Li-Ion is not hard to manage. With a standard BMS, all you need is a
voltage-regulated and current-limited wall wart - quite routine
nowadays.
- Jerry KF6VB
On 2021-07-21 05:40, Louandzip via Elecraft wrote:
Oops. That commercial pack is LiFePO4, not Li-Ion. Doh.
W7HV.
On Wednesday, July 21, 2021, 6:38:50 AM MDT, Louandzip
<louand...@yahoo.com> wrote:
There is a protected Li-Ion pack for the K2 available. With Lio-Ion,
proper battery management is essential.
https://www.batteryspace.com/custom-lifepo4-18650-battery-12-8v-4500-mah-57-6wh-7a-rate-w-pcb-and-connector.aspx
I briefly looked at putting together a LiFePO4 pack for the K2, but
haven't yet done anything with that idea. LiFePO4 is more forgiving
and more lead-acid-like in its care a feeding. Lower energy density
than Li-Ion, but still much better than lead-acid.
Lou W7HV
On Tuesday, July 20, 2021, 7:52:06 PM MDT, jerry <je...@tr2.com>
wrote:
On 2021-07-18 19:50, Douglas Hagerman via Elecraft wrote:
Next step, adding the the immensely heavy internal lead-acid battery.
*** I wonder how hard it would be to add instead a much lighter
lithium-ion
battery pack? Individual 18650 cells are now routine at 2.5A-H, and
available up
to 3.5A-H. The technology has gotten standardized, and you can buy a
BMS ( Battery
Management System ) card off the shelf. The only hard thing is spot
welding the tabs.
A 3S1P ( three cells in series, 1 in parallel ) pack would probably do
fine.
I just got back from the garage where I repaired such a pack. It was
out of an 85W
cordless vacuum cleaner. Just four cells.
Like any battery, the voltage varies with charge. These cells are
about 4.2V fully
charged, and 3.4 when dead. For three cells, that would be 12.8V fully
charged, and 10.2
when it's time to recharge.
I got all set up to weld the cell tabs for an ebike project. The
ratio of energy storage to battery weight is much better than
lead-acid.
- Jerry KF6VB
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