lwatson

My Feedback: (2)

I have a Futaba 7C TX. I am getting really tired of plugging it in overnight to charge. Seems like when I notice it is low, it is too late. So, I was thinking of peak charging the battery using my good charger. Unfortunately this means taking it in and out of the case because their is some curcuitry that blocks the charge if you try it through the regular side plug.

I was thinking of just attaching a tap to the battery so I could charge it without removing it. Another reason I don't want to keep removing it or switching batteries is the plug into the curcuit board looks like a good point of failure. I can just imagine my transmitter going dead in mid air because I didn't push the connection in hard enough.

So back to the question, will a tap work? or will it damage something?

Thanks,
Larry

BadSplice

My Feedback: (1)

as far as I know, it should be fine. With the power switch off, the only thing it should be connected to is the side plug, so the extra power shouldnt hurt any circuits. I have a 7c, and if I dont have time to charge overnight Ive been pulling the battery and peaking it. Never worried about it coming unplugged, but thats a good point. I tried to make a jack that I could plug into the side, but when it didnt work, I assumed the plug itself (the one hooked to the charger) was bad. Never thought of circuitry protection.... Guess that would explain why the 2nd plug didnt work either. Woulda thought you could at least hook a voltmeter to it. (I know, the 7c reads it on the display anyway )

exeter_acres

My Feedback: (2)

Here is another option.....

I ahve a 9C so didn't need to do this, but many have done this mode without problem

http://www.siriuselectronics.com/dio...ets/fut7cd.htm

Flypaper 2

Hobbico quick field charger will charge it even with the diode in there. Been doing it for years using it at home on a power supply.

Trogdor the Burninator

Hey flypaper - how does the HObbico know when to stop if it can't test voltage through the diode? or do you just manually stop it?

I always unplug and fast charge my tx battery packs but on my Hitec Flash 5X, I noticed last year that if I moved the battery connection with my finger it would actually disconnect the contacts and shut off the TX!! It had broken loose from removing it and sometimes would be connected but if you shifted the tx it sometimes would open the circuit!Man, glad I caught that on the ground. I found the soldering jub was kinda weak at that point so I touched it up and its been fine since... although I do like the idea of some kind of Y connector so I don't have to actually mess with the plug in the tx boards itself.

Flypaper 2

Afraid I'm electronically lacking but I think t detects that rise or drop in the voltage when it's fully charged. Maybe someone more electronically inclined than I could explain it better.

Trogdor the Burninator

I thought all detection of voltage would be blocked by the diode. Interesting. Maybe I just don't understand diodes!

Flypaper 2

I don't understand them eitherI'll see if I can find out from one of my more knowledgeable friends. Maybe you can borrow one from a friend, or try theirs out at the field. Been using this one for about 10 yrs and hasn't failed me yet. Charges both trans. and rcvr at the same time.

warhwk

My Feedback: (3)

I use a Hanger 9 Double-Vision. It will peak charge my TX/RX in about 15 minutes between flying sessions. I also have my diode jumpered so I can peak charge and discharge through the charge jack. I can even charge my TX/RX on the drive to the field, using a car adaptor I pigtailed onto the alligator clips.

The purpose of the diode is to prevent damage to the radio if you have a charger with reversed polarity, ie JR. Since all I have are Futaba/Hitec, this is not an issue. It is also benneficial if you use a battery cycler.

-pkh-

My Feedback: (2)

A diode will have a fixed voltage drop across it if it has a fixed forward biassed current through it. If the delta-peak charger monitors the pack voltage while it is charging at the selected current, it should detect the delta-peak voltage just fine (since the delta-peak calculation cancels out any offset voltage due to the diode). If the delta-peak charger cuts off the charge current, and then attempts to measure the pack voltage, that will cause a problem. In this case, the diode is not forward biassed... one side of the diode is at the batt pack potential, the other side is at a high impedance node (the "voltmeter" input inside the charger), so the voltage across the diode is not well defined.

Flypaper 2

Sort of sinks in halfway, Paul, What your saying is, depending how the diode is wired in, it can detect when the peak is reached and shut the charger off ?

-pkh-

My Feedback: (2)

The diode should always be wired in the same way... so that it is forward biassed when you pump current into the batt pack. If your charger measure the batt pack voltage while it is charging (i.e. the diode is forward biassed), then it will probably work. If your charger cuts off the charge current before it measures the pack voltage, then it probably won't work..

Flypaper 2

Paul:
So it doesn't matter whether the diode is in there or not for the charger to know when to cut off the charge ? Afraid i'm a little electronically declined so bare with me. Is it the delta peak charger that makes the difference.? Thanks for your help.

-pkh-

My Feedback: (2)

Depending on how your charger senses the pack voltage... it may or may not work with the diode in the TX...

Flypaper 2

Thanks Paul . I guess the Hobbico has the right goodies so I'll just let it do it's thing