LiPo low voltage buzzers

[ogrejager]

Question:

Do the LiPo low batter buzzers that plug into the balancing charging port (or whatever they call it) draw juice from the liPo, and, if left plugged in for a while, maybe draw the LiPo to zero? That, of course, kills the battery. I'm talking about things like these:
http://www.hobbyking.com/hobbyking/stor ... fgod-JsAVg

That should be in the instructions if that's the case. I think I killed two batteries.

[Cyclops]

I would think they would draw some power but not much. I wouldn't leave it plugged in for a long period of time (Keeping it plugged in while being stored or something).

[ogrejager]

Yeah, the battery compartment in my SAW is little of a PIA to get to and I just spaced taking it out. I assume it set in my shop and beeped until the battery finally died. Note to self has been made. Good thing I have more than one battery.

[ClownBaby]

Noob mistake.

I kid.

[Shortbu]

Noob mistake.

I kid.

Man crush...I don't kid

[ClownBaby]

Watch out, you might be next!

[ogrejager]

Watch out, you might be next!

Naw, I'm pretty sure you're next. I had already put a bounty on your head for Rick's last game, but you bailed.

[ClownBaby]

Yep, if you recall I had to take my dog into emergency surgery.

Priorities.

[Pacman]

I had one of those and forgot to take it out of my SR10. After a week it had killed my LiPo so I quit using them. I just drop shooting now when it first starts to slow.

[Shortbu]

I had one of those and forgot to take it out of my SR10. After a week it had killed my LiPo so I quit using them. I just drop shooting now when it first starts to slow.

That's what my side arm is for till I have time to swap the battery to the one that's in my admin pouch. I considered the "buzzer" but I know I'd leave it plugged in. Plus it's just one more gadget to screw with, and I've already got to much crap, lol.

[Pacman]

I've already got to much crap, lol.

Major understatement brother

[Shortbu]

I've already got to much crap, lol.

Major understatement brother

Agreed. I just wanna swipe the "Gear Whore of the Year" honors from Jew, lol.

[Steve]

They do draw current. Not a ton, but still.

Also, most of them have a polarity bias. If you plug it in backwards, they burn out. Only screwed it up once, but I didn't realize my mistake until it was emitting smoke. Not sure if it would have gotten all the way to actually on fire, but could be a problem.

I got as far as designing and building a circuit with a relay that would cut off the lipo if the voltage got too low, but by the time I had everything working, it was about 4" x 6" and was using $40 worth of microcontroller and parts. I then said "screw it" and now I just swap batteries every few thousand rounds because I'm too lazy to do the work to build a production piece in miniature. I still have the (non-optimized) arduino code somewhere if someone else cares enough to give it a whack.

In order to make it work, I ran power from the battery to a relay, a parallel circuit from the NO tab on the relay to the AEG and to the microcontroller, and wires from the lipo balance port to the analog in ports on an arduino uno. Also ran power and ground from the arduino through a transistor out to the control line on the relay and a power / ground pair from the battery through a push button to the arduino. Basically, you plug everything in, hold the button down to get power to the arduino, it does the voltage reads from the cells, and as long as they are good, it powers the relay to keep power going to the arduino and the AEG. As soon as the voltage drops too low, it disconnects the battery and requires you to press and hold the button again to start the microcontroller. Kind of a pain, but once the voltage gets too low, it stops using power from the battery so you don't have to worry about overdischarge from the thing that is supposed to protect you from overdischarge in the first place. I'm pretty sure that somebody smarter than me (or at least someone with more free time) could probably put it all on a stripped-down single board not much bigger than the current lipo alarms, assuming the market was there for it. Failing that, Adafruit Trinkets are probably burly enough to run everything, and are about $7 a pop compared with $30 for an uno, and are small enough to fit into a buffer tube. It'd still be about $15 - $20, but that is about the cost of a small battery, so I imagine it would pay for itself pretty quickly.