zig123

I have my DX7 wall charger for the 4.8 factory battery. Getting a plane (Kyosho Focke Wulf 50) that has seven servos (one retract) and going to go with a 6 volt reciever battery. Question will my little wall charger work and if so how long should I charge it??

Zig

Jetdesign

My Feedback: (8)

To add to this, my Airtronics wall wart has a 6v 75ma output for the Rx battery, which I believe is actually meant for charging a 4.8 volt battery. So am I correct in assuming that a 6v output is not actually sufficient to charge a 6 volt battery since the voltage of a charged battery is actually greater?

brett65

My Feedback: (18)

Garcfield is right, this has been discussed before. You'll probably want to invest in a nice field charger that you can use for anything.

BarracudaHockey

My Feedback: (11)

Get an Accucyle Elite or something similar. That wall wart will never fully charge a 5 cell battery.

RCKen

My Feedback: (9)

They are correct, the wall wart that comes with your radio will not charge a 5 cell pack. In order for a charger to charge a battery pack it must put out at least, or more, voltage than the pack you are charging. For Ni-mhs and Ni-cads the max voltage is 1.5v per cell. So for a 4 cell pack the max voltage is 6 volts, and for a 5-cell pack the max voltage is 7.5 volts. So for your wall wart to charge the 5-cell pack it must put out at least 7.5 volts. Follow the advise of BarracudaHockey and get a good aftermarket charger.

ken

capt17

I posed this same question several weeks ago when I made the same switch. I use this cheap wall charger for 12 buck from Mpi. It works great and the price is right!

http://www.maxxprod.com/mpi/mpi-9.html

Model CH72

Hope this helps!

Jr25

My Feedback: (7)

I'm not sure I agree with many of the posts here. I'm no expert, so please, no flaming. I am simply speaking from my own personal experiences. I too have a DX7 and use 6v/2300mah nimh batteries in all of my planes. Although I occasionally charge with my Accucycle Elite (mostly at the field) 99% of my charges are done overnight with the wall wart that came with my DX7. Never experienced a problem, and typically get between 5-6 flights on an overnight charge. FWIW, I typically fly 3-4 times a week, and have used this method since November 07 without a problem. I'm not questioning, but am interested to see how I am able to do this if my packs are not being properly charged.

Thanks in advance,
Jr

capt17

Jr25, Here is the link to the thread I asked the same question in a few weeks ago. Basically with a standard 4.8V wall charger you will get approx. 6V output to fully charge the battery in the 5.xV range. If you charge a 6V 5 cell pack with this charger it will partially charge but not go over 6V. A fully charged 6V 5 cell should be in the 7.x range. A range where a 6V output wall charger cannot take you. You need to fully charge your battery and hook it up to a volt meter to see the charge. You might just be running off a half charged battery. Please reference the link below for more info.

http://www.rcuniverse.com/forum/m_78...tm.htm#7848977

2slow2matter

My Feedback: (1)

I have an Ace digipulse charger that has 6 outputs on it. I charge everything from 4.8 v rx batteries, to 6 v rx batteries to 9.6 v tx batteries with it, and nowhere does it have a setting for voltage. You simply tell it how many milliamps to charge (based on the size of your battery, at .1 C), and it charges for 15 hours then goes to trickle (at .01C (I think)), whereas C is the current (in milliamps) that you set it on. It states very clearly on the instructions that voltage does not matter on the chargers. The only thing that matters is the output, and the charger has to have a strong enough output (in current, not voltage) to sufficiently charge the battery back up. I've used this charger for years without any problems, and I've not had a battery fail yet. It's my favorite charger. My dad has 2, and my brother has 2.
The only time voltage would matter would be when you are using a charger that detects voltage. For example, I also have the triton charger and I set the number of cells on it so that it can correctly detect peak and shut itself off.
On the timed chargers (like the digipulse and your wall-wart), it doesn't matter. You'll just have to charge it longer. Probably like 24 hours or so (just guessing since you didn't say how many mA the battery is).

Jr25

My Feedback: (7)

I fully understand what is being said, however, when I leave my 6v/2300mah batteries on a wall wart for 8 hours, I start the day with 7.2-7.3v (measured by a digital v meter.) I am not trying to start trouble, but I have to stand behind that a wall wart will fully charge a 6v battery if left on an overnight charge.

Jr

capt17

Jr25 Then your charger you have is certainly charging it to full capacity. The wall wart that came with your radio obviously outputs enough volts to charge your 5cell 6V. Most wall warts will not. this is the exception.

Missileman

Back to the original post.
Don't go to a 6V pack for the wrong reasons.
7 servos do not need higher voltage and higher voltage will not prolong battery life. In fact it will lesson it slightly.
You need higher capacity ie... a 4.8 volt 2,000mah battery will last you longer with those 7 servos than a 6 volt 1,000mah battery will.
That said, there are other reasons for wanting a 6V system, higher torque on servos for example.

plasticjoe

My Feedback: (22)

Go to A123 2 cell pack.... 7.2 volts and the spektrum will handle it.... you get awesome performance from the pack and it can easily handle the draw from the servos. Also when you charge it... it stays charged... there's no degradation over time.... charge today... and fly a week from today and it's still 99% charged

Allfat

My Feedback: (1)

Problem with that is that you have to buy a special charger for them instead of just throwing it on a wall wart the night before you go flying. Is it really that difficult to keep your batteries charged?

2slow2matter

My Feedback: (1)

I believe having a spektrum/JR 2.4 ghz system installed is reason enough by itself to go to at least 5 cells because of the low voltage threshold they have. Regardless of the number and type of servos, go with a 5 cell pack for peace of mind. Plus, those radios come with digital servos (if you are using the ones it came with), and 7 of those will definitely be going through a battery pack.
Now, I agree that if you go with the same mAH rating, but just increase the voltage you won't be gaining anything, and will mostl likely be losing some capacity. But increase it to at least 1500 mAH @ 6 volts and you will be good to go.

And voltage has nothing to do with charging the batteries (to an extent). It takes CURRENT flowing back through the battery to reverse the chemical reaction that took place when the batteries were depleted. As long as your charger has enough potential to push current through the battery, then it will work. The weaker the charger, the longer it will take to fully reverse the reaction.

Now, I would like (not to steal the thread) to know more about using 7.2 v lipo batteries. So the rx and servos can handle the extra voltage?
I don't have any 2S lipos, but I have plenty of 3S. I have a friend who uses 3S lipos in his radio, and they last forever. What is the maximum V on a 2S lipo? Can the servos handle the V?