Executive summary – Even a properly maintained (periodically charged) LiFePO4 battery should be undergo a charge/discharge/charge cycle to maximize performance after long periods of idle time.
I’ve had a few entries concerning my original LiFePO4 battery, a 9.6AH K2-Energy pack with built-in battery management. I’m mostly using larger batteries now, but still use that pack for QRP operation, and I ran my IC-9100 with it last Field Day to make several satellite contacts. So after Field Day, I charged it up, then recharged it in December, and finally again yesterday.
K2B12V10EB LiFePO4 Battery (12V, 10AH, 2.5Lb)
Since the battery now had 3 years I felt it would be a good time to retest the capacity. I ran the identical 4.8 Amp constant-current discharge, and found that the battery had a usable capacity of 9.0 AH. Not bad for something that is 3 years old, basically 94% of its original nameplate capacity. However, since I had not used the battery in essentially a year, I wanted to recharge it and test it again.
Within minutes of the test starting, I could that things had improved. The battery voltage which had decayed quickly to about 12.4 volts after that discharge test yesterday, was now closer to 12.8 volts. While the 12.0 volt mark was reached after 7.14 AH yesterday, it was reached at 8.30 AH today. The final capacity was 9.00 AH yesterday, and 9.14 AH today. This compares very favorably to the capacity tested a bit over a year ago, of 9.22 AH.
Clearly this charge/discharge/charge process had restored some of the “missing” capacity
After 3+ Years 95.3% of nameplate capacity remains.
Robert
I just purchased one of these for QRP
What is the best way to charge these
Do you have any advice?
Brian
Hi Brian,
This is a “Drop-in SLA” replacement, which generally means you can use your original SLA charger. That said, the BEST charger will be a DC supply that is voltage limited to 14.60 volts, and current limited to 4.8 amps or less. I use a bench power supply with a 3 amp current limit. Bioenno Power Sells chargers for LiFePO4 chemistry batteries very inexpensively, in my opinion. Although they don’t list it for sale on their website, I suspect they will sell you one if you call them. Their “equivalent” to the K2-Energy battery can be seen here:
http://www.bioennopower.com/collections/12v-series-lifepo4-batteries/products/12v-9ah-lifepo4-battery
Thanks for the reply
I do have a Tenergy TB6AC charger that I can adjust the settings on. How do you know when it is fully charged?
Hi Brian,
Assuming you are talking about a K2-Energy battery, I generally take mine off charge once it reaches the 14.60 volt point, but every couple of charges I will leave it on for another 10 hours to give the balance function enough time to complete.
Knowing when your battery is fully charged depends on the internal Battery Control Module and what technique they use for individual cell balancing. It can take up to 10 hours for the balance process to complete.
The charger you have is designed for charging RC Hobby Batteries, specifically those that have a balancing connector. The K2-Energy and many other “Drop-in SLA” batteries don’t have that connector, because the charge controller is internal to the battery. To use your charger you won’t be able to use the Balance Mode, and will simply set it to a 4-Series LiFePO4 chemistry. Let it reach the terminal voltage, then you are fully charged. And every few charges, let it stay for another 8-10 hours.
73, Bob, WB4SON
Bob
That is great advice. THANK YOU!
I will try my first qrp this weekend
I might also try my first SOTA activation.
Thank again
73 Brian
Bob
Thanks again!
Charging figured out.
Worked QRP for about 3-1/2 hrs.
Yaesu 857D and K2 7AH battery