@ottaross I believe you're wise in the ways of electronics? I've got a project with a solar panel delivering 6W, 5V output and I want to charge 6 x 3.7V 18650 batteries in parallel (not series). I want overcharge and overdischarge protection. I've seen plenty of these (see link) but nothing for the number of cells I want to use. They are all for one cell. Those that can do multiple cells always seem to assume the batteries are in series.
@Aussiemandias If I were facing that task I'd prob find a custom IC and build a circuit around it. The TI chips are a good choice. (link) Data sheet would offer some circuit examples. Parallel shouldn't be a prob as long as the cells are balanced (same ratings).
Typ charge controller will use current & voltage tracking, plus a temp sensor in the pack.
I'd prob have a separate dischg controller w a voltage set point. They're easy to find on ebay/amzn for a few bucks.
@ottaross I see someone else using it, but with super capacitors. My plan is to have LTO batteries instead. I know nothing about super capacitors for this sort of application.
@Aussiemandias LTO is famed for temperature range performance, so should work out well. I'd imagine a super cap would do well in lower current, cold weather use, but i haven't explored them. LTO will have them beat on current tho I'd think.
Li-ion batteries in general aren't great in the cold, but compared to everything else they're much better (esp against alkaline!) Lithium-Sulfur batteries are in the future, and will be great for our cold climate. Still a while out though :(
@Aussiemandias the current sense resistor sounds handy, given you mentioned cells in parallel. So given an appropriate voltage for a single cell of your chosen chemistry, you could get higher current to supply all the cells with good efficiency.
@Aussiemandias on the cell voltage front, I think LTO has a lower cell voltage, right? Like it's 2.4V rather than typical Lithium Ion up around 3.7V. The charge controller will need to be aware, though it should be easier having sufficient voltage compared to reg LiIon.
@ottaross Yes, lower voltage. Also less energy dense. But good for cold climes. I want to have it robust and low maintenance. I also have to find a place to put it with good line of sight to a good chunk of the city.
@ottaross It will probably take time to source the LTO batteries that I want, so I might start with some Lithium Ion batteries for when it's warmer then upgrade later.
Add comment