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Why are we using NiMh...really?

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Old 07-08-2012, 11:45 AM
  #26
llindsey1965
 
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Default RE: Why are we using NiMh...really?

right burn down your shop or house just what we want unstable lipos NEVER and you need regulators something else to go bad
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Old 07-08-2012, 11:49 AM
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Default RE: Why are we using NiMh...really?

thats right you can burn up your plane LMFO
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Old 07-08-2012, 11:51 AM
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Default RE: Why are we using NiMh...really?

true i left my tx on for 2 days and didnt catch it had nimh batteries 2100 mah , slow charged cycled they are like new if they had been lipo i would have been toast
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Old 07-08-2012, 12:03 PM
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Default RE: Why are we using NiMh...really?

Hi dabigboy
So right about NICADS being better than NIMH batteries
I started flying in 1989
NICADS handle vibration better than NIMH I would like to ad to the list of things they do better
Flying nicads for 22 years
The ONLY battery technology there was in 1989 and i never had it fail me
Only had 2-3 NIMH packs but did identify there poorer quality early on my battery test equipment
Charge NICADS slow and do not use peak or fast chargers on them to have them perform for a maximum long life
Keep them fully charged to prevent them from developing shorts-I charge every two months if they are idleand cycle when taking a plane that has been idlebefore it goes to be flown
I use an ACE DIGIPACE ( model one or two ) to cycle the batteries
Always cycle batteries 2-3 times when a new packtake a MA readingwhen the bats are cycled in the future and fall 20 % below your first established reading the battery is done
I do not go by the disgard the bat after 3 years ruleif it cycles above 20% of my established reading i fly it
I have not lost a plane to battery issues to date using NICAD technology
The enloope technology seems interesting as does the 123 type bats
I will never buy a LIPO and put my family and valuables at risk for any hobby

IF IT AINT BROKE-DON"T FIX IT ! ! !
Regards Tony
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Old 07-08-2012, 12:27 PM
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Default RE: Why are we using NiMh...really?


Quote:
ORIGINAL: TheWoodCrafter

Why does anyone use NiXX type batteries today/

LiPo have so much more power/weight that they makes NiXX obsolete.

When the receivers and servos start running on 7.2v I'll start thinking about it. Until then I'm not buying a $50.00 voltage regulator for every plane.
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Old 07-08-2012, 12:39 PM
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Default RE: Why are we using NiMh...really?

I'm in the process of changing over to A123's. They are much safer to charge than lipos. They can dump their enery much faster and safer than a Nimh or Lipo. You do have to learn a new way to charge and monitor them than the other types but I have a few planes changed over already and can say that I'll never look back. They won't work well for the electric guys due to their size but, if you fly Gas or glow, they are the only way to go IMO. There is a very large thread over at FG concerning the A123's. There may be one here as well but I have not looked.
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Old 07-08-2012, 12:49 PM
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Default RE: Why are we using NiMh...really?

Aren't the lifes and the a123 and fromecos are all the same chem? I have been switching over to the Hobbico lifes for rx and a hk life for my dx7.
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Old 07-08-2012, 01:05 PM
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+1 on LiFe. LiPos are good for a high discharge rate, but need to be taken out of the model to get charged. LiPo fires happen more often then you'd think.
LiFe cells have a low self discharge rate, can be charged in less then 1 hour and provide enough current for your radio. In most cases you will need a voltage regulator, make sure it has a high enough amp rating.
I still use lots of Nimh and it is a hit and miss, some never reach nearly the labeled capacity.

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Old 07-08-2012, 01:06 PM
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Quote:
ORIGINAL: av8tor1977

I hate NIMH batteries and have had tons of troubles with them. I have nicad packs that are 6 years old that still cycle perfectly. I've never had a NIMH pack last a year. Of course mine suffer from high temps in my storage area and sometimes lack of use, but Nicads beat the h e l l out of them.

I've gone back to Nicads in many cases, plus half my fleet is on Lipolys, but my next step will be to outfit everything I own with A123 batts...

AV8TOR
What he said!
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Old 07-08-2012, 01:11 PM
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Default RE: Why are we using NiMh...really?


Quote:
ORIGINAL: Desertlakesflying


Quote:
ORIGINAL: TheWoodCrafter

Why does anyone use NiXX type batteries today/

LiPo have so much more power/weight that they makes NiXX obsolete.

When the receivers and servos start running on 7.2v I'll start thinking about it. Until then I'm not buying a $50.00 voltage regulator for every plane.
I don't know about you airplane boys, but the helicopter guys are using HV RX and servos now.
No regulators needed.
I think all the manufacturers make HV stuff now.


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Old 07-08-2012, 01:11 PM
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Quote:
ORIGINAL: OliverJacob

+1 on LiFe. LiPos are good for a high discharge rate, but need to be taken out of the model to get charged. LiPo fires happen more often then you'd think.
LiFe cells have a low self discharge rate, can be charged in less then 1 hour and provide enough current for your radio. In most cases you will need a voltage regulator, make sure it has a high enough amp rating.
I still use lots of Nimh and it is a hit and miss, some never reach nearly the labeled capacity.

With LiFe chemistry you do not need a voltage regulator for servos and receivers. You will need one for ignitions unless you have one of the newer high voltage ignitions. LiFe voltage quickly drops to 6.6 volts and stays there as soon as they see a load. Been using LiFe for two years and that has been my experience.
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Old 07-08-2012, 02:34 PM
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Default RE: [Awaiting Approval]

A123's have a little better density than life's but both are the same voltage. Also if you have been running 6volt nicads or nimhs you do not need voltage reg. The a123's are 6.6 volts nominal. They will be at 7volts immediately after charging but will drop to 6.6 or 6.8 very rapidly. There is fact page at hangtimes hobbies.
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Old 07-08-2012, 04:59 PM
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Default RE: [Awaiting Approval]

it depends on the radio equipment. A receiver and servos rated for 4.8 Volts better have a regulator in between.
Many people 'never had any problems' until something burns up. If you equipment is rated for a higher voltage, fine. Otherwise drop the voltage.
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Old 07-08-2012, 05:24 PM
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Quote:
ORIGINAL: OliverJacob

it depends on the radio equipment. A receiver and servos rated for 4.8 Volts better have a regulator in between.
Many people 'never had any problems' until something burns up. If you equipment is rated for a higher voltage, fine. Otherwise drop the voltage.
Of course, you can't run the old 4.8V servo on a 2S LiPo.
Most ESC have a BEC in them that will work on the older stuff.
And if you are not running electric, regulators are cheap.


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Old 07-08-2012, 06:40 PM
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exactly - a BEC is nothing but a voltage regulator embedded in a speed controller.
There have been people giving other the 'advice' that it's ok to use these batteries with their standard radios. Do not listen to those.
A regulator is a lot cheaper then replacing a crashed plane with fried electronics.
Even just a diod works fine to drop the voltage if it's rated for the load.
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Old 07-08-2012, 06:55 PM
  #41
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Default RE: Why are we using NiMh...really?

Another advantage to NiCd's is their weight. I fly a lot of scale aircraft where I use very large NiCd packs for nose weight instead of lead. For instance I have a Spitfire with a 3500 Mah NiCd attached to the engine mount. The SR NiCd can handle the vibration and heat. A balance plug is often difficult to access in this type of environment and would be very inconvenient to remove from an engine mount for safe charging if it were a Lipo. A NiMh would not work in a high heat (or cold) environment. They really work best at room tamperature.

Internal impedance is another large advantage of NiCd over NiMh.
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Old 07-08-2012, 07:03 PM
  #42
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Almost everything being sold today is rated for 6v nominal and alot of it is rated for 7.2v nominal. Manufactures know full well what battery systems are being used and rate thier stuff accordingly. Voltage regulators cost money, and put another item in the system that could fail and if not sized correctly will. 6v on current equipment is of no concern. With all the high voltage stuff coming out, 7.2v won't need regulators either.
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Old 07-08-2012, 07:13 PM
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I fly Nicads, tried LiFe, went back to Nicads, cannot see any reason to fly Nimh or LiPo. Many valid points being made, so each to his own.
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Old 07-08-2012, 07:36 PM
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Default RE: Why are we using NiMh...really?

Quote:
Why are we using NiMh...really?
Just because . . .

Because they work very well.  Because I have many and my existing rechargers can handle them easily.  Because my flying style (glow/gas) is well suited to using NiMH receiver & transmitter packs.  Because they are safe to leave unattended and top off for an hour a day so they are always ready to fly.
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Old 07-08-2012, 07:52 PM
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We are using NiMh batteries because they don't burst into flames and burn down our house, our car, our other planes and our garage. The risk of using LiPo is not worth losing everything. I stick to nitro, and gas.

No electric for me!
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Old 07-08-2012, 08:13 PM
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Default RE: Why are we using NiMh...really?


Quote:
ORIGINAL: Airplanes400

We are using NiMh batteries because they don't burst into flames and burn down our house, our car, our other planes and our garage. The risk of using LiPo is not worth losing everything. I stick to nitro, and gas.

No electric for me!


I have heard stories about spontaneous combustion but thought it was mostly legend caused by the charger operator that didn't want to admit he screwed up.
Lots of stories flying around, hard to tell what is true and what isn't
And I'll bet you are dead set against the new energy source called nuclear fusion too.

.
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Old 07-08-2012, 08:31 PM
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Nope.  I'm all for fusion.  The Sun does very well being powered by it.  Grows my vegetables.  Not so easy to duplicate on Earth . . . so far.

I fly with a fellow who lost a garage, almost his house, and about 40 planes from leaving a LiPo charge unattended.  Nothing "urban legend" about it to him.
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Old 07-08-2012, 08:45 PM
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Well there you go.

Operator error again.
One of the first rules with charging a LiPo. NEVER charge unattended.
If you know what you are doing, treat them with respect, don't screw up and you will be fine.

They don't spontaneously burst into flames no matter what you have heard.
There is nothing magic or mysterious about them.
If they get warm or hot during charging you did something wrong.
You set the charger wrong, you dropped one on the floor or you crashed and made the mistake of bringing it the house and are charging it.

Just different technology with new procedures to learn.


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Old 07-08-2012, 08:57 PM
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Default RE: Why are we using NiMh...really?

Quote:
ORIGINAL: dabigboy

I started RC in the early 90's, all my radio equipment was on NiCad batteries. As I gradually updated equipment, the NiCads went away and the NiMhs seeped in. At first I thought ''great, I can move on to the newer batteries!'' But after several years of almost exclusive NiMh use, I don't like them. At all. Compared to NiCads, I see only disadvantages, with NO advantages over NiCad. What I have learned and observed:

1. NiMhs take longer to fully charge....not a lot longer, but longer at any rate.

2. New packs require an incredibly long charge cycle the first time in order to get the best performance out of them.

3. They run down VERY quickly when just sitting.

4. They run down faster in use, even right after a full charge...more frequent charging is required.

Point 3 is really my main area of concern. My time is very limited, my schedule chaotic at times, and the weather in central OK somewhat unpredictable. I may find myself with an hour of two of free time on a sunny evening, but my batteries are too low because I charged them two weeks ago. I can charge a NiCad and pick it up a month later and still see 5+ volts on a 4.8v RX pack under a simulated load.....plenty for a couple of flights. My heli's relatively new NiMh pack was charged less than a month ago and now shows less than 4 volts WITHOUT a load (under a load it's only giving me about 3 volts and gradually dropping...to get the same thing from a NiCad, I would have to leave it on the shelf for months on end).

Overall, NiCads seem far more forgiving and resilient, and more efficient. So why exactly did the industry ditch our trusty NiCads and give us these inferior batteries? Any thoughts? Similar experiences?

Matt

Amen....HATE 'EM! My new radio came with them....oh yeah, did I say: "HATE 'EM". Give me Ni-Cad any day...worked good for 30 years......still working good and the best IMO[>:]

Jeff
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Old 07-08-2012, 10:33 PM
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Default RE: Why are we using NiMh...really?

Because I have been flying profiles, using a Lipo for a flight pack would be out of the question. I can't open tiny wing hatches and dig out a flight pack every time I need to recharge it outside the airplane. So most of my flight packs are Nimh. I too have been discouraged by many of their traits, especially having to recharge at low current settings and the lousy self discharge rates. I have several Nicad packs that are 10 plus years old and still have 80% capacity and hardly any self discharge. I always thought going to a Nimh would be good in 2 ways. Higher capacity and lower weight. It turns out that the weight savings isn't a concern at all, and the self discharge problem reduces the total pack capacity. So, net gain =0. I am moving into the 21st century and have ordered some Life packs to play with. If all is Ok with the Life packs, goodbye Nimh.
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