I opened up my Oakter Mini UPS and it's not really a UPS

Spent some time debugging an issue with my Oakter “Mini UPS for 12V WiFi Router Broadband Modem”. (Affiliate link: I may earn a small commission if you buy through it. Same goes for the Amazon link further down.)

TL;DR: This is not a UPS as you know it. It’s just designed to be thrown in the trash barely over its warranty period! :(

Why I bought it

I bought this a little over a year ago just to keep my router powered through a brownout. My society’s power backup kicks in within about 30 seconds, so the UPS only had to cover that gap. No heavy duty use case at all, but I really needed it during Zoom meetings while working from home.

So over its whole life, this unit carried the router for ~30 seconds, a handful of times.

The router started rebooting

Around the 12th month, my router started rebooting randomly even when there was no power cut. Last month it got worse and was happening multiple times a day.

So, just like any other scientist, I ran an experiment to rule out the router itself. 🔎

1. I disconnected the Oakter Mini UPS and ran the router straight off its adapter, with no backup. It worked perfectly.
2. To be sure the Oakter was at fault, I deep charged the UPS for a whole night and connected the router again. Same result, random reboots. 😕

So the router was fine. The UPS wasn’t!

What’s inside

Next I wanted to understand why the battery had died so quickly when it had barely been used. I opened the case, and the battery pack is taped together and quite poorly soldered to the PCB for power. 🔋

What the multimeter showed

Then I checked it with my multimeter and noticed something even more interesting than the bad soldering. 👀

A traditional UPS runs your device off AC mains while mains is connected, and only falls back to the battery when the power cuts, usually within ~5ms.

The Oakter isn’t built like that. I took three readings with the router connected.

The input from the 12V / 1.5A adapter, mains on: 11.91V.

The output going to the router, mains still on: 10.89V.

The output with the adapter unplugged, so 0V coming in: 10.87V, and the router stays up.

The output barely moves whether mains is connected or not, and even with mains on, the router never gets the 11.91V coming in from the adapter. The router is running off the battery all the time. This thing just keeps charging the battery 24/7 and powers the router via the battery all the time!

Which results in…, you guessed it, serious battery degradation. Once the battery can’t give the router a suitable voltage anymore, the router gets undervolted and reboots, which is exactly what mine was doing.

Customer support: “out of warranty”

I tried my luck with Oakter’s customer support. They took a look at the invoice, shrugged, and said they couldn’t help because the product went out of warranty last month. 🤷

I didn’t want to throw it in the trash and add to a landfill, so I asked if they could at least replace the battery, since this is a clear case of battery degradation. No help there either.

It’s a shame. Oakter calls itself an “Advanced Indian ODM” (Original Design Manufacturer) on their homepage, and yet they can’t design a sustainable, repairable product. ♻️

What I’d expect instead

As an engineer, I get that a smart switching circuit like a traditional UPS may drive up the cost or cut into profit margins. But what I found inside is a cheap passthrough power bank with a soldered barrel port and some adapters.

I would expect the Oakter team to at least think about refurbishing these at some cost, so they don’t end up in landfills in bulk once their lifecycle is over. 🪫 Swapping the unit at ~50% of the price might make good economic sense for both the company and the customer.

Their competitor Cuzor already does this. They run a “MiniUPS Battery Renewal Program”: at the end of the battery’s life you contact them and they renew it, at some cost. A great initiative! I wonder, what’s stopping you, Oakter? 🤔

If you own one of these

If your router has started rebooting at random and there’s a mini router UPS in between, try the same test I did: take the UPS out and run the router straight off its adapter. If the reboots stop, the UPS battery is the likely culprit.