Most LIFePO4 battery discharge curves are based on the full C rate This is an example of a battery you might be interested in. 20 AH, 20 Amp Max CONTINUOUS Discharge Current. There isn't a good "standard" for what the capacity is based on. You need to check with each vendor. LiFePO4 batteries are very Coulomb-efficient -- what goes in is what goes out, and this tends to keep your capacity very close to rated values no matter what the load is. It also means that unlike SLA batteries, a LiFePO4 doesn't get hot charging or discharging (at least not at 20 Amp values) -- this is because the internal resistance is so darned low -- so there is little wasted energy in a charge/discharge cycle.
My Bioennno 30 AH rated battery, tested at C/4 rate of 7.5 amps (the limit of my test equipment), provided me with 29.88 AH of usable capacity, and that was stopping the test at 12.00 volts, which is several volts higher than absolute minimum (8.8 volts). Speaking of which, I would highly recommend you stop using your battery when the terminal voltage falls below 12.00 volts -- there will be very little remaining capacity at that point anyway. http://www.bioennopower.com/collections/12v-series-lifepo4-batteries/products/12v-20ah-lifepo4-battery That 7 pound battery is $198 including the charger, and will outperform a 40 AH SLA battery (will last 5 to 10 times longer, will weigh 1/5th as much). 73, Bob, WB4SON On Mon, Aug 4, 2014 at 9:02 AM, Bob N3MNT <[email protected]> wrote: > Another *KEY* consideration, especially since you indicate it is a rare DX > location ( I read as air travel required) is what you will be allowed to > take on the plane. Even if the battery meets your electrical and weight > requirements it will be of little value if you can't get it There. I echo > the LiFePo selection as they a are safer and more closely alighed with the > operating range of ham equip. > > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/Internal-Impedance-of-Li-Ion-Battery-Packs-tp7591903p7591907.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > 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 > Message delivered to [email protected] > ______________________________________________________________ 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 Message delivered to [email protected]
