Immediate power drop

when I insert a fully charged battery the saber reads it at around 20% but in deep sleep it reads 100%. I can use the saber for maybe 20 minutes then it dies. I cannot figure out what is causing such a large drop. ant suggestions?

Sounds like a weak battery. (or wiring)
What kind of battery is it?
What current is it rated for?

they are 18650 the kind i use in all my sabers.

I believe 3200mAh

This is not a current rating, this is a capacity rating.
Current is measured in amperes (A), and to drive a neopixel saber, you want a battery that can handle at least 10A. 15A is recommended.

ok not sure. these are the batteries that come with my sabers bought from ThePachStore.

I recommend trying a different battery that you know is good, like one of these:

It’s possible your battery is fine, but that would mean that the wires or soldering have high resistance instead…

ok so in the event the batteries are fine. i see you said something about the soldering. i feel everything was working fine until I resoldered a few things to the board and i also cut and shortened my wires. before i would connect to the app and get a volt reading and now i get nothing. Should i just scrap this and start over?

It’s all fixable.
It might just be a cold solder joint somewhere.
Cold solder joints can have fairly high resistance, which causes exactly these sort of problems.
Cold solder joints can be fixed by re-melting the solder.

If you have a multimeter (which you should if you solder) you should be able to identify the bad joint(s) by measuring their resistance.

I think PachStore is one of the companies that uses unprotected flat tops with a protection circuit wired into the chassis.


ok, thanks! I was about to just tear it down.

how do I figure out what resistance number I’m looking for. can you recommend any good videos on the subject?

A solder joint should have a resistance very close to zero.
If your battery monitor registers an 80% drop in battery level, that would mean that you’ve lost ~1 volt somewhere. A neopixel blade draws maybe 3 to 6 amps depending on color and type of LEDs.
Let’s just estimate 5A for now. A resistance of 0.2 ohm would cause you to lose one volt at 5A.

What you want is resistance that is more in the 0.01 ohm range (or better), but not all multimeters are good at mesuring low resistances like this.

Ok, thank you!