How to tell the power went out

The pedestal breaker trips at two in the afternoon and nothing in the rig makes a sound. The air conditioner stops, the converter stops charging, the residential fridge starts its slow climb, and the first you hear about it is when you get back. Almost everything else in this cookbook is downstream of this one question, which is why it goes first.

There are six ways to know, they cost between nothing and a few hundred dollars, and they are not equally good. The fastest is a couple of minutes. One of them takes an hour and tells you something you already needed to know anyway. The interesting part is not any single method — it is what two of them together rule out.

Every way to detect it

a. The shore power monitor goes dark

A Hughes Power Watchdog runs its own electronics off the pedestal side. When the pedestal dies, the Watchdog dies with it — so you do not get a tidy zero-volt reading, you get a device that stops answering. The hub connects to it every 30 seconds, and a Watchdog that misses several connections in a row is the fastest signal you can buy.

The catch is Bluetooth range, and it is a real one. A portable Watchdog sits at the pedestal, which makes it the furthest device from your hub and the one most likely to drop out for reasons that have nothing to do with power. A van parking between the two of you looks exactly like an outage. That is what method (b) is for.

b. The house battery stops being charged

On shore power your converter holds the house battery up: somewhere between 13.2 and 14.6 volts depending on charge stage. Cut the pedestal and the voltage settles back to resting — roughly 12.6 to 12.8 for a full lead-acid bank, about 13.2 to 13.3 for lithium, which is close enough to charging voltage that lithium owners need a tighter rule than lead-acid owners do.

Any voltage source works: a Victron SmartShunt at 60 seconds, a Lancol at 120, a BTHome voltage sensor. Add a couple of minutes of settling time before the reading is trustworthy.

c. The current flips to discharge

A shunt sees direction, which a voltmeter cannot. On shore power the current into the battery is positive or near zero. Lose the converter and it goes negative, immediately, because the rig is now eating the battery. An example rule: warn below −5 amps, critical below −30.

This is the method that separates a real outage from a Bluetooth dropout, and it is the reason the SmartShunt is the second thing to buy rather than the fourth. It has the same solar caveat as (b) — panels keep the current positive all afternoon — and it twitches whenever a slide motor, a water pump or a furnace cycle pulls hard for a few seconds. There is no way to tell a rule to wait: it fires on the reading crossing the line, period. So set the warning below what your own transient loads reach, and use the chart rather than the alert to tell a real outage from the furnace starting.

d. The hub itself goes quiet

The hub has no battery. If it is plugged into an AC outlet fed by the pedestal, it dies at the same instant the pedestal does, and our servers notice the silence and tell you. This is the crudest method on the list and the only one that costs nothing.

It is also ambiguous by design: campground Wi-Fi failing, a captive portal expiring, a router reboot or somebody unplugging the hub to charge a phone all look identical. It means something is wrong. It does not mean the power went out. And if the hub died, nothing from the gap is recoverable — which is the argument, made at more length in power and connectivity, for running the hub off 12 volts instead.

e. The temperature drifts — the lagging indicator

Any supported temperature sensor will eventually notice. A closed fridge takes one to three hours to climb past 45 °F; a sealed rig in summer sun takes under an hour to reach a pet ceiling. The sensors poll every 60 to 120 seconds, so the delay is the physics, not the Bluetooth.

This is not really a power alert. It is the alert that matters most, arriving late. Set it regardless — it is the one that catches the failures the electrical methods cannot see, like the fridge being switched to the wrong mode.

f. The soft starter, for confirmation only

A Micro-Air EasyStart only accepts a connection while the air conditioner has power. If the hub is reading current from it, the A/C has power right now. Useful as a positive confirmation, useless as an outage detector: it drops the connection between compressor cycles as a matter of course, so an unreachable EasyStart means nothing at all.

The combinations are where the value is

One alert tells you something happened. Two tell you what.

• Watchdog dark + battery discharging — the pedestal is genuinely gone and the rig is running on the battery. How long you have is now a battery question, and the shunt is already answering it.
• Watchdog dark + battery still charging — that is Bluetooth range, not an outage. The converter is running, so the pedestal is fine. Go and look at what parked next to you.
• Watchdog dark + hub offline at the same moment — the hub is on a pedestal-fed outlet and died before it could tell you anything. Move it to 12 volts; this is the one combination that is really a note about your own install.
• Watchdog dark + EasyStart still reporting current — the A/C is running on something else. A generator through the transfer switch, or a large inverter.
• Watchdog dark, then the fridge climbs an hour later — the fridge is on the dead line. If the fridge doesn’t move, it is on propane and quietly doing its job.
• Hub offline but every last reading was normal — probably the internet rather than the power. The hub is logging locally and will upload when the link returns.

What none of this tells you

Why. Park fault, tripped pedestal breaker, a neighbor who unplugged you to run a heater — the readings are identical for all three, and the only way to know is for somebody to walk over and look.

And a shore power alert is an ordinary alert, not a safety alarm. It rides the normal notification ladder and it respects your quiet hours. Only safety alarms are exempt from quiet hours, and a shore power rule is not one, so there is no per-rule way to buy an exception. If losing power at three in the morning is something you need to be woken for, the setting to change is quiet hours themselves — and know that you are then choosing to be woken by a tripped breaker as well as by a real emergency.

What to buy first

The shore power monitor. It is the only direct reading of the pedestal, it is the fastest at 30 seconds, and it protects the rig from the low voltage that kills air conditioners as a side effect of being useful to us.

Then a shunt. Not for the outage detection — for the current sign, which is the thing that stops you driving back from a hike because a van parked between your hub and the pedestal. It also answers the question the outage raises: how long does the battery have.

If you own neither and want the cheapest useful version of this: put the hub on 12 volts, add one temperature sensor where it matters, and accept that you will find out in an hour rather than a minute. That is still the difference between a warm fridge and a ruined one.

Where to get one