Battery question

On Saturday, June 20, 2020 at 2:43:06 PM UTC-4, Delta8 wrote:
I would like to build a 5 volt system to run Kobo with Top Hat/GPS as
well as power my I phone with ForeFlight and a Stratux receiver for
ads-b in . I like the audio collision avoidance that ForeFlight provides
.
Currently using power banks but during long flights changing batteries
is a pain .
I don't have Flarm yet but planning on in the future.
I have a 14v SLA battery for everything else.
Am I better of searching for a larger power bank ? Biggest I've seen is
70,000 mAh .
I've seen ways to convert 12v to 5 but they seem like they will drain
battery life of the 12v .
Sorry for what may be a simple question with an obvious answer.




--
Delta8

Replace the SLA with LFP (lasts longer), and add a 12V-5V converter. A large "power bank" is basically the same thing (has a voltage converter inside) but is of the less-safe type of lithium battery. You don't want it catching on fire. Also you don't want it loose in the cockpit.

On Saturday, June 20, 2020 at 2:52:55 PM UTC-4, wrote:
On Saturday, June 20, 2020 at 2:43:06 PM UTC-4, Delta8 wrote:
I would like to build a 5 volt system to run Kobo with Top Hat/GPS as
well as power my I phone with ForeFlight and a Stratux receiver for
ads-b in . I like the audio collision avoidance that ForeFlight provides
.
Currently using power banks but during long flights changing batteries
is a pain .
I don't have Flarm yet but planning on in the future.
I have a 14v SLA battery for everything else.
Am I better of searching for a larger power bank ? Biggest I've seen is
70,000 mAh .
I've seen ways to convert 12v to 5 but they seem like they will drain
battery life of the 12v .
Sorry for what may be a simple question with an obvious answer.




--
Delta8

Replace the SLA with LFP (lasts longer), and add a 12V-5V converter. A large "power bank" is basically the same thing (has a voltage converter inside) but is of the less-safe type of lithium battery. You don't want it catching on fire. Also you don't want it loose in the cockpit.

I should add that I use a 12AH 12V LFP running FLARM, Nook (via 5V converter), radio and 2 varios, and it's capacity is effectively infinite: enough for TWO very long flights, at least. My estimate of the consumption: Nook 0..25A (on the 12V side), FLARM 0.15A, radio and varios under 0.1A each (when not transmitting). At 0.6A total the 12AH battery will nominally last 20 hours. (If you get a transponder the consumption would be significantly higher.) With a 12AH SLA that is a couple of years old (say 8 AH real capacity) and that you don't want to drain more than half-way (or its life years will shorten even more) you're left with 4AH usable capacity, only 7 hours in the example above.