I forgot my macbook pro charger at a friends place and I won't have it for a week. I saw that there are 3rd party chargers being sold for half the price of official chargers. Can 3rd party chargers damage my macbook pro? After I get my normal charger back in a week I will be mostly using that one and keep the new one as an extra, so I won't be using it fulltime.
It's unlikely they will actually damage your MacBook Pro by delivering too much power to it. But there are many cautionary tales to be found on the internet of third party chargers overheating, and occasionally catching fire or exploding. Technically, using a non-Apple charger without Apple's written permission may also void your warranty if anything did go wrong.
Personally, I wouldn't risk it.
Even an Apple charger can damage a Mac. It's far, far more rare since Apple tends to have superior QA and more motivation to make sure the adapter fails over the computer than the average knock off manufacturer.
That being said, there are many good chargers that will work just fine. The main risk is fire from a poorly constructed transformer as opposed to down stream damage to your Mac since the magsafe port delivers between 3 V and 25 V DC it's not a huge amount of power or danger to life or hardware.
Yes it may hurt your battery, you need to be very careful when using 3rd party products. The charger needs to be compatible with your battery, check the information on it (input/output values - how many V and A), if they are the same as your original one then you shouldn't worry much. Still this doesn't guarantee that it won't damage the battery or the mac.
Try Nekteck PD 65W charger, it worked pretty good for me and it's certified by USB-IF. https://www.amazon.com/Nekteck-Certified-Delivery-PixelBook-Nintendo/dp/B0721KG2Q7