Four battery types.
Pros and cons.

This is
the lineup.

For trail cameras in AA format there are exactly four types of cell. Two are single-use, two can be recharged. Each one has a characteristic discharge curve – and that curve is precisely what decides what your camera gets out of it.

Four symptoms,
four causes.

Almost every trail camera user knows these four patterns. None of them is a defect – each one can be traced back to a cell type and its discharge curve. They'll come up again and again in this guide.

AA cells or
manufacturer pack?

Practically every trail camera runs on AA cells. Alongside that, almost every manufacturer offers its own lithium battery pack that only fits its own cameras. These packs work well, and there's nothing to be said against them – but there are two points you should have thought about beforehand.

Suitability for the field

If you run out of power out in your hunting grounds, you can get AA cells at any petrol station, in any DIY store, in any supermarket – if need be on holiday at the other end of Europe. If the manufacturer's pack is empty, on the other hand, your day is over. Replacements are only available from specialist dealers, and usually not straight away.

The lifespan of the investment

A trail camera in the 150 to 250 euro range is not an heirloom. Technology and designs change every year, and at some point the camera is done for or gets replaced. The battery pack then no longer fits into anything and is worthless. A good set of AA rechargeables, by contrast, easily outlives the camera and moves on to the successor model, to the second camera, or at worst into the torch.

Alkaline.
The curve shows the limits.

Alkaline cells are the obvious choice: cheap, available everywhere and supported by every camera. For short deployments at mild temperatures they're perfectly adequate, too. In trail cameras, though, you keep running into their limits – and their voltage curve shows exactly why.

You'll never get the capacity printed on the pack

Battery manufacturers determine the printed capacity by running the cell all the way down to 0.8 V. Everything that comes out up to that point goes on the pack. Camera manufacturers know, however, that an alkaline cell stops delivering enough power for the infrared flash well above that limit. So that the camera doesn't produce black night shots, they shut the device down completely before that point – depending on the model at around 1.0 V.

The entire range between 1.0 V and 0.8 V is therefore included in the capacity figure, but it's unreachable for your camera. Of the stated 2,000 mAh, you never get all of it. You're paying for capacity that your camera is designed never to touch.

Why the night shots are black

This is where symptom 01 and symptom 04 both resolve themselves at the same time.

Alkaline cells cope badly with sudden load peaks. At rest – with the camera just waiting – a used cell dutifully shows its 1.5 V. Everything looks healthy. Then game walks past, the infrared flash fires and abruptly demands many times the power. The cell can't deliver, the voltage collapses below the threshold the flash needs: black image.

As soon as the flash is off, the cell recovers and climbs back to a value that's perfectly sufficient for a daytime photo. That's exactly why the camera seems in perfect health during the day and fails only at night. No-Glow cameras are hit particularly hard, because their invisible 940 nm flash draws considerably more energy than a Low-Glow model – and so are video recordings, where the flash doesn't fire briefly but keeps going for 10 to 15 seconds at a stretch.

Cold: the failure that disappears on its own

The chemistry of an alkaline cell is water-based, and cold cripples it. If the temperature falls from 15 to 20 °C down to −5 to 0 °C, voltage and usable capacity collapse drastically – below freezing point around half the capacity is lost, and sometimes the cell quits entirely.

The decisive point: this is reversible. When it gets warmer again, power and capacity come back. That is exactly symptom 03 – the camera quits during the coldest spell, stands in your hunting grounds for weeks apparently defective, and resumes operation in spring as if nothing had happened. The cells were never empty. They were too cold.

For Europe that's not a fringe issue but the normal case: the driven hunt and high-seat season from October to January regularly falls within the freezing range in Central Europe, and all the more so in Scandinavia.

And then they leak

The classic: after the season, the cameras go into a box with the cells still inside. The next summer you open the battery compartment – and find a white, crystalline, corroded mess. Leaking alkaline cells destroy the contacts and take the camera with them. A battery problem turns into a total write-off.

Single-use lithium.
Strong, but expensive.

Single-use lithium cells are the opposite of alkaline: technically superior, and in several respects without competition. Even so, many people don't use them, and the reasons are solid.

What speaks for them

• The highest capacity of all AA types. No other cell lasts longer.
• About half the weight compared to alkaline or NiMH. If you walk into remote hunting grounds on foot or kit out a dozen cameras, you'll notice it immediately.
• Almost independent of temperature. While alkaline loses half its capacity below freezing point, lithium gives up a tiny fraction at most.

What speaks against them

The price. A single-use lithium cell costs many times as much as an alkaline. It lasts about twice as long – so on paper there's still a clear deficit. For a single camera at a critical location that may be justifiable. But with a double-digit number of cameras in continuous operation it simply gets seriously expensive.

One round and gone. Like alkaline, they're waste after a single run – just at many times the price.

Shipping by air freight. Loose lithium metal batteries are subject to strict restrictions as air freight and are not permitted on passenger aircraft. If you send cameras together with cells abroad, you'll hit a real limit here. This doesn't apply in the same way to your own air travel: cells with up to 2 g of lithium content are permitted in hand luggage, and an AA lithium cell is clearly below that at around 1 g.

The smell. A point that has only come to light in recent years and is particularly unpleasant for trail cameras: single-use lithium cells give off a gas that is clearly perceptible even to humans. Field research reports that canids – wolf, fox, raccoon dog – can smell the cells and reliably locate the camera site as a result.

NiMH.
Check the voltage first.

NiMH rechargeables are attractively priced and unimpressed by the cold. For the European hunting season from October to January that's precisely the decisive point – the winter that alkaline fails in doesn't bother NiMH at all.

Before you buy, however, you have to settle one question. And it decides whether NiMH will run sensibly in your camera at all.

The weakness is heat, not frost

Above roughly 27 to 29 °C the capacity drops significantly. That's not an exotic limit: a European midsummer day is already enough, and inside a closed camera housing in blazing sun the temperature is noticeably above the ambient air. If you run a sun-exposed camera through July and August, you should factor that in. That makes NiMH more of a winter rechargeable than an all-year one.

Approved for air travel

Unlike single-use lithium, NiMH are allowed to travel with you without special rules. If you take cameras along on a hunting trip abroad, you've got a clear run here.

Self-discharge

NiMH begin to discharge as soon as they come off the charger. You can't charge them fully, put them in a drawer for two months and then fit them fresh – the set goes into your hunting grounds already weakened. So only charge them when you're actually heading out.

Big differences in quality

There's hardly another type of cell where claim and reality diverge so far. Very cheap NiMH rechargeables often have so little usable capacity that their runtime even falls short of good alkaline batteries – and then you pay for the rechargeability with constant check-up trips.

The charger
is what decides.

This point is almost always overlooked – and it ruins more rechargeables than any deployment out in the field.

The early NiMH rechargeables were charged with timer chargers: cell in, eight hours of current, done. The problem is obvious as soon as you say it out loud: every cell comes back from the field with a different residual charge. Stubbornly charging a half-full cell for eight hours means overcharging it – and that destroys the battery. A good part of the bad reputation of rechargeables comes from exactly that: it wasn't the cells that were bad, it was the chargers.

What you need instead is an intelligent charger. You can recognise one by two things:

• Individual bays – every cell is assessed and charged separately, not the set as a whole.
• Trickle charging – the device checks the charge level of each individual cell, charges it accordingly and switches to trickle charging once the target is reached, instead of continuing to push current into it.

Lithium-ion.
Closest to the goal.

If there is such a thing as a universal solution, then it's rechargeable lithium-ion cells in AA format.

They pay for themselves quickly. They're expensive to buy. After the second charge, or the third at the latest, they've paid for themselves – from then on you charge for free.

Temperature is a non-issue. Neither heat nor cold impresses them. Whether in blazing midsummer sun or in Scandinavian frost: unlike with alkaline or NiMH, you don't have to choose between the seasons.

No smell. Lithium-ion rechargeables don't have the outgassing behaviour of their single-use relatives. So game – and canids in particular – can't pick out the camera via the cells.

The trick: a microprocessor in the cell cap

The native voltage of a lithium-ion cell is 3.7 V – but trail cameras expect 1.5 V per cell. How does that fit together?

In the cap of the cell sits a microprocessor that regulates the output voltage. No matter what the native voltage does inside and how far it sinks over the cell's lifespan: exactly 1.5 V comes out at the contact. Immovably.

That makes it the most constant power source you can get. A current draw of 1 A, an invisible No-Glow flash, even video – the cell carries it. Internally the voltage may briefly dip during such a load peak and come back up again; at the output it stays 1.5 V. Precisely the collapse under load that causes the black night shots with alkaline is ruled out here by design.

The catch – and how it's been solved

For a long time, the constant voltage came at the same price as with single-use lithium: symptom 02. If the cell shows 1.5 V after a month and still 1.5 V after three months, then every measurement is worthless. A reliable check of the remaining capacity was simply impossible.

This is exactly where the cell generation of recent years has taken a decisive step forward. Modern Li-Ion rechargeables deliberately let the output voltage sink slowly and predictably from around 80 % of their lifespan onwards instead of holding it until it crashes. Depending on the camera and trigger frequency, that gives you a window of several months in which you can see: this set needs replacing soon.

What a cell like that delivers

As an example, the key data of the XTAR CLR 4300, a cell developed for trail cameras:

Four types,
all the figures.

The cell is
only half the battle.

As important as the right battery type is – it doesn't decide the runtime on its own. Two identical sets of cells last for different lengths of time in two cameras, and drastically so. These factors play their part:

• The camera's standby current draw – the silent permanent drain that no data sheet advertises
• Triggers per day and the ratio of daytime to night shots
• Images per trigger – three instead of one deliver more information, but also cost three times as much
• Photo or video – with video, above all the length. A long night video is the most expensive operation of all, because the IR flash runs along the whole time
• The number and strength of the IR LEDs
• Cellular reception, file size, transmission frequency – often the biggest lever on cellular cameras
• Communication interval – does the camera really have to ask the server every 15 minutes whether there are new commands?
• Outside temperature and the camera's cut-off voltage

Eight rules
for practical use.

1. Never mix. Don't mix types, brands or charge levels – the weakest cell determines the whole set.
2. Always change all the cells together. One fresh cell next to five tired ones achieves nothing.
3. With black night shots, swap the cells first before you suspect the camera. That's by far the most common cause.
4. Only measure under load. A resting voltage of 1.5 V says nothing about whether the cell can still carry the flash.
5. Rechargeables belong on an intelligent charger – and Li-Ion on its own. Timer devices destroy the cells.
6. Keep an eye on the contacts. Dirty or oxidised contacts increase the contact resistance and rob you of power at exactly the moment the flash needs it.
7. Take the cells out before storage. Alkaline especially. It costs two minutes and saves the camera.
8. Change them in good time instead of waiting for the failure. Before the rut, before the driven hunt, before a longer absence: better to swap out a half-full set than to miss the decisive shot.