Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Alternator output voltage vs usable voltage at the bus

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List
View previous topic :: View next topic  
Author Message
Kellym



Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

PostPosted: Fri Dec 24, 2010 4:40 pm    Post subject: Alternator output voltage vs usable voltage at the bus Reply with quote

Your reasoning is correct, but the goal is not. You want 14V +/- 0.2 at
the battery when you have enough rpm for significant positive output
from the alternator. Your avionics and most everything else electrical
will function fine at 12 to 14 V and are not that picky. Voltage is set
to fully recharge the battery, so you have maximum endurance time
available if the charging system quits. The rest of the electrical
system doesn't care that much once the minimum voltage is present. So
the cable size(s) from the alternator to the battery via the regulator
and any resistance induced at connections are what matters.
On 12/24/2010 3:03 PM, Neil Clayton wrote:
Quote:
Is my reasoning correct here?

On my pusher, the _internally_ regulated alternator puts about 13+
volts on the bus behind the panel.
If there is 10 feet of #6 wire between the alternator and the battery
(alternator, all the way forward to the 40A panel breaker, then to the
bus).

10 feet of #6 wire at 0.004 mOhms/foot pulling 15 amps of current
would see a voltage drop of 10 x 0.004 x 15 = 0.6 volt drop. Add a few
more losses along the route and 13v is a reasonable expectation at the
bus. So if the electrons start out their journey from the alternator
at 14 volts, I'd see about 13.0 volts on the bus.

Furthermore, if I _externally_ regulated the alternator using +14 bus
voltage as the target voltage, the regulator would compensate for the
line voltage drop, and I'd see 14+ volts at the bus?

Right, or is this Mech Engineer counting electrons wrong?

Thanks
Neil

*

*


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group