TheBug - Eaton 3S Mini UPS

Introduction

The Eaton 3SM36B Mini UPS is a simple to operate battery backup solution, designed for use with small electronic devices, e.g. routers, cameras etc. This UPS ensures uninterrupted power during a mains 230V outage, providing emergency support to compatible devices that normally rely on an AC/DC adapter. It has the option of switching the output voltage between 9/12/15/19Volts DC. The Eaton 3S is rated capable of delivering up to 36Watts output.

The Eaton 3SM36B has one output, permanently connected via a 1meter lead terminated in a proprietary connector. The UPS is supplied with a set of 4 adaptor jacks to allow it to connect to a variety of barrel/pin sizes. 3.5/1.3mm, 4.75/1.7mm, 5.5/2.1mm and 5.5/2.5mm.

Four LEDs are used to indicate multiple states of the batteries, the output voltage and the UPS operation. It is controlled by a soft touch Power ON/OFF/Mode button.

The power input socket is an IEC C5 three pin and can accept 100V-240V AC power.

The Output voltage is set by pressing and holding the mode button for 8 seconds and then pressing it again to toggle through the 4 voltage options, the first LED indicates 9V, the second LED indicates 12V, the third LED indicates 15V and the fourth LED indicates 19V. Once the chosen voltage is indicated the mode button is held for 8 seconds to set the output voltage.

Key Points

Supplier Specification https://www.eaton.com/gb/en-gb/skuPage.3SM36B.html#Specifications

Quoted prices Feb2024 £51.00 from Amazon UK directly.

Can Supply up to 36Watts e.g. 3Amps @12VDC

Variable output voltage setting 9/12/15/19V

Emergency Runtime for a typical Router (6-8Watts) is between 2Hours and 1hours30"

Battery recharge power allowance 4Watts. Recharge time from empty ~5Hours

Manual On/Off through soft button.

No Audio warning of power and battery status.

Built in AC/DC adapter, so no need to reuse an existing adapter.

The UPS can be turned ON/OFF by pressing and holding the Power Button for 3 seconds and releasing.

When the UPS is switched On and connected to a 240V input source, a single LED will be illuminated indicating the output voltage selected.

When the UPS is switched On and the input 240V is switched Off(power cut), the status of the remaining battery charge will be indicated by the 4 LEDs

Three Solid Green, Fourth LED Flashing: Battery charge remaining >75%
Two Solid Green, third LED Flashing: Battery charge remaining 50% to75%
One Solid Green, second LED Flashing: Battery charge remaining 25% to 50%
One Slow Flashing Green LED: Battery charge remaining 5% to 25%
One Fast Flashing Green LED: Battery charge remaining <5%

When switched On and recharging, the status of the battery recharge is not directly displayed. The battery recharge status can be found by briefly pressing the Power/Mode button; the number of LEDs lit solidly Green equates to the nominal percentage stored.

The 3SM36B contains 2 off 2200mAh lithium-ion cells, arranged in a 2P form, with a nominal total capacity of 16.3Wh.

The 3SM36B does not provide an audible warning when a mains input power cut occurs, the only indication of a power cut is that the Four LEDs illuminate and then indicate the status of the battery charge. In the event of an extended power cut, the UPS can be turned Off and back On again, thus allowing the remaining battery charge to be managed.

Connection

Designed for ease of use, the Eaton 3SM36B is simply connected directly between the electronic device and a standard 3pin 240V socket. It directly replaces the AC/DC adapter (rated up to 36Watts) associated with the electronic device. This setup introduces a useful battery backup function with minimal effort and manages any concerns that may arise through mismatched AC/DC adapters. The UPS is simply switched On by a power/mode switch.

Testing and Performance

Performance testing on a unit found that the usable capacity, when supplying 6 Watts at 12VDC, was 11.8Wh compared to a theoretical maximum of 16.3Wh, or 72% usable capacity. The UPS required ~20Wh to fully recharge the batteries. The maximum battery recharging observed power was ~4Watts, so a full recharge takes ~5Hours from fully discharged. When fully charged and connected to an operational device, the UPS uses 1-2Watts for its normal function, so has low overhead running costs.

It was observed that when supplying the maximum rated 3Amps (nominal 36Watts) the UPS casing warmed to ~42DegC.

Using the 3SM36B with a B4RN supplied Zyxel VMG8825 Router.

The Zyxel VMG8825, used for testing, was supplied with a 36Watt 12VDC AC/DC adapter. The 3SM36B is rated as capable of supplying up to 36Watts at 12V DC and therefore a directly equivalent replacement.

When powering a Zyxel VMG8825 from the 3SM36B in battery mode, the router ran for 1Hours 33Minutes. The router had two ethernet link in use along with Wi-Fi active and low power USB device plugged in. No Telephone ports were being operated. The router average power demand over the test cycle was 7.6Watts