I bought the ac3 to use to run my solar through to charge my 100-watt lithium ion sodium battery along with charging the internal one. i see no answers to this question
I see no question posed by you to answer
Agreed, what are you asking? If you’re wondering if they will both charge at the same time then yes, as long as you have enough solar to support that and your battery charger doesn’t draw too much current.
If I understand you correctly, this 100 watt battery is not part of the Bluetti Expansion Batteries, right? Otherwise it’s plug and play, automatically charges when connected to the ac300.
Pretty sure you can’t use the ac300 just as a solar charge controller as there is no output for this. However you normally charge this external battery (ac adapter or whatever), you could just plug it into the ac300 just as you would a wall outlet. It has pass-through charging, (you can use it to power something while it’s charging.)