Charger means 1) to load, 2) to charge (up), i.e., a battery, 3) inflate, 4) charge (at) in the sense of attack, 5) to overload. It is not used in relation to charging a fee or anything about a price. Duo's use of such a sentence misleads English speakers into thinking it is an inquiry about a price. It is not.
For charger, I'll refer you to http://www.larousse.fr/dictionnaires/francais-anglais/charger/14622. As noted there, to charge (money) would be "faire payer". As far as the English "charge" in the sense of accusing someone, the French would probably use inculper: http://www.larousse.fr/dictionnaires/francais-anglais/inculper/42351
Not sure why it says that. If you look at the definition, charger is intransitive when it means "to charge" in a military (or violent) sense, so you have to use a preposition if you're specifying an object. http://www.collinsdictionary.com/dictionary/french-english/charger
I know this message tom which I'm replying is 4 years old, but I also thought that the audio sounded like "cherche".
A situation, group or individual can be charged or even highly charged which means it is loaded with emotion.
An electrical circuit or device can be charged which means it is loaded with electricity.
An individual or group may be placed in charge which means they are loaded with responsibility, authority or both so as to deal with a set of conditions or objectives.
An individual or group may choose to charge (attack) a figurative or literal objective when they are loaded with determination, energy and usually with little, apparent regard for any inherent danger. This can be applied to companies trying to increase market share or military maneuvers.
An individual, group or institution can be charged or have charges laid against them, when they are loaded with assumed guilt, by other parties or institutions. In criminal situations it is a government agency that lays the charges.
A person or group can charge their weapon or drinking glass which means they they load or fill it.
A person or group can place an explosive charge somewhere which means they have loaded some point with explosives in a condition, and usually with the intention, to be detonated.
And, of course, charge means to require payment of some kind.
But, as bonnie.sjoberg has pointed out in her post charge is never used to refer to loading or filling a truck.
The procedure is: Gentlemen, charge your glasses. Then, after a suitable interval, a toast is proposed. In circumstances where language like that is being used, the toast will generally be pretty formal such as a toast to the guest of honor or the Queen etc.
Unless you travel in circles where toasts to the Queen are a regular feature, you probably won't have need for that sort of usage.
I have encountered charger, or a variation, many times and in nearly all cases the translation has been a variation of the rather ambiguous 'to charge.' Now in is very vague statement, 'charges' is WRONG and only LOAD is correct. Really, the more I use Duolingo, the less I like it.