Hi,

Can someone answer this question for me !!!!!!!!

How important is it to Discharge your flight pack batteries ???????? is it really nessesary ?

As i have a onfield charger etc, but not a discharger i was looking at the Futaba BR2000 but its not avalible in the uk, well i havent seen it over here so will it be worth me spending $35.00 for postage to get it from Tower Hobbies, or should i just buy some spare batt packs ?

Thx for any advice on this

Very important for NiCd batteries, since they develop (as it's called) 'memory'. Without discharging/recharging, you'll only get a flight or two out of a NiCd rx battery. You'll double that with proper cycling.

I don't believe that NiMh and Lithium-ion batteries have the same issues, so if you are considering additional packs and don't want to worry about cycling, you might look at those types.

You should always keep a battery tester handy that can load-test. That's the only way to be sure of how much you got left on a given pack. Without a load, you might read 5.5 volts, with a load you might be at 4.8 (which is too low to start a flight on). I've seen this first hand.

Any discharger will do - I've seen some that are simply a string of light bulbs connected to battery plug. I use a combination charger/discharger unit myself.

Cheers!

MrJB

My tester has a 300mah load it uses to test. Wondering if I might be able to use that as a discharger!!!

You can, but it's kinda hard on the tester to be constantly on and loaded.

I presume that Dragon Heart (good handle) is flying gas engine planes using ni-cads for the flight packs. If so, discarging, also known as cycling, only needs to be done periodically. Not constantly.

Over cycling a battery pack can be much more damaging that not cycling them at all. Too many heating cycles. A couple of times a year should be adaquate. Get a good battery charger/cycler that includes with it some way to monitor the charge/discharge times. This will give you a fair idea of the condition of your batteries as they age if you note the readings and compare them later.

I use nicads almost exclusively, and I never discharge them. If my batteries have ever developed a "memory", they seem to "remember" to keep working.

I'm with Minn. I've been flying electric as well for 3+ years and never had a problem and I don't discharge my packs. To each his own though. Hope not to get this thread flaming.

The "memory" issue with NiCds had to do with the early cells. That problem was resolved years ago, so I wouldn't worry about it.

I cycle mine about 3 times over the winter, but never during the flying season when I'm using them regularly.
Dennis-

If I'm not mistaken, what people originally took for "memory" problems wasn't memory at all, it was pack failure due to overcharging. They would discharge their battery part-way, but then use a non-peak-detect-charger to charge it back up, over charging it. Do this 2 or 3 times, and voila, your battery doesn't hold much juice. Since you could avoid the problem by discharging all the way, at first glance it looked similar to the actual "memory" issues, which do exist in industrial settings, where a battery might be discharged to _exactly_ the same point many many times. Our usage has enough variability in the discharge level to avoid memory problems.

I suspect it was the chargers that got better several years back, not the batteries.

-Rick

P.S. Please feel free to correct me, since if I'm wrong I'd rather know it than not!

I cycle my battery packs, (both Nicad and NiMH), at the start of the season just to see that they charge all the way up to rated capacity. As the cells wear out, the battery will not reach full capacity, causing me to go and get (or make) another pack.

Jesse

I feel it is very important to cycle your batteries at least every other month or so, I have found this is the best way to find out if you have a cell going bad. If a 600 ma flight pack is only giving you 350 ma after cycling it a few times, it is time to get a new pack. I read a few years back that 8 out of 10 crashes are battery related, that was good enough for me to not take them for granted, they do fail eventually.

Me to.
I have to say it surprises me when I hear people say that you must discharge packs before charging them. I have never done this and have never had a problem. At most I might cycle the TX once every month or so.
But this is one topic where every one has an opion.

Hello, I have been in this hobby for 3 years. When I started flying, my questions were much like yours is now. Since then, the electronics part of the hobby can still stump me at times. (I have several questions now in the batteries forum) Anyway........ I am finding from my experience and procedures, that there are a LOT of variances that can be appied to NiCads and they will still perform very good. EXAMPLE: The first year I discharged my trainer rx battery to 4.4 volts using my loaded voltmeter. I did this 95% of the times I charged it !!!! Now I know that is not necessary. BUT.... this pack is 3 years old now and is the strongest of my 600 mAh packs!!!!
Try this link....... this guy knows his stuff. I built a "custom version" of his loaded digital voltmeter. I mainly use it in my shop as a way to discharge my batteries with a simulated load. ( I installed more than one socket, bought at Radio Shack, to combine bulbs for various mAh drain). I use a timer to "REMIND ME" to watch the pack that it doesn't go below 4 or 4.4 volts. That part is a PIA, but it didn't cost but a few dollars to build.

[link]http://rcbatteryclinic.com/[/link]

I have discharged and charged, just charged what I "took out", etc. (meaning here... if I took a plane out and only flew it 2 times, I may put it on the charger for 4 hours or so when going out next time). A lot of guys will say this is wrong. A lot of the opinions I hear are direct opposites!!! I may not have done things correctly....... but I can fly 4 or 5, 10 minute flights SAFELY, on my 600mAh packs. I have NEVER had a battery failure in the 3 years, and NEVER had to quit flying after a 3rd flight because of a low battery. All this, and I have basically done things "wrong", according to many experts. I feel most of these guys are very educated and ARE CORRECT in their advice. BUT I feel the NiCad batteries today...... are very forgiving and they will tolerate a lot of abuse from guys like me who may make mistakes.
Just try to use common sense in getting advice, (including mine), Good luck.....lownslo....

From post #10

It's pretty hard to get stats on this but if I had to guess I would agree that battery and/or switch failure is probably the #2 cause on the list. Pilot error would be #1.

I have never done it and last set I got 8 years out of!

I've been using NiCads for the last 46 years and have NEVER been able to make one get a memory. That is an old tale that has been around since some of the early satalites where they erouneously attributed their problems to memory which could never be duplicated in the laboratory no matter how hard they tried. NiCads do have a limited life although it is twice as good an NiMh has. There is a gradual degredation with age and with number of cycles of use so it does pay to cycle them once or twice a year just to see if you are nearing the end of their life cycle. This is more important if you do a lot of fast charging (greater than .1c) as fast charging does degrade them faster than the .1C charge rate does.

I have used NiCd batts in planes, boats, and cars. Never have I had any memory problems. Saying you can only use them 2 or 3 times is a lie [sm=thumbdown.gif]where is your source. It is a good idea to do it ONCE every couple of months but not every time. If you discharge the thing and then charge them back up immediatly the batt gets wicked hot and that is the most damaging thing you can do. Just buy a NiMH or Li Poly if you can afford it.

I also don't believe that 2 of every 10 crashes are battery related. Make sure you are the only one on your freq and do range checks before your flight and you shouldn't have any problems.