Acer R13 not chaging with Anker PD1 PD USB-C charger ?

Welcome to Android Central! From the specs, it looks like the OEM Acer charger is 45W, while that Anker is 30W: https://www.cnet.com/products/acer-chromebook-r13/specs/. It's probably not delivering enough power.

Thanks for your reply. I thought that if it was lower wattage, 30 W, that it would still charge but at a slower rate?

I thought that’s what PD specification was all about, negotiating between the charger and the device for different wattages ?

My Dell laptop has 45 W factory charger, but works fine with the 30 W USBC anker charger
 
Sorry, not sure about that. Maybe Acer didn't implement the charging protocol correctly, or maybe it really needs 45W to charge appropriately. I've tried a lower wattage charger on my Pixelbook, and it gives me a warning that the charger is underpowered, and not much happens with the battery level. It might be worth contacting Acer support about it: https://www.acer.com/ac/en/US/content/service-contact
 
It looks like the Anker charger you're using might not be the right fit for your Acer R13 Chromebook. Even though it works with other devices, it's causing issues with your Chromebooks's brightness and the flashing lightning bolt symbol. This usually means there's a power problem.

The original Acer charger and a Dell USB-C charger work fine, which suggests that the Anker charger might not be compatible with your Acer R13. It's best to use a charger that's made for your specific Chromebook model or check with Anker's customer support to see if they have any insights about this issue.

Using the wrong charger can harm your Chromebook, so it's important to stick to chargers that are known to work safely with your device.