The Aimpoint ACRO: Battery Life Brightness Settings

Let’s talk about the elephant in the ACRO’s room:

Battery life.

Aimpoint’s goal with the ACRO is to produce an optic that has the rugged reliability that their long gun optics have become known for. They accomplished this by using an enclosed emitter design with a significant amount of armoring surrounding it. This “tube within a tube” method protects the electronics from the shock and impacts of the slide cycling and from the inevitable abuse that the optic will receive when users rack the slide with the optic itself rather than by using the serrations on the slide of the pistol.

It is tough to get the kind of durability that Aimpoint intended with the ACRO into a footprint that will fit relatively unobtrusively on a slide. It was also clearly a priority for Aimpoint that users should not have to remove the optic to replace the battery. Swirl all the intended design requirements together and it likely became clear early on they would have to use a different size battery.

Most slide-mountable red dot optics use a CR2032 coin-style battery, but the ACRO uses a CR1225 series battery. The size difference between them is roughly similar to the size difference between a quarter and a dime. The typical CR2032 has a power capacity of roughly 200 miliamp hours. The CR1225 has a power capacity of 45-50 mAh…around one fifth of the total capacity.

The ACRO has ten brightness settings accessible through the large up and down buttons on the left side of the optic. When you turn the optic on, it defaults to brightness setting 7 at which Aimpoint claims the CR1225 battery will last for a year. I’m sure they’re right.

Aimpoint’s reputation for optics with long battery life comes from careful engineering to make their LED circuits consume as little power as is technically possible. They are so good at this that their flagship long gun products have battery lives that can extend longer than a presidential term. That kind of battery life useful primarily because it means the end user doesn’t have to pay much attention to the state of their optic. If they are proactive enough to replace the battery in their Aimpoint CompM5 once a year, the optic will simply work whenever they reach for the gun it is attached to. This is a nice feature for defensive equipment that is usually needed with little to no advanced notice. If you are heading to a fight, odds are you are part of a military unit or a specialized law enforcement team and you have some time to get your equipment ready for it.

The typical Defensive Practitioner, whether they wear a uniform or not, is responding to an ambush attack that is usually a strictly come-as-you-are event. A police officer who gets a gun pulled on him during a traffic stop doesn’t have time to check the status of his weapon and his optic before the shooting starts. Average Joe trying to use the ATM doesn’t get to make sure his weapon is in a ready state before the violent felon pulls a gun and demands money.

There are advantages to an optic attached to a piece of life-saving equipment that will work even if you neglect to conduct any preventative maintenance for a prolonged period of time.

Trouble is that LED circuits, even the ones used by Aimpoint, consume power on an exponential curve. The battery life for an Aimpoint CompM5 on a night vision setting can extend to almost a decade. On setting 7, the battery life is roughly 5 years. On setting 8, the claimed battery life is one year. Each higher brightness setting pulls exponentially more power from the battery.

The ACRO’s LED is no different. I’m sure that the CR1225 battery in it will last for a year at setting 7, but I find that setting 7 is not useful in a lot of circumstances. It is worth noting here that the ACRO does not have an auto-adjust feature on it, so ensuring that the optic is on the right setting for conditions is entirely up to you. If I’m in a rather tamely lit indoor environment setting 7 works fairly well. If I am in, say, a very brightly lit store with white tiles on the floor and a white ceiling (Think the aesthetic of a Target) then I’m going to need the optic on at least an 8 to reliably pick it up.

If I am outdoors on the range on a sunny day, I have to have the optic set to maximum output to be able to pick up the dot.

Everyone sees the world through a bespoke set of hardware and so what my eyes need might not be the same as what your eyes need. Maybe you need less power, maybe you need more. I have no way of knowing what the world looks like through your lenses.

It does bring up an interesting problem, though…what setting do I use for my optic? Some say that the correct approach is to use the lowest setting where you can see the dot. This has merit as it tends to make the dot appear crisp and perfectly round while avoiding the dot becoming misshapen or irregular as it can be on higher settings than necessary.

But the lowest setting for what lighting conditions?  

Think about a typical trip to the store on a typical afternoon. When I pull into the parking lot with the sun near its zenith, there’s no way I’m going to pick up the dot on setting 7. If I dial up the dot  to the setting 9 or 10 I need for the parking lot, once I get into the store I’m going to have more of a smear than a dot…and on the highest settings I will actually see smear-like red artifacts around the outside edge of the optic’s window. Working with the optic in lower light situations I have most certainly confused some of the “bloom” artifacts from the too-bright-for-conditions LED setting for the actual aiming point of the optic.

Well then, you might say, leave the optic on maximum and practice until you can tell the actual aiming dot from the bloom on the edges. Way ahead of you.

Trouble is that in the process I discovered that leaving the optic on its brightest setting drops the battery life to just a little over ten days.

Now you can start to see why I consider having a complete and useful set of iron sights on the gun an absolute requirement. The idea of using the tube of the ACRO itself as sort of a rear ghost ring sight with a suppressor height front sight isn’t something I’m a fan of for reasons I will discuss in a future post. Suffice it to say that because I’m not sure if the brightness setting will be right for the conditions, I most definitely want iron sights I can refer to if I draw the gun and can’t see the dot.

After living with the ACRO for a while I’ve come up with some strategies that give me decent battery life and the highest chances of having a visible dot should I need to draw the pistol.

Firstly, I bought 50 Renata CR1225 batteries. You can buy ten batteries for less than 9 dollars from reputable outlets so it’s not a major financial imposition to have a bunch on hand. I keep five in my car’s glovebox, ten in my range bag, five with whatever case of 9mm ammunition I’m working through at the moment,  five in my briefcase, five in my desk at the office, and the rest at home. As a result I am rarely more than a few steps from a supply of at least 5 batteries in my daily life.

In addition, I trimmed the packaging on one of the batteries down enough so that I could keep one in the empty space behind the magazine well of my Glock, retained with a grip plug:

With this I have a spare battery literally on the gun at all times should I find that the battery is dead.

Aimpoint designed the ACRO to give you a warning that the battery needs to be replaced. When the battery is low it will reduce the output of the LED until the battery runs entirely out of power. Because I rarely have the optic set to the maximum brightness level, if I find I can’t bump the brightness of the dot up while I’m indoors it means that the LED is operating in battery saver mode and it’s time to replace the battery.

Because batteries are cheap and I keep a bunch of them, the sensible thing is to simply replace the battery proactively. Rather than push the boundaries of battery life, I simply replace the battery in the optic once a month. I am typically performing some level of maintenance on the pistol around then anyway (usually just a wipe-down and lubrication) so it isn’t a hardship to take the two minutes necessary for a battery change at the same time.

I know, I know…somebody out there is going to be awfully perturbed at the idea of having to change the optic’s battery once a month, but please note what I said: I’m performing some level of maintenance and inspection on the pistol I’m carrying anyway, so it doesn’t cost me anything extra in terms of time or effort to just replace the battery.

If you aren’t at least inspecting and lubricating your carry gun once a month, consider starting that practice.

So while there has been much Sturm und Drang about the battery life of the optic, having spent time with it for a while I don’t think it’s really a big deal. I’m willing to trade the larger battery of the RMR for the benefits that Aimpoint’s enclosed emitter design brings to the table.

An auto-adjust feature would certainly be nice, but I can certainly work with the optic as-is. I just dial the optic up to setting 9 in the morning and then down to about 6 when I take off the gun at home in the evening where I’m going to be reaching for a shotgun if I need a weapon anyway.

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