I use some outdoors solar-powered loggers in conditions where LiPo typically do not survive very well (like, -15 degrees celsius). In these conditions, in my experience, LiFePo4 works fine enough, but LiPo do not work well at all.
I cannot find any solar chargers for LiFePo4, except this one, which seems a bit primitive (though it seems to work fine):
So my question is, could Sparkfun develop and produce a single cell solar charger tuned to the LiFePo4 characteristics, similar to the one available for LiPo ( https://www.sparkfun.com/products/12885 )? That would be extremely useful to everybody doing in-situ sensing in the polar regions for example. This is actually a quite large geophysics community that would benefit from it
Our engineers have visibility in the forums and can see your post. I can’t guarantee we will be able to design something, but thanks for letting us know there is a demand for this.
I’m wondering if a “quick and dirty” fix fpr this would be to put a diode (with a 0.6 to 0.7 V forward bias drop and a 1.5 A rating) might be added in series with the charging circuit of a TP4056-based LiPO charging circuit might do the job in a pinch…
Well I don’t know if that charger would be better, I only made the recommendation if one only had some LiPO chargers and wanted to modify one to make it work for LiFePO4 cell chemistry.
I think that a big part of the problem is that I believe that it is difficult to implement a true, MPPT (maximum power point tracking) for an arbitrary charger. Probably many companies would like to sell you some, but the market might be too small to justify the expense of design and testing, etc. I think MPPT is fascinating but might be too complex for small-power applications.
I would love to see the “guts” of an MPPT charger/interface.
