Why certain automotive voltages used
Why certain automotive voltages used
(OP)
Why do we use DC voltage in vehicles?Why dont we use low AC voltage since alternator is generating AC
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
Why certain automotive voltages used
|
RE: Why certain automotive voltages used
Second, it's hard to store AC.
Third, the AC frequency varies as the engine speed. A varying frequency is problematic for many AC devices.
Alternators have many advantages over generators in automotive applications, but automotive alternators had to wait until the development of small, dependable and relatively cheap semi-conductor rectifiers before being applied to automotive use.
AC in vehicles is not a new or unused idea. 400 Hz AC has been used in aircraft for well over 50 years, probably over 70 years. However the economics of aircraft are much different than the economics of automobiles. The importance of saving weight in aircraft design is vastly more important than weight saving in automotive design.
With increasing emphasis on fuel economy, weight saving is gaining in importance in automotive design. If the economic importance of weight saving continues to increase, a point may be reached when the proven technology of mobile 400 Hz AC power may become an automotive solution.
A note; When 400 Hz aircraft systems were introduced, cheap, small and dependable rectifiers had yet to be developed. A DC generator was much heavier than a 400 Hz alternator of the same capacity. (As a general rule, higher frequency means less weight.)
We may still need stored energy for engine starting.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Why certain automotive voltages used
RE: Why certain automotive voltages used
TTFN
I can do absolutely anything. I'm an expert!
homework forum: //www.engineering.com/AskForum/aff/32.aspx
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: Why certain automotive voltages used
Just think of the simple things like seat and window motors with AC all reversible motors would likely have to be 3 phase, the switch and wiring becomes more complex the motor itself more costly. And what about the AC em fields that would induce AC into wiring you don't need that sort of interference in? Its a no brainer to keep what we have in the auto industry. Using AC in cars would be like manufacturing dinner plates from titanium.
RE: Why certain automotive voltages used
----------------------------------------
The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Why certain automotive voltages used
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Why certain automotive voltages used
TTFN
I can do absolutely anything. I'm an expert!
homework forum: //www.engineering.com/AskForum/aff/32.aspx
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: Why certain automotive voltages used
The last time I looked, which was quite a while ago, it was illegal to sell, and perhaps possess or use, ANYTHING containing a DC voltage greater than 30 volts within the City of Los Angeles unless it bore a UL listing. There are probably similar gotchas in other city codes, but LA is known to be particularly picky.
UL doesn't list automobiles, and it would cost much money and time to cause them to develop such a standard, horrendous amounts to gain a listing for a particular model, not to mention the cost to do it all over after every running line change.
They probably could have grandfathered 24/28V systems with no hassle.
Mike Halloran
Pembroke Pines, FL, USA
RE: Why certain automotive voltages used
RE: Why certain automotive voltages used
Hence the series parallel switches and 12/24 Volt systems that served well for at least 50 years.
Lamp technology must have improved as today, straight 24 Volt systems are common on equipment such as front end loaders and there does not sem to be an issue with lamp burnout.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Why certain automotive voltages used
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Why certain automotive voltages used
TTFN
I can do absolutely anything. I'm an expert!
homework forum: //www.engineering.com/AskForum/aff/32.aspx
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: Why certain automotive voltages used
As time passed interoperability most likely became the driving force to stay with the 12:24 systems. Many drivers are not expected to wait while a trailer is loaded or unloaded. They pull into a yard, drop a trailer, hook up to another trailer and go.
Can you imagine the logistics of working with a mix of 12 Volt and 24 Volt trucks and a mix of 12 Volt and 24 Volt trailers?
On the other hand, 20 years ago I was running into straight 24 Volt front end loaders from Caterpillar. It probably helped that the head lights and work lights were rubber mounted but there were no longer lamp burn-out issues.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Why certain automotive voltages used
More efficient alternators
better starter motors
LED lights
better battery technology
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Why certain automotive voltages used
RE: Why certain automotive voltages used
----------------------------------------
The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Why certain automotive voltages used