So Wahl went out of their way to make a shaver that caters for 'Afro' issues. That is, a shaver aimed at preventing razor bumps or Pseudofolliculities Barbae. So, they created the Wahl Afro What A Shaver Trimmer.
I first read about this shaver in a magazine somewhere, I can't remember, about 10 years ago, and decided to give it a try. I have since owned two of them, as they lasted so long. After about 2 years, the battery does weaken and you'd have to change the battery, but that's normal for any battery - there is a finite number of charge-recharge cycles.
There are two options, depending on what's convenient for you.
1. Rechargeable Battery option: Wahl Afro What A Shaver Trimmer Rechargeable 9947-801
2. Non Rechargeable Battery option: Wahl Afro What A Shaver Trimmer Battery 9945-801
They are identical, apart from the battery charging circuitry in the rechargeable option, which is why it is slightly more expensive.
I found this trimmer to be the best I'd ever used when it comes to preventing bumps, provided you 'shave' in the correct direction. All the rules for shaving with a razor still apply.
It works by making sure the beard area is not shaved too close to the skin, making ingrown hairs a lot less likely. As long as you're not looking for a clean close shave, this is the trimmer for you!
They last so damn long as well. I've only had 2 in the past 10 years!