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Old 01-10-2003, 10:55 PM   #1
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Default charge AA NIMHs thru radio jack?

i just got a ex-1 mars radio. it has a jack on the outside to charge an optional nicad pack. the nicad pack plugs into a female 3 pin connector.

curretly i'm using a square 8 cell battery box for dry cells. the battery box has a 9 volt type of connector at the end of the box which clicks in place when placed in the transmitter. If i were to get a 9 volt connector and connect it to the female 3 pin connector, could i charge my rechargeable AA NIMHs thru the tx jack?

the reason i ask this is because i want to peak my NIMHs for my tx without having to remove the batteries each time i want to charge them.

thanks
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Old 01-11-2003, 06:45 AM   #2
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Usually (other radios) there's a diode between the external charging jack and the pack. Normally this diode simply have to be short cut'ed.

But I havent done it yet on my Presto, since it's still under warranty, so I dont know for sure if the above applies to KO TX's.
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Old 01-11-2003, 11:12 AM   #3
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you don't have to cut any diode to charge a regular nicad tx pack... so how would using the 8 cell box with male connector be any different?
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Old 01-11-2003, 11:55 AM   #4
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I didnt say "cut", however, the right words are that the diode have to be dead shorted. This is neccesary on some TX, but it might differ from brand to brand.
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Old 01-11-2003, 11:31 PM   #5
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Aren't the diodes usually there to allow charging but not discharging through the jack?

Why have a charging jack if there is a diode on the other side to prevent charging the TX batteries?

Seems to me it's just a connector issue, and having the extra length of wire should make no difference, just be careful how much current you use to charge the batteries. The batteries can probably take more current than the battery holder. Those things are not made for carrying large currents, which is probably why TX packs you can buy are usually welded or soldered.
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Old 01-12-2003, 12:12 AM   #6
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yea i think concillian is right. the diode prevents over discharging.

concillian, you bring up a good point, the connectoins aren't going to be as solid... i DO KNOW that the current drain from my mars is 250mah... and i plan to charge at 500 mah (.5 amps)... so it's really not THAT much more...what would happen if the battery holder can't carry that much current?
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Old 01-12-2003, 05:12 AM   #7
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Quote:
Originally posted by Concillian
Aren't the diodes usually there to allow charging but not discharging through the jack?

Why have a charging jack if there is a diode on the other side to prevent charging the TX batteries
Diodes prevent several things: Discharging, deadshorting of TX pack, reversed input voltage. The diode even rectify AC, if an AC wall charger are mounted. The producer simply protects the TX from abuse.

Normally, those TX's are charged by a wall charger. In this case, the diode do no harm. But the diode also "confuses" peak detecting chargers. Therefor the need of deadshorting the diode, if a peak charger are used.
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Old 01-12-2003, 05:17 AM   #8
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Quote:
Originally posted by torchedlh
concillian, you bring up a good point, the connectoins aren't going to be as solid... i DO KNOW that the current drain from my mars is 250mah... and i plan to charge at 500 mah (.5 amps)... so it's really not THAT much more...what would happen if the battery holder can't carry that much current?
There can happen 3 things: The wires insulation might melt or the wires can burn over. The worst: If the batteries get really, really hot, the battery case might melt.

Personally, I wouldnt worry by charging at 0,5 amps. I've done it with other TX's.

If you want to be sure, you can try it out, while you are wahtching. Ensure, that neither the wiring, connectors nor batteries get warm / hot.
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Old 01-12-2003, 01:57 PM   #9
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actually i don't think i would be charging the "pack" while it's in tx anyway because i can't seem to find a ko propo charge lead that fits the jack. so i'll probablay just charge it externally and that way i can also monitor the heat.

thanks for the help.
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Old 01-14-2003, 10:42 AM   #10
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Default TX charging

Guys;

Here's what I have done to charge my TX batts. I cut a battery bar in half and soldered one each to the +/- of my pack. I just remove the battery compartment cover and put my charger clips on and charge away. I have always charged at 1 amp and never had any problems. I can go 2 weekends with 2 cars and still be above 10.0 volts on the display (Futaba 3PDF).
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