Why don't camera flashes use proprietary batteries?

Question

In trying to explain Why Cameras Use Proprietary Batteries, many have claimed that it is because proprietary lithium rechargeable batteries have better high-current capabilities than any AA (though nobody has linked any reputable source substantiating this) and that camera makers are greedy companies that want to force you into buying their expensive battery.

Why, then, do flagship flashes like the SB800 use AA batteries? If you've got supposedly superior high-current battery technology in those proprietary lithiums, here is the place to use it. Imagine the faster recycle times.

And if you're greedy, then you're greedy - why not take the opportunity to shaft customers on your flash batteries just like you do for the cameras?

Something doesn't add up here. What's the truth behind using AAs in flashes? (And as a bonus, go answer the original question - we should be able to develop a consistency between the two answers that explains the opposite choice made by camera makers).

Answer 1

The ergonomics and weight balance of a camera are more important than that of a flash. By incorporating a proprietary battery into the camera design the manufacturer has more flexibility on its size, shape and position in the camera. This can reduce the size of the battery compartment, simplify the access door and battery contacts, and means that more power can be stored in a tighter space. This is particularly important in compact cameras. I don't think it's just about the power output and capacity of the batteries. I imagine a more holistic approach to the design of the battery and how it integrates with the camera is involved.

Also, considering that the voltage options for off-the-shelf batteries tend to be nominally 1.5V per cell with the exception of a PP9 (9V), more than one cell would be required to deliver sufficient current to operate the mirror, shutter and lens effectively. In an SLR I expect you would need at least 4 or 6 AA batteries to achieve that, adding considerable bulk to the camera and your camera bag (imagine the spares). :)

Finally, let's not forget that the flash contains a capacitor because of the high voltages involved and that power is transferred from the battery to the capacitor prior to firing -- in this respect, the battery isn't directly driving the flash, the capacitor is, so the battery specifications are less important in the design.

Answer 2

The Godox V850 (also sold as the Cheetah Light V850 or Neewer TT850) does use a proprietary lithium battery, and the recycle times are amazing. Watch this (promotional) video showing the difference. As this Fstoppers review notes, the V850 retains its fast recycle times even as the battery drains, which isn't the case with any sort of AAs.

I can't speculate on exactly why no one else has done this (especially when, as you note, camera bodies already do), but the performance of this (very low cost) flash certainly proves the basic point. The Flash Havoc blog believes that this new flash will cause a revolution... time will tell if that turns out to be true.

Personally, I'd love it if my flashes took the same lithium batteries as my camera body. That'd be quite convenient. Unfortunately, that certainly isn't true with the V850. I know Itai warned against giving the camera makers any ideas, but if they are going to take them, let's hope they at least aim for this.

Answer 3

A camera can, usually, take several thousand shots between charges. The advantages of a proprietary battery can, therefore, be incorporated into the design without impacting the average user. More demanding users can purchase multiple proprietary batteries, if their use case requires it.

A flash unit will, usually, require that batteries are replaced more often. This limitation would, potentially, affect the average user. Manufacturers have, therefore, designed the majority of flashes so they can be powered by replaceable, inexpensive batteries that are widely available. Rechargeable versions of these batteries are also available.

Many flash manufacturers offer models which can be powered by battery packs that do include proprietary battery designs and, therefore, can incorporate some of the advantages you mention.

So I think it basically comes down to; for the average user, a proprietary camera battery has no negative impact, but a proprietary flash battery would be inconvenient.

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Edit: Let me put it another way. If you have a DSLR with an external Flash - both with fully charged batteries - and you took pictures that required a reasonable amount of flash to fire on every exposure, until the battery in the camera was exhausted, I would expect the batteries in the flash to need replacing several times.

Answer 4

If I had to take a guess, the problem would be deciding which battery pack to use. Not all cameras in a line up use the same battery pack, but they can all use the same flash. You could segment the flashes like you do the cameras by how high end it is, but then you run in to battery consistency issues for people using mixed flashes which can get very aggravating. People are going to be using one, maybe two different kinds of cameras, but may be using many different types of flashes. It isn't practical to have different types of proprietary batteries for each type of flash.

That said, they are more than happy to sell you their external battery packs for the high end flash units which provide more power (even if still based on AAs) and are a fairly expensive item (though it does include it's own charging unit to provide power to the flash).

Answer 5

For a camera, there are many reasons to use a proprietary battery.

Flash systems are a fundamentally different design. The key to the flash is the capacitor which very briefly powers a high voltage flash tube. How you get the power to the capacitor is much more forgiving in most cases than a camera - one typically isn't after a long duration, high power, strobe on the flash.

Thus, the camera's flash can use a much simpler design - all that matters is charging that capacitor.

There could be some performance gains when using a specialized battery pack. Keeping in mind that its about charging the capacitor, there is a SD-9 battery pack for use with some Nikon Flashes. What is it? Its a way of putting 8 AA batteries rather than 4 in a flash. And yes, if you use better performing batteries (the Ni-MH rechargeable claim the fastest cycle times) you get faster cycle times or more flashes per battery (B&H has a battery performance chart).

Answer 6

"If so many cameras use custom batteries, why do so many flashes use commodity cells?"

Excellent question. I'm disappointed I hadn't thought to ask it.

I suspect it has to do with market demographics.

(To make the argument clearer, let's assume Camera X has only 1 available flash, Flash X)

In most cases, more people will buy Camera X alone than will buy both. I suspect that most camera buyers don't want to bother with external flash. Those that do are most likely "prosumers" who are used to carrying around pocketfuls of AAs. While your stereotypical might buy your high-end camera and appreciate that it uses a single battery, the will get online and complain mightily if the flash doesn't support the AAs they've been using for years.

Actually, if my camera manufacturer made their external flash use the same battery as my camera body (and it gave as good or better performance) I'd consider that a win.

Answer 7

Many professional grade flashes do have proprietary battery packs available that boost the performance of the flash, so stop saying, "flashes don't use proprietary batteries." Some do: especially the kind that were used by photographers who also had professional grade cameras before the digital revolution made DSLRs ubiquitous for practically every amateur enthusiast.

Before the technology advanced to the point of semiconductor controlled flashes that communicate in a sophisticated manner with the camera's "brain" the flash one used was rarely made by the camera's maker. Pretty much any flash could be used on any camera if the trigger voltage of the flash was within the acceptable range for the camera. So the use of off-the-shelf batteries in flashes is probably as much of a legacy thing as anything else.

Battery technology back then was also nowhere near the sophisticated level it is today. Alkaline batteries could outperform rechargeable batteries with the same form factor several times over. Even today, a lot of photographers compare notes concerning which type and brand of consumer sized rechargeable batteries give the best performance in modern external flashes. Even 2500mAh AA eneloops don't always outperform good old AA Alkalines in a speedlight. I seem to get a few more total flashes out of the eneloops, but a fully charged eneloop cycles the flash slower than a fully charged alkaline can.