Hi Ed, Terminology can be a tricky thing! So can the specifics of different battery types and how to charge them. You raise a number of excellent questions.
In order to assist other readers who may not be as familiar with the topic, and to assure I am being clear, I will go in to some detail. -- Balance and Equalize I think we are using these two terms synonymously. Balancing chargers have access to each cell and during the charge cycle will send different amounts of energy to each cell so that each cell is properly "topped off" on its own. If a multi-cell pack is rapid charged, there is the risk of undercharging some cells (an inconvenience) and overcharging other cells (causing damage, and in some cases causing catastrophic failure). I suspect this is exactly the same as equalizing. I purchased my LiFePO4 packs and iCHarger 106B+ balancing charger from a vendor (EP Buddy) in the radio control model hobby, so that is why I picked up the "balance" term. One must/should use a balancing/equalizing charger when rapid charging a battery pack, especially when using extremely high charge rates. When slow charging, the balancing/equalizing function, though beneficial, is not required. -- Charging LiFePO4 Batteries When talking about charging batteries using this specific chemistry, one must clearly state if they are talking about charging a pack that has no internal electronics (for charge control and safety) or a pack that is set up with cells and a control board inside. The latter style is often configured as a drop in replacement for a traditional sealed lead acid (SLA) battery. I did not make that distinction in my earlier post in this thread, thus introducing the possibility of confusion. Some LiFePO4 batteries are the exact same size and shape as SLA batteries and are advertised as drop in replacements. These units have an internal charge controller that handles the actual charging of the cells, often (but not always) with balancing/equalizing capability included. Externally, the battery is connected to whatever was charging the original SLA in the application. Thus, an uninterruptible power supply, any application using a standard SLA charger, or a solar power application may gain the benefits of the LiFePO4 chemistry and still provide charging current/profile as if the battery is an SLA. The controller inside the battery does the "translation" to manage the actual LiFePO4 cells. In these types of applications, a "standard" solar charge controller (which is designed for lead acid batteries) may be used as is because the battery mimics an SLA. Some LifePO4 battery packs are just made up of cells only, have no control board, and must be charged by a system that is designed for this specific chemistry. Just as with any other type of battery, slow charging may be performed without balancing/equalizing and rapid charging does require balancing/equalizing. This is the type of pack I am using. They are supplied by EP Buddy, BuddiPople, and many others. Note that a LiFePO4 pack of the same nominal capacity as an SLA battery will have significantly more actual usable capacity within a single charge. SLA batteries have dramatically reduced life if discharged more than 50% of capacity and have significant voltage drop even at that point. LiFePO4 batteries on the other hand may be safely discharged much more (80% or more?) without damage or diminished life, while retaining almost full voltage until discharged about 80% or so. LiFePO4 also seem to have a significantly longer "shelf life" and "service life" than SLA batteries. Those who have experience with overall life of these types of batteries may wish to comment with their findings. -- Solar Charge Controllers There is nothing magic about solar charge controllers. They are like any other charger, except that they are designed to handle the wide voltage and current range presented by a solar panel or array. Just as with any type of charger, they must know the type of chemistry utilized by the battery so that the proper charge profile is used. It is commonly known that lead acid, NiMh, and Li-ion all use different charge profiles, so the proper type of charger (or solar charge controller) must be used with each. Just as with "standard" battery chargers, solar charge controllers are not all alike. Choose the proper type for your battery chemistry or battery pack profile. This isn't always made obvious to the prospective purchaser since, historically, most general purpose consumer solar applications involve SLA batteries. -- For the KX3 I plan to use the following portable power options and charging equipment/methods: Internal lithium primary cells (8 AA size Energizer L92 Ultimate Lithium) - Non-rechargeable - used only as emergency spares (Alkaline make very poor spares in this application, although due to their common availability are the ultimate spares of last resort.) Internal NiMh low self discharge (LSD) cells (8 AA size Eneloop XX nominal 2500mAh) - Normal charging (with batteries inside the radio) using low current timed charge without balance/equalize - Elecraft KXBC3 fed from external DC power supply - Periodic testing with balance/equalize charging (with the batteries outside the radio) - Maha MH-C9000 External LiFePO4 pack (4S1P 26650 size A123 nominal 2300 mAh) - Field solar charging using low current controlled charge without balance/equalize - BuddiPole Solar Battery Charge Controller - Fixed location periodic testing with balance/equalize charging - iCharger 106B+ fed from external DC power supply Another solar option for the LiFePO4 packs: - Field solar charging (including possibility of medium to high current) controlled charge with balance/equalize - larger capacity solar panel/array feeding DC-to-DC regulator feeding iCharger 106B+ All battery packs, regardless of chemistry, benefit from a periodic balance/equalize charge. -- Hopefully this has clears up more questions than it generates! 72/73 de JP WF4Z On Mon, Jul 2, 2012 at 1:47 PM, Edward R. Cole <[email protected]> wrote: > Not exactly sure what "balancing" means but suspect this is the same > as equalizing charge. I have used solar charge controllers at remote > sites for two panels charging two batteries and do not recall any > equalizing function in them. The Buddipole appears to be a simple > current regulator. It may be adequate for your situation? > > Solar regulators are widely available, just google them. Prices > about $150+ (from memory - may be higher now days). > > > 73, Ed - KL7UW, WD2XSH/45 > ====================================== > BP40IQ 500 KHz - 10-GHz www.kl7uw.com > EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? > DUBUS Magazine USA Rep [email protected] > "Kits made by KL7UW" http://www.kl7uw.com/kits.htm > ====================================== > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
