I say comment and downvote if you so choose, but choose downvoting carefully. Answers that are wrong should be downvoted and commented on, because I have found no flag that says you can delete, because it is wrong.
But in my opinion the Answer is both wrong and right. The answer could be interpreted that no answer could be found by that user and if no safe or healthy alternatives can be found then the answer even though stating "No" could be correct. Whose to say the other answers are safe and therefore good answers.
I plan on leaving a comment on the person's post who answered to see their insight into the post, but I for one think that all downvoting and flagging should be paused until it is ruled out that this answer is not the best answer. In the future if you don't understand a answer you should comment about improving it, but if it is to far gone then you should flag it. But asking on Meta is appropriate, as well.
Here are some questions you should ask before downvoting:
Because just because users are posting "answers" doesn't mean that there are answers to a problem. The answer states:
you should buy a better charger, that can charge any number of
batteries at the same time; anything else probably isn't worth the
effort, probably isn't safe, and could damage your batteries.
Unless the other posts can guarantee that they're methods don't damage your battery in anyway the answer could be correct.