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NiMH Battery for RX, the achilles heel of your model

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Old 06-09-2014, 03:54 PM
  #26
acerc
 
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Here ya go.
http://pages.suddenlink.net/arlyn/rcvotagedrop.html
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Old 06-09-2014, 04:01 PM
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Ditto on the Nimh batteries. there ok for a small four or five servo plane with little draw non digital servos. I have lost many planes to Nimh and brownouts on spectrum dsm2 and only use a 5 cell if it is Nimh. I will use a 4 cell for ignition systems on gas engines. I only fly Life batteries on anything worth more then 50 bucks. dual batteries on the larger planes. there price is worth the insurance. Blake
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Old 06-09-2014, 04:37 PM
  #28
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I lost two planes in short time with almost brand new hydrimax NIMH packs. I always cycled them and followed the recommendations, but...
I've since switched every plane I own over to 6.6 LIFE packs and never looked back. I can fly all day long and not even put back 1/4 of the capacity. I simply top em off when I get home, and if it's four months till I fly again, I don't have to worry, because they don't really self discharge. I get peace of mind from them.
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Old 06-09-2014, 05:13 PM
  #29
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Wow, I've used Nimh forever, never even thought about another type, and I've never had trouble with them.....
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Old 06-09-2014, 05:22 PM
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Maybe I got a bad batch. I used them for years too before that.
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Old 06-09-2014, 07:22 PM
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Quote:
Originally Posted by stevegauth30 View Post
I lost two planes in short time with almost brand new hydrimax NIMH packs.
No matter what kind of batts you're using you would be better off using dual, parallel packs. http://www.hangtimes.com/parallel_packs.html

With this setup it just doesn't matter if a battery or switch fails...you're still able to complete the flight.
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Old 06-09-2014, 07:45 PM
  #32
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A few of my planes use a dual redundant set up. After my two incidences, I was really paranoid and set up a few of my bigger planes with two switches, two LIFE packs, and a BatShare. A couple just have the two packs and switches with no BatShare . My faith has been restored after the switch to LIFE. Who knows, maybe it was something I did to make those two batteries fail, or maybe it wasn't.
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Old 06-09-2014, 08:57 PM
  #33
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Quote:
Originally Posted by stevegauth30 View Post
A few of my planes use a dual redundant set up. After my two incidences, I was really paranoid and set up a few of my bigger planes with two switches, two LIFE packs, and a BatShare. A couple just have the two packs and switches with no BatShare . My faith has been restored after the switch to LIFE. Who knows, maybe it was something I did to make those two batteries fail, or maybe it wasn't.
You didn't do anything wrong. They were just crap from the start.
My Duratrax Nimh was still working after one and a half seasons but I pulled it and installed a A123.
Three Hydrimax Nimhs didn't make it two seasons and one bad out of the box. Tower credited me and I bought a Duratrax instead.
Use what works for you but I have moved on from Nixx batteries. Oops, I do have one in my Tx but it will be going soon. Lol.
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Old 06-10-2014, 03:46 AM
  #34
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My Two Cents

For years now I,ve been using 2S Lipo packs (2) for my receiver in my giant scale planes.
I use a regulator and a smart fly system. I get a constant 6volts to my receiver.
I buy 2200 mah packs (inexpensive),I velcro them in and remove them when charging or not using the plane.
I can then put them in the next plane I am using .

I use 6 volt NIMH 2000 mah for ignitions I have two 50 cc planes 2 30 cc planes and one 75cc. I have no issues with them and wall charge over night.

I have two Futaba radios they both have 2500 mah ENELOPE cells . I wall charge these also and date them I chuck them after 3 years

By the way no one else in my club does it this way but it works for me

Most in the club are using LIFO which I understand once depleted go from 6.6 volts to 0 quickly

Just my two cents


Bill (Splinter)
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Old 06-10-2014, 05:01 AM
  #35
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Quote:
Originally Posted by splinter View Post
Most in the club are using LIFO which I understand once depleted go from 6.6 volts to 0 quickly
I think you're saying that if you run a LiFe battery below 6 v it will quickly die completely? This is true. The best practice with LiFe cells is to never discharge them more than about 50%. Fortunately, this is easy to do. LiFe's are so light that its possible to carry far larger capacity batteries than you will ever use in a day of flying. Much the same as you are doing with your 2200 mah LiPos only you don't need a regulator, and you don't have the likelihood of the battery catching fire.

I use two 1100mah LiFe's in parallel in my .60 size planes and use 1450's in my large planes.
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Old 06-10-2014, 05:06 AM
  #36
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LiPos are great for high current applications. A large scale plane with some high torque digital servos would benefit from this setup.
But for most planes LiFes will provide all the current you need (I have them in my helicopters, too).
They are easier to handle and can stay in the plane when charging.

Both have a relatively consistent voltage output until they are almost discharged, they the voltage will drop quickly, so you need to monitor
your flight time and charge status. On a new plane, I will note the flight time with a full battery and recharge after a few flights, that will give me a good idea on the max flight time, while I'd never use up more then half of the capacity.
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Old 06-10-2014, 05:27 AM
  #37
rcmichael
 
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I am still using NIMH batteries with good results. Without naming brands, I will say there are some batteries that are better. I only use low impedance NIMH cells on flight packs. I also cycle them after flying to monitor capacities etc. I use as big a pack as is feasible for the plane. My scale stuff gets 2 3000 ma batteries on flight controls and electric landing gear. If you cycle and check voltage before every flight you should almost never have crashes due to battery. Why use NIMH? They are heavier and therefore make good ballast for scale. They generally cost less, and are not prone to burning up with charging. I personally know of an experienced modeler and Hobby shop owner that came very close to losing his shop due to lipo fire. If the charger you have fails on a lipo you could easily have an expensive disaster on your hands. We have all see the safety columns saying charge your lipos in a fire proof container. How many modelers take the batteries out of a plane(excluding electrics) to charge them? Are Life and lipos bad? No, but they can be hazardous if not handled properly. My 2 cents worth.
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Old 06-10-2014, 06:17 AM
  #38
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NiMH batteries are generally very stable and safe. That having been said, NiMH batteries can smoke/burn, although not usually with the same fireworks of a LiPo battery. One of my flying buddies had a charger short out while charging a NiMH pack, and it went up in flames. It never was determined if the bad pack blew the charger, or if the bad charger blew the pack.

I had problems with a particular brand of NiMH packs (Hi Energy) not peak detecting on my Hobbico Quick Field Charger II. I'd set up my TX and RX batteries to charge while I was helping other pilots with their planes, or while instructing students on a club trainer. After a while, somebody would say, "Hey Ed, your airplane is smoking!" I melted down the same RDS8000 transmitter twice before I learned my lesson; always remove your transmitter battery from your radio when quick charging. I was fortunate to not lose an airplane when the receiver battery went up as well.

I still have the same charger and I use it all the time; it peak detects fine with other brands of NiMH packs. I guess the point is that no battery technology is completely safe or fool-proof. It's a bad idea to leave a battery absorbing energy and leaving it unattended, no matter which battery chemistry is being used.
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Old 06-10-2014, 07:20 AM
  #39
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Nothing much to add to discussion now, taking my batteries and charger and meter to hobby shop to have some of the local experts take a look.

This has been a great discussion. Keep it coming! lol
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Old 06-10-2014, 08:09 AM
  #40
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Just my opinion but get rid of all your 4.8 packs.in today's rc world if you are using nimh then use 60 packs.you have little margin of safety on those 4.8 pacs.make sure your charger is putting out the juice u need use the 1 rule. I recently got the bug to go back to nitro and bought a life battery.charges easily and won't cause a fire like my lips and hold charge a very long time.
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Old 06-10-2014, 08:18 AM
  #41
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I've had excellent luck with Hydrimax 2000 mah packs and Eneloops for a very long time . Vast improvement over nicads .
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Old 06-10-2014, 10:16 AM
  #42
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Never have been a big fan of Nimh, i still use Nicd's with 2 planes using A123's. So far, i really like the A123 Life packs and they have been very reliable. On a nice (scale) plane if using Life i would use a redundant 2 battery system. The issue that worries me the most with Life if you lose one cell, you are in big trouble.
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Old 06-10-2014, 10:35 AM
  #43
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!00 percent LIFE packs for about 6 years. Only failure has been the occasional instance of leaving the switch on and the battery depletes. My fault there. Brand of choice has been HobbyKing. Flame away if you must, but I have been very pleased with the quality and performance. Applications range from 18 ounce sport planes to 25 pound, twin pack Warbirds.
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Old 06-10-2014, 10:39 AM
  #44
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No flaming here on HK packs. I am using a 3 cell HK Life in one of my transmitters. I fly quite a lot and it is starting the second year with no issues at all. I do watch the voltage closely but so far so good.
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Old 06-10-2014, 10:44 AM
  #45
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I've had good service out of their Turnigy LiPos. Just be sure to use the US Warehouse if you need it soon.
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Old 06-10-2014, 11:15 AM
  #46
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Quote:
Originally Posted by OldScaleGuy View Post
The issue that worries me the most with Life if you lose one cell, you are in big trouble.
That's the beauty of a dual battery system. A battery can fail and you still have the other one to get you through the flight. Check both batteries before each flight by switching them on one at a time.
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Old 06-10-2014, 12:08 PM
  #47
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I love nickle metal batteries. They have higher capacity than nicads for the same weight and they self-discharge slower. I don't have any high amperage draw planes though and if I did I wouldn't use NiMh batteries for them. I've never lost a plane due to a battery.
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Old 06-10-2014, 12:33 PM
  #48
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i used the enloops in my tx.have switched over to lipo.just had to charge the battery after 2 months of use.i wonder why anyone would use a nicad battery.i use a123 in my gasser .one for the igntion other for rx pack.gives me peace of mind.i may crash but it wont be from poor battery management.which i was notorious for back in the old days of nicads.
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Old 06-10-2014, 01:36 PM
  #49
Tony Iannucelli
 
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No problems with Hydrimax batteries ever. I've used them for decades. They do not need to be recycled; it's a waste of time because they don't have a memory like nicads. Good duration, and good capacity too. All types are OK with me. Just follow the rules! I've used Life in my transmitters but am going back to NiMH. I've let a Life deplete by mistake, and it wasn't pretty. I've overcharged a Life by mistake, equally ugly. Hard to teach an old dog new tricks. The Lifes did come back to almost perfect size in a month (in the ammo can). I HAVE gone to five cell NiMH with the advent of 2.4 brownout issues. Never experienced them, but I have read about others having problems. I did crash once flying an eight year old battery on a one hour charge. Stupid I am, I know. I did get three flights on the plane before the crash, and the crash came on the downwind leg of flight #4. It was really nice, it went to fail safe, the wings leveled, low motor, hit high grass, only the firewall was messed up. 12 year old airframe. I'm still stupid. I miss that plane.
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Old 06-10-2014, 01:38 PM
  #50
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Ive been using 5 cell Hydramax 6 volt 2000 ma for several years, and have had no trouble from any of the packs.
But I only have 40-60 planes, standard sport type servos.
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