[Yaesu] Voltage

[A10382]

Agreed...

My understanding of battery operation...
All input is welcome for our education....
==========
The 'nominal' voltage in an auto while the engine is running
(read:alternator or generator is running at adequate speed) is 13.8V.  It
can vary from 13.6 to about 14V and the entire charging system - including
the battery - is still considered to be operating normally.  An alternator
running at over 14.2 may very well be defective.

The 'nominal' voltage in an auto lead-acid batter while the engine is not
running is 12V plus a bit (6 lead-acid cells x 2 v each).  This non-charging
voltage does drop as the battery charge diminishes, during heavy loading
(starter motor), with cold weather, or as cells age.

Automotive charging systems have little protection against overcharge.  The
alternator does not go to 'trickle charge' current when the batter is fully
charged.  The system relies on the voltage of the battery getting closer to
the alternator output as the battery reaches full charge, diminishing the
current flow from the alternator.  However, lead acid batteries do work best
when kept at about full charge all the time - they do not exhibit what's
commonly called the 'memory effect' that nicads suffer from.  To use nicads
or NMHI in an auto would require a much more intelligent charging system AND
frequent battery re-cycling (full discharge-recharge re-conditioning).
Marine batteries are better suited for applications where the battery does
discharge a lot between charge cycles.  Additionally, 'sealed' lead acid or
gel-cell batteries are used where there is the possibility of upset or
operation at 0G or less(aerobatic airplanes).

The lead acid battery has a few benefits over other types:
High current output
Fast recharge
Operates well when kept at full charge
Relatively linear voltage drop as it discharges
Relatively low cost

It's drawbacks:
Frequent full discharges can destroy the cells
Explosive gas (hydrogen) is produced while charging
Heavy
Life limited to about 5 or 6 years - sometimes less.

The 'explosive' nature of hydrogen is what usually mandates either gel-cells
or sealed lead-acid for indoor use (shack emergency power).  I ran for quite
a while with 4 gel-cells in parallel with a 500ma trickle charger on all the
time.  Given MY typical 5% duty cycle, the batteries never discharged.
Heavy duty cycles like packet store & forward or CW contesting would have
required a much larger charger.
------
And on to radio.. The manufacturers generally designed their mobile to work
at a 'nominal' 13.8V plus or minus a bit.  However, they most certainly
should work about 12 volts plus or minus a bit (when the engine is not
running).   I'd say the goal should be to have normal operation from 11V to
14V... and not have any damage to the rig outside these..

Many mobile rigs will not transmit at full power on 12V.  Many '12V' base
station power supplies for the shack do put out about 13.8V.  Other than the
slightly reduced transmit power at a real 12V (vehicle not running or
running off a lead-acid battery at home), the rig should operate normally.
Any radio that won't operate on 12V has no right calling itself  a 'mobile'.
Any radio that is speced by the manufacturer at 13.8V  plus or minus a few
tenths needs to by better investigated by a potential purchaser for mobile
operation.  I think you'll generally find that the manufacturer is trying to
put the radio in its best light and does NOT want to state something like:

100W @ 13.8V
 78W  @  12V

Marketing hyperbole at its best!

There are 'voltage booster' devices to increase 12V to 13.8 for mobile rigs
running off of battery power alone.  They are usually limited to low current
applications like QRP.  The FT-817 is typical of these picnic-table (as the
Euros call them) radio that need the 13.8 V to get the full 5W as speced.
Perhaps an 817 owner could tell us what the 12V wattage out is.. my guess
would be about 3.5W.

-----
Personally, I'd like to see ARRL lab test mobile rigs to low voltage - say
down to 11V to simulate a battery that's running down a bit -- typical of
the stationary operation in campers and mobile homes when operating off the
vehicle's isolated second battery.

Then there's the issue of what's a 'mobile' rig.  Yaesu calls my FT-847 a
mobile AND base rig.  Without a detachable face plate, and given it's
operating complexity, I would hardly call it a mobile!



73
Frank
 ._._.

 ._._.
----- Original Message -----
From: "Jerry W. O'Dell" <jwodell@provide.net>
To: <yaesu@mailman.qth.net>
Sent: Saturday, August 10, 2002 11:38 PM
Subject: [Yaesu] Voltage


> Lately, again and again, I hear that rigs won't operate at less than
> 14 volts or something as silly.
>
> If a rig won't operate at 12 volts, which is the nominal value, and I mean
> through the production cycle, the amateur population should be notified,
> and the manufacturer should fix such items gratis.
>
> To be honest, I think this is a bunch of bunk. The real nominal value, I
gather
> is 13.8 volts. If you need 15, there is something wrong with the radio.
>
> Grump grump grump
>
> 73 jerry w8gnd
>
>
>
> Moderator: Ray Brown, KB�STN
> _______________________________________________
> Yaesu mailing list
> Yaesu@mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/yaesu
>