frisconick

Hi All,

Hoping someone can help me out here. I just bought a JR9303 radio setup for my TF GS P-51. I ordered the 9303 with a 6v receiver battery. The charger that came with it (NEC222) puts out 5.8v @ 150mha on the receiver side. My other radio is a JR6102 with a 4.8v receiver battery, but it has the same charger at 5.8v on the receive side. What gives? I'm pretty sure batteries should be charged at a higher voltage than their operating voltage (not 100% sure though). What voltage should each system be charged at? Did they send me the wrong charger for the 6v system? When fully charged, what should the 4.8v system put out? What should the 6v system put out? What's the minimum safe flying voltage for each system?

The more I learn about this hobby, the more questions I have !!

Thanks in advance,
Nick

alan0899

G'day Mate,
That charger won't charge a 6volt pack properly, you will need a different charger, you are right in assuming that the charge voltage needs to be higher than the rated pack voltage, the 5.8volt charger is right for a 4.8volt pack. Your 4.8volt pack should sit on 4.8volts when in use, meaning under load, that is why battery checkers, that plug in to check you pack, do so with a known load to simulate some servo load. Obviously any size pack will read a higher than rated voltage straight off the charger, because it is charged at the higher voltage, BUT it is the packs rated volyage, eg. 4 cells x 1.2volts = 4.8volts, 5 cells x 1.2 volts = 6volts, that is important, because this is the voltage that the receiver & servos will be powered at, see simple! Ha Ha.

frisconick

Thanks Alan,

Just wanted to be sure I was on the right track before I complained about not getting the right stuff.

Thanks again,
Nick

starry

so the charger i got to gharge my 4.8 pack and tranny wont charge my 6 volt pack then[&o]

alan0899

G'day Mate,
Depends on the type of charger, if it is a Swallow advance etc. it will be able to charge it, but if it is a wall charger, rated at about 5.3VDC output at whatever current, then it won't charge a 6Volt pack. Sorry.

P-40 DRIVER

JR only lists 2 wall chargers, a 50 ma and a 150 ma, both are for 4.8 packs. Your going to need to invest in a charger, not a fast charger but one that will do 10% at the correct voltage. Ace makes a nice one. It seems JR wall chargers have not caught up with thier flex equip.
I would invest in a regulater if I was you. some receivers don't like the voltage a 6V pack puts out when fully charged.

frisconick

Can't believe JR would sell 6v packs, but no way to charge them. It may force me to go back to a larger 4.8v pack like the rest of my planes; new charger, voltage regulator, hastle factor - may be too much !!

Thanks low

NCIS

I'd keep the 6V pack. It will make the servo's produce more torque and they will respond faster. A charger for the 6V is at Tower Hobbies for $69.99. This is a great charger and will charge two batteries at a time. Hope you stay with the 6V you will like it better than the 4.8.

Gibbs

dbacque

My Feedback: (3)

Which charger is that?

Dave

Newc

No need to get another charger, as the normal 'wall wart' that shows on the label the output for 4.8v will work well for a 6v set up. I've been doing this for years (running 6v batteries with normal '4.8v' chargers from Futaba and from JR), and before each flight I check the voltage with an ElectroDynamics digital volt meter with load. The reading is always right around 6.6v before the first flight.

And, here's a picture that I just took of another 'wall wart', this one from Cermark. Note that it has the outputs for both 4.8v and 6v for each lead and there's no adjustments available.

If you need to prove this to yourself - and I would - simply charge the 6v pack with the normal charger and then measure the output with an Expanded Scale Volt meter such as you should have - even like a simple one from Hobbico.

frisconick

Newc,
I'm in the process of discharging the 6v pack right now to try exactly what you recommend. I've heard the same thing from a couple of other sources. Do you run a voltage regulator on your planes ?? What's the max voltage the receiver and servos will tolerate ??

Thanks,
Nick

frisconick

Thanks Gibbs,

I looked at that one today. I may still be in the 6v business!!

Newc

I don't run a voltage regulator and have never seen any reason to, including after talking to Andy Low, the owner of ElectroDynamics. The servos - unless they specifically state that they shouldn't be used with 6v batteries - have no problem operating at the typical voltages slightly over 6v such as I have ever encountered.

Make sure that you don't discharge the batteries too far! I believe that you shouldn't let them get below 1.1v per cell, meaning 5.5 volts for a5 cell battery when discharging. Are you using a cycler? If not, you may want to consider getting one as this will allow you to keep track of all your batteries as they are used and age, and allow you to cycle them in the off season - always a good idea.

Richard L.

My Feedback: (24)

I would invest in a "smart" charger, such as one by Sirius, that can detect when the battery cells have reached their peak charge and shut down. Most wall chargers are dumb and can overcharge a battery pack if left on too long. I would also stay with 6v because if one cell fails, then you can still fly the plane home.

Newc

Nick - What did you find when you did your charge with the 'normal' wall charger that comes with the Tx/Rx?

I just charged two of my 6v batteries with the 'normal' 4.8v (on the charger label) wall charger and the end voltage (under load) was 5.86v.

Comfortable with using a 'normal' wall charger for your 6v batteries now?

Richard L.

My Feedback: (24)

5.86V on a 6V pack under load is not good. A freshly charged 6V pack should read around 6.6V. One should stop flying when it drops down to 6V.

alan0899

G'day Mate.
They are effectively flat at 5.5Volts for a 5 cell pack, so stop flying at 6Volts is a not a good idea.
A 6Volt pack should hold at 6Volts, under load, remember the 1.2 Volts per cell, that was under load, stop flying when it drops BELOW 6Volts, to be on the safe side is OK. If you stop flying when it drops TO 6 volts, then you won't be flying for long. Because that is it's normal loaded voltage.

frisconick

Thanks guys, but the more I hear, the more confused I get. I called JR and they said: "yes, we sell 6v batteries. Yes, our receivers and servos are designed to run on 6v packs. No, a voltage regulator is not needed unless it goes over 7v. No, we don't sell a charger for 6v batteries". I'm losing faith in JR. Why sell 6v systems without the ability to charge them fully?

I did run the 6v pack down and charged it with the 4.8v charger (that really says 5.8vdc as its output) and it did charge it to more than 6v. Don't remember the exact number, but I know I was surprised at the result. I'm tired of worrying about it, so I'm going to pop for a cycler/charger. Probably need one anyway to cycle all my other NiCads.

Anybody using a voltage regulator with their 6v systems? Comments?

Nick

frisconick

One more thing: If you should stop flying when your 4.8v packs reach a certain voltage (say 4.8v) shouldn't you be able to keep flying until your 6v packs get down to that voltage? Or, should they not be run down past 1v per cell?

js3

My Feedback: (3)

I've avoided contributing to this thread because I am not a battery expert by any means. Please! Somebody correct me if I'm wrong here but I've always been told that the output voltage of the charger isn't what's important. It's the Mah output that charges your batteries.

Have you seen those charging power panels? The ones that'll top off your nicd glow lighter? If you check the voltage while charging you'll see that it'll be between 11.5 to 13.5 volts--the voltage of the gell cell battery powering the unit. Now you're using that to charge your 1.2v one-cell nicd head lighter.

Your wall wart charger that came with the radio will work to charge your 6v pack. That being said, I would advise you to invest in a more advanced charging/cycling system. It is money well spent.

If you were to post this thread in the [link=http://www.rcuniverse.com/forum/forumid_84/tt.htm]battery/charging[/link] forums, I'm sure you would be rewarded with good advice from the experts.

frisconick

Thanks John,

I did post the same original questions there, too, but this seems to be where the action is. I also am not an expert, but I current and voltage are quite different and I don't see how a low voltage source can charge something to a higher voltage. As to the glow lighter, I've always been afraid to charge mine from my field box power panel for the exact reason you brought up. It puts out 12v and the lighter is only 1.2v. I was afraid there would be some kind of meltdown!!
Nick

jaka

Hi!

Those simple wall chargers that you get when buying a radio (Futaba , JR,etc) is OK for charging either a 4,8v, 6 V battery pack.

The reason for this is that those chargers don't charge with constant voltage. It's not really true that they charge with 4,8V! This is just a number and is not really important.
They charge with constant ampere (milli amps)!so voltage alters when you charge a battery pack.
So a 6Volt battery pack could be charged just fine with one of those chargers, that's why JR and Futaba ...and the other radio manufacturers say as they do..."work equally good with a 6Volt pack".


You cannot measure Volt on those chargers just by putting a Volt meter across the leads!

So 4,8V or 6 Volt packs don't matter just charge them with the simple wallcharger and be happy!
I charge all my NiMH packs from just 3 , 30 year old 50-100mAh JR and Futaba wall chargers. The batteries I use are mostly from 1000 mAh 6,0v packs up to 2300mAh 4,8v NiMh batteries.
I charge for 16-48 hours depending on capacity.
I never use voltage regulators! Works just fine without one.


Regards!
Jan K

frisconick

Now that makes sense. But what about charging the glow lighter (1.2v) from a 12v field battery????

Charlie P.

It needs a ballast resistor. I run my 1.5v glow driver clip driect through a power panel connected to a 12v, 7A gel battery. Some power distribution panels have glow-charge "stations" built right in (looks like a glow-plug screwed into the face plate). The circuitry is behind the plate. Or, you can add one of these:



May also have a step-down transformer, but I don't think they are that sophisticated.

How does your household 117v wall plug know whether you are plugging in a 75W bulb,, a 1000W microwave or a 1500W hair-drier? Same "magic."

Newc

Boy, I screwed the Moose here, didn't I. When I said I meant 6.86v. Good catch guys.