On Tuesday, July 24, 2018 at 7:31:44 AM UTC-7, Dan Marotta wrote:
In my last experimental glider I used two rather stout SPST toggle
switches to control my two LiFePO4 batteries.Â* At some point of the
flight I would switch the second battery on and then switch the first
battery off.Â* I don't think it was really necessary given the longevity
of these batteries compared with the SLAs that I used previously, I
simply switched about half way through the flight so that both batteries
would get some use.Â* I like John's idea with the MOSFETs.

On 7/23/2018 10:43 PM, Andy Blackburn wrote:
On Wednesday, June 20, 2018 at 6:27:33 AM UTC-7, OHM Ω http://aviation.derosaweb.net wrote:
Andy,

I have used the ideal diodes mentioned by Shaun McLaughlin (http://re-voltage.eu/ US$27 each) as I was given a pair to test with. They do what they say with minuscule voltage drops across them. Full disclosure, I am currently using two 1N5821 Schottky diodes in my panel right now (page 74 of my presentation) - small, simple, cheap, plentiful, robust, and easy to mount.

That being said - the availability of inexpensive ideal diodes has exploded in recent years mainly for use in systems like solar panel arrays. See https://www.ebay.com/sch/i.html?_fro...es%29&_sacat=0. I also like the increasing range of mounting styles available allowing for placement options behind our increasingly cramped panels.

John (OHM),

Yup, I have one of Shaun's (on your recommendation) and some of the anti-revere-irrigation ones. I haven't installed either.

My current install uses the Schleicher rotary switch to select: Battery 1, Battery 2, Battery 1+2 (through diodes), Battery 3 (tail). I use a bank of capacitors connected through a power resistor to energize the circuit when the switch is between batteries.

If I had to do it again I would use ideal diodes (though as others have mentioned this is really not nearly a necessary with LiFePO4 batteries since they go through voltages below 11v quite quickly on my battery tester). I would also separate the batteries to individual switches to eliminate the switch as a single point of failure.

Andy Blackburn

9B

--
Dan, 5J

Here is a demo circuit board you can buy that does pretty much everything:

http://www.analog.com/en/products/mo...-evaluationkit

Tom