Google Pixel 7a charging test: running at very low temperature

Google doesn’t provide a charger in the box with the new Pixel 7a, so you’ll have to choose a compatible third-party charger. Before you do, you’ll want to learn more about how the Pixel 7a charges, what specs it uses, and how long it takes to fill it up. We tested the phone to give you everything you need to know.

The Google charger supports USB Power Delivery PPS to quickly charge the Pixel 7 series, but the Pixel 7a defaults to the standard USB Power Delivery protocol. It draws a maximum of 18W (9V, 2A) from this plug, so you can buy a lot of lower powered 3rd party alternatives and still run 7a without a problem.

At 18W, the Pixel 7a takes 1 hour and 46 minutes to complete, which is very slow. Getting to 25% takes 16 minutes, getting the battery halfway through takes 36 minutes, and getting it to 75% a full hour is rather painful. As you can see from the graph above, the end of the charging process is by far the slowest part, but the phone isn’t that quick to charge in short bursts either.

It’s even slower than the Pixel 7, which boasts a similarly sized 4,355mAh battery. That might be expected since it supports 20W USB PD PPS charging but is marginally faster, but we saw the same charging time when using 18W USB PD. And not just for a full charge, either; The Pixel 7 hit 50% and 75% completion several minutes faster, too. It seems charging temperatures may have something to do with it.

Even if you choose the right phone charger, the Pixel 7a takes a long time to charge compared to other phones. This is because 18W is already a very low power level, and it is not even used for the entire charging cycle. The last stages charge at 11W before dropping below 5W to finish charging the battery. Furthermore, Google’s charging algorithm is sensitive to temperature, and aims to keep the cell below 40°C by reducing power further.

We can see this clearly in the chart below. The Pixel 7a conserves 18W of power for a decent portion of its early charge cycle when the device is cold (unused starts at 20C). But once temperatures approach 37 degrees Celsius, the Pixel 7a throttles charging power to 14W and then only 11W until temperatures drop. When this happens, it adds several minutes to the already slow phone’s overall charging time. We noticed that it takes just over two hours to charge the phone with a slightly warmer starting temperature, and the phone gets quite hot while charging either way.

This temperature issue is consistent with the slower charging pattern we’re seeing in the mid to late parts of the charging cycle compared to the Pixel 7, which doesn’t exhibit the same throttling issues when using 20W or 18W charging. The exact reason for this is not entirely clear. However, it’s possible that the Pixel 7a’s body can’t dissipate heat at the same rate as the Pixel 7 series or that Google is being careful about the sensitivity of this (cheaper?) battery to higher temperatures.

This also makes sense in the context of the Pixel 7’s low-power wireless charging capabilities. The Pixel 7a takes more than 3 hours to reach a full charge on the Pixel Stand (2nd generation) due to its poor 7.5W charging power level. While wireless charging is a welcome addition, it is very slow and not suitable for charging your phone quickly.

Google’s Pixel series has always been slower to ship than its competitors, and the Pixel 7a is no different. The good news is that it’s easy to find compatible USB Power Delivery and Qi wireless products that meet your phone’s conservative power needs. The downside is that the phone seems to be limited by temperature restrictions that make charging slower than expected in certain conditions. If you think you’ll need to top up your phone quickly, choosing the Pixel 7 or Pixel 7 Pro would be a better choice than the budget model.