Hi fellas,

I bought an airplane (.46 size) and radio about 4 years ago. I fly off and on maybe 4-10 times per year, my interest comes and goes. I always charge my batteries over night if I'm going to fly overnight. The problem is, I've still got the original batteries! Just curious as to how long these things are supposed to last? The ones in my Tx read a full charge (on the battery scale on the TX itself)...well, they always have. However I've never tested the battery (4.8 V-600mAh) on my Rx. I've got a multimeter, but have no idea how to use it or if it'll even tell me anything I need to know. Can anyone tell me the proper way to use this thing and how to determine if it's time to replace these batteries?

Thanks!

There is no easy, good, quick answer to your questions. Go the the battery clinic http://www.rcbatteryclinic.com/ and read the articles that are relevant. Red is also the moderator in the battery forum on RCU.

After looking at that site and what pertained to me, I think I'm to understand that there is no certain way to determine if my batteries need replacing, aside from inability to sustain a charge or separation of the cells (which may or may not be visible from the outside)? I think I also understand that replacing your batteries once every 52 weeks or so is proper maintenance? Wow, I've had mine for 4 years, never properly stored them and still don't notice any degredation! Better get some new ones before my luck runs out!

yes there are good tests - they are load tests - I use a Whatt meter - and use electric motor as a load - this will show how well the batt handles high drain .
there are other tests
ask the Batt Clinic.

If I remember right after three you have a low percentage of failure that goes up every following year. I think 4 years should be ok. I had some packs that were around 9 years old and one was bad. The other seemed ok but was replaced.

It shows how to build a "load tester" using a multimeter and a lightbulb. I may do that, seems easy enough. But, it doesn't say how to setup the multimeter in order to run the test. I've never used the multimeter and the instruction booklet isn't very clear....do you turn the dial to the 20V setting then touch the red probe to the red wire on the batt and the black probe to the black wire? Or turn the multimeter to the 200m Amp setting and attach the leads the same way? I've tried both ways, but get a spark each time the ground touches....neither way seems right.

I use a cycler, to determine how long the battery will last at the field. Since you don't have one, but have a multimeter, you can make a test. It will require more attention than my cycler, but you can do it.

A few days before you want to fly, charge your batteries overnight. Check the no-load voltage and write it down. Now turn on the transmitter and receiver, and sit there for the length of 2 flights (at least a half hour) working the sticks back and forth in all directions. That will keep both batteries putting out at the load seen in operation. Be sure the transmitter antenna is pulled out, some people say that keeps the innards from overheating.

At that point, you note the voltages again. The transmitter is always under load, so this is a valid check, if the voltage is still up, it's good for a long flight. The receiver is another matter, since you don't have a load voltmeter. But if the voltage is still over 4.8 V, you can rely on it for a flight.

Then recharge, before you fly.

Good luck,
Dave Olson

How about something like the hobbico voltwatch? It's only $11. Simple and accurate.

http://www2.towerhobbies.com/cgi-bin...?&I=LXMZ56&P=7

dano13

Yes, but, you can not get an accurate reading without the load.

I tried it this way, but the wires running from the battery (RX) got VERY hot VERY fast without giving me a reading on the multimeter. I'm just trying to figure out how to work this thing first.....THAT couldn't have been the best way! Any other takers?

That voltwatch looks exactly like what I need! Thanks for posting the link to that....very inexpensive as well!

Jjboomer install the battery in the aircraft, place the multimeter in the 20 volt DC position, apply the red lead to the POS on the meter and to the red wire of the battery, the black lead to the NEG on the meter and the black wire of the battery, turn on the receiver and transmitter and utilize the controls, this will place a load on the battery. With a fully charged battery your voltage should not reduce to less than 4 volts.

I hope this helps.


fly the airplane first,


73 Lee K5MRC

I cycle my batteries regularly, and am using 3 transmitters, all with batteries from '96 and '97 and they hold a good long charge still! Cycling is the key. Bill

Cycling meaning running them down to no charge, then charging them back up? Or Cycling from one battery to the next every time a battery runs down?

Thanks for the tip LEE! I'll try that and see how they do.

Cycling means drawing the voltage down to preceisely 1.1 volts per cell, then fully recharging. That is one cycle, and is tough to do accurately without a "cycler".

The "Voltwatch" will help, but keep in mind, once the Rx pack's voltage hits 4.8 volts, then the voltage will fall off pretty quickly. As the pack gets older, I'd suggest recharging when it hits 5.0 volts.

You can also buy a "loaded" voltmeter, commonly called an ESC (Expanded Scale Voltmeter) at hobby shops for around $15. (But will require buying/making leads.) They'll give you a pretty accurate way to check voltage between flights.

Good luck,
Dennis-

By "cycling" I'm referring to depleting the charge in both the Rx and Tx, ie. I bring the Rx down to 4.4 vdc and the Tx to the no fly zone on the radio meter then charge for 14 hrs. Do it a few times it really conditions the batteries. Bill