John in CR
100 TW
I'm going to be putting together all of my miscellaneous battery into a large pack, actually 2 (one Lifepo4 and one lipo, mostly Konions). They will be single cell solar charged for constant balance. My thought is that since these will sit at high voltage so much of the time, and I want to run them conservatively, that I will put an extra cell in series, but charge to the same top of charge voltage as my bikes.
My primary voltage is 20s of Lipo, which I cutoff at 4.15V/cell, 83V. The Home pack would get 21s of lipos, and 24s of Lifepo4, and I'd just go to 84V top of charge on the home pack, since there will always be some voltage drops even with quite direct connection to charge my ebikes...just a resistor and maybe a big diode on each ebike charging wire (different values for different charge rates). Since my bike packs will have so close a voltage to the supply pack, charging that way should be more efficient than any charger. Plus I'll get to finally have a fast charger for those rare times I want to fill up and go right back out.
I realize I'll give up some capacity, but battery life is more important to me. Is it reasonable to expect significant extra life by charging my 3.6-3.7V nominal cells to 4.0V top of charge and 3.5V for lifepo4 ? I'd go really conservative on the LVC too, say 3.5V for lipo and 3V for lifepo4.
My primary voltage is 20s of Lipo, which I cutoff at 4.15V/cell, 83V. The Home pack would get 21s of lipos, and 24s of Lifepo4, and I'd just go to 84V top of charge on the home pack, since there will always be some voltage drops even with quite direct connection to charge my ebikes...just a resistor and maybe a big diode on each ebike charging wire (different values for different charge rates). Since my bike packs will have so close a voltage to the supply pack, charging that way should be more efficient than any charger. Plus I'll get to finally have a fast charger for those rare times I want to fill up and go right back out.
I realize I'll give up some capacity, but battery life is more important to me. Is it reasonable to expect significant extra life by charging my 3.6-3.7V nominal cells to 4.0V top of charge and 3.5V for lifepo4 ? I'd go really conservative on the LVC too, say 3.5V for lipo and 3V for lifepo4.
