A complicated question about LiFePO4 batteries, - and switching.

On Thursday, July 26, 2018 at 10:10:25 AM UTC-7, Dan Marotta wrote:
Right on, Mark.



As a former jet jockey, myself, I prefer simplicity and fewer
switches.Â* And, whereas one big battery would be nice (forgetting
single point failures), space quickly becomes an issue.Â* It's much
easier to locate two or more smaller batteries around the ship than
finding a place for a big one.Â* One of my friends removed the nose
ballast from his glider and replaced it with an SLA battery.Â* A much
better use of lead, don'tcha think?



...And if you want more switches, go to an air museum and take a
look in the cockpit
of a MiG-21...




On 7/25/2018 8:55 PM,
wrote:



There's a lot to be said for reducing component count.

Yes, there is a definite charm to single point-of-failure systems.

But charm don't count when the failure occurs and you are out of backups and ideas.






--

Dan, 5J

I always thought the Migs looked best while on fire!

On 07/26/2018 12:34 PM, Jonathan St. Cloud wrote:
On Thursday, July 26, 2018 at 10:10:25 AM UTC-7, Dan Marotta wrote:
Right on, Mark.



As a former jet jockey, myself, I prefer simplicity and fewer
switches.Â* And, whereas one big battery would be nice (forgetting
single point failures), space quickly becomes an issue.Â* It's much
easier to locate two or more smaller batteries around the ship than
finding a place for a big one.Â* One of my friends removed the nose
ballast from his glider and replaced it with an SLA battery.Â* A much
better use of lead, don'tcha think?



...And if you want more switches, go to an air museum and take a
look in the cockpit
of a MiG-21...




On 7/25/2018 8:55 PM,
wrote:



There's a lot to be said for reducing component count.

Yes, there is a definite charm to single point-of-failure systems.

But charm don't count when the failure occurs and you are out of backups and ideas.




I got an idea! How about you keep flying the A/C? Do you fly a glider
that crashes if you lose the panel? In 40 years of flying with a
single battery for the avionics, I've never lost the panel. Absolutely
could happen. Not catastrophic if it does.

The reality is all the solutions proposed have single points of failure.
If you can't handle an occasional failure, maybe find a different hobby?

On Thursday, July 26, 2018 at 3:42:56 PM UTC-7, kinsell wrote:
On 07/26/2018 12:34 PM, Jonathan St. Cloud wrote:
On Thursday, July 26, 2018 at 10:10:25 AM UTC-7, Dan Marotta wrote:
Right on, Mark.



As a former jet jockey, myself, I prefer simplicity and fewer
switches.Â* And, whereas one big battery would be nice (forgetting
single point failures), space quickly becomes an issue.Â* It's much
easier to locate two or more smaller batteries around the ship than
finding a place for a big one.Â* One of my friends removed the nose
ballast from his glider and replaced it with an SLA battery.Â* A much
better use of lead, don'tcha think?



...And if you want more switches, go to an air museum and take a
look in the cockpit
of a MiG-21...




On 7/25/2018 8:55 PM,
wrote:



There's a lot to be said for reducing component count.

Yes, there is a definite charm to single point-of-failure systems.

But charm don't count when the failure occurs and you are out of backups and ideas.




I got an idea! How about you keep flying the A/C? Do you fly a glider
that crashes if you lose the panel? In 40 years of flying with a
single battery for the avionics, I've never lost the panel. Absolutely
could happen. Not catastrophic if it does.

The reality is all the solutions proposed have single points of failure.
If you can't handle an occasional failure, maybe find a different hobby?

Early on when I was more careless about checking on the health of my battery, I have had electrical failures while flying. Since then I have only been inconvenienced a few times on the ground when my batteries were incapable of starting the engine. That said, having a backup is not a bad idea. Especially for my new glider where the primary flight display is electronic. Even then, I could still fly the glider by visual reference only.

Tom

Let's get something straight. I am NOT going to bail out if I lose the battery, OK? But IF the panel goes out when I am 100 miles away from the home 'drome, and it's getting late in the day, I don't necessarily need the added hassle of not having my moving map, electronic vario and instruments, my transponder, radio and all those helpful little devices.

We enjoy the benefits of many technologies on cross-country flights. It's not to say that we HAVE to depend on them, but we use them to our advantage much of the time.

When I am way out of simple glide ratio of the field, I like to have some information about the wind, along with things like communication and traffic avoidance.


If I was a "twirly bird," screwing around the airport no farther away than a 20:1 glide, I wouldn't care. But with the sort of flying I prefer, I will not depend on a single power source. And, yes, I had a failure earlier this year due to a poor ground connection on one battery. But I switched to number two, flew two more hours and tightened the screw on the ring terminal when I got back. My own fault for not securing the connection in the first place, BUT!...

I had a backup. And another after that.

Talking about backup batteries, I sometimes carry a portable USB "power bank" as a backup power source for my flight computer (Nook), in case of problems with the main glider battery, 12v-5V converter, or the associated cabling. I found one of the rare models with a real (slide) on-off switch - the far more common ones with a pushbutton seem to turn themselves off whenever the Nook isn't drawing enough current.

So, unlike the LiFePO4 batteries discussed in this thread, this is a lithium-polymer battery, a less stable chemistry, albeit a lot smaller (about 2-3AH at 5V). Is it safe enough to carry in the cockpit? Before you reflexively say "no", remember that you are (probably) carrying at least one such battery, in your cellphone. There's also one inside the Nook, and any other tablets people use in the cockpit. And inside some varios, Portable powerFlarm, who knows what else - almost anything that is rechargeable these days.

I use a cheap android phone with xcsoar, kept in the side pocket, fully charged. Powered off it can be going in a minute, and using its own GPS.
I have a mechanical Winter as vario backup. You dont get to go solo here without the ability to do a circuit and land with all instruments covered.
Losing power would little to no inconvenience.
A truly independent backup that costs less than $100.

On Friday, July 27, 2018 at 4:21:41 AM UTC-4, Charlie Quebec wrote:
I use a cheap android phone with xcsoar, kept in the side pocket, fully charged. Powered off it can be going in a minute, and using its own GPS.
I have a mechanical Winter as vario backup. You dont get to go solo here without the ability to do a circuit and land with all instruments covered.
Losing power would little to no inconvenience.
A truly independent backup that costs less than $100.

I have a mechanical variometer and a chart. They have gotten me home when needed for more than 40 years. I expect they would again albeit without a flight log.
That said the only power issue I've had was due to a very low primary battery and a backup that wasn't charged as I thought. I turned everything off except the ClearNav and got around OK.
FWIW
UH

On Friday, July 27, 2018 at 1:21:41 AM UTC-7, Charlie Quebec wrote:
I use a cheap android phone with xcsoar, kept in the side pocket, fully charged. Powered off it can be going in a minute, and using its own GPS.
I have a mechanical Winter as vario backup. You dont get to go solo here without the ability to do a circuit and land with all instruments covered.
Losing power would little to no inconvenience.
A truly independent backup that costs less than $100.

I have a LxNav S3 with the UPS battery pack, which according to specs should give me 8 hours of vario with audio should I lose ship's main bus, and all those pretty glass instruments. Coupled with a JSW, Super Class, wiz wheel it is just like my first 300 hours of xc flying before I purchased the most modern flight computer made, at the time, the B100. I also have a real sectional(s) for the area I fly, and iGlide loaded on a phone zipped into my pants on flight mode.

On Friday, July 27, 2018 at 8:24:30 AM UTC-7, Jonathan St. Cloud wrote:
On Friday, July 27, 2018 at 1:21:41 AM UTC-7, Charlie Quebec wrote:
I use a cheap android phone with xcsoar, kept in the side pocket, fully charged. Powered off it can be going in a minute, and using its own GPS.
I have a mechanical Winter as vario backup. You dont get to go solo here without the ability to do a circuit and land with all instruments covered..
Losing power would little to no inconvenience.
A truly independent backup that costs less than $100.

I have a LxNav S3 with the UPS battery pack, which according to specs should give me 8 hours of vario with audio should I lose ship's main bus, and all those pretty glass instruments. Coupled with a JSW, Super Class, wiz wheel it is just like my first 300 hours of xc flying before I purchased the most modern flight computer made, at the time, the B100. I also have a real sectional(s) for the area I fly, and iGlide loaded on a phone zipped into my pants on flight mode.

I'm using an iPhone X with iGlide as the primary tactical display. If the avionics battery and everything connected to it fries, iGlide simply switches to internal GPS, barometer and battery. It will give a warning about the charge power going out, if you miss that it is seamless enough that you may fly the rest of the day without noticing. The main thing I notice is no more Flarm targets to leech from.

On the other hand, with a well done installation the chances of the whole panel failing should be quite remote. I'v got two independent batteries with two independent supply paths to the power bus - which is the single point of failure but being a solid piece of copper fairly reliable.