Network Power Update

I’ve been a user of APC small computer UPS products for 20+ years. It seems that whenever one is needed, the battery is flat. As yet another round of battery replacements started, I decided to switch to portable power station products for the UPS role in my home network. But which one?

Revisions

2026-07-30 Original

References

Uninterruptible Power?

Just what is uninterruptible power in an home network environment? Why is uninterruptible power desirable?

An uninterruptible power supply is a power source that is designed to continue to provide power to a load of specified size for a specified period while commercial mains power is interrupted.
Paraphrase of [3] by the author

An uninterruptible power supply is uninterruptible in the sense that it protects the load from interruptions of the primary power source.

[7] gives US DOE Energy Star requirements for uninterruptible power supplies to be Energy Star rated.

Enterprise Scale UPS

Corporate computer systems commonly have some form of uninterruptible power supply designed to permit continued operation of mission critical computing.

When I worked for Combustion Engineering, a nearby C-E owned data center hosted an IBM/Amdahl system used for corporate record keeping and a CDC 7600 system used for nuclear engineering design. Both were mission critical and the CDC 7600 was essential to nuclear reactor design. So we had a custom UPS provided with the data center.

Remember Murphy? He had a hangout at our data center. When the UPS was needed, things went wrong. So test startup and loading periodically. Fix any mishaps or casualties discovered. It just wouldn’t be a Dismal Manor Dispatch without a sea story so here’s one.

C-E’s Data Center UPS included two gas turbine generators powered by natural gas, a large battery and inverters, and various relays and devices to sense interruption of mains power, start the TGs, and shift the building’s vital AC buses to TG power.

One day, a truck knocked down the power pole in front of the data center. One TG failed to start. The second started but couldn’t reach full power.

Our data center rigged for reduced power by securing the smaller IBM kit and non-vital house loads. Nuclear limped by on the 7600, 6400 front end, and the V470 Amdahl.

After mains power was restored, technicians found one TG with starting system problems and a glove in the fuel filter of the one that started.

Small System UPS

A traditional small computer UPS is a power appliance that connects between the mains and the AC loads to be protected against outage.

A relay normally connects the AC load to the AC mains. When the power drops, the inverter starts and the relay transfers the AC loads from the mains to the inverter. Internal batteries supply power to the inverter.

APC and CyberPower make UPS systems ranging in scale from under the desk bricks to back lot backup generators with batteries and inverters.

These systems have a mains dropped alarm and mains dropped messaging to the host computer.

A host daemon listens for the mains dropped message, forwards it (maybe), and begins orderly shutdown if so configured.

The primary intent is to give a users time to save their work and the system time to complete any file system transactions needed to shut down.

Power Station Gadgets

The availability of Lithium Iron Phosphate (LiFePO4) rechargeable batteries from the battery electric vehicle industry has spawned a new product category, the portable power station. These devices are designed to provide a portable source of power for use in the outdoors away from line power. A subset of these are designed to function as uninterruptible power supplies.

Anker products like the 757 and 767 are mains powered and have received UPS certification. The standard and certification activity are not identified in Anker marketing materials.

Bluetti makes similar products and both have recently introduced home-scale UPS products.

Bluetti appears to be unique in offering small lunch-bucket sized devices for use in the UPS role in addition to the portable power role.

EcoFlow has its Delta and River product lines. Delta is the luggable product line originally promoted to power outbuilding and provide portable power tool power for tradesmen. River is the carry-about product line for camping and standby power for small appliances. All versions power the AC loads from the mains when AC power is available.

Solar Generators?

When combined with solar panels and accepting DC power for charging, these gadgets are called solar generators. The solar cells provide DC power used to charge the battery. The inverters provide AC power and standardized DC power for phone charging and similar uses. All 3 mentioned companies make such devices. Note that DC input rating limits the power available as a solar generator. Being hybrid devices, they can supply up to rated inverter power for short periods.

When mains powered and normally carrying the AC loads on the mains, these devices are also UPS equipment. See [7] for standards.

The references include the Anker 521 [2] and Bluetti EB3A [1] products. These are very similar conceptually but differ in detail.

Each vendor offers models for semi-stationary applications like providing power to an outbuilding, portable tool power for tradesmen, etc and smaller models to provide small appliance power away from the mains or during outages.

Aggressive Competition

The portable power station marketplace is aggressively competitive. As battery prices come down, power station manufacturers lower their prices to maintain customer attention in a crowed market place.

This product category is crowed with manufacturers. The three mentioned here are are among the better known and each makes product appropriate for the small UPS role. Bluetti was first at the $250 price point but EcoFlow River 2 series also has a $250 entry.

Many manufacturers have just freshened their product offerings after Prime week summer clearances. The new products are usually less expensive that those they replaced as they take advantage of lower battery prices and improved battery types. As battery prices drop, the power station companies are eying the installed home standby power application dominated by Generac and others.

I strongly recommend purchasing directly from the manufacturer to obtain fresh product at fair prices. Anker, Bluetti, and EcoFlow all engage in direct sales.

Power Station as a UPS

Here, I contrast the Anker 521 and Bluetti EB3A products having similar price and similar battery capacity. Both are well regarded products. The intent here is to show show you what features a power station must have to serve as a UPS. Not all power stations have these features. The light portable power oriented Anker 521 does not. The Bluetti EB3A and EcoFlow River products do.

Both products can be used in the portable outdoor power role but the Bluetti differs from the Anker in several ways that allow it to serve as a UPS.

The Bluetti is directly mains powered.
The Anker is USB laptop charger powered from the mains. The mains ground is not available and the charger selected limits mains draw.
The Bluetti has NEMA 5-15 outlets with ground.
The Anker has ungrounded floating (the “neutral” is not grounded) AC outlets. The AC sockets are not polarized.
The Bluetti carries the AC loads on the mains when mains power is available. It is likely that the AC output floats while on the inverter.
The Anker inverter is rated for 400W total load, the Bluetti for 600W, both well in excess of our 100W load.
Neither product specifies reactive power ratings. Assume a 0.8 power factor.
The Bluetti AC to DC converter is rated for 250 watts. The Anker uses a laptop USB charger as its mains powered DC source.
The Bluetti AC inverter is rated for 600 watts and 1200 for starting transients.

The Bluetti carries the AC load on the mains with automatic bus transfer to the inverter when the mains drop. Bus transfer time is advertised as 30 milliseconds or about 2 mains cycles.

Note that partially loaded switching power supplies like those in computer equipment can have really low power factors like 0.3 as measured by our UniFi rack power distribution equipment.

Bluetti EB3A UPS Setup

To use the Bluetti EB3A as a UPS takes the following actions.

Connect the mains power.
Connect the loads.
Confirm that the battery starts to charge and let charging current settle.
Start the AC power output by push button. The bus transfer relay will select the mains source and the panel will begin to indicate load demand.
Confirm that load demand is less than the inverter rating. The EB3A will likely raise an alarm and take protective action if loaded out of limits.
Note the load demand to use to estimate run time on the battery.

The front panel AC start and DC start buttons are a bit tricky to see. I cheated and used the Bluetti App to turn on AC power. You can do without the APP. Everything needed is on the front panel.

Surge Protection

Neither Anker nor Bluetti specifies AC surge suppression so I used a Furman Power M8X2 power distribution strip [5] for surge protection of network equipment while carried on the mains. Furman Power is an established supplier to broadcast, recording, and performing arts. This stuff is robust and wired for continuous rated power draw without overheating.

Estimating Run Time

How long will the Bluetti EB3A carry my home network core?

The Bluetti front panel and the iPhone App agree that my running load is about 100 watts. The battery is 250 Watt hours. So 250/100 is about 2.5 hours. What is being powered?

Cable modem or MetroNet ONT
UniFi Dream Machine Pro with DVR disk
Two UniFi In-Wall Pro access points
Three UniFi G3 Pro cameras
OOMA Telo base station for VoIP POTS

Pesky Cox Fades

While updating its network plant to better hold off the coming MetroNet Fiber challenge, Cox was really, really fade prone. So I configured automatic power cycling of of the cable modem on an Internet fade. The Dream Machine working with UniFi power distribution bits provides power cycle restarts.

For things away from the rack power distribution, Ubiquity offers a NEMA 5-15 smart outlet [6] for the task. Like any Ubiquity kit, you adopt it, update firmware, and configure it at the UniFi console.