a Phantom 4 Pro from a woman who’s husband recently passed. She said he flew it a couple of times before he got sick, but that was four or five years ago. So, I buy this drone, which looks like new, but the battery wont charge. After reading on the internet it appears it can be reset (maybe) by getting into the case, but it hasn’t had a charge in a very long time. At this point, would the cells be dead? My question…. Is it a waste of my time to open this battery up and see if a reset would work, or should I just get a new battery? Thanks for any advice you might have.
Do not take the chance with the original battery, even if you like to tinker. Spend the cash for peace of mind.
 
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