12V charger needed

I'd like to leave the plane overnight in the car (lazy, aren't I!) and have the receiver batt charge from the cigar lighter connection.
The receiver batt is only a 4-cell nicad - 500ma, 4.8V.
I'd like the charger to either turn itself off or go to trickle charge when the battery is fully charged. I'd also rather slow charge than fast charge (I've got all night).
The best I've found is the JETI mini-peak at Hobby Lobby for 36.90 - anyone know of anything better (cheaper?) <http://www.hobby-lobby.com/chargers.htm and scroll down a bit.
Cheers -
LeeH
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LeeH wrote:

Which one, better or cheaper? There's lots better, and probably many cheaper too. Anyway, something in the same price range, but possibly more versitile is the Hobbico Quick Field Charger MKII: http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCTZ5&P
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C G wrote:

Good point, CG - it does lipos as well and there are 2 separate circuits so I could leave the radio in the car as well. Yeehah! -LeeH
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<<Good point, CG - it does lipos as well and there are 2 separate circuits so I could leave the radio in the car as well. Yeehah! >>
Watch out, leaving the plane in the car may be bad for the covering...
You don't have to leave the charger actually charging over night. I have this same charger (Mk II) and just charge everything while I'm driving to the field. It can be done by the time you get there and get unloaded (unless you only have to drive 5 min to get there....).
Steve
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Which one, better or cheaper? There's lots better, and probably many

I just bought this charger for similar reasons. mk "
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You can make a cheap current limiter out of a voltage regulator (i.e 7805) and a resistor. Limit the current to 1/10 to 1/20 the battery capacity (50 to 25 mAmps) by choosing the correct resistor.

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LeeH wrote:

You can trickle charge a 500mAH battery overnight. Use a 180 ohm resistor in series with the battery, and you can plug it directly into the lighter output. You can buy lighter plugs from Radio Shack. That will give you around 50mA, which isn't enough current to hurt the battery if you forget it for a few days.
Make sure you don't get it backwards. If you don't have a multimeter, buy an LED, a diode, and a 1k resistor as well. Connect the diode and the LED together, in parallel, so that the side of the diode with the line is connected to the long lead of the LED, and the other side of the diode is connected to the short lead. Now, connect one side of the 1k resistor to the long LED lead (along with the line side of the diode), and connect the other side of the resistor to one terminal, and the short terminal of the LED to the other terminal. If it lights up, the side with the resistor is the positive side. If it doesn't, the resistor side is the negative side.
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Bob Monsen wrote:

Hmmm - and save $50.00? Hmmm.../ thanks, Bob Cheers - LeeH
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I use my Hobbico Mk2 charger all the time. it will charge RX (4 and 5 cell) TX(Nicad and Nimh) and my turbine ecu battery. I use a special Lipo charger for lipos.
Regards
Tom Watson Sydney Australia

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Firstly, I wouldn't like the idea of leaving anything charge unattended inside my car at night.
Secondly, 95%+ of car cigarette lighters only have power when in the accessory or ignition position. You don't plan on leaving the keys in the unlocked car do you? Perhaps you plan to run your own wiring to the charger, just make sure it's fused and safe.

What's wrong with a standard wall charger running overnight? Even my humble wall charger will do that in 2 hours.
I suspect you are in the same boat as me. I want to load up the car the previous night so I can have a fast getaway before dawn on Sunday (my standard flying day). I feel much safer charging the TX and RX on the wall charger overnight than hooking up my charger in the car....

Most decent fast chargers will support a trickle charge. Supernova 3000 (which I have) has two pairs of outlets: one is for fast charging (or whatever you set - which can essentially be a trickle) and the other is a fixed 250mAh.

--
The Raven
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| Secondly, 95%+ of car cigarette lighters only have power when in the | accessory or ignition position.
That's not true. Maybe it's true of whatever you personally drive down there, but here in the US many cars have the cigarette lighters powered when the car doesn't even have keys in. For example, the two Fords we have have them powered, but I don't think the VW I used to have did.
The figure is probably closer to 50% than 95%, and I'm not very sure about the 50%. But 1 in 20? No way.
| You don't plan on leaving the keys in the unlocked car do you? | Perhaps you plan to run your own wiring to the charger, just make | sure it's fused and safe.
Cigarette lighters are almost always fused. They generally don't do very well with currents over 10 amps, so if you have a serious charger and are charging big batteries, you may need to run some of your own wires. I also suggest having a fuse in your cigarette lighter adapter, preferably one smaller than the one in the car for that circuit so it blows first.
| > The receiver batt is only a 4-cell nicad - 500ma, 4.8V. | | What's wrong with a standard wall charger running overnight? Even | my humble wall charger will do that in 2 hours.
Overnight is 2 hours? The problem is that many fast chargers are 12 volts, and many people don't have 110 v -> 12 volt transformers set up for that, so they just do it in their car instead.
| I suspect you are in the same boat as me. I want to load up the car the | previous night so I can have a fast getaway before dawn on Sunday (my | standard flying day). I feel much safer charging the TX and RX on the wall | charger overnight than hooking up my charger in the car....
Personally, I do a lot of my charging in the car, often on the way to the field. It's just convenient. But I have one Triton for the car, one Triton for the house, and a few others for various things.
--
Doug McLaren, snipped-for-privacy@frenzy.com Yow! Everybody out of the gene pool!

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