Quick answer: The PVS-31 PRO runs on a single CR123A or AA cell in the main housing, plus an included AA x4 battery pack that mounts at the rear of the helmet and connects by cable. Plan on a full night of use from the onboard cell and several nights from the pack; across configurations and conditions the working range is roughly 15 to 75 hours. In cold weather, 1.5-volt lithium AA cells are the correct choice, alkalines are the backup, and the pack earns its keep twice: extra runtime up front, counterweight out back.
What powers the PVS-31 PRO?
Two sources, and you can run either. The main housing takes a single onboard cell, your choice of CR123A or AA, which makes the goggle fully self-contained with no cable at all. On top of that, every PVS-31 PRO ships with an external AA x4 battery pack and its cable in the box. The pack mounts at the rear of the helmet, feeds the goggle through the cable, and quadruples the fuel on board.
That included pack is worth pausing on. At many dealers an external power pack for a dual-tube goggle is a separate line item, priced accordingly. Here it is part of the standard kit, along with both tubes' QC sheets and the mount, which is one reason the out-the-door math on this binocular works the way it does. The full first-party rundown of what arrives in the box lives in our PVS-31 PRO review.
A safety note that belongs at the top rather than buried: use standard 1.5-volt AA cells (alkaline, lithium primary, or NiMH rechargeable) and standard CR123A primaries. Never substitute 3.7-volt rechargeable cells that share the same shape, such as 14500 or 16340 lithium-ion cells. They fit the compartment and they overvolt the electronics. That mistake has ended more devices than any winter ever has.
How long does the PVS-31 PRO actually run?
Honest answer first: runtime is a range, not a number, because it depends on which cells you use, how fresh they are, how cold the night is, and how the unit is configured. The published working range runs from roughly 15 hours on the short end to around 75 hours with the external pack in favorable conditions. In practical terms, think of it this way: a fresh onboard cell is a night of use with margin, and a fresh set of four AAs in the pack is several nights of normal sessions.
Two habits keep that range from ever becoming your problem. First, treat the top of any published range as a bench figure: mild temperature, fresh premium cells, everything in its favor. Plan your night around the bottom of the range and let the rest be a bonus. Second, start planned long sessions on fresh cells and demote the half-used set to backup duty. Cells cost little; a dead goggle at 2 a.m. costs the whole night.
Runtime behavior across chemistries, and why a device this efficient still deserves good cells, is covered in our wider night vision battery guide.
When should you run the onboard cell and when the pack?
Run the onboard cell alone when you want the lightest, simplest setup: short sessions, quick property checks, handheld use, or any night where a cable is more nuisance than benefit. One cell, no wires, done.
Run the pack for everything longer. Helmet-mounted sessions that go for hours, multi-night trips, and cold weather all favor the pack, because four AAs of capacity means you are changing batteries on your schedule instead of the goggle's. A sensible standing arrangement many dual-tube owners settle into: the pack is the primary fuel tank, and a fresh cell rides in the onboard compartment as the reserve, so a cable snag or an empty pack never turns into a dark walk home.
The cable itself asks for one minute of care. Route it along the helmet shell with enough slack that turning your head never tugs the connector, and secure it so it cannot catch on branches or straps. Helmet routing, strap placement, and the rest of the setup discipline are covered in the night vision helmet setup guide.
What happens to your batteries in the cold?
Cold does not hurt the goggle; it hurts the chemistry feeding it. Every battery is a chemical reaction, and chemical reactions slow down as temperature drops. Voltage sags, usable capacity shrinks, and the effect is sharpest with alkaline cells, which can give up a large share of their capacity once the night dips below freezing. The device is fine; its fuel is the weak link.
This is why the standing cold-weather rule is simple: run 1.5-volt lithium AA primaries. Lithium primary cells hold their voltage well below freezing, weigh roughly a third less than alkalines (which matters when four of them sit on your helmet), do not leak the way tired alkalines do, and store for many years without losing much charge. They cost more per cell, and in the cold they are worth every bit of it.
| Cell type | Cold behavior | Weight | Best role |
|---|---|---|---|
| Lithium AA (1.5V primary) | Strong output well below freezing | Lightest AA option | First choice for cold nights and the storage cache |
| Alkaline AA | Voltage sags near and below freezing | Heaviest AA option | Mild-weather use and backup sets |
| NiMH rechargeable AA | Moderate; better than alkaline, below lithium | Similar to alkaline | High-frequency users who cycle cells often |
| CR123A (lithium primary) | Cold-tolerant, like lithium AA | Compact | Onboard cell option; less common in roadside stores |
One field trick worth knowing: cold-sagged cells recover some of their output when warmed. Keep your spares in an inside jacket pocket rather than in an outer pouch, and a set that seems finished on the helmet will often serve again after twenty minutes against your body heat. How the rest of the system behaves when the temperature drops, from eyecup fogging to tube behavior, is covered in night vision in cold weather.
What does a smart spares routine look like?
Spares discipline is boring, which is exactly why it works. The routine that covers nearly every failure mode costs a few dollars and one pocket:
- Carry one full reload. Four AAs for the pack plus one cell for the onboard compartment, carried on your body, not clipped to the helmet you might set down in the dark.
- Start long nights fresh. New or fully charged cells at dusk for any planned long session. Demote partials to backup duty rather than guessing at their remainder.
- Never mix. No mixing of chemistries, brands, or old and new cells inside the pack. Four matched cells drain evenly; a mixed set drains to the level of its weakest member and can drive the tired cell into reverse.
- Mark your sets. A strip of tape with a date turns "which of these is fresh?" into a non-question.
- Store the unit empty. For storage beyond a few weeks, take the cells out of both the housing and the pack. A leaking alkaline in a sealed compartment is the most preventable damage in this hobby.
- Cache lithium. Keep a sealed pack of lithium AAs with the goggle case. Their long shelf life means the kit is ready even if it has not been touched all season.
Why is the battery pack also a counterweight?
A dual-tube goggle carries two pods, two tubes, and a bridge out in front of your face, and every gram of it works on your neck through a lever arm all night. The rear-mounted battery pack pushes mass to the back of the helmet and pulls the system's balance point toward the center of your head. The load stops fighting you and starts just sitting there.
This is why experienced dual-tube users run the pack even on nights when the onboard cell alone would cover the runtime: the pack is doing a second job as ballast. It is also why the pack earns a permanent spot on the helmet rather than in a pouch. Weight you were going to carry anyway, placed where it cancels the goggle instead of adding to it, is the closest thing to free comfort a helmet rig offers. Positioned correctly, the difference between minute ten and hour three is the difference between a balanced head and a sore neck.
Our pick: the PVS-31 PRO ships with the external AA x4 battery pack, cable, and mount already in the box, plus both tubes' measured QC sheets. PVS-31 PRO - from $3,799.95. Battery pack and mount included, 1-year warranty.
Frequently asked questions
What batteries does the PVS-31 PRO use?
The main housing takes a single CR123A or AA cell, and the included external battery pack takes four AA cells. Standard 1.5-volt AA chemistries all work: alkaline, lithium primary, or NiMH rechargeable.
How long does the PVS-31 PRO run on batteries?
Depending on configuration, cell chemistry, and temperature, the working range is roughly 15 to 75 hours. As a practical planning figure, a fresh onboard cell covers a night of use and a fresh set of four AAs in the external pack covers several nights.
Is the battery pack included with the PVS-31 PRO?
Yes. The external AA x4 battery pack, its cable, and the helmet mount all ship in the box as standard kit, along with both tubes' QC sheets. The pack is not a separate purchase.
Are lithium AA batteries safe to use in night vision?
Yes, as long as they are 1.5-volt lithium primary AA cells. Never use 3.7-volt rechargeable lithium-ion cells such as 14500s, which share the AA shape but deliver more than double the voltage and can destroy the electronics.
Do alkaline batteries work in cold weather?
They work, but poorly. Alkaline cells lose a large share of their usable capacity once temperatures drop near and below freezing, and their voltage sags under load. For cold nights, 1.5-volt lithium AA primaries are the reliable choice, with alkalines kept as mild-weather backups.
Can I use rechargeable batteries in the PVS-31 PRO?
Yes, standard NiMH rechargeable AAs work and suit high-frequency users who cycle cells often. Keep sets matched and charged together, and remember that NiMH cells self-discharge on the shelf, so a pack that sat for months should be topped up before a long night.
Should I store the PVS-31 PRO with batteries inside?
No. For any storage beyond a few weeks, remove the cells from both the main housing and the external pack. A leaking alkaline cell inside a sealed battery compartment is one of the most common and most preventable forms of damage to night vision equipment.
How many spare batteries should I carry?
One full reload: four AAs for the pack plus one cell for the onboard compartment, carried in an inside pocket. Body heat keeps the spares warm in winter, and an inside pocket means the spares stay with you even if the helmet is set down.
Does cold weather damage the tubes themselves?
No. The image intensifier tubes handle cold field temperatures fine; it is the batteries that lose performance as temperatures drop. Feed the unit cold-tolerant cells and manage eyepiece fogging, and the goggle itself will run through winter without complaint.
Why does my runtime vary so much between nights?
Because runtime depends on cell chemistry, cell freshness, temperature, and how the unit is configured on a given night. A fresh lithium set on a mild night and a tired alkaline set on a freezing one can sit at opposite ends of the published range, which is why fresh cells at dusk is the habit that matters most.
Power is the smallest cost in dual-tube ownership, and the easiest to get right: lithium cells in the cold, one reload in a pocket, and the rear pack doing double duty as ballast. Every PVS-31 PRO ships with the external battery pack, both tubes' measured QC sheets, a free G24 helmet mount, and a 1-year manufacturer warranty - 17,000+ orders since 2023, worldwide with duties pre-paid. The PVS-31 PRO starts at $3,799.95.