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Model Forum / Radio Controlled / Land Models / October 2004Charging batteries
OK, my newbie saga continues.... Last night I bought a 'Dynamite Prophet Plus LCD' charger and two cheap-ish ($25) 3000mAh NiMH batteries. I started charging the first battery at about 3.5 amps, then went to work on my car (I killed the steering servo gears on my first run). When the charger beeped to indicate it was done, the battery pack was *blazing* hot. The mAh meter reading was too high, the battery was overcharged. Damn! I thought perhaps I had charged it too fast, so I charged the next battery at around 2.8 amps. True to my nature, I forget about it until it beeped, at which point the mAh meter read 3600 mAh! 600 mAh over the capacity of the battery, and the battery was almost too hot to touch. The whole reason I traded in my timer charger for a peak charger is that I'm absent minded, I just want to fire-and-forget not babysit. This charger claims it's "advanced peak prediction circuitry calculates when the peak will occur and stops fast charging at exactly that point". Not. Is this normal? >OK, my newbie saga continues.... > [quoted text clipped - 16 lines] > >Is this normal? I've heard and read that brand-new batteries are unreliable for their first half-dozen charges.... --- Losi XXX KE <the racer> Losi XX "CR" <the basher> Associated RC10GT <the other basher> http://ripperd.com email: dean (at) the above domain > >OK, my newbie saga continues.... > > [quoted text clipped - 19 lines] > I've heard and read that brand-new batteries are unreliable for their first > half-dozen charges.... This last part I'll agree with, as I had a similar problem, only with an old set. Worked OK for the first charge taken from mains, on a slow charge, but got increasingly poor results, after each fast charge. Turned out I was charging too often, and not allowing the poor this to cool down. Elastictrickery, is not so much as a science, but a black magic art, or so I was once told ;-) Vaughn > Is this normal? Blazing hot means what? My packs get about 135 degrees. 135 is really hot to the touch. First few times of using a new NIMH battery it's not real stable. It needs about 5 charge/discharge cycles to work properly. > My packs get about 135 degrees. 135 is really hot to the > touch. Well, I didn't measure it. You could hold it in your hand, but it wasn't comfortable, like the steering wheel of a car that's been sitting in the sun with the windows rolled up on a hot day. I just charged it again, this time it stopped at 3010 mAh and the pack is merely warm to the touch. Last night it just felt ridiculously hot. None of my packs have been that warm, ever. > First few times of using a new NIMH battery it's not real stable. It > needs about 5 charge/discharge cycles to work properly. Seem to be already doing better on the second cycle, but I'll be watching it closely from now on. ;) Cheers, Eric > Seem to be already doing better on the second cycle, but I'll be > watching it closely from now on. ;) Personally when in the house I charge my packs directly on the stove top. In case anything were to happen that's the best place. I've had about three different packs explode in about 2 years of charging. Good sizzling, lot's of smoke. 3 packs in 2years, you better check your charger ! in 15yrs this only happend me twice starting from 1200mha til 3300Mah My NiMh get very hot when i use my LRP quadra charger and from this summer i use a Robbe ultimate Li much more like it (digital display). very simular to an simprop in intellicontrol TM PS to Eric I dont like the RC3000 cells > > Seem to be already doing better on the second cycle, but I'll be > > watching it closely from now on. ;) [quoted text clipped - 4 lines] > I've had about three different packs explode in about 2 years of > charging. Good sizzling, lot's of smoke. > 3 packs in 2years, you better check your charger ! It all happened to packs I've bought used off of ebay. Never any of my new 3300's I built myself. Hah! So much for ease of use. Packs exploding, smoke and such overcharge undercharge Have to cycle the pack 5 times before works properly. Guess you guys left this out in the other thread. Yet degraded nitro because you have to break-in the engine. Seems your doing the same thing with your packs, breaking them in by cycling them 5 times, worry if they get corectly charged. > Hah! So much for ease of use. Packs exploding, smoke and such overcharge > undercharge Have to cycle the pack 5 times before works properly. Guess you > guys left this out in the other thread. Yet degraded nitro because you have > to break-in the engine. Seems your doing the same thing with your packs, > breaking them in by cycling them 5 times, worry if they get corectly charged. I read the other thread and didn't see anyone 'degrading' nitro. You must be a bit sensitive over this topic, huh? ^_^ Really, it's apples and oranges. Nitro is undeniably cool, ballsy, visceral, lots of power and noise and smoke. But it's also messy and high maintenance. I can whip the electric out and be driving in 20 seconds -- run it around the living room, out the front door, do a couple donuts on the lawn, run it back in the house and put it right back in my closet -- all at 3:00AM. It doesn't get any more convenient. As for the battery woes, I think you overstate them. A "cycle" is an ordinary charge-and-run cycle, not special treatment. It's spent bashing, having fun. "Working properly" means fire-and-forget charging with a peak charger. Not "working properly" means old-school charging using a timer. No biggy. Peak chargers are a luxury not a necessity; my brother did this for years and never owned one. As for melting batteries, my brother never did. I suspect it's rare. Twice in 15 years for dingo. You raced electric for 15 years, but act as if this information is a revelation to you -- so it must have never happened to you at all. I was just concerned that my fancy new charger was not working correctly, but after one cycle with a new battery it's cutting-off at the right place. All and all, this has been a totally no-fuss hobby. For the moment, it's all about driving for me. I like setting up little tracks and trying to improve my times. The source of locomotion is secondary. <snip> /I can whip the electric out and be driving in 20 seconds -- run it around the living room, out the front door, do a couple donuts on the lawn, run it back in the house and put it right back in my closet -- *all at 3:00AM.*/ </snip> AHAhahahaaa... GUILTY AS CHARGED... what else ya gonna do when the bars close and you're not allowed to bring home a toothless bar chick from the local watering hole? (Not that I would, honey, I'm just saying. *wink*) Hell, the wife's asleep and nothing on tv except informercials. >> Seem to be already doing better on the second cycle, but I'll be >> watching it closely from now on. ;) > > Personally when in the house I charge my packs directly on the stove > top. In case anything were to happen that's the best place. And the metal top will wick away heat, also.  SignatureL.V.X., brother mouse http://cbsrmt.mousetrap.net/RMTdb/ CBS Radio Mystery Theater database http://greyhound.mousetrap.net/altus/ retired racing greyhound http://www.mousetrap.net/~mouse/cs.html How to get good phone support >> Seem to be already doing better on the second cycle, but I'll be >> watching it closely from now on. ;) [quoted text clipped - 4 lines] > I've had about three different packs explode in about 2 years of > charging. Good sizzling, lot's of smoke. Maybe you should remember to turn off the stove? SignatureQUIPd 1.02: (462 of 622) -> As Robert Heinlen wrote in Tunnel in the Sky, the best survival -> weapon is your brain, provided it's loaded. My photo albums: http://www.pbase.com/sny > Seem to be already doing better on the second cycle, but I'll be > watching it closely from now on. ;) I usually charge a new NiMH about halfway the first time, let it rest for a bit, and then top off. This has helped my chargers find the peak more consistently. I think it has something to do with the very low voltages of batts that have sat on a shelf for months... SignatureL.V.X., brother mouse http://cbsrmt.mousetrap.net/RMTdb/ CBS Radio Mystery Theater database http://greyhound.mousetrap.net/altus/ retired racing greyhound http://www.mousetrap.net/~mouse/cs.html How to get good phone support I will check on the NiMH batteries during the charging. If they become overly hot, simply unplug them and let them cool for 30 min.-hour then plug them back up and let them finish. Heat is a NiMHs worst enemy. > OK, my newbie saga continues.... > [quoted text clipped - 16 lines] > > Is this normal? > Heat is a NiMHs worst enemy. Not necessarily so. there's new evidence 3300's should be hot (130 degrees) before running them in racing conditons. Read on: http://www.hobbytalk.com/bbs1/showthread.php?p=741810 Generally so, Yes. I've never seen a pack go bad yet because it was kept at a cool to warm temperature. The point was that overheating them is going to mess them up. Every NiMH pack I have seen around here that was ruined, was because of heat..(overcharged or insufficient cool down time between charges and use). Everything that I have ever read about NiMH explains this as well.. i.e. "Charger MUST be able to adjust the negative deltaV peak charge rate." "Heat or overcharging will damage NiMH cells." "NiMH chemistry for no cell memory" "Dead Shorting: Not Recommended, it will damage the batteries." "Ni-MH cells have no discharge memory so there is no need to deep discharge them by shorting out the cells. This will hurt the cells." "Do not use standard NiCd charger, it could damage the cells." "Charge battery pack only with a charger specifically designed to charge NiMH type cells." > > Heat is a NiMHs worst enemy. > > Not necessarily so. there's new evidence 3300's should be hot (130 > degrees) before running them in racing conditons. Read on: > > http://www.hobbytalk.com/bbs1/showthread.php?p=741810 > Everything that I have ever read about NiMH explains this as well.. Check out the link I posted, read it, tell me what you think. I did read it. It is one persons statement about someone elses issue. The example he gives says he wasn't even at the event to witness it. It is interesting, yet all "hearsay" to me. This person also says he deadshorts his NiMH cells. I'm not sure what effect that any of this has on the performance of a NiMH battery but,from what I have read and still read about proper care of your NiMH cells, excessive heat and dead shorting is a big no-no,..and with no cell memory,discharging is not necessary. For a professional expert racing level where tolerances and perfect matches and so forth are scrutinized and monitored with expensive high tech equipment, I would say there are some exceptions to the care and treatment of the cells. What I am saying is for all general common day purposes where the battery is fully used, as the average back yard basher, average sponsorless racer, average RC user that the large majority of users are,should be careful to let them cool down between charge/use use/charge cycles,and not overheat,deadshort,overcharge your NiMH cells, or more than likely they will be buying some new ones. And even in worse senarios they will melt your RC,explode,catch on fire,catch something else on fire, damage your stovetop...=) "Follow the manufacturers directions" > > Everything that I have ever read about NiMH explains this as well.. > > Check out the link I posted, read it, tell me what you think. > "Follow the manufacturers directions" Here's the manufacturer's directions in two PDF files: http://www.ftupet.com/~kenji/gp3300info/ If you really mean distributor's directions, Not Gold Peak's directions...then we are back to square one because you can take 10 distributors and have 4 differing opinions on what's best for te cells in RC usage. In general again, even your GP Cells manual has the basics stated.. "Using or storing the battery beyond the recommended temperature range leads to deterioration in performance. For example:leakage,shortening of battery life,and lowering of charging efficiency may occur at higher temperatures." It also states on over-discharging/overcharging, shorting, incorrect charging. All of which my point was. Granted the GP "high heat" cells may tolerate heat better than your everyday NiMH cell, but the point remains the same...excessive heat ,inproper handling as applied to charging,discharging, shorting will damage the cells. > > "Follow the manufacturers directions" > [quoted text clipped - 6 lines] > distributors and have 4 differing opinions on what's best for te cells > in RC usage. > .excessive heat ,inproper handling as applied to charging,discharging, > shorting will damage the cells. Every A Main racer I know, and many of the distributors are saying to not use the GP info, but to do just the opposite, and do what many of the distributors. I think upper end racers don't care if a battery lasts a long time, meaning over 3-6 months. Where as a basher/regular racer would want his batts to last a year or longer. > I think upper end racers don't care if a battery lasts a long time, > meaning over 3-6 months. Where as a basher/regular racer would want his > batts to last a year or longer. Bingo. These are the same guys that go thru several pairs of tires in a weekend of racing, caring only about the best traction. Where a basher like myself is concerned with longevity as well. |
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