old AA nihms
 

I have some older AA nihms(2000 and 2300 mah) I found in the garage. They have been probably out of use for a good 3-4 years, maybe more. I am using them in my radios and I am finding 1 cell always seem to drain strait to zero with in a few minutes. So I'll take it out and place another fresh cell in and the same thing happens and keeps happening. Is there anything I can do to make these usable again?

--pakk

Get a holder from radio shack for 4 cells or two cells and charge them really slow, like 0.1 amp, then discharge them at the same. You might have to do this a couple of times. Then hit them at an amp for one charge, and discharge at 0.1 amp. Then charge them up and see what happens. You might get them to be usable again. Basically all you are trying to do is give them a good deep cycle.

ok sounds like a plan. I have a TP601c which is capable of 14 nihm cells. Would it be a bad idea to hook up 14 of them to try to get this process to go by a little faster?

--pakk

Yeah that's what I have to do with my old enegizer 2500's. with 8cells it was showing 1.3v, they are SLOWLY getting better and better. Each time they hold a higher/better charge than the last. I charge at .1amp and then use them in my radio, then charge them again at .1amp.

It's a VERY LONG process, but to me it's worth it. I guess in theory 2500mah would take 25 hours to charge at .1amp, and my Team Check Point charger has an automatic shut off if it runs too long... like 12hours or something. I'm sticking with it though.

J

Thats theoretically possible, but its not practical. When I've done that, there are cells that just don't seem to get a good charge. I'd stick to a 4 or 8 cell holder and do either 4 or 8 at once. Make sure you rotate their position in the holder from charge to charge also.

If time is an issue, buy new ones, saving these is going to take time after leaving them sit for 3-4 yrs, and you may not be successful with all of them anyway.

Like Duster said it takes a lot of time... but I kind of get my kicks taking something that's all messed up, and bringing it back to life. So to me it's worth it

Jay

Hmm...I got a bunch of these as well, that just don't seem to hold a charge anymore. I was thinking of cooking them at 3A, but a lower amperage is the trick?

Yeah if you run them at a high rate, they are just going to false peak. Slow and stead is the key! Oh yeah and time, and a ton of cycles.

Jay

I'll give that a try then. Right now I have a ton of generic alkaline batteries, and all my radios are the newer Spektrum 2.4Ghz RTR's and a DX3S, so only use 4 batteries each. The DX3S manual states I should see about 16 or so hours out of a fresh set, so I think the current draw from these newer radio systems is far less than the older setups......

Yeah the new DSM style radios dont need to put out a brute force style signal, they pick a crystal clear 2.4ghz feq, lock it out from other people and next thing you know your racing!

Jay

So maybe those cheap AA wall chargers from Wal-mart for 5$ are not such a bad idea then? :lol:

Nope I guess not. But I still like using my team checkpoint 1030 so I can monitor voltage and mah.

Jay

I am still in the process of doing this(right now the cells are charging at .1amp). My charger can also discharge and charge at .05 amp, would that be better? And once these cells are in good shape, I was just curious to what the highest amp I can charge them at was.

--pakk

Charge it at .1amp, .05amps would take FOREVER! Don't forget they have to be cycled. So you my have to do a full charge-full discharge cycle anywhere from 5-10 different times. Some times though there's no bringing a dead battery back. Good luck

Jay

Camera guys have done a lot of work with AAs and they say max charge rate for AAs is 1amp.

I have a $100 AA/AAA charger, Maha MH-C9000 WizardOne. In the skimpy instructions they outline a recovery plan for batts that have been unused for 3months or longer thats similar but diff than whats been talked about here. They have it as a canned charge routine in the charger - 0.1C charge for 16hrs followed by a 1hr rest.This is followed by a 0.2C discharge, another 1hr rest and finally another 16hr 0.1C charge. Takes 39 to 45hrs to complete.

Their advice is to do this 1 to 3 times but only if capacity increases mor ethan 10% between steps. Their adive for AAS that don't increase - discard.

ok, I am now pushing 29hours @ .1amp. My charger claims it's putting on average 100mah an hour, putting me close to 2900 mahs. Is this right?

--pakk

29hours x 100ma = 2900mah, so yes, thats right.

but what doesn't make sense to me is that these are 2000mah batteries. So aren't I well over the mah they are suppose to hold? Or is it 2000x8=16000 mah which is going to be a long long time...

--pakk

Mine are 2500mah's and one day I out a collective 3700MAH into them! I think as long as they aren't getting hot you should be OK. You could always stop the charge and let them rest for a few hours then start again. Remember you said that your cells we're sitting for 2-3 years right? I'm sure they were WAY bellow their nominal capacity, so not only are you charging them...you've got to bring them back to life too.

These are just my opinions on this topic, I could be wrong, but I think your OK

Jay

So should I just leave them on there till the charger thinks they are good? Normally my charger starts getting really low on amps then will beap letting me know they are done. Am I waiting for that with these cells? I am now 30hours+.

Sorry if I have a lot of dumb questions.

--pakk

I might try to do a few single cell charging to see when the numbers are at, as I have a few chargers. Then I can put the best 4 cells together for my Tx.

As long as you setup your charger properly I.E. how many cells, and charge rate it should "Delta Peak" on it's own. Like I said if your really worried about it stop the charge for a hour or so. What voltage are you at right now? and on how many cells?

Right now I'm charging my 8cell and my voltage is....about 11.7v right now... that's while charging. Once I stop it will fall, probably to the high 10 volt range.

Jay

8 cells at 11.4 atm. It just seems like 30+ hours @ .1 is too long. Ill leave it on there and see what happens.

--pakk

If I had a radio (other than my DX6) that still took a 8 cell holder, I would just put a 2500Mah 11.1v LiPo in it, and charge it once a month. :lol:

TrueRC 2500mAh 11.1V 3S1P pack TX pack = 30$ + ship
(just search for DX6 to find it....one long page)

http://home.comcast.net/~truerc/read...eady_packs.htm


I am going to order the above for my DX6, I just have not bothered yet as it's not really warm enough out for flying....I just keep putting it off.

My Spektrum car radios all use 4 AA's, so can't use a LiPo really.

The problem that I'VE SEEN with AA cells is that if you charge higher than .1 or .2 amps they tend to false peak. Like I said earlier in this post, bringing back old cells takes a LOT of time and patience.

I think your at the point where you can stop your charge, wait a couple of hours and start a discharge cycle at about .2 amps (this is going to take a long time too) After that you've got to charge at .1A again, then they should be ready for use

Jay

yeah I wanted to go to a Lipo in my DX6i too, but I just throw my radio in the wall charger the night before I go flying. It lasts me more than all day. I fly a ParkZone T28 Trojan modded with flaps... I love it!

J

Enigizer makes a nice little 4 AA charger that charges in 15 minutes. I got my wife one for her digital camera. I think it says that it charges them at 2.5A, but they are 2500Mah batteries....so that logic does not make too much sense.

It even has a little fan that kicks on to cool the batteries, as they come off too hot to hold almost. But you think being a manufacturer they know what they are doing?

This is it.....works great so far.....wonder how the battery life is going to be.....

http://www.amazon.com/Energizer-Rech...YYVNS1KFBHRVMH

Yup, I've got one of those too. It works OK, but I still like being in control.

J

I might get a 2nd one for myself, to have a additional charger for the track for AA's.....I have a stockpile of Alkaline AA's currently, and the new Losi\Spektrum seem to last a really really long time on a set. The DX3S manual claims up to 16 hours of use.

Oh yeah I believe it about the DX3S lasting 16hours! Those new Spektrum systems sip batteries. M11 on the other hand is like a college frat guy, drinking all it can till it's out cold! :cry: I'll go Lipo eventually

J

MY DX6 used to drain pretty fast as well....there are a couple mods to double the life of the batteries, and a LiPo won't hurt either....

Are you talking about a mod for the M11, or the DX6? My DX6i lasts me for a REALLY long time! I could probably fly for a week 2-3 hours at a time without needing to charge it.

Jay

The DX6...it uses a 600Mah Nicad, which is 8 cells. i believe the DX6i is the successor of this radio, which only uses 4 AA's....

People have successfully modified the DX6 for longer run time with a part swapout of the Voltage regulator (DE-SW033 voltage regulator)...I assume spektrum (horizon hobbies) have since included this newer\better\faster\stronger regulator in the current line of electronics, among other changes....


http://www.dimensionengineering.com/...ektrum_mod.htm

Yeah my DX6i only uses 4 AA's and it's DSM2

J

Yeah, I had mine since it came out, I think....about 3 years or so....I just fly 3D foamies in my front yard now and then, but I catch people flying gas planes now and then around my subdivision (lots of farms), so I did not want to cause, or get any frequency conflicts....

Yeah I know what your talking about here in Germany the USA RC freqs are the German emergency freqs... not a lot of fun when an ambulance goes by LOL

J

They are alive!
 

or at least they finally peaked. So here is just a recap of what I did.

First discharged at .1a. This happened fast, less than an hour if I remember right.
Then charged at .1a. This lasted ~30 hours and never peaked. I gave up waiting for it to peak.
Discharged at .2a. This took about 4 hours.
Charged at .1 amp. After 24hours, they finally peaked.

Now the real test would be to see how long they last. Is just leaving my radio on a good enough test, or do I actually have to use the radio? Right now my radio is on and sitting at 10.6v. How long "should" 2000mah AA last in an xs3?

Thanks for all the help.

--pakk

I'm not sure how long the Xs3 should last, but 10.6V is a good voltage. It doesn't matter if your using your radio or just leaving it on. Either way it's pretty much doing the same thing, putting out a signal. I would say that it's safe to use now, just like you would normally. When the batteries die just charge em' back up at .1amps and away you go!

Jay

well they just went under 9 volts. So they lasted about 7 hours. I tried looking around, but can't seem to find how long others are lasting with their Xs3. Probably going to be hard to find seeing that it is an older radio. I am continue to keep cycling these until I see diminished returns then just start charging then up like normal.

Thanks for all the help.