[Elecraft] KX3 interal battery charger

[JP O'Connor]

The balance charging operation requires access to each cell and requires a
smart charger that is appropriately programmed for the specific chemistry
and for the balance operation. The idea is to be sure that each cell is
properly and fully charged without overcharging or damaging any of the
other cells in the pack. This is quite common with the all the various
lithium chemistries, and when using NiCd or NiMh smart chargers that charge
each cell independently. Most of the inexpensive consumer NiCd
and/or NiMh chargers do not treat each cell independently. Only the more
expensive models include the test/refresh modes. Although NiCd and NiMh
cells are often overcharged by many slow chargers, apparently that is not
the best practice when performed on a regular basis. Thus, the smart
chargers.

If I am understanding correctly, a PbAcid (e.g. SLA) equalize charge
operation does not have access to each cell and instead is an operation
that uses a carefully controlled "overcharge" function, within the safe
"operating envelope" of the battery, to bring up the lagging cells without
damaging the stronger cells.

It sounds like equalize and balance are two different operations, intended
for different cell chemistry and charging styles.

Starting with a fresh set of Eneloop (white label 1,900 mAh or black XX
label 2,500 mAh) or other brand of "pre-charged" or low self-discharge
(LSD) NiMh batteries that have had at least one test/refresh cycle
performed, the need for removing the batteries from the KX3 for a
test/refresh cycle should be VERY infrequent as long as they are not abused
significantly. As Jim mentioned, hopefully this won't be too often. Who
knows, even with heavy use, maybe the batteries won't need to be removed
for over a year - or two. Yes, Greg, I plan to do things exactly as you
stated: check after a few months, but then pretty much leave them alone in
the radio for a long while as I see how things work out. I will be
interested to hear from folks here on the reflector as experience is gained.

With the traditional non-LSD high capacity NiMh batteries, the need for
test/refresh may be a bit more frequent. For example, the Energizer 2600
mAh (?) AA cells are notorious for extremely rapid self-discharge and may
need a bit more care and feeding.
72/73 de JP WF4Z


On Wed, Jul 4, 2012 at 3:25 PM, Greg Troxel <gdt at work.lexort.com> wrote:

>
> In "balance" vs "equalize", I also hear about equalization charge to 12V
> SLA batteries without access to individual cells.  PbAcid cells have a
> higher charge/discharge marginal ratio as they get full, so a mild
> overcharge should tend to cause all cells to be fully charged.  NiMH is
> almost certainly similar, especially during low-rate overcharge as is
> typical, so I'd expect that all cells end up full.
>
> To understand the KXBC3 behavior, it seems that one should use a Maha
> C9000 or equivalent to measure/record the capacity ("refresh/analyze")
> of all the cells, and then put then in the KX3 and use them for a while,
> and then when the KX3 says they are charged pull them and do a discharge
> measurement followed by a refresh/analyze.  I'll report back later :-)
>