As I think through buying a ready-made battery for my mother and building my own DIY LiFePo battery setup for myself, I'm trying to understand charging speed limitations.
Something like this unit on Amazon only charges at 50 watts from solar. It's 300 watt hours, so if I'm right, that's 300wh / 50w = 0.16 C (correct?). What would be a reason to limit the charging rate so severely?
Then there's a unit like this one, which will charge at 220 watts (120 through the solar /DC input and 100 through the USB-C). That amounts to 622wh / 220w = 2.82 C (yes?). It seems to be "standard" Li ion (so not LiFePo) but I'm guessing the same logic applies (again, please correct me if wrong).
That's like an order of magnitude in different charge rates; any ideas what might explain these different choices?
For my DIY build, I notice that the MPPT charge controllers just basically specify a max amperage (smallest I find on Amazon is 10 amps), which at 12v is 120 watts. My solar panel is 120 watts, so I'm inclined to believe that any LiFePo battery with at least 120 wh of capacity can safely charge at the full 120 watts?
I'm asking because although I understand the emphasis on capacity, I will mostly be using my setup to be nimble and mobile when it's sunny out, and I have a 120 watt solar panel, so I regardless of the battery's capacity, at a minimum I need it to be able to pass all of the power coming off of my panel through to my devices and charge with any excess. I'd hate to be "throwing away" good solar capacity.
Thanks for any tips on this!
Something like this unit on Amazon only charges at 50 watts from solar. It's 300 watt hours, so if I'm right, that's 300wh / 50w = 0.16 C (correct?). What would be a reason to limit the charging rate so severely?
Then there's a unit like this one, which will charge at 220 watts (120 through the solar /DC input and 100 through the USB-C). That amounts to 622wh / 220w = 2.82 C (yes?). It seems to be "standard" Li ion (so not LiFePo) but I'm guessing the same logic applies (again, please correct me if wrong).
That's like an order of magnitude in different charge rates; any ideas what might explain these different choices?
For my DIY build, I notice that the MPPT charge controllers just basically specify a max amperage (smallest I find on Amazon is 10 amps), which at 12v is 120 watts. My solar panel is 120 watts, so I'm inclined to believe that any LiFePo battery with at least 120 wh of capacity can safely charge at the full 120 watts?
I'm asking because although I understand the emphasis on capacity, I will mostly be using my setup to be nimble and mobile when it's sunny out, and I have a 120 watt solar panel, so I regardless of the battery's capacity, at a minimum I need it to be able to pass all of the power coming off of my panel through to my devices and charge with any excess. I'd hate to be "throwing away" good solar capacity.
Thanks for any tips on this!
