On Mon, Aug 26, 2019 at 09:50 AM, Adrien F4IJA wrote:
I'll make a 3S battery pack (3x 4.2V fully charged, so 12.6V), and I've ordered 3300 mAh cells. I'm thinking about making a 3S4P battery pack, so the capacity will be 13200 mAh.
Lithium-Ion batteries have a voltage operating range of 4.2V (fully charged) down to 2.8V? , hence 1.4V.
?Question : would 3x2.8V= 8.4V be adequate to operate the Ubitx ?
If not I would suggest you use 4 sets of (parallel) cells in series . This would give an operating voltage range of? 16.8 V - 11.2V , hence 5.7V??? , assuming 16.8 V is acceptable for the complete radio .
Also ensure that you use? a max voltage equalising circuit to prevent overcharging of any of the cells being charged as part of the pack.
FYI : Chinese on-line retailers can supply (low cost) compact 18650 battery holders for either 1 or 4 cells permitting cells to be flipped-in (hence no soldering or spot welding)? These holders also enable easy cell replacement .
I have recovered good cells (capacity checked) from discarded laptop battery packs .
When a laptop pack is no longer usable for its intended purpose , often only 1 of the usually 6 cells is no longer OK , but the others still are.
Frank?? ,??? EI7KS
