Charging For Dummies

[starrd]

Several years ago my son and I got into RC Air (what a great father son activity). We started with GAS and after smashing several stick builds we moved to ELECTRICS to learn to fly.

We purchased a Dymond Turbo Charger (on the advice of a friend) and while it works well (most of the time) it came with VERY poor documentation and NO charging basics.

We now own 12 aircraft (gas and electric) but still know “jack” about charging NiCad & NiMH (other that when all else fails use C/10) now we need to purchase some Li packs for an indoor, craft #13. There is nothing worse that getting to the park and your battery pack struggling to get the craft airborne.

I have been able to pick up some great info in this forum (THANKS ALL) but is there a good resource i.e. “Charging For Dummies”?

Starrd

[purehobby]

Starrd,
I am not sure where you can find a guide to help you but if you have any questions I would be more than happy to try and help you.

Robert
sales@purehobby.com if you want to email me.

[aeajr]

Let me put my own twist - car analogy

Gas tank = battery

gallons of capacity = amp hours = how many amp hours can the battery hold

gallons per hour = amps per hour

thousandth of a gallon per hour = mili amps per hour

horse power = volts

So, the more volts, the faster the battery can push the motor

The more miliamps in the battery the longer it can push the motor

If the battery holds 1 amp hour = 1000 mili amp hour = mAh

if the motor draws 1 amp of electricity from a 1 amp hour battery then the
battery can run the motor for one hour.

if the motor draws 10 amps from a 1 amp hour battery then the battery can run
the motor for 1/10 of an hour or 6 minutes.

Is it getting clearer?


NICD = Nickel Cadmium - chemical make up of he battery

NIMH = Nickel metal hydride - chemical make up of a different kind of battery

LIPO - Lithium Polymer - chemical make up of a different kind of battery.

Batteries are gas thanks

milliamp hours are a measure of how much electricity they can hold regardless
of what the chemical make-up is of the battery.

500mAh NICD = 500 mAh NIMH = 500 mAh LIPO

All three have the same electrical capacity

The NICD is the heaviest

The NIMH is the next lightest

The LIPO is the lights of the three type of batteries for the same electrical
capacity

Each one needs a specific kind of charger

Some chargers can do one kind of battery

Some can do two kinds

Some chargers can do all three

Put a LIPO battery on a NICD only charger and you could burn your house down.

Rate of delivery - AMPs

One final point relates to the ability of a battery pack to deliver power to
the motor. Batteries come in different size cells. You know this from
household batteries; C, D, AA, AAA. Well in general the bigger ones, in
addition to having higher mah ratings, can deliver more electrical current
than the smaller ones. This is measured in amps. It is like having a bigger
hose vs. a smaller hose connected to the same water tank. The amount of water
in the tank doesn't change (mah) and the pressure of the water coming out may
not change (volts) but how fast you can drain the tank does change (amps).

Amperage delivery is often referred to in C which is short for capacity. You
might see that a 500 mah pack can deliver current at 5C, which means 5 times
500 miliamps, or 2,500 miliamps which is 2.5 amps. Try to pull the power out
faster than that and it just won't happen. Your plane's motor will probably
run, but it won't develop full power. So if your motor needs 5 amps to run
properly this pack won't do the job.

Sitting next to it on the shelf could be a pack rated at 500 mah that is also
rated 10C which means it can deliver its power at 5 amps. This will get the
job done.

Depending on the motor set-up in you plane, you need to match the battery
pack's ability to deliver current, or amps, to the needs of the motor. This
is usually spelled out by the manufacturer so read the instructions.

Charging rates of battery packs are also expressed in C, so a 500 mah pack
that can be charged at 1.5C can accept current from the charger at 1.5 times
its rated capacity, or in this case 1.5 X 500 miliamps = 750 miliamps. Charge
it faster than that and you might damage the cell, or worse. In the case of
LIPO batteries, charging too fast can cause a fire. READ THE INSTRUCTIONS!

Is that all of it? No, but it touches the major points.

Did that help?

[Lucky Strike]

If I may butt into someone elses original post... I found that very helpfull, however can you help me with the settings I need to input on my charger/cycler. I am running the standard Futaba 6YG tx with its 8cell pack. In the plane(gas powered 60), I believe its a 4cell for the Rx.
The plane was a RTF so the Rx batts were already installed, so I'm not sure on the settings. I have kind of figured out that there are no "set" settings that you can change them around, I'm just looking for some general guidelines on what most flyers use for their batts in the tx and Rx.
thanks in advance
John

[aeajr]

If I may butt into someone elses original post... I found that very helpfull, however can you help me with the settings I need to input on my charger/cycler. I am running the standard Futaba 6YG tx with its 8cell pack. In the plane(gas powered 60), I believe its a 4cell for the Rx.
The plane was a RTF so the Rx batts were already installed, so I'm not sure on the settings. I have kind of figured out that there are no "set" settings that you can change them around, I'm just looking for some general guidelines on what most flyers use for their batts in the tx and Rx.
thanks in advance
John

Transmitter and Receiver Batteries

These are typically made from NICD or NIMH cells that are designed for lighter loads than motor batteries used to power electric planes. As such, they need also to be charged at slower rates. The general rule is 1/10 C charge rate where C is the rated capacity of the battery. So, on a 600 mah transmitter or receiver pack would be charged at 60 mah. At this rate you would charge an empty pack for 10 hours to bring it fully up to charge.

This is handled nicely by the charger that comes with the radio system. This is an example of such a charger.
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXN66&P=ML
The key is to read the instructions that came with your radio and follow them. If you didn't get any instructions then use the 1/10 C rule and you can't make a mistake.

Quick charging these packs is not recommended as a standard practice. However some people will quick charge them if they run down at the field. Just be aware that this can lead to a shorter life and can cause pack failure. If you do quick charge, try to keep it below the 1/2 C level and don't do it too
often. They just don't like it.

If you quick charge them, they will likely get hot. Don't quick charge them
in the plane or the radio as the heat build up could damage some of the
surrounding electronics or might deform plastic or epoxy based components near them. Fast charging at 1C will generate a lot of heat and can lead to early pack failure which could happen during a flight.

There are after market chargers that are focused on transmitter and receiver
packs. Here is an example from AccuCycle
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXL357&P=ML

Charge 'em slow and treat them right and they should last for years. If you
tend to fly for long periods, pick up an extra transmitter and/or receiver
pack and charge them slowly, at home. Then, you can just swap packs at the field. That is what I do.

Most radio makes offer extra packs and there are a number of third parties that make them. Here are a couple of examples.
http://www2.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=futaba+battery&FVPROFIL=++
http://www.amondotech.com/index.asp?PageAction=VIEWCATS&Category=228

Nuff on transmitter and receiver packs :)