View Single Post
Old 03-29-2014, 06:56 AM   #3 (permalink)
bwilson4web
Engineering first
 
bwilson4web's Avatar
 
Join Date: Mar 2009
Location: Huntsville, AL
Posts: 843

17 i3-REx - '14 BMW i3-REx
Last 3: 45.67 mpg (US)

Blue Bob's - '19 Tesla Std Rng Plus
Thanks: 94
Thanked 248 Times in 157 Posts
Quote:
Originally Posted by Old Tele man View Post
A 12Vdc drop-in for "model" airplane or "real" passenger-carrying airplane?
Do a Google search for N19WT.

Quote:
Originally Posted by Old Tele man View Post
Schottky diode voltage drop is ~ 0.3Vdc, is that acceptable? Either a contact relay or FET would be much lower, but relay is vibration prone. . .
The Schottky is just to prevent reverse flow from the battery through the solar array. In the dark, the ones I've tested have a small but significant current flow. But in bright sunlight, the 12V panel I tested easily generated over 20V.

I would prefer to use a buck regulator so when the solar panel generated excess power, we could get a closer match to the battery load. But we are talking about 1.5W. For now, KISS makes more sense and if I need more power, adding a second panel is cheap. But let me get some metrics, first.

For the battery isolation, I'm open to a suggested part:
  • 30-60A - bidirectional
  • default OFF - an asserted gate is needed to go to a conductive state
  • minimum voltage drop
But this is an option to look at with some operational metrics. Disconnecting the 12V NiMH battery wipes out the ECU memory and there is significant in-rush.

The primary issue is the solar panel generating enough power in daylight to handle the 24 hour, parasitic load.

Bob Wilson
__________________
2019 Tesla Model 3 Std. Range Plus - 215 mi EV
2017 BMW i3-REx - 106 mi EV, 88 mi mid-grade
Retired engineer, Huntsville, AL

Last edited by bwilson4web; 03-29-2014 at 07:01 AM..
  Reply With Quote