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NiMH vs NiCD - 5/7/2005 3:11:38 PM   
johnnychimpo



Posts: 386
Joined: 3/17/2005
From: ft rucker, AL, USA
Status: offline 		Now im being told that NiMH is not as reliable as NiCD batteries under alot of vibration. Can anyone attest to this? I have lost 2 vipers in the past 2 months and oddly i use the same battery pack on both and it was a 650mah hobico NiMH. The last crash of the viper was done after one successful test flight around the course, then on flight 2 i started it up, checked the wiggle and throtle, then up and away with no control. It flew like the battery was unpluged strait into a torque roll to inverted dive into the ground.

I am just trying to figure out is this battery pack was the culprit. Im sure its quite possible. Reguardless it will never be used in a racer any more.

Are NiMH more sensitive than good ole' NiCD's?

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Scott
NMPRA# 26Q
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RE: NiMH vs NiCD - 5/7/2005 3:48:35 PM   
Bill Vargas



Posts: 1554
Joined: 1/6/2002
From: Team Coldies, CA, USA
Status: offline 		Hi Scott, how old was the battery on the first plane?

BV

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If it ain't leaking oil, then something's wrong,,, USMC, RETIRED!

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RE: NiMH vs NiCD - 5/7/2005 4:06:20 PM   
johnnychimpo



Posts: 386
Joined: 3/17/2005
From: ft rucker, AL, USA
Status: offline 		Bran spanken new. I have had them for only 3 months and a total of about 15 flights. Not consecutive of course.

BTW Bill, won 2 of your Racer II kits in the NEPRO raffel with a TT Pro .40

Looking fwd to building and flying them.

< Message edited by scott roney -- 5/7/2005 4:07:34 PM >

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Scott
NMPRA# 26Q

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RE: NiMH vs NiCD - 5/7/2005 4:50:07 PM   
Bill Vargas



Posts: 1554
Joined: 1/6/2002
From: Team Coldies, CA, USA
Status: offline 		Cool on the kits and I hope you do well with them!

Ok so let me see if I got this right,,, new battery, plane crash and you used the same battery in a new plane? Take the battery plastic covering off and you'll probably see the culprit,,, a broken tab. Also while your at it,,, check the battery switch also, it doesn t take much to upset those also. I used to use Airtronic switches and had a string of bad luck with them. The vibration would shake them apart,,, went to JR switches and this problem went away.

Let us know what you find.


BV





_____________________________

If it ain't leaking oil, then something's wrong,,, USMC, RETIRED!

(in reply to johnnychimpo)
       Post #: 4

RE: NiMH vs NiCD - 5/7/2005 6:10:41 PM   
johnnychimpo



Posts: 386
Joined: 3/17/2005
From: ft rucker, AL, USA
Status: offline 		I know old battery, new plane issue but the battery worked fine, or apeared to, for almost 20 or so flights back home until the friday before the race. So it has been proven air worthy quite a few times. This recent crash was not on a first flight.

Battery connections are all good, no tabs broken or anything. But i do detect a strange almost sweet odor coming from the battery. It maybe because of it being fuel soaked from the wreckage. This battery is going to be trashed i think. I have peeked it and cycled it almost 4 times and no noticable problems with the battery or life compared to other tests done prior to the crash.


The old switch which was in the first wreck broke on last crash so its not available for inspection. What is the best switch out there then? Can i use the JR switches for futaba gear? Guys i raced with n lucasville said the futaba switches are crap and cheap. I cant seem to find the heavy duty futaba swiches everyone was using.

< Message edited by scott roney -- 5/7/2005 6:12:59 PM >

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Scott
NMPRA# 26Q

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RE: NiMH vs NiCD - 5/7/2005 6:47:05 PM   
garys


 

Posts: 755
Joined: 1/31/2002
From: San Diego, CA, USA
Status: offline 		I've been using the standard Futaba switches for the past 11 years with no issues. One thing I've always done, even before I flew Futaba, was to throw any crashed switches in the trash right away (well, not always, but after I had a crashed switch fail). I've also been using NiMH battery packs for the last couple years without issues. The ones I've been using are the 370ma and 500ma packs from www.flyfastcomposites.com.

Gary Schmidt
Team Futaba

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GS

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RE: NiMH vs NiCD - 5/7/2005 8:58:13 PM   
johnnychimpo



Posts: 386
Joined: 3/17/2005
From: ft rucker, AL, USA
Status: offline 		Well, i guess i made a good purchase a few days ago because thats where i ordered more batteries from. I got the 2 of the 370's and 2 500's to check out.

Thanks for the info, i got another futaba switch.

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Scott
NMPRA# 26Q

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RE: NiMH vs NiCD - 5/7/2005 10:20:49 PM   
HighPlains


 

Posts: 2663
Joined: 3/2/2003
From: Over da rainbow, KS, USA
Status: offline 		All the switches today are crap, some much more so than others. Years ago you could buy switch harnesses made with the Noble switch and it was very reliable with multiple redundant contacts and a positive detent.

As to the pack, what kind of instillation did you have? Vibration is very hard on any pack, as to the amount of charge inside, the insulation between the + and - sections of the battery is very thin so you can wear through it with excess vibration.

A side note on batteries – I have old Corvette with the extra firm racing suspension. I used to buy the best high capacity battery I could for it – just about every year. Then it would die and I would have to go get another. Finally one year I decided just to buy the cheapest battery with less cranking amps, and it lasted about three years. The next one did as well. Why? Because with fewer plates and less capacity, it has more room in the box for more insulation thickness and thicker plates. It held up much better since it was physically more robust.

< Message edited by HighPlains -- 5/8/2005 3:33:46 AM >

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RE: NiMH vs NiCD - 5/8/2005 2:03:31 AM   
daven



Posts: 6895
Joined: 12/7/2001
From: Andover, MN, USA
Status: online 		I have not had great luck with the standard switches out there, and I toss them after every crash. I really like the JR Deluxe gold switch, but the heavy duty futaba is being used by a lot of competitors with good success.

Never reuse a switch, just toss them.

As too batteries, I'm using mostly NIMHS now, I like the 500 mah from www.flyfastcomposites.com (same as Gary). I just don't quite trust the smaller 370 and 300 mah packs. If you decide to use them, just keep a good eye on them with an expanded scale voltmeter. Lots of people using them, just watch them closely.

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Dave Norman

klasskote.com
supertrc.com

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RE: NiMH vs NiCD - 5/8/2005 1:26:11 PM   
johnnychimpo



Posts: 386
Joined: 3/17/2005
From: ft rucker, AL, USA
Status: offline 		I use to use 250 NiCD batteries for racing 10 yrs ago with no problems after 10 flights. And those were with standard servos. Now im using the mini sevos hs-85 and 225s now. I dont think 370 would be an issue at all as long as you checked them. I never had the ability to check my batteries back then though with the 250mah NiCDs.

< Message edited by scott roney -- 5/8/2005 1:41:46 PM >

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Scott
NMPRA# 26Q

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RE: NiMH vs NiCD - 5/8/2005 2:34:31 PM   
daven



Posts: 6895
Joined: 12/7/2001
From: Andover, MN, USA
Status: online 		I agree about running 270 mah nicd packs with analog servos, we all used them for years, but I'm using quite a few digi's and they tend to draw a little more juice.

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Dave Norman

klasskote.com
supertrc.com

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RE: NiMH vs NiCD - 5/9/2005 5:56:12 PM   
DHG


 

Posts: 896
Joined: 4/24/2002
From: Arvada, CO, USA
Status: offline 		Here's a tip about NiMH batteries ... I got two of the 370s from Fly Fast Composites and with the first one I simply charged it at the 1-hour rate, with a charger that said "Charges NiMHs at 1-hour rate". (The issue here is that NiMH batteries have much less of a voltage peak when they're topped off, so the charger has to be more sensitive than most NiCD chargers.) Well, it didn't test as high as it should've, so I cycled it a couple of times and it never got there. So I went on the Web and did a little research. It turns out that NiMHs want to be charged at least once the "old way" -- steady, overnight, at a constant rate of 1/10 the rated capacity (C/10). Apparently this conditions them somehow. I did that with the second one and sure enough, it tested as rated.

Re HighPlains' comment on his Corvette battery, the little NiMHs work a similar way: They not only weigh less, but they're so small that you can use more padding around them to protect them from vibration. I'm using 2 layers of bubble-wrap, secured with clear package tape to make sort of a balloon with electricity inside. It's only a little bit smaller than the 320 mAh NiCD it replaced, but weighs half as much ... plus, it bounces!

Duane Gall
RCPRO

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RE: NiMH vs NiCD - 5/9/2005 6:56:44 PM   
RANIERY


 

Posts: 133
Joined: 6/9/2003
From: davie, FL, USA
Status: offline 		I'M USING 2/3 OF AAA BATTERIES 300 MILLIAMPS 1.5 OZ AND 6 VOLT AND I CAN HAVE 5 FLIGHTS WITHOUT ANY PROBLEMS BUT ALLWAYS CHECK THEM AT LUNCH BRAKE

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RE: NiMH vs NiCD - 5/11/2005 2:57:04 PM   
DMyer


 

Posts: 487
Joined: 10/16/2002
From: Potomac, MD, USA
Status: offline 		Battery fads come and go but the good ol NICAD just keeps rolling.... I still primarily use the 350MA nicads... tough as nails and you know you can count on them. I tried some of those little 300MA NIMH... but I just couldn't develop the level of trust I have always enjoyed with the NICAD. Since the 2/3 AAA's are up to 350MA these days... that is generally plenty for a days racing. If there are no weight issues... I see no reason to go with anything else IMHO.

< Message edited by DMyer -- 5/11/2005 2:59:30 PM >

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RE: NiMH vs NiCD - 5/11/2005 5:39:24 PM   
Ed Smith


 

Posts: 2834
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline
In regard to the use of Nicads.

quote:

I see no reason to go with anything else IMHO.


In a few years time we will have to "Go with something elser" Nicad batteries will be non existant. The manufacturing process creates toxic waste which will very soon be unacceptable.

Ed S

(in reply to DMyer)