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Charlie,
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I fly radio controlled airplanes and use LiFeP04 batteries to power my receivers. They are great! When fully charged each cell will be 3.7 volts; a 4S pack will be 14.8VDC. Here is a pack that would run a transmitter for a long time. A 30 C rated pack can produce 30 times 4.2 amps. Yes, the pack will get very warm and be drained rapidly, but for lighter current loading, it will work great. It can be charged by a low priced hobby charger like one of the following: I own both of these chargers and they work great. I charge at 1C rating. This (in theory) means it takes an hour to fully charge the battery. For the battery URL listed above, I would set my charger to 4.2 amps and 4 cells and it will automatically stop charging when the pack is fully charged. WARNING: NEVER LEAVE CHARGING BATTERIES UNATTENDED! Flame proof 'sacks' are available to contain a charging battery. If you keep them stored in a reasonably cool place, don't discharge them below the minimum cell value, and don't drop/damage them, you can expect to get 300-500 cycles (probably years of service). When storing the batteries, always make sure you use the battery charger to charge or discharge the cells to the 'storage' voltage. I have LiPo batteries that are 2 years old and still going strong. Some I fly daily. Others, weekly. So far, I have not had any issues. Best Flying, Oh, correction Best DX! :) Garry / WD0DUD -----Original Message-----
From: g4sra via Groups.Io Sent: Saturday, September 22, 2018 11:52 AM To: [email protected] Subject: Re: [QRPLabs] Was :OLED screen for QCX Now: Thermal considerations for QCX John, Thanks for the pointer. Unfamiliar with LiFePO4 so just carried out some quick research. An interesting technology, the safety aspect certainly appeals and so does the reduced weight. Battery charge management seems a little complex with each cell having its own controller, I wonder what the reliability is like. Prohibitively expensive here in the UK. 73 Charlie On 22/09/2018 19:07, John VA7JBE via Groups.Io wrote: If you're looking for a more stable battery chemistry without sacrificing (too much) energy density, then you might look into LiFePO4 (lithium iron phosphate) batteries. It's the kind of chemistry that's used in electric vehicle batteries because you can basically cut them in half while they're discharging and they won't even start smoking. The nominal voltage per cell (3.2v vs. 3.7v) is lower than lithium ion batteries, but a 4S configuration can act as a drop-in replacement for SLA batteries. In particular, you might look at cells manufactured by A123, or the batteries made by BioEnno ( ). |
