[Milsurplus] Can.military use of 14V/12V

[WA5CAB at cs.com]

Nerd,

Creatures like you just take the fun out of everything.

In a message dated 11/16/2012 17:52:17 PM Central Standard Time, 
nerd at verizon.net writes: 
> An aircraft with engines off can actually glide quite far.  A large 
> aircraft 
> losing engines at cruise altitude can glide about 10 to 1 meaning that 
> starting 
> at say 39,000 feet could glide for 74 miles before landing.
> 
> 12 vs. 14, 24 vs 28.  What do you say the line voltage is?  110? 115?  
> 117? 
> 120?  And do you mean nominal or acceptable normal range?  A "12 volt" 
> system 
> might have a low cutoff voltage of 10.8 but be floating at 14.4 (or maybe 
> even 
> slightly higher) volts.
> 
> Peter
> 
> 
> 
> On 11/16/2012 6:25 PM, WA5CAB at cs.com wrote:
> >As I've written (perhaps tongue in cheek) before, aircraft radios and 
> other
> >electrical equipment are typically marked (or called) 14V or 28V (the 
> fine
> >print on the dynamotors may actually give the performance at slightly
> >reduced voltage but always above 12.6 or 25.2 volts).  Ground vehicular 
> equipment
> >at least into the late 40's was marked 6V, 12V or 24V.  This is because a
> >truck or tank with its engine off will glide much further than an 
> aircraft
> >will.  :-)
> >
> >In a message dated 11/16/2012 15:19:15 PM Central Standard Time,
> >ka2ivy at verizon.net writes:
> >>On 11/16/12 10:05 AM, Ralph Cameron wrote:
> >>>I am told by former Canadian military staff that 14V was often stated 
> on
> >>>RCAF equipment because a fully charged 12V battery is 13.8V and that 
> was
> >>>close enough to call it 14V. At some point in time it was renamed 12V 
> as
> >>>being a nominal value and to conform to other services.
> >>>
> >>>Ralph
> >>>VE3BBM
> >>>
> >>Calling it 14 volts is a compromise. A fully and recently charged 12
> >>volt lead acid battery will deliver about 12.7 to 12.8 volts under light
> >>load. This will decrease to about 12.6 and remain fairly steady until
> >>the charge nears depletion. Conversely, charging regulators adjust the
> >>voltage for battery temperature to insure full charging. A battery at -5
> >>degrees C. will need about 14.2 volts for a while. At about 5 degrees,
> >>13.8, dropping to about 13.2 at 30 degrees will assure a full charge.
> >>Because aircraft batteries tend to be in cold locations, they usually
> >>receive these higher voltages. Aircraft electrical systems were often
> >>set for 14 volts, and if the battery life was shortened, it was just a
> >>cost of operating the aircraft.  They tended to be at minimum size that
> >>would start the engine for weight saving, and had to be as fully charged
> >>as possible. It was a great source of batteries for me in high school, a
> >>battery that would not start a Beechcraft Bonanza (or a DC-3!) on a cold
> >>morning was still great for radios.
> 

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480