Wongsakorn 2468/Shutterstock We may receive a commission on purchases made from links. Apple's flagship Watch Ultra 3 is known for its relatively longer battery life in the company's smartwatch lineup. It is claimed to last up to 42 hours in the standard mode and up to 72 hours in the low power mode, which is significantly higher than the battery life claims for the Apple Watch Series 11 and the Watch SE 2. However, unless you don't have a problem plugging your Apple Watch in for charging every other day, the 42-hour battery life isn't very long, and let's not forget that you are spending $799 for the Ultra 3. Fortunately, if your heart isn't completely set on the Apple Watch lineup, manufacturers like Amazfit, CMF by Nothing, and Garmin offer smartwatches with multiday battery life at a fraction of the Ultra 3's price. More importantly, all these smartwatches are compatible with iPhones.…