[Elecraft] KX3 Please evaluate LiFePo4 battery/charger choice

[Alan Biocca]

A few years ago I picked up a couple of the Hobbyking LiFePO4 packs, and a
couple friends of mine did also. Every one puffed after some months despite
being properly balance charged, not overdischarged, and not really used
very hard. They continued to operate, but they were clearly outgassing.
I've had many, many Hobbyking Lithium Ion packs without this problem, only
the LiFePO4 seemed to suffer in this way. That was a few years ago, so
perhaps it's not the same now. As was noted there's no BMS which means a
balancing charger is needed, and extreme care to not overdischarge them. A
small per-cell meter would be important to monitor the cell voltages
periodically.

Many folks report good results from the Dakota and Miady LiFePO4 batteries,
as well as the Bioenno of course. Miady overstates their capacity and
current ratings, so more reasonable data should be used. I've just graphed
a Miady 8AH discharge (Amazon $35), and it puts out a solid 7 amp hours
rather than the rated 8. Right now I'm graphing a Bioenno 6AH that's less
than 2 years old and it just stopped at under 4.6 amp hours out of it's
rated 6 (testing at 10 hour rate). You don't really want to run them fully
out anyway, so expect about 80% of the rated amp hours and value
accordingly. I also ordered some Bioenno in May for Field Day and am still
waiting, so apparently they are having supply problems like many others.
The Miady came a bit out of balance, letting them sit on the charger for a
day or two will allow the BMS board to balance them which increases useable
capacity. Clearly when selling a LifePO4 battery at these low prices they
can't spend too much time on them, so the final QC is left to the buyer.
It's easy to return Amazon items so charge them and check their voltage and
amp-hour capacity, or buy more expensive brands that do more testing for
you. The two Miady batteries I've tested seem to have 85% of their rated
capacity out of the box, but their cost is about 35-40% of the brand names.
Even the brand names don't always reach label capacity. I use Bioenno for
the high current loads but for lower current items perhaps the lower cost
battery is a good budget choice. Test it during the return period and see
if you agree. There are quite a few Miady (and other) reviews on utoob,
most who actually use them for awhile have had decent results.

73 de w6akb

On Sat, Nov 16, 2013 at 9:57 AM Esquer Dave <dave.esquer at gmail.com> wrote:

> Hello Arno,
>
> I just picked up 2 of these 13.2v, 4200mAh LiFePo batteries from
> HobbyKing. So far, they are working great. I retired my SLA 12v, 5Ah
> battery too. Twice the amp-hours at 1/2 the weight. They run at 13.2 volts,
> so portable I can run the 12 watts for a bit.
> http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14067
>
> They are in the US Warehouse too, no shipping from China.
>
> This guy turned me onto them:
>
> http://www.worldwidedx.com/hf-bands-hf-rigs/143215-ultimate-portable-power-elecraft-kx3.html
>
> At $46.00 each, a good deal in my pocketbook!
>
> Dave, K6WDE
>
> More static, more of the time …
>
> Dave Esquer, K6WDE
> dave.esquer at gmail.com
> http://www.daveesquer.com
>
>
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