Battery question

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.

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.

Another item on your list has a very high current draw: The Stratux is based on a Raspberry Pi and those have more current draw than most of the rest of your panel!

I have a 15000mAh LimeFuel external pack I run with my Stratux (Pi 3 based). It goes too low for effective operation of the Pi in about 4.5 hours. The spec for the Pi says it needs a 2.5 Amp 5-volt power supply.

But I have found that some of the Pi devices have lower current needs, and especially if you are making your own Stratux, you should check out a few different units and pick the one with the lowest power draw.

The Stratux software will run on a Pi 2 or 3. The Pi 4 is definitely over kill and uses the most power of the bunch.

Mike

Thanks for all the replies ! I was leaning toward a 50K bank but now will re think replacing the SLA.

On Sat, 20 Jun 2020 21:13:49 -0700, SoaringXCellence wrote:

I have a 15000mAh LimeFuel external pack I run with my Stratux (Pi 3
based). It goes too low for effective operation of the Pi in about 4.5
hours. The spec for the Pi says it needs a 2.5 Amp 5-volt power supply.

Don't forget that that's a peak rating, and that most Pis only hit that
value during boot or when working continuously on a compute-intensive
task.

The Pi Zero uses 140mA during boot and 50-70mA when idle, but may not
have the connectivity to run, say, a navigation system which will need a
serial connection to a GPS receiver and, maybe, another to a FLARM.

The model A+ peak consumption is 500Ma peak and typically 180MA but, like
the Zero, may not have the connectivity needed for some applications.

The model B+ uses 600Ma peak and 330mA average, but you're unlikely to
want its Ethernet connection in your glider, but it does have 4 USB
sockets.

Its only the models 3 and 4 that start to use serious amounts of power.

All models can drive touch-sensitive displays that connect via the 40 pin
GPIO header. You can now find these using both multi-colour TFT displays
and eInk display technology with decent display resolution (I have a 4"
TFT display with 480x400 pixels) and, of course, a TFT screen turned up
bright will use quite a lot of amps too. Advantage, eInk.


--
Martin | martin at
Gregorie | gregorie dot org

Originally Posted by SoaringXCellence

Another item on your list has a very high current draw: The Stratux is based on a Raspberry Pi and those have more current draw than most of the rest of your panel!

I have a 15000mAh LimeFuel external pack I run with my Stratux (Pi 3 based). It goes too low for effective operation of the Pi in about 4.5 hours. The spec for the Pi says it needs a 2.5 Amp 5-volt power supply.

But I have found that some of the Pi devices have lower current needs, and especially if you are making your own Stratux, you should check out a few different units and pick the one with the lowest power draw.

The Stratux software will run on a Pi 2 or 3. The Pi 4 is definitely over kill and uses the most power of the bunch.

Mike

My last flight I noticed the cooling fan running constantly before I closed the canopy . I believe I have the Pi 3 version . Crew Dog electronics purchase from 2 years ago

On 6/21/20 6:56 AM, Martin Gregorie wrote:
On Sat, 20 Jun 2020 21:13:49 -0700, SoaringXCellence wrote:

I have a 15000mAh LimeFuel external pack I run with my Stratux (Pi 3
based). It goes too low for effective operation of the Pi in about 4.5
hours. The spec for the Pi says it needs a 2.5 Amp 5-volt power supply.

Don't forget that that's a peak rating, and that most Pis only hit that
value during boot or when working continuously on a compute-intensive
task.

The Pi Zero uses 140mA during boot and 50-70mA when idle, but may not
have the connectivity to run, say, a navigation system which will need a
serial connection to a GPS receiver and, maybe, another to a FLARM.

The model A+ peak consumption is 500Ma peak and typically 180MA but, like
the Zero, may not have the connectivity needed for some applications.

The model B+ uses 600Ma peak and 330mA average, but you're unlikely to
want its Ethernet connection in your glider, but it does have 4 USB
sockets.

Its only the models 3 and 4 that start to use serious amounts of power.

All models can drive touch-sensitive displays that connect via the 40 pin
GPIO header. You can now find these using both multi-colour TFT displays
and eInk display technology with decent display resolution (I have a 4"
TFT display with 480x400 pixels) and, of course, a TFT screen turned up
bright will use quite a lot of amps too. Advantage, eInk.



Since we're talking about a Stratux, it requires two rather high-powered
Software Defined Radios and a GPS to make it work, which adds
considerably to the power drain. You should use a high-current charging
cable to supply power, as short as possible, as you can lose several
tenths of a volt in the cable due to IR drop.

You might look at a uAvionix pingUSB as a better alternative, somewhat
more expensive though.


-Dave

On Sunday, June 21, 2020 at 12:13:51 AM UTC-4, SoaringXCellence wrote:
Another item on your list has a very high current draw: The Stratux is based on a Raspberry Pi and those have more current draw than most of the rest of your panel!

I have a 15000mAh LimeFuel external pack I run with my Stratux (Pi 3 based). It goes too low for effective operation of the Pi in about 4.5 hours. The spec for the Pi says it needs a 2.5 Amp 5-volt power supply.

But I have found that some of the Pi devices have lower current needs, and especially if you are making your own Stratux, you should check out a few different units and pick the one with the lowest power draw.

The Stratux software will run on a Pi 2 or 3. The Pi 4 is definitely over kill and uses the most power of the bunch.

Mike

Be careful when you evaluate the capacity of "power banks". The AH rating is often misleading, even if it is true. E.g., if it has one 3.7V lithium-ion cell (or several in parallel) then when it converts that up (internally) to 5V the AH would be less, by the factor 3.7/5 (plus some energy loss in the conversion). If the power bank has cells in series, e.g., 2 cells, 7.4V, then the voltage conversion to 5V is downwards, and the AH at 5V should be higher - unless (and likely) they rated it at 5V, or simply added up the AH of the cells in series. But all the (smaller) power banks I've seen just had one cell (or two in parallel). The best way to rate them is in watt-hours not amp-hours, but the sellers prefer to make the rating sound better.

Talking about watt-hours, a "12V" LFP battery outputs 13.x volts through most of its discharge, thus outputs somewhat more watt-hours than an SLA that yields the same amp-hours. Most of our modern avionics use less current when fed a higher voltage, very unlike ye olde light bulb. I've measured that behavior in my Portable PowerFLARM, for example.

On 6/21/20 8:18 AM, wrote:
On Sunday, June 21, 2020 at 12:13:51 AM UTC-4, SoaringXCellence wrote:
Another item on your list has a very high current draw: The Stratux is based on a Raspberry Pi and those have more current draw than most of the rest of your panel!

I have a 15000mAh LimeFuel external pack I run with my Stratux (Pi 3 based). It goes too low for effective operation of the Pi in about 4.5 hours. The spec for the Pi says it needs a 2.5 Amp 5-volt power supply.

But I have found that some of the Pi devices have lower current needs, and especially if you are making your own Stratux, you should check out a few different units and pick the one with the lowest power draw.

The Stratux software will run on a Pi 2 or 3. The Pi 4 is definitely over kill and uses the most power of the bunch.

Mike



Talking about watt-hours, a "12V" LFP battery outputs 13.x volts through most of its discharge, thus outputs somewhat more watt-hours than an SLA that yields the same amp-hours. Most of our modern avionics use less current when fed a higher voltage, very unlike ye olde light bulb. I've measured that behavior in my Portable PowerFLARM, for example.


The OP said he was using a 14 volt SLA, which I suppose proves how he
absolutely must use SLA.

Back to the original topic, he said he's thinking of adding Flarm, and
most of those products have ADS-B In. I'd suggest going ahead and add
that, get a decent size screen, and forget the Stratux and iPad.