WB4SON

In an earlier post, I described a rather inexpensive 16 AH LiFePO4 battery.  I’ve used that for my last three activations, and so far it works as expected.  A few folks have asked me “What charger do I use?”.  I decided to go with a 4 Amp LiFePO4 charger like this one from HamRadio.com (the charger used for BioEnno batteries):  https://www.hamradio.com/detail.cfm?pid=H0-014845

Similar chargers are also available on eBay

LiFePO4 batteries are VERY efficient, like 98-99% efficient.  In other words, if you take 10 AH of capacity away from it, you are going to put almost exactly the same amount of power back into it.  In other words, a 16 AH battery, fully discharged, will take 4 hours to fully recharge using a 4 Amp charger.

Please note that the Battery Management System (BMS) installed in a multi-cell packs has cell balancing circuitry built-in.  It tries to make sure that the series connected batteries never get into a condition where the voltage on one cell differs from the voltage on another cell.  Because of the BMS, it is often necessary to keep the battery connected for a few hours after the charger indicates full charge.

I purchased my first LiFePO4 battery a decade ago from a company called K2 Energy (still in business today).  It was the same size as a 7 AH Lead Acid battery, but 1/3 the weight with a 9.6 AH rating.  It quickly became obvious to me that this was an outstanding battery technology for ham radio use (voltage above 12.0 volts for more than 90% of the battery capacity, and thousands of charge-discharge cycles of life).

After ten years of use, with hundreds of charge-discharge cycles under its belt, it still has 8.8 AH tested capacity (92% of its original 9.6 AH capacity).  This was based on a constant current C/5 discharge (1.92 Amps).  Under those conditions the battery remained above 12 volts output for 96% of its capacity, and had a total run time of 4 hours and 35 minutes.

BOTTOM LINE: LiFePO4 batteries, from a credible vendor, will serve well for more than a decade!

I’ve been a HUGE fan of BioEnnoPower LiFePO4 batteries and have been using three of their devices for many years.  I had put together a presentation for my radio club (Newport County Radio Club) suggesting a couple of configurations of radios and antennas that would be useful for park activations.  Part of that presentation was a suggestion to use a 16 AH BioEnnoPower battery, which costs about $150 (without charger).  I still know that is an excellent vendor and fine product.

I did run across a vendor selling a 16 AH LiFePO4 battery on Amazon for $55 (free Prime shipping).  Since this was 1/3 the price of the BioEnnoPower battery, I felt compelled to buy one and test it out.

Yesterday I ran it through my battery tester to confirm the capacity rating.  It tested out at 15.2 AH (95% of capacity rating), and maintained a voltage above 12.0 volts for 90% of its capacity.  I note two things:

1. The battery was fully charged prior to the test, but I had never cycled it before — sometimes a few cycles are needed to achieve full capacity (and at the price 15.2 AH is certainly close enough)
2. The charging process presented a somewhat unusual condition.  After reaching full charge, the current dropped to zero, then remained off for about 30 seconds, then turned back on at full current for 30 seconds.  That pattern continued for several hours, with the amount of “on” time growing shorter, and the “off” time growing longer.  My best guess is that this was the internal battery management board equalizing the voltage on the internal batteries.  Every other battery I’ve owned just slowly tapers off the charge current.

The key specifications are: Charging voltage 14.6 volts, typical charge current is 0.2C (with C determined at the 5 hour discharge rate).  So a 3 AH charger would be ideal.  But they also say you can use up to a 10 amp charger.  Maximum discharge current is listed at 42 Amps

A second test yielded 15.253 Ah capacity