Could I charge my AC180 directly from a lead/acid battery with the DC7909 with alligator clips? If so what is the max size of battery I should get?
Highly unlikely. The resting voltage of a LiFePo4 in the AC180 is 13.1 to 13.2VDC. An AGM or lead acid battery rests at around 12.8V fully charged. To charge a power bank you need over 13.8VDC.
The best you might expect is some trickle effect whilst the power bank is in use and connected to the lead acid. i.e. Pass through effect. Notwithstanding a lead acid deep cycle battery should not be discharged more than 50%.
If you are referring to a standalone wet cell cranking battery, forget it.
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Thank you for the information. I wonder what the purpose of the DC7909 is?
I’m guessing the AC180 uses it’s MPPT to adjust the voltage to something usable. Both the manual and the page they sell the DC7909 on both claim it’s for charging the AC180 from a lead acid battery. The DC Input voltage range does go down to 12V, so I’m assuming it would work, but don’t have a clue how fast it would charge or how much it would pull from the battery. At least since it might only goes down to 12v, it won’t damage the battery.
Another option would be to use two batteries in series, though you’d want to watch the battery voltages to make sure they do not drop too low and damage the batteries.
Thank you. That’s kinda what I was thinking the purpose of it. Maybe somebody on YouTube will do a test.
D7909 is the DC input to the AC180. Solar or other input. However, its intent is to use an idling or running vehicle where the voltage and current are augmented by the alternator. Or, use of a LiFePo4 2nd battery as a source.
You would get some charge from a standalone lead acid, albeit, not a lot and slow.