[Elecraft] KX3 interal battery charger

[Matthew Zilmer]

There are other ways to achieve charge parity (balance).  One of them is the multi-cell charge controller.  An example for LiPo chemistries is the AAT 3663.  Datasheet is available at  www.analogictech.com.  Doesn't help with AA's, but there is probably an equivalent out there for lower voltage single cells.

Looks to me like Greg is correct about the difference between balancing and equalizing.  Xantrex / Trace refers only to "equalizing" with their controlled overcharge on solar charge controllers.  EQ is used with FLAs to "stir the pot" and disturb sulfation on the Pb plates, and the process basically allows the sulfates to debond from the lead.  With FLAs, I run an EQ for two hours about five times a year.

Matt Zilmer, W6NIA
KX3 #6 / FT


-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of JP O'Connor
Sent: Thursday, July 05, 2012 8:58 AM
To: Greg Troxel
Cc: Elecraft at mailman.qth.net
Subject: Re: [Elecraft] KX3 interal battery charger

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 :-)
>
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