T8J charger issue

[Andrew Cousins]

Hi all hope you can help me. Just got back into flying after a 20 year break. I bought a Futaba T8J 8 channel TX.

The charger that comes with this radio has two outputs a red and white cable and a black and white. The charger has two LED that are red when charging and green when finished. Ok both batteries for the RX and TX are 4.8 volts

If I plug two 4.8V battery packs in that have done five flights and on the battery checker they read low. The charging transformer only took 30 minutes to say both were charged. This can not be right can it. Also only one of the LED turn green the other just goes out?? on the charger.

1. is the dual output from the charger both 4.8 to 6 volt for both outputs.

2. how long does it normally take to charge a 4.8 volt (2200ma) tx or RX battery pack.

3. could my charger that came with the radio be faulty?

One more bit of information. I have now only plugged one battery into the charger (black and white wire) and so far its been going 3 hrs and still showing red on the charge LED.

Many Thank guys.

[Andrew Cousins]

sorry guys ment to say ihave read the instructions but it makes no reference to my questions

thanks

[Peter Beeney]

Andrew,

This is a topic that crops up from time to time, there was another similar thread only recently. I believe.

Without going into a great deal of detail at the moment, I’d personally just play with it for a while to run the batteries down and then recharge one or three times. You may find that the packs soon start to improve. Plus the fact that if you start changing from a fairly charged up state the packs will soon be full anyway.

A standard charge capacity is the pack capacity plus 50%, so in your case 2200 + 1100 = 3300mAh.The charge time is this amount divided by the charger output; I don’t know the output value of your charger but if it’s say 100mA then 3300 divided by 100 = 33 hours. In practise, if the pack is in good nick it will normally get by ok on less than this; depends to some extent on how often you use it and the self discharge rate. Some Low Self Discharge, (LSD) types will stay charged for many months.

Don’t give up until you cannot get anymore capacity out of the packs, but if it does fail just return it as per, if you tinker they may well say the guarantee is void as a result.

Finally, a tiny word of caution, which I’m sure you won’t need reminding, don’t fly it until until you are 100% confident it’s ok; and always use an on board voltage monitor…
That way you will always know the exact state of the receiver battery at all times.

Good Luck.

PB

[Allan Bennett]

Assuming we're talking about regular rechargeable NiMh cells, and not disposable AA cells that seem to be the basic spec for that transmitter, the usual way to charge them is at about 1/10C for 14 hours or so. So for 2200mAh packs, that means 220mA. So, what output does it say on the label on your charger? The reason for the long slow charge is it's a low enough rate that it won't harm the cells if it's left on after they're fully charged, and it's long enough that all the cells will have time to fully charge -- a basic way of balancing the pack.

If you try to charge small NiMh packs (generally AA size or smaller) quickly you often find that they need a few charge/discharge cycles before they will charge up to full capacity.

Having said that, if one of your lights goes out completely, rather than changing to green, it would seem to indicate that there's some kind of fault in the charger.

[Andrew Cousins]

hi guys many thanks for the replies . the output on the charger is 600ma and the batteries are ni-mh

what i find strange is if i have two batteries plugged into the charger it reports (green led) in about 30 minutes. if i have one plugged in it takes three hours to reach green led. now if the charger kicks out 600ma iwould think it would take twice as long to charge the two thats

6 hours not 30 minutes.

something is amiss

[Peter Beeney]

Andrew,

Would you care to come back with any product numbers and details you have for your batteries and chargers, please? I’ve had a very quick look around and it seems a bit confusing at the moment. For example, it’s seems that in at least some instances the radio can be supplied with a LiFe receiver pack. And the only Tx/Rx NiMH charger listed seems to be an American version.

Many thanks.

PB

Addendum        And having thought a little bit more, I now suspect the transmitter at least will run on a set of 4 dry cells, nominal voltage each 1.5, total 6 volts, or a pack of 5 rechargeable NiMHs, nominal voltage each 1.2, total, 6 volts. So I think you’d need a charger labelled a nominal 6V (for tx) for a start…    

 

 

Edited By Peter Beeney on 27/05/2016 22:55:24

[Former Member]

[This posting has been removed]

[gangster]

Ripmax don't seem to have been particularly interested in the supplying of rechargeable packs for this TX and Futaba may as well not bothered to have translated to manual from Japanese for all the clarity on this issue ie how many cells and what to set the low voltage alarm to. Not properly differentiating between 1.5v cells and 1.2v cells. I am however using a 4.8v rx pack in the TX and it works well.

Not sure if my charger is one of the naughty ones but cannot see any reason for concern. Wasn't it a pin insulation issue that meant you could touch the live pin if your fingers were less tha 1mm thick

Edited By gangster on 28/05/2016 08:16:40

Edited By gangster on 28/05/2016 08:17:47

[Denis Watkins]

I dont want to cause a fuss, but output claims on chargers are notoriously ambitious when under load, and 2200 is a fair load. It can be measured with a multimeter, but as has been said, at 1/10th C, 220ma should be an adequate charge, and the 600 ma claim on the charger, like you say, does not work adequately. This does suggest, even if you nimhs are brand new, they could have an issue with a cell being down. If you can, try your pack on a field charger, or someone elses charger that has some output control. Apologies, but I suspect your pack as the weak link.

[Andrew Cousins]

Hi Guys sorry should have put the part numbers on her for you. Gangster totally agree the manual is next to useless concerning this topic.

Ok the TX came with a 1200ma 4.8 volt 4 cell Ni-MH battery part number O-HE4N1200AASF

The charger has a part number of P-FBC32D/4

As my son and I would be using the same TX (will get him his own when I know this isn't another fad) I bought two 4.8Volt 2200 ma packs part number O-HE4N2200AASF. One for the RX and one for the TX. Hope this helps.

OH can you buy different chargers to charge these batteries. I don't mind spending a little more for something I can trust to charge these batteries correctly, after all the planes they go in can be expensive especially if one goes in.

Thanks All

[Denis Watkins]

Hi Andrew, Do not buy any more chargers until you ascertain that your flight pack is ok. So far your description points to a faulty flight pack, not the charger

[Andrew Cousins]

Denis

I'm going to get a multi meter on the packs now when I dig it out of the cupboard. I assume that if I have a dead cell we are looking at a voltage of 3.6 volts. Or is it a case with batteries that they will only show a fault while under load. I have put my battery checker on them and they come up green. My checker puts a load of 500ma when it does a load check.

will update in a bit

Thanks

[Andrew Cousins]

Ok right found the multi meter and checked both batteries.

1st one measured 5.54 volts

2nd one measured 5.56 volts.

on another note the manual said to set the TX low voltage alarm to 5.2 Volts is this right should it be 4.6 volts as I am using 4.8 volt packs (which came with the TX)

Thanks

Andy C