In article <45915074$1@quokka.wn.com.au>, Richard <DK@Hotmail.com.au> wrote:
| "Alibi10 Jerry" <alibi10@webtv.net> wrote in message
| news:504-45913DB4-249@storefull-3276.bay.webtv.net...
| >
| > The TX chews up batteries!
| >
| > If I get 8 ni-cads, the TX has a charge port, can I use my 120
| > volt-to-12 volt charger adapter (that plugs into the balance charger) to
| > charge the TX batteries?
| >
| > Ni-cads are 1.5 volts x 8 = 12 volts.
| >
| > My manual doesn't show any other charger/adapter.
|
| Ummm, are you sure the nicd's are 1.5 volts?? I think they're 1.2 volts.
They're nominally 1.2 volts. Freshly charged, they're about 1.4 volts.
And since he's talking about charging them, he'll need even more than
that -- 12 volts might work, but it might also charge at a really low
rate (which isn't automatically a bad thing..)
| 1.2 volts x 8 = 9.6 volts
Yeah, and your fully charged TX says 9.6 volts, right? No -- it says
about 11.1 volts. 9.6 volts = pretty close to time to go home and
charge your TX, or at least time to swap the pack out.
| The volts doesn't matter as much as the current so in theory a set
| of 2500 mah nicd or nimh AA batteries should last (roughly) 5 times
| longer than the dry cells. I say roughly because of the voltage
| diffference.
Say what?
The largest AA NiCd cells I've seen are 1200 mAh. For NiMH, it's 2700
mAh. As for dry cells, do you mean alkaline? (I hope you don't mean
zinc-carbon -- seriously old school!)
I believe that average quality alkaline AA cells will gove about 2500
mAh - 3000 mAh -- slightly more than good NiMH cells, but not enough
to make it worth using batteries you can't recharge.
| You could probably still use the AC adapter with caution. Find out the
| output current of the AC adapter, should read in milliamps (mah) or amps.
| Take the current of the batteries and divide by the current of the AC
| adapter to figure out how long you will charge them for. BATTERY / AC
| Adapter = Charge Hours
This advice is reasonably good. If your adapter says 12 volts and 100
mA or so, it'll probably charge your pack at a reasonable rate. I'd
suggest not using a charger rated at over 300 mA.
I'd suggest putting a fuse in your charging circuit -- 0.5 amps is
probably a good value. The fuse will help protect your radio and
charger from accidents, like short circuits or getting things
reversed.
Once the batteries start getting warm, they're charged. (As long as
you charge at a low rate -- charge at a high rate, and they'll get
warm before being fully charged (and get hot once charged.)
The first few times you use your charger, feel your batteries so you
can get an idea of how long it'll take. Math is good, but with random
wal-warts it's hard to know the right figures to use (and often what's
marked on the box is only close to what you'll see.)
| The charger for my JR Radios says the output voltage is 11.6 volts but when
| checked (without a load) it shows closer to 13.2 volts.
Of course, you can't really trust your multimeter here. The wal-wart
probably only has a diode and transformer, and maybe a resistor in it,
so you're measuring a signal that is zero over half the time, then
ramps up to some voltage and then back down to zero 60 times a second.
How exactly your multimeter registers that depends on the multimeter.
| You might want to make sure the charge jack on the radio is wired the same
| as the your AC adapter too.
Most definately check this.
| I think the centre pin on the radio is negative (-).
I think you're right, but I'd have to check mine to be sure.
--
Doug McLaren, dougmc@frenzied.us
Lead me not into temptation; I can find the way myself.
--Rita Mae Brown