nimh battery charging in 9x

[heman37]

after much reading on the subject , iam now totally confused . I would like to use 8 of the Turnigy LSD 2400 1.2v nimh batteries in my 9x , would this be too much power? I was gonna charge at 800mah as i understand that the 9x wont allow you to charge over 1amp which is ok with me. the other question is what should i set the low voltage alarm at with this setup? thanks . and i am using ER9X , thanks

[MikeB]

Should be no problem, I use 8 LSD NiMh cells. I charge at 700mA, and set my low voltage alarm to 9.5V.
Make sure you calibrate the voltage measurement!

Mike.

[Flaps 30]

There should be no problem using that pack.. I take it that it is a welded pack rather than individual cells?

I like to follow old fashioned charge rates for my LSD pack and that is one tenth the capacity charge rate for 14 Hrs..

As for where to set the alarm.. Mine is set at 8.5 Volts. Not that I would leave the house with the battery with such a low voltage...

[jhsa]

It's interesting to see the peoples decisions for the voltage alarms.. Some more conservative than others
When I used NiMhs I had my alarm at 9.0V. Now with 3 cell LiFe the alarm is at 9.3V.

João

[Flaps 30]

You can bet that many of us have the alarm set at different voltages.. Mine is really low as I don't want to get annoyed by the low TX battery alarm, unless something drastic has happened. It is rare for me to walk out of the house without the voltage indicating something above 9.6 Volts, and even then there is a lot left in the pack.. In the old days with pack capacities of around 500/600 mAh and transmitters drawing around 200 mA you wouldn't dream of going out on a flying session without having fully charged the pack the night before.

As we know.. You can use the 9X transmitter down to a voltage of 7.2 Volts without any worry.. Okay.. I wouldn't worry.. You might

[jhsa]

The problem even with nimhs is that under a certain voltage it goes down very fast.. so, let's say for example, under 8V, it would reach 7V in just a couple minutes..

[heman37]

There should be no problem using that pack.. I take it that it is a welded pack rather than individual cells?

I like to follow old fashioned charge rates for my LSD pack and that is one tenth the capacity charge rate for 14 Hrs..

As for where to set the alarm.. Mine is set at 8.5 Volts. Not that I would leave the house with the battery with such a low voltage...

it is just single batteries in the original 9x battery tray, other thing is what would the low voltage cut off be for duracell alkaline batteries? although i think i will stick with the idea of the nimh batteries

[Flaps 30]

Err true João.. I was thinking more along the lines of a two cell Lipo rather than Nimh when I mentioned 7.2 volts.

As for using dry cells.. Yeah,.. Stick with the other batteries.

[jhsa]

ahh, I thought you were talking about the NiMhs because you said you use them in your radio..
I do apologise for the misunderstanding..

João

[heman37]

so i can use the charge port on the 9x with the original battery tray attached? would 10v for the low voltage alarm be to high (too soon to cut off) ? I do not mind charging , just dont want to do it all the time , was hoping i would get 4 or 5 days to the field and then charge the transmitter, lots of good advice ,thanks guys

[Flaps 30]

Yes you can use the charge port. The centre pin is positive. The only possible exception would be if you are using an intelligent charger that uses short discharge cycles to top off the battery pack, as that would not work properly due to the diode that is in line with the charger port that would stop the discharge phase.. If the charger you have is a simple one, then there is no problem at all.

Ten Volts is too high.. Mike's 9.5 Volts would leave you with a very good safety margin and more.

[heman37]

Yes you can use the charge port. The centre pin is positive. The only possible exception would be if you are using an intelligent charger that uses short discharge cycles to top off the battery pack, as that would not work properly due to the diode that is in line with the charger port that would stop the discharge phase.. If the charger you have is a simple one, then there is no problem at all.

Ten Volts is too high.. Mike's 9.5 Volts would leave you with a very good safety margin and more.

i have a regular computerised charger it is like the accucel 6 charger that i can set the charge rate and the cut off points and all that stuff. i should be good then. thanks for the help . I will set the low cut off alarm to 9.6 volts , would this voltage cut off alarm apply to Alkaline 1.5v batteries aswell or do they allow for lower discharging?

[heman37]

thanks for all the help , This is a great forum for the 9x, it never amazes me as to what the 9x is capable with the open software in it.

[sgofferj]

Isn't 9,6V the regular voltage for a block of 8 NiMH cells? Why set the alarm to that level?

[ReSt]

And don't use the original battery box.
It's known to fail makeing contact between the cells and to the box contacts in many cases.
Slight knocking at the side may break contact

Reinhard

[Helle]

Hy,


Hy I use Sanyo Eneloop as a ready pack with 8 Cells

Akku empty is about 1,1 to 1,05V

Set Low Voltage to 1,1V*8=8,8V for NiMh so set it to 8,8V ... 8,7V

Akku is full with 1,27*8V=10,2V

the Diode you must short with a bridge to use a today normal uC-Charger, so it can read back the Voltage
of the cell-pack

Helle

[Flaps 30]

the Diode you must short with a bridge to use a today normal uC-Charger, so it can read back the Voltage
of the cell-pack

That is part of what I was talking about with regard to intelligent chargers, rather than the simple constant current charger.

If you are going to short the diode out, you do run the risk of damaging your radio if for any reason you short out the charging leads whilst they are connected to the transmitter. To reduce the chances of any damage I installed a 1 Amp wire ended fuse in place of the diode.

[jhsa]

Or you can make sure that the leads are always connected to the charger before you connect the cable to the radio..
It's the same as turning always the tx on before the receiver, and off after you turn the receiver/model off. Different things but the same principle

João

[Flaps 30]

João - You know as well as anyone.. It only takes that one occasion where you forget to do things in the right way.. How many people have managed to reverse the battery connections and the like, causing the magic smoke to come out of the radio. Fuses are cheap.

[jhsa]

No no, I didn't say you should't put the fuse.. In fact why not putting it shorting the diode as it has been done before??.. If the fuse blows the diode will still be there protecting the radio anyway and you are still be able to charge the radio with an old charger..

João

[Flaps 30]

You could do it that way.. Or save yourself all the hassle by using a simple constant current charger/charging system in the first place.

[heman37]

could i not just use a regular nicad or nimah charger that you would use to charge digital camera rechargeable batteries with? i have heard that this is hard on the batteries, i dont want to kill the batteries or the transmitter,

[ReSt]

Or you bypass the diode with a resistor of 1 to 10 kohm, as many 'intelligent' chargers only need to sense a voltage to start charging.

Reinhard

[heman37]

i am not using an intelligant charger it is a computerised charger , it is a V6AC which is like a turnigy acccell charger , I do not wish to put a resistor in the radio, what is the point in having a charge port in a radio if you can not use it to charge the batteries.getting frustrated with this thing,

[Kilrah]

Computerized charger = intelligent charger.
The 9x was designed with old wall-wart "dumb and slow" chargers in mind as that's what people commonly had back then.

Sent via mobile

[heman37]

i found an old 10hr timer charger for rechargable batteries that does 4 at a time it ,it outputs 250ma and has 10hr timer controlled , so i will just charge with this when needed and repeat twice as i have 8 batteries , is there any problems besides time waiting in this? i figure put them on over night .then do another set during the day, so max time if batteries were low would probably be 20hrs

[heman37]

when pulling the batteries out of the 9x battery tray , i dont know how they could pop loose as some are saying that the batteries will come apart at the ends in the battery box , i had to pry them practically out , unless Hobbyking has fixed this issue as i was looking out for that issue.

[ReSt]

One problem with the holder is, that it holds the cells to tight. Whenever they are shifted against the spring, they will not return and therefor loose contact.
Another problem were poorly crimped wires and strange material on the contacts that gave poor contact.

Put the batteries into the holder. Then shift them against the spring and release them slowly. If they immediately slip against the + pole of the holder, than the holder may be ok. Try this with every set of two cells.

Reinhard

[heman37]

thanks for the information on the holder , i did not realise that was the problem , i thought it was the batteries where poping out of the holder, and thought that will be hard to do. thanks again i will check this stuff as well.

[Helle]

hy,

each modern charger detect your akku before start of charging.
If you have connected wrong it will not start to charge
Current is set at the Charger.
So short the diode or set a Resistor of 100 Ohm paralell.

There can nothing go wrong!
because Power switch must be off for charging
(green line and arrows)

look at the shematic of Power

At Graupner or Futaba there is a jumper to short the Diode.

helle