maybe it is time to do so.


one more question, is there something wrong with cycling the batteries with use? I mean, my A9 radio has this function called "monitor" that get all the servos to work by moving the throttle stick. Iuse to do this until the Rx battery gets to 4.5V (when the low battery warning starts to beep)

Discharging the battery by any means works equally as well. It just ties you up from doing something else while they are running down.

Hi,
Ni-Mi batteries like to be charged SLOWLY, around 10% to 20% of their RATED mAH capacity. Do Not crank up the current and get the battery pack hot, it will take the charge, but the batteries will be damaged and not last nearly as long as packs that were not over-heated while charging. Your charge rate for Ni-Mi should be 10%-15% of the rated battery capacity. A 1000 mAh battery pack can be charged at at 100-150mAh for 10 hours. A 2000 mAh pack can be charged for 10 hours if your charger puts out approximately 200 mAh. Again, DON't Let your Ni-Mi pack get HOT.

Ni-Cd batteries can take lots of abuse, over-charge, getting hot, and over drained. But, they do need to be cycled and checked for capacity. Any Used Ni-Cd or Ni-Mi packs should be thrown away if they will not check out to within 80%-85% of it's original rated capacity.

Battery manufacturers rate the capacity of their batteries with a normal discharge of 50 mAh.

A normal 4 channel .40 size airplane with 4 standard Servos will pull approximately 250 mAh
per hour of constant use. For many Years, Radio manufacturers use standard 600 mAh batteries in the Transmitter and Flight pack. This gave a TOTAL of about 2 Hours of Flying Time before the batteries required a re-charge. 600 mAh / 250 mAh = 2.4 Hours of battery life.

Larger capacity batteries may give you a warm and fuzzy feeling, but don't forget to re-charge every time and re-cycle once each month to verify those batteries.

Batteries are cheaper than airplanes.

Ken AMA 1528

with the Aurora 9 you can actually leave it alone to do the job for you

There is no purpose for discharging the battery other than to cycle them in order to find out their capacity. Simply putting a load on the battery and letting it drain down serves no positive purpose for the battery, and in fact it can damage a battery. If a battery is discharged below 1.1v in any cell it risks what is called cell reversal. When this happens the cell is shot and is not longer usable for flying. If you are going to discharge a battery it needs to be done by something that can monitor the voltage and stop it when the voltage gets down that low.

Years ago batteries got a benefit from cycling them regularly (this always seems to get a lot of discussion too as many will argue the point), but with current battery chemistries there is no benefit from cycling the batteries. The reason a battery should be cycled now it to determine it's capacity, nothing more. When a pack is new it should be cycled 3-5 times to determine (it can take several cycles for a new pack before it settles down and is "broken in", so to speak) it's initial capacity. Then periodically the pack should be cycled to see what it's current capacity is, and then compared to it's initial capacity. For me I will take a pack out of service when the pack is 80% of it's initial capacity.

Ken

I'm getting a little confused here... so there is no need to cycling the batteries, but then, can I charge them even if they are.. let's say, arround 1.3 per cell?   I remember when I first got into the hobby some years ago, a friend of mine told me I should never charge a battery until they are fully discharged (he was talking about NiCd batteries).</p>

Yes, you can charge a battery regardless of it's state. You do not have to discharge a battery prior to charging it.

Ken

Ken,

You wrote"A normal 4 channel .40 size airplane with 4 standard Servos will pull approximately 250 mAh
per hour of constant use. For many Years, Radio manufacturers use standard 600 mAh batteries in the Transmitter and Flight pack. This gave a TOTAL of about 2 Hours of Flying Time before the batteries required a re-charge. 600 mAh / 250 mAh = 2.4 Hours of battery life."

My 600 mah was giving my 4-servo planes 3 flights of about 8 minutes each. This is why I just switched to 1,100. So there must be something wrong on both of my planes.

Also, you mentioned to cycle a few time to determine capacity. How do you determine the capacity? I have a regular Hangar 9 voltmeter with 3 levels 2A, 1A and .5A. Whicj one should I use?

Thanks,

<font size="2">

RCKen
My charger manual has the following note:</p></font><font face="ArialMT"><font face="ArialMT">

<font size="2">"Some rechargeable batteries are said to have a memory effect. If they are</font></p>

<font size="2">partly used and recharged before the whole charge is drawn out,</font></p>

<font size="2">they‘remember’ this and next time will only use that part of their capacity. This</font></p>

<font size="2">is a ‘memory effect’. NiCd and NiMH batteries are said to suffer from memory</font></p>

<font size="2">effect. They prefer complete cycles; fully charge then use until empty, do not</font></p>

<font size="2">recharge before storage-allow them to self-discharge during storage. NiMH</font></p>

<font size="2">batteries have less memory effect than NiCd."</font></p></font></font>

<font size="2">Is that old-time technology?</font></p>

Regarding in flight use of battery and consumption, there is something that not a single person has in common with another and that's flying style.

When I was learning to fly, my instructor watched me for a few minutes while I was flying on the "box". It was at a time when he was confident enough in my flying abilities that he could watch me instead of the plane. He noted that I was using a lot of input to the sticks to make minor corrections as the plane was flying.

He told me to make a turn and fly straight and level, which I did. Then he told me to let go of the sticks.. both of them.. so I did. The plane did the same thing on it's own as it was while I was trying to correct for with the sticks.

My point is that the plane, once trimmed up correctly, will pretty much fly by itself. Making minor corrections does one thing... it consumes battery power. So, some do it some don't. I would be willing to bet that those that are having less flight duration out of a battery pack are doing as I was doing.. overcorrecting.. or trying to correct every movement the plane makes, which is totally unecessary.

Learning some control over the aircraft does not necessarily mean correcting every movement (or trying to correct) it makes. There are to many environmental factors here to try to correct for.

The bottom line is fly the plane, but don't try to correct for every movement it makes. Your batteries will last longer and you will find that you are more relaxed during the flight. The down side of this, and this is by no means a down side... is that you may.. just may.. get more enjoyable flights in that day on that charged pack!!

CGr.

Retired,

I am new to the hobby. Every piece of advice help.
I used to do a range check everytime I go flying. I noticed I was the only one doing it so I stopped.
I will try not to overcorrect during flights too.

Thanks,

Don't stop doing a range check. That should be in EVERYONE's pre-flight process along with a sanity check to see if your radio channels are somehow reversed (wrong model selected for instance), a battery check, all that stuff that you learned as a student just don't expire.

They are all good and, I can say this with absolutely certanty, WILL save your airplane one day.

CGr.

Yes, this is old info. Memory was an issue many many years ago (10-15 or more). But batteries today do not suffer from memory issues. Just recharge your battery after you are done using it and you wont' have any issues.

Ken

To determine the capacity of the battery you need a charger that is capable of doing a discharge/charge cycle on the battery. The charger will discharge the battery down to the 1.1v/cell level and then it will recharge the battery and display the amount of charge the battery took. This will give you it's capacity.

Ken

perhaps Ken was talking aobut regular servos, some kind of servos drain more power.

What Iposted has nothing to do with servos at all. I'm not quite sure where that came into the conversation.

Ken

I was talking about this

Oh, ok. I had missed that. sorry

The answer is yes, different servos can have different loads on a battery. Heck, even the way you fly can have an effect on the rate at which a battery is used. The more you move a control on the plane the quicker a battery is going to drain.

Ken

correct me if I'm wrong but even the presure that air gives to the surfaces make them drian more power than usual.

Maybe a little bit, but it's really not enough to worry about.

Ken

chocorrol, that charger scooter linked to is worth the few extra dollars. If you stay in this hobby, you'll grow into it.

Not necessarily a 'deceptive trade practice', more like industry standard term. 4.8v is usually a 'nominal' term, meaning 4.8v charger for the same size battery. The charger has to put out near 6.5v to fully charge a 4.8v pack, due to various losses and EMF (electromotive force).

A 20% increase from 10 hours should be 12 hours methinx.

I'm not sure I agree with that. (Plz don't ban me!)[8D] Not much has changed in Nicad chemistry over the last 10 years or so, and I haven't seen any battery makers recommending against cycling. Then again, some makers still debate the 'memory' thing. I still cycle my Nicads, new and old. 'Forming' new nicads (5 slow charge/discharge cycles before use) is something I still do, you can see the increase in volts and milliamps in a charger/cycler with data reporting like the Triton, Chameleon, etc. 

AMEN! [8D]

<p class="MsoNormal" style="MARGIN: 0in 0in 10pt"><font face="Calibri" size="3">Assuming that the cycling is still good for Nicd, my question is the following: is it only to increase the life of the battery, or does it help in getting more charged time at the field when flying?</font></p><p class="MsoNormal" style="MARGIN: 0in 0in 10pt"><font face="Calibri" size="3">Thanks,</font></p>

</p>

<p class="MsoNormal" style="MARGIN: 0in 0in 10pt"><font face="Calibri" size="3">I followed every bit of advise and I think I am fine now. Thanks for your help.</font></p><p class="MsoNormal" style="MARGIN: 0in 0in 10pt"><font face="Calibri" size="3">First I changed my 600mla Nicd that came with the radio to a 1,100mla</font></p><p class="MsoNormal" style="MARGIN: 0in 0in 10pt"><font face="Calibri" size="3">Second, I gave the battery 2 cycles before using it (discharged to 4.4amps)</font></p><p class="MsoNormal" style="MARGIN: 0in 0in 10pt"><font face="Calibri" size="3">Finally, I avoided over-controlling the plane during flights.</font></p><p class="MsoNormal" style="MARGIN: 0in 0in 10pt"><font face="Calibri" size="3">The results: I made 5 flights this morning and still had juice left for a couple more.</font></p><p class="MsoNormal" style="MARGIN: 0in 0in 10pt"><font face="Calibri" size="3">Now, if someone could figure out how to quit my job and fly all day, I would really appreciate it.</font></p>

Short answer: both. Congrats on the flights!

I'm not quite sure anyone knows the "combined resistance". Well, someone knows, but probably not the average "joe" in the hobby. Ummm... ok. Suffice to say that charging with about 20% overhead is probably sufficient.

CGr.