Old futaba tranny not charging

[vintage1]

..its my third and least used one..simply won't charge..so I tried three diferent chargers on it. None worked. And yet a few seconds of fast charge on a power pack charger showed voltage rising fast..its on trickle now on that..but I suspect the charge circuit in the TX is gone AWOL..anybody know what's in there?

It's an old skysport 6 I think. The light on the charge comes on when its plugged in, and goes out when I switch the tranny on..

Pack is an old 700mAh nicad one with a 'servo connector' on it. Its been replaced in the last couple of years IIRC.

Don't want to splash out on a new battery if the transmitter itself is duff..

[AndyOne]

I'd still suspect the battery, I've see this kind of behavoir from Ni-cads that are on their way-out, not charging on one charger but charging on another type.

Anyway, I'm sure a man of your callibre could sort it out by process of elimination.

Andy.

[Chippie]

V1,

If its the Challenger series from the late 80's then afiak there arent any active electronics as such for charging the tx battery....maybe a diode to protect against reverse polarity or discharging the pack if left conencted to the wall charger....
Can you charge the battery external to the tranny itself? i.e take it out altogether....

[vintage1]

well its up to 7v and holding after charging tricklish for an hour on my old nicad charger. Has enough power to at least give a meter reading on the tranny.
It's not the Challenger tranny - its a 90's Skysport 6A.

There must be something gone in the charger circuit.

I was hoping someone had seen the fault before. Ah well. I'll take a screwdriver to it and poke around inside.

Hmm. May also try a forum search...perhaps its come up in the radios forum.

Its not exactly urgent--got a couple of FF6's I normally fly with..

[vintage1]

All very puzziling.

The charger comes in via the on off switch, so that switching the tranny on disconnects it.

Then a diode, then the battery..and that's it.

I wonder if the switch was stuck 'midway'...and simply wasn't switching the battery in to the charge circuit.


Switches do get icky when not used..

Anyway, put it back on normal trickle, and it appears to be charging off the jack..but time will tell.

[vintage1]

stil very puzzling...It didn';t seem to want to charge...or maybe I was impatient, or maybe it was discharging fatser than I was charging it..but anyway I got impatient and put it on fast charge at half an amp.

Never seen it read so high on the transmitter..maybe it juts need a bit of a zap..time will tell.

[Chippie]

well its up to 7v and holding after charging tricklish for an hour on my old nicad charger.


7v after an hour seems lo imho :confused:

Either your charger is duff or there's some dud cells in the pack...

[andrew b]

Replace all the cells, I swear to you they WILL be duff :)

[Gary Warner]

Sorry for late reply to original queston - been off-line all day :rolleyes: .

BAD BATTERY!!!

Replacment is your only option. Sorry :(

BTW, Wal-Mart sells 8 x 2500ma rechargable batteries for under $20 (here in the States - I know you are on the other side of the 'pond'). It's a great value for the performance.

Gary
--

[dll932]

How about installing a battery box in the tranny so the batteries are removeable, and using an external charger? Should be able to find all the stuff at Radio Shack. Not elegant, I know, but it'll work.

[VinceHaworth]

You can get a new tx 2000mah nicad off ebay for £10. Handy to have a spare anyway even if you find that it is your charger thats faulty.

[andrew b]

Vintage1, I just posted a relevant post in "Smallest Battery" in this electronics forum

http://www.rcgroups.com/forums/showthread.php?t=504850

I haven't bothered with "store bought" packs for a long time, although they are new, they are sometimes quite "old" having been in storage for months and chemically ageing.

NiMH cells should never ever be allowed to drop below 0.9V per cell in storage. Best to do a C/10 charge and check them every month or so and give them a bost if they are nearing 1.1 per cell.

I have read of thousands dying in warehouses from just sitting.It also just happens that the higher the capacity for a given cell size the faster they self discharge in general.

Kinda makes you wonder about all those hobby shop packs sitting on the shelves for months. We never stock NiMH packs, we make them make to order with new cells with a charge in the cells. You can buy NIMH packs anywhere, but not professional ones. That's why we see all these threads on "what happened to my new NIMH pack!"



I bought the cells for my packs from a "99p" shop (laugh if you want) but believe me they are excellent cells.
They are made by "Konnoc" , are green in colour (see pic) and are rated at 1100mA/Hr and in my test I have consistently had 1020 mA/Hr at 250MA rate. They cost 99p for 2 IF you can find them, I would advise you to buy thier entire stock!! Also by the same manufacturer"Konnoc" are AAA 900mA/Hr cells at the same price, my advice is to buy them all .

http://konnoc.com/en/product_list.asp?typeid=48