T8J charging

[J D 8]

Just gone 2.4 with a T8J and have found the supplied charger puts out 600 mah's and the batts are getting very warm at this rate,anyone found problems with this?Should I be concerned? Ta John.

[steve-richards]

Never had a problem with mine

Steve

[Les Littleton]

Mine is fine , maybe its worth checking the output from the charger ?

[J D 8]

Could be you are on to something there Les,the charger supplied with the set did not work at all and now I have doubts about it's replacement,output seems to fluctuate quite a bit.Thanks John.

[CARPERFECT]

What charger are you using ? Is it the std one with the double rx ouputs with a conversion lead to plug in to the tx.

[J D 8]

Yes that's the one.

[CARPERFECT]

That`s the correct one, same as mine. Take it back to shop. My batteries do not get warm.

[Barrie Dav 2]

Take Carperfect's advice John. Futaba is a premium product and there should not be a problem like this. It could of course be a battery problem, Have that checked too.

[Simon Chambers]

The 8J charger is a fast charger with built-in Delta Peak cut off. So even though it charges at a faster rate, as it knows when to turn off automatically its perfectly safe charging at the faster rate. NiMh will get warm as they are nearly charged and its perfectly normal for this to happen. They should be only getting warm, not hot/too hot to touch though!

Si.

[J D 8]

OK,thanks everyone,it may have been I checked the batt just as it reached full charge and delta peak cut off not yet operated. Inwood models have been helpfull and have offered to replace charger again [first one did not work at all] It may be all normal operation as in Simon's post, just not used to this with TX/RX batt's but on next charging will observe often to make sure.

[Martyn K]

I have moved back to trickle charging on my T8J Tx battery.

I found that using the supplied charger for both a Tx and Rx battery (4,8v NiMh packs) concurrently then it would not cut off although both worked OK if charging a battery individually using either of the two outputs.

Martyn

[Biggles' Elder Brother - Moderator]

I charge my Tx battery at 0.1C on my standard Lipo/NMh charger. OK not the quickest - but I've not had any problems either - looks around for a piece of wood to touch. I'm sure Simon is correct (and Futaba!) in that these batteries can be charged at a higher rate - but you know what its like you get into a routine,....

BEB

[Simon Chambers]

Delta peak charging is ok if the algorithm in the charger is good. However most chargers they are not! The other problem with using Delta Peak is that it doesn't balance the cells. Like LiPos, NiMh packs can become unbalanced. As there is no balance port, the usual way of balancing a NiMh is deliberately overcharging them. When a cell is fully charged, it'll dissipate the excess energy as heat (hence why the get hot as they're almost fully charged). However this must not be done at a too high a rate that the cells can't sink the heat. Charging at 0.1C, most cells can dissipate this heat almost indefinitely. Note, I have seen that eneloop type cells don't like being overcharged constantly at 0.1C and it damages them.

Personally, I don't use NiMh any more. My T8J and all my (glow) models now use LiFe packs. These have:

• Almost zero self discharge - so always ready to go)
• Can be safely fast charged - for when you forget to charge them, so you can do it at the field
• Lighter for the equivalent capacity - so you can fit a bigger pack and never worry about the pack going flat in a day
• Perfectly safe chemistry - they won't catch fire if overcharged, punctured or flattened. So you can safely install them tucked away in a model.
• Flat discharge curve - servos will respond with the same speed and force no matter how much left in the pack. Note that this something you have to watch out for, as you can't tell if a pack is flat on voltage alone.
• Equivalent to 5 cell NiMh pack - Once you've taken the top off the voltage (which is lower than a fully charged 5 cell NiMh pack), they'll give a nearly constant 6.6v
• Higher current draw - high current servos (actually a lot of modern servos are now much higher current than old ones) won't make the voltage sag. So again the servos response will be the same as the battery discharges. However also, it means there is far less risk of voltage Brown-Out on the receiver
• Cheaper!!

Kinda a no-brain'er really. 

In my T8J I use this pack - **LINK**

At 1100mAh, is pretty much the same capacity wise as the original stock pack and it fits nicely in the back of the transmitter. Unlike the picture on HobbyKing, my pack came with 2 servo type connectors, so it fitted straight in without any soldering/crimping! For Charging, I just use my normal LiPo charge BUT set onto the LiFe charge mode.

Si.

Edited By Simon Chambers on 13/12/2013 12:24:18

[J D 8]

Having done some tests it seems my charger is the same as Martyn's, that is charge one pack at a time and delta peak cut off works as it should however with two pack's connected one may cut off but the other keeps charging getting very warm or sometimes both keep charging. I have all ready returned one charger that did not work at all but don't think I want another,so will do same as Martyn and return to slow charging the T8 with the 150 mha rx output of one of my old chargers for now and look into Simon's LiFe route for the future.

[Martyn K]

I have ordered 3 of the batteries recommended by Simon. I'll see how I get on with them

Thanks Simon

Martyn