Battery cycling

| Is there a good reliable way to cycle a battery without having to invest | in battery cycling unit?

Yes, but you need to be patient.

Hook up a light to your battery. The size of the light depends on the capacity of the battery, and you want a light that can handle the voltage that the light puts out (putting a 3v light on a 12v battery will blow out your light rather quickly, but the converse is ok.) It doesn't matter how bright the light gets.

Also hook up a multimeter to the battery to measure the voltage. When the voltage drops to 0.9 - 1.1 volts per cell, stop. If you let it drop much below 0.9 volts, you risk reversing a cell which causes damage to the pack. (if it's just one single cell, no need to watch it -- it can discharge to zero just fine.)

You don't need a light. A resistor, motor, anything that draws current can be used. Ideally, you'll use something that will totally drain the battery in about an hour -- you don't want to drain the battery too fast, and if it's too slow, you'll go nuts waiting, because you do need to pay attention.

You can buy cheap dischargers that will automate this for you, and they'll pay for themselves pretty quickly as they prevent you from making mistakes and forgetting to stop the discharge (which you will!)

For 4 or 8 cell packs, this --

Note that discharging your batteries like this, even with a discharger/cycler, uses up some of their useful life. It's not something you want to do all the time, and many people believe that it's not even useful at all unless you do it to measure the capacity of your battery (which will require more equipment -- at least a constant rate discharger and a timer.)

yep...put a load on the battery such as light bulbs or small motors, while measuring its voltage with a voltmeter would do well for discharging. Measure nicads to 0.9V/cell. As for charging, if it's a radio rx or tx, you can use the charder that was included and charge longer than you might think. At C/10 charge about 15 hours because the lower current, the lower the charge efficiency is. Do this about three times.

OR you can get a cheap cycler...or lose a plane because you don't know what the real capacity of your batteries. $70 for a cycler with a capacity display or $300 for a wrecked plane...your choice.

Sure, just turn your radio on and sit in front of the TV for a couple of hours twiddling the sticks. When the meter goes into the red, you have just cycled your TX batteries. If you want to cycle the RX battery, sit the AC in front of you and let it move the servos until it doesn't. Then, look at your watch and note how much time you just tinkled away.

Or, you could get the "Simple Cycler" which is just a box that plugs into your batteries and drains them. Again, you then look at your watch and note how much time...

Or, you could invest in any number of RC battery chargers on the market that include cycling capabilities. It'll cost you about 1/2 cent per week because it will probably last as long as you do.

MJC

. . .

These are good tips, but the discharger links are for products that won't keep track of how much capacity your packs have.

While it is a "cycling unit," a cheap alternative is to cruise eBay or rcuniverse.com for an Ace Digipace I or II. These generally go for $20 or $25 plus shipping, and will discharge at 300 mA, and time the discharge of either receiver or transmitter packs. The only limitation I've found, when I use 5-cell receiver packs, is that I can only discharge the packs on the transmitter side (which will do both 9.6 and 6 volt packs). But once they're discharged I can charge them simultaneously.

Bob Kopski, the Electrics columnist at Model Aviation, has written that he might publish a simple homebrew discharger with cutoff voltage you can set. If you write him (he doesn't do email, at least for the modeling public) and offer encouragement, maybe that'll be sooner rather than later. Still no timer, though - - urge him to add one!

I would not consider flying RC without a battery cycler. My planes cost a heck of a lot more, in money and time, than a cycler.