Dennis Johnson
Joined: 10 Jan 2006
Posts: 89
Location: N. Calif.
|
 Posted: Wed May 19, 2010 10:59 am Post subject: 24 volt and 12 volt Sharing Common Ground? |
 |
|
This isn't an airplane application, but the answer may also be helpful for people with mixed 24 volt and 12 volt systems on their airplanes.
I'm building a generator to help charge a large (2,500 pounds) stationary 24 volt battery pack. I have a small, single cylinder, air cooled, diesel engine that will drive a 24 volt truck alternator via "V" belt and pulleys.
The diesel engine has a 12 volt starting battery, 12 volt starter, and a 12 volt alternator. It is negative ground, through the crankcase.
The truck alternator is nominal 24 volts, 70 amps. It is negative ground, through its case. The output of the alternator will charge only the large stationary battery pack, not the engine's 12 volt starting battery. It is driven by a rubber "V" belt and pulley from the diesel engine.
Both the 12 volt and 24 volt systems are negative ground. Both the diesel engine and the truck alternator will be bolted to the same steel rack. If I don't do something to separate the grounds, both will be grounded to the same rack. Is it okay for them to share a common ground?
The large battery pack, the large diesel generator, and my 120/240 volt AC house circuits are all grounded to the earth (as in planet earth) in compliance with US electrical codes. It seems like the 24 volt and 12 volt systems sharing a common ground should be okay, since everything else is happy to share connection with the earth, but some 24 volt alternators are supplied with an insulated ground terminal so that the case is not grounded. That makes it seem like sharing a common ground might be a problem.
Note: This may not be an ideal use of either the engine or the alternator, but my main purpose is the fun of learning something new and if I happen to get something useful out of it, that's even better!
Double note: The large battery pack is normally charged by solar photovoltaic panels with a large diesel generator for backup. This new generator system I'm building will not be the primary charging source; it's a backup to the backup.
Thanks for your help,
Dennis
Lancair Legacy, Z 13-8, with over 300 hours.
| | - 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 |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
