Joel Dare

Replacing a Dead Speaker Battery

Today I replaced the battery in my old OontZ Angle 3 bluetooth speaker.

OontZ Bluetooth Speaker and Old 18650 Battery

It’s something that I rarely use but my ears have been sore lately and my headphones are uncomfortable, so I decided to try the OontZ for audio. It was acting oddly and I suspected an ailing battery.

The OontZ Angle 3 has a single 18650 2200mAh Lithium battery in it. I don’t have an extra 18650 sitting around but I do have some AA NiMH batteries. I tested the 18650 from the speaker and it read 0 volts. So, I looked up the 18650 and found that it’s a 3.7v battery. AA NiMH’s are 1.2v each so a set of three should make 3.6v. I figure that’s probably close enough.

I didn’t really set out to do this but I got started wondering if I could and I just pulled out a screwdriver and my soldering iron and started working. Within an hour or so I had the new batteries soldered in and everything re-assembled. I’m glad I gave it a shot but my haste means that I didn’t capture and pictures of the process.

I’m a computer programmer but I’ve never been any good at electronics. As a kid I took apart a lot of items but I rarely got anything back together again. Replacing a battery should be a pretty easy job but I don’t have a lot of confidence for stuff like this.

I pulled the old battery out and used the metal bars attached to it to solder my NiMH batteries together. So the only parts I needed was some solder, flux, and about an inch and a half of wire.

The 18650 has a small circuit board on it. I don’t know what that was but I suspect it either controls the output voltage or prevents the battery from over charging (a danger with Lithium).

Will the new battery charge?

The old battery was Lithium and the new one is NiMH. I didn’t know if the circuitry in the OontZ would be able to charge the new battery chemistry. It turns out it does charge. I’m still not sure how safe it is, so I’ll only charge it while I’m watching.

Will the new battery stop charging?

This is another fear. Will the circuitry in the OontZ stop charging the NiMH battery when it’s full? What if it relied on that circuitry built into the 18650 battery that I removed?

After some time plugged in the OontZ light turned solid red, indicating that the battery was fully charged. Connected to my Mac it reports a 90% charge. So, it seems like it does stop charging when it’s full (or nearly full).

Why don’t you just use your laptops speakers?

I typically run my laptop closed and attached to an external monitor. I started doing this when I started working from home in 2020.

Written by Joel Dare on February 19th, 2023