Today's Message Index:
----------------------
1. 04:28 PM - OVP relay in B+ lead bad idea (Finn Lassen)
2. 07:45 PM - Re: OVP relay in B+ lead bad idea (user9253)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | OVP relay in B+ lead bad idea |
Putting a relay between the alternator B+ lead and the battery for over
voltage protection is a bad idea!
If the battery fails open and the alternator voltage momentarily drops
below voltage to energize the relay, you no longer have system power: no
battery and no voltage from alternator even if alternator works.
This happened to me Saturday resulting in a hay field landing with a
ground loop to avoid a fence. Buckled outer part of right wing and tore
off right landing gear leg with damage to engine mount, firewall and
forward part of fuselage. (In the RV-4 the landing gear leg sits in a
socket in the engine mount.)
In the process of trouble shooting noise and other issues in my
electrical system I changed from a 160Amp schottky diode to a relay. My
original thinking was that the diode would act as a fuseable link in
case of an alternator over voltage run-away event, and leave the battery
unaffected in case of an alternator short.
I had experienced the breaker to the alternator field popping when
reducing RPM. So I restored the alternator to its original integrated
voltage regulator configuration and added the relay to ensure the
alternator could be disconnected from the system in case of an
alternator run-away event (over voltage crowbar shorting the power to
the relay).
Interestingly the alternator voltage regulator start-up input apparently
also draws enough power to pop a 5A breaker when RPM is suddenly
reduced, as I had this happen even after restoring the alternator to
factory configuration.
So this event could be the result of both a bad battery and alternator.
Finn
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: OVP relay in B+ lead bad idea |
Finn, I gather that your engine ignition system is electrically dependent.
What type and brand is it?
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=514422#514422
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|