I don't know what the cause might be for slow charging. I usually charge externally and swap batteries. When I used the usbc charging I was pleased with how quickly it charged. It seemed to be just as quick as the external charger. If the batteries are ok then I would say that is not normal...
I would say that sounds normal. I always shut the unit off before my last pull and try to fit my sessions in 2 - 3 minutes. This thing uses lots of power so I would get a spare set of batteries if you are going to use it often.
Last night I enlisted the help of my friend who does metal work to fab an aluminum insert for my heat shield. I dropped my voltage by about .5 to account for the increased efficiency over my tin foil shield. More importantly, there is no need for a primer hit or to draw slowly with a wide open...
https://www.amazon.com/gp/product/B08FMMZGYR/
https://www.amazon.com/gp/product/B07TSMN9ZG/
https://www.amazon.com/gp/product/B08T5R1Z2M/
https://www.amazon.com/gp/product/B07VVP9ZQQ/
These are all the parts I used. I drilled a 1" diameter hole through the bottom of the wooden cup and secured...
Using the world famous HLT thermal core I made my very own "Log Lamp":clap:
Thank you for making the design open source! I believe the voltage is set at 6.32 in these photos.