Anyone “repurpose” old batteries?

[Kranmc]

All - I have a P4P battery from March of 2016 that needs to retire.

I heard that some vendors have a cable to use a battery after flight to charge the controller. Has anyone heard of this?

Are there other applications for old batteries as a back up power for computers?

The battery I have still seems to be ok, but Healthy Drones consistently shows deviations in the last cell. So, I think it’s prudent to keep the battery out of the air.

 

[Mark The Droner]

If the battery is simply showing cell deviations which are making you nervous, you might consider keeping it and using it in certain situations anyway - but shorten your flight. Rather than landing at 20% or 30%, land at 50% or 60%. This might not make much sense - why take such a risk? But if you're out and about with your drone, you've flown it once or twice with your good battery/batteries, and you see a beautiful and interesting place to fly, you have no choice but to keep driving home because everybody knows you don't launch with a partially charged battery. But with a fully charged battery such as you describe, you can fly for a short time safely and get that last flight in. There is little chance the low cell will cause you a problem with a short flight.

Otherwise, yes, you can retire it from flying and use it as a power bank provided it's not swelling.

DIY: Module Discharge Battery Phantom 3

 

[Kranmc]

If the battery is simply showing cell deviations which are making you nervous, you might consider keeping it and using it in certain situations anyway - but shorten your flight. Rather than landing at 20% or 30%, land at 50% or 60%. This might not make much sense - why take such a risk? But if you're out and about with your drone, you've flown it once or twice with your good battery/batteries, and you see a beautiful and interesting place to fly, you have no choice but to keep driving home because everybody knows you don't launch with a partially charged battery. But with a fully charged battery such as you describe, you can fly for a short time safely and get that last flight in. There is little chance the low cell will cause you a problem with a short flight.

Otherwise, yes, you can retire it from flying and use it as a power bank provided it's not swelling.

DIY: Module Discharge Battery Phantom 3

Thanks Mark! Is there a good place to “go” to get the cables to offload the power if I use the battery as a power bank?

 

[Mark The Droner]

I don't think you can just go buy a cable. I think you have to buy the "step down usb" and then solder something to it so that it can connect to the battery as illustrated in the link. Good luck.

 

[John Locke]

All - I have a P4P battery from March of 2016 that needs to retire.

I'm curious how many times you have charged that battery? Can you disclose? How much of a deviation to you see? Is this deviation when fully charged, or when discharged, or both?

Keep in mind the GO4 app will tell you the voltage of the weakest cell in your battery pack. If it's not close to 3.3V as you approach 20% you're OK. But you need to keep an eye on it of course. Just remember the pack will shut down at 3.0V on the weakest cell, so that's the critical area you don't want to get to. The danger with a marginal cell is the cell dipping down to 3.0V during hard acceleration. If the smarts detects 2.99V, the battery shuts off! Avoiding hard acceleration is key to prevent major voltage dips if you want to fly the battery and mitigate the risk. This was more of an issue with P3 batteries because the margin of safety was lower for 10% readings versus P4 voltage readings at 10%.

Voltage deviation are a sign, but not necessarily a reason to retire it unless they are huge deviations beyond .15V deltas.