Ask any iPhone owner for a list of what they’d like to see in the next iPhone, and a bigger battery is almost certain to be on that list. Well, if you’re one of those people wishing for a bigger battery, it looks like your wish might indeed come true.

But don’t get too excited.

Photos posted on Chinese microblogging site Weibo show two batteries – presumably for the iPhone 7 and iPhone 7 Plus – with capacities of 1735 mAh and 2810 mAh. Compared to the iPhone 6S and iPhone 6S Plus, which have batteries with a capacity of 1715 mAh and 2750 mAh respectively, this represents a capacity bump of 1.5 percent and 2.1 percent respectively.

However, these batteries are smaller than the packs inside the iPhone 6 and iPhone 6 Plus, which are 1810 mAh and 2915 mAh respectively. Compared to these, the leaked batteries have 4.2 percent and 5.8 percent less capacity.

So, why might the iPhone 7 need a bigger battery than the one found inside the iPhone 6S, but not one as big as the iPhone 6? Well, all the rumors so far point to the iPhone 7 being a modest upgrade on the iPhone 6S, and that means that the power requirements will be about the same. About the only rumored feature for the iPhone 7 that’s likely to need more power is the second speaker that’s rumored to replace the headphone jack. Since two speakers are likely to draw more power than one, Apple is not going to want the audio and video playback numbers to take a hit, and a bigger battery – even if it’s only a percent or two bigger – should help realize that.

Why doesn’t Apple just outfit the iPhone 7 out with the biggest battery it can fit into the shell? The answer is down to three factors – price, weight, and thickness. Not only does Apple have an obsession with making new products lighter and thinner, but it also wants to maximize profits, even if this means keeping the battery life as it was previously.

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