>> RG batteries are quite tolerant of
>> high recharge rates and the few seconds of connection needed
>> to crank an engine are not likely to heat things up even in
>> a relatively tired battery.
>>
>
>That's good to know. I recently jumped mine and can attest it suffered no
>apparent ill effects. At least I think it is an RG Battery. It's a "Gill
>Aero 30 Sealed Battery" which Aircraft Spruce terms a "Gell Cell Battery".
>However, I would infer from Bob's comments that it's really an RG.
>
>I do have one nagging concern about my Gill Aero 30, assuming it's really an
>RG: Aircraft Spruce's catalogue has some language in it (see p. 362 under
>"Sealed immobilized Electrolyte Batteries (Gel Type)") suggesting that the
>charging voltage must be precisely regulated at 13.8 v. +- 0.2 volts to
>avoid shortening the life of these batteries. They recommend a $200
>regulator to accomplish this. My question is, is this true? Does it apply
>only to bona fide gel cells or does it apply also to RG batteries? My
>charging system charges at about 14.5 v. Do I need a $200.00 regulator?
>Finally, if I forget and leave the master on and need to recharge the
>battery in the hanger, do I need a special charger to avoid zonking it? The
>Aircraft Spruce Catalogue implies that this is the case for "gell cell and
>sealed batteries" --see the write up for the "Electronic Power Systems"
>charger, same page.
The conventional wisdom being circulated conforms to
the fondest wishes of the folk who build and sell batteries.
"Treat my product with tender loving care and it will
give you the best performance possible." This always
begs the question, "how far outside the envelope of
TLC will the product still provide satisfactory performance?"
We know that an RG battery (or any other lead-acid battery)
will eventually achieve 100% charge when maintained at 13.8
volts at room temperature. We also know that automotive and
aircraft OEMs have favored 14.2 to 14.4 volts as a level
that speeds up recovery of a battery's state of charge soon
after the engine starts . . . the higher voltage also favors
performance in cold weather.
A couple of years ago, I purchased a used GMC Saffari van
and until September a year ago, had no occasion to check on
the health of the electrical system. When the flooded battery
barfed, I stuck in a used and several times deep-cycled RG
battery I had purchased from B&C to power portable test
equipment in some testing I was doing on the Beechjet. The
battery was just laying around the shop so I decided to
use it up in my van.
After installation, I did a quick check of the charging
voltage and was astounded to find it running 15.1 volts!
Hmmmmm . . . how long had it been that high? Did the
elevated voltage barf the flooded battery? The date
code on the flooded battery was over three years old.
The regulator was built in to a 100A alternator and I
wasn't eager to replace the thing. I decided to leave it
and see what happened.
14 months later, the alternator barfed and I had to replace
it. The new charging voltage is 14.4 volts. The RG battery
is still there and about to enter its second winter
of operation. I also know that when we tested the RG
batteries for B&C's STC, one of the tests the FAA asked
for was to show resistance to thermal runaway. This involves
putting 16.0 volts on the battery and see what happens.
Well . . . not much. The battery soaked up some more charge
but in less than an hour, the current going into the battery
dropped to less than 100 milliamperes. The battery warmed up
less than 1 degree C.
Now, all of the above is anecdotal. The experience I
can share speaks to observations on two batteries. However,
there is a strong suggestion from these observations that
RG batteries are not fragile creatures to be pampered
lest they sigh and die.
The short answer to the question above is, "no" a $200
regulator is not required . . . it may "help" but I'm
beginning to suspect that "helping" means 24 months of
service as opposed to perhaps 22 months of service. The
real bottom line of battery reliability in airplanes is
to KNOW what it's capacity is by either periodic testing
after one year -OR- periodic replacement at cycles which
insure e-bus capacity equal to or greater than fuel
capacity. The real trick here is consdiered preventative
maintenance, not agonizing over how well your regulator
works.
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
http://www.aeroelectric.com
|