Is it possible to charge a 9v volt battery using Arduino?

(MOD EDIT)

https://data.energizer.com/pdfs/nh22-175.pdf

Battery:

Obviously the battery can be recharged, but, how can I do it with Arduino?

You can start by removing all your smiley faces.

Take your pick:

For some reason there isn't a whole lot of ways to do that with an arduino. In general you could pwm a mosfet and monitor the battery using a voltage divider and reduce the pwm the closer it gets to 9V.

An Arduino requires power to operate. It's not a source of power.

Tell us where the power is coming from and maybe you could use an Arduino to control it.

That is a good question, and the answer is yes if you assume it is the charge controller. Start by getting the specifications on charging the battery from the manufacturer, including the chemistry, that will give you a start. You will need to read voltage and control current. Current control can be quite simple or complex depending on the battery chemistry, I do not know what chemistry your battery is but for simplicity lets assume it is a Lead Acid, Nickel Metal Hydride, they both follow very similar algorithm. First you will need a charging power supply that supplies the current and voltage required to charge the battery. The lead acid battery uses the constant current constant voltage (CCCV) charge method. A regulated current raises the terminal voltage until the upper charge voltage limit is reached, at which point the current drops due to saturation. The charge time is 12–16 hours and up to 36–48 hours for large stationary batteries. See this link where I got the previous: https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil

The pdf says RECYCLED Nimh, odd, I don't see an Energizer trademark anywhere...Ⓡ...?

This is not a beginner project.

Just get a battery charger for NiMH cells with connections for PP3 sized 8.4V batteries like this one!

like this one!

(FYI, there's no link)

raschemmel:
(FYI, there’s no link)

For 8.4 NiMH batteries like this one - the one (battery) in question - sorry I was ambiguous there!

8.4 NiMH batteries like this one - the one (battery) in question - sorry I was ambiguous there!

The sentence is complete without "like this one" (which suggests a link has been posted)

Or you could have put "like the 8.4 NiMH battery photo you posted".