how to completely discharge a battery?

This might sound crazy, but I need to completely discharge the battery in my Garmin camera. The camera won't let me do so, as it stops whenever it gets to the point where the battery has about 1/2 charge remaining.

A few more details: I've got an older style Garmin Virb camera and it seems to have a well-known bug. The theory is that it typically arrives with a 1/2 charged battery, and if it's initially powered on with the battery in that state, it gets confused and thinks that 1/2 charge is 0 charge. Then whenever it gets to 1/2 charge, it turns off, thinking the battery has run out. So, I can only get 1/2 of the available battery life when using the camera. There is also no way to completely discharge the battery using the camera---which just might get the camera to realize that 0 charge is actually at 0, and not at 1/2.

Thanks for reading...

What type of battery? If it's lithium ion or poly then you do not want to completely discharge it, it will never come back. If it is a lithium, you want to leave between 20-22% charge in the battery, this will cycle it properly.

Sorry I can't help with the discharge, but you could always just wire it to an electric motor or the like and let it run.

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Hot wire it to 12volt led lights

Here's the battery.

So, it seems the trick is to get it down to 20%. How would I know when I've reached that point?

Wire it to a digital multimeter and a low way motor or light and sit and watch the numbers go down...... I'm guessing it would be comparable to watching the grass grow?

Going to try and bring some knowledge in here from my RC Helicopter hobby and try and help!

The voltage on a 1 cell Li-Ion or Li-Poly fully charged is 4.2v. So, discharging it to 3.7v will be a 79% discharge. The battery may see 3.3-3.5 under a heavy load (which you don't have to worry about), but as long as the unloaded voltage is 3.7-3.73 (21% and 27% remaining capacity) you should be set for proper discharge and cycling.

Before throwing away li-polys we discharge to 0% (it won't come back from that) by connecting them to an old school light bulb, it drains them surprisingly quickly. So I'd try and wire it to a light, and check it with a voltmeter to get 3.7 - 3.73v, then give it a FULL charge and you should be good to go.

Also, some information for making it last. Lithium batteries are supposed to be good for 300-500 charge cycles, though many people see far less due to improper care. When charging, lithium batteries don't "trickle charge" after they've received a full charge. This means once your battery reads 100% it shuts off, it won't continue trickling in mAh like a lead acid charger will, as lithium batteries hold a charge much much longer. It is also best to fully cycle the batteries if possible, drain them to 20% and then do a full recharge, rather than constantly topping off a battery thats got a fuller charge every time. When storing the batteries, it's best to store them at 80% charge.

I realize that last bit probably isn't pertinent information for a small battery that's easily replaced, but it's certainly important for bigger things, like the laptop I'm typing this on! Maybe someone will find it useful!

 

Thanks for the info---I'll give that a try.

I didn't do anything to try to drain it, but I get 3.16v or 2.42v, depending on which contacts I measure. Not sure how to interpret that...

I wonder if you are in fact draining the battery down to 3.1? It's really hard to tell honestly, I'm not that smart, my RC batteries have connectors and I have a battery checker 

Funny thing... After fiddling around and trying to measure the battery for a while, I put it back in the cam and it showed no charge. So I charged it, and it now seems to be working. I guess I'll know for sure next time I'm OTW.