Okay I just bought a new Rx pack today which is 1100mAH, I am wanting to know if it will be okay to use my towerhobbies Tx/Rx wall charger to charge the pack. The charger says it will charge 9.6V and 4.8V Rx packs, just dont want to fry the battery or charger. Also I am using a futaba FP-R127DF Rx, will it be okay to use this battery with my Rx? I hooked everything up and it all seemed to work properly, nothing got hot or exploded so that was good.

yes, you should be OK. The new Rx pack - with 1100 mAh capacity. Is it 4-cell 4.8 Volts? If so, then everything is OK. To fully charge it, you may need to leave it on charge for 24 hours. Read the mA output on your Futaba charger. It is probably 50 mA. Divide 1100 divided by 50 and you get 22 hours. Allow a little extra.

No the Rx battery pack is a 5 cell 1100mAh 6.0V pack, but I did place it on my charger when I got home and within about an hour or two the charge light had went out so I would guess it had fully charged? Now it will not harm my futaba Rx will it?

A 5 cell pack is 6 volts vs. 4.8 You need a new charger. I would recommend the accucyle elite. You can charge all kinds of batteries, and cycle them. Plus it has two outputs so you can quickly charge your tx and rx or two rx's at one time. Welcome to the wonderful work of 6 volts and faster stronger servos.

OK> good to know it is 5 cells. This is a different issue. First - it will not hurt the receiver or most servos. Many people, myslef included, use 5-cell receiver packs. The servos will be faster and have more power. There is very little downside to using 5-cell instead of 4-cell.

However, charging is another matter. The wall wart charger that is rated at 50 mA (most likely) may only charge the pack at 20 or 30 mA or maybe not at all. And the light may go out long before the pack is charged. The wall charger is designed to charge a 4-cell pack at 50 mA. I have tested a few chargers with 5-cell packs and they tend to charge the pack at a lower rate. So if the charger is rated at 50 mA, it may be reduced to 30 mA with the 5-cell pack. So a 1100 mA pack may take 40 hours to charge.

If you have an ammeter, you can measure the charge rate. IF not, I'd find somebody to either measure the charge rate, or find someone that has a battery tester. Charge the pack with your charger and then have them discharge the pack and measure its capacity. Do this a couple times before you trust the wall charger.

Or just buy a 5 cell charger? Also this pack is an APS racing pack for cars is that a problem for my plane?

A car pack is probably okay but I would cycle it twice to check the capacity especially if it a nimh

Some servos can't handle 6 volts, in particular Digital servos but I have seen some analog that might have a problem. Check the manufacturers recomendations to make sure.

Man this all has to be so complicated, I think I might just spend the $10 bucks again and buy the futaba 4 cell 600mAH Rx pack

Most standard servos are ok with 6 volt batteries, the problem is with some digital or specialty servos.
Here is the batteries I use:
http://www3.towerhobbies.com/cgi-bin...?&I=LXNRH6&P=7

Okay http://www3.towerhobbies.com/cgi-bin...?&I=LXH333&P=7 heres what I was thinking about, this is the standard pack that comes with most flight packs I had this pack before I fried it. See I just dont want to use anything thats going to fry my gear or mess things up, I have worked extremely hard to get my nitro model together and I just want it to come out right.

I would encourage you to go ahead with the 5-cell pack. 99% of all servos made will work OK with 5-cells. And your standard charger will also work OK - it will just take longer to charge than if you used a 4-cell pack.

Okay, thanks for your help I really appreciate it!

I am sorry but you are wrong. A wallwart charger designed to charge a 4.8 volt battery can not be used to charge a 6 volt battery. The charging voltage has to match the battery being charged.

Missileman - the wall wart chargers designed for 4.8 volts CAN charge 5-cell packs. I have done it many times. The wall wart chargers are current-limited devices. Here's one way to prove I'm right. Take an aileron extension. cut the red wire somewhere in the middle and strip off some insulation. Connect your ammeter in series with the charging circuit. When I do this I can measure that a 4-cell pack gets charged at 50 mA. Disconnect the 4-cell pack and connect a 5-cell pack. The charge rate drops to 40 mA but it is still charging. Charge the pack overnight and then discharge it using your discharger. You will discover that it has indeed been charged OK with the wall wart charger. After 7 cells, the charge rate drops off to 18 mA. I have done all my measurements and testing with JR wall wart chargers. But you should find similar results with any wall wart charger - they all work on the same principle.

I do not know about your existing charger. There's disagreement in the replies over whether you can use it with a 6 volt pack. I do not know so I'll stay out of that argument.

If you want an inexpensive wall wart charger that will charge high capacity 4.8 or 6 volt packs in less than 24 hours, you can find one at Cermark under 'General Modelers Necessities'
http://www.cermark.com/index.html
The CH-84 and CH-85 are the ones I'm looking at. They're 12 bucks each. For the 1100 mah packs I'd probably choose the CH-84. My packs are 1650 mah so I went with the CH-85.

We can agree to dissagree.
I am a journeyman electrician and have been dealing with batteries and chargers for 30 years.
You may think you are getting a full charge based on whatever readings you are taking but I can assure you you are not.
A charger designed to charge specific size batteries and used to charge anything other than what they are designed for is dangerous and it is irresponsible to recommend others to do the same.
I know first hand how dangerous electricity is and the deliberate missuse of any electrical equipment, including that wallwart charger, can have serious consequences.

Missleman,
I too am a journeyman electrician and I think I'm going to have to take issue with you.

Not being an expert in the field of DC charging and batteries, I have a simple question for you.

I have a Triton 2 charger running on a converted computer power supply with an input of 12.3 volts, the Triton is rated to charge 5s Lipo to a cutoff of 21 volts, how is this possible?

Gunfighter

Oh! I know, I know, choose me! (While frantically waving my arms in the air like a schoolboy). But I will give others a chance to respond first.

DMcQuin is correct. Most wall warts designed for charging the typical 4 cell packs have an open circuit voltage much greater than the battery to be charged. When you connect it to the battery to be charged, the internal impedance of the charger is enough to limit the current and the resulting voltage measured at the batter (while it is connected to the charger) is in the proper range. The same thing happens when you connect it to the 5 cell battery, it is just that the current is now less. To determine how long it will take to charge the 5 cell battery, just connect an ammeter in series with the battery and charger. The time it will take to fully charge that battery will now be the capacity of the battery devided by the measured current multiplied by 1.6 to account for the ineffeciencies of the charge chemistry and to insure that all cells wind up fully charged and balanced. Check out www.rcbatteryclinic.com for some good advice on how to use wall warts for batteries they were not intended for.

I don't know the circuitry of the Triton charger so I would have to guess.
If it is series charging the lipo I want to say it is using an amplification circuit consisting of diodes and transisters.( although alot has changed over the years with printed circuits)
You probably remember DC amplification circuits from your apprentice classes.
Balance charging charges each cell individually in parallel so no amplification is needed

Don,
Jump right in!

I think I know the answer, were not charging at pack voltage, were charging at cell voltage. The only way you get to pack voltage is put cells in a series.

GunfighterII

To charge each cell individually, (balancing charge), you would have to bring out a separate wire from the + side of each cell and a ground wire that is common to all cells. To charge a 5s Lipo as a pack, using only two wires and a +12V source, you would need a charger that looks something like the attachment below.

1. The 12V DC in can come from a battery or a computer power supply.
2. The first stage is an inverter circuit that converts 12V DC to 12V AC.
3. The 12V AC is input to a 1:3 step up transformer that will have an output of approximately 36V RMS.
4. This is rectified and filtered to provide approximately 40V DC to the regulator circuit.
5. The regulators will get their control voltages from the D/A ports of the microprocessor and you will have a charger that can deliver up to 35V DC and is current limited to whatever current is selected.

However, if you intended to charge a 5s pack up to 21V at a 1 amp rate that would be a 21 watt load. A charger is only going to be about 75% efficient so the source supply would have to be capable of sourcing about 28.5 watts. On a 12V supply it would have to source about 2.4 amps.

What Don said,

Rockandroller6, Bottom line, you have an 1100 mah 5 cell battery, either NiCad or NiMh (works with either) and a wall wart. You do not need anything more to get your battery charged. Yes, it will take about 40 to 50 hours but you will not damage the battery by leaving it on charge for much longer at the rate it will be charging. And yes, you do wind up with balanced cells when charging for this long a time at low rates (much better on the battery and safer than a fast charger). Sure, a fancier charger would be nice but is NOT NECESSARY if all you want is a reliable charge that will not harm your batteries. And yes, the 5 cell unit will work fine with your other equipment.