NiMH failures

NiMH failures
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[Poll]

NiMH failures

Never had a problem.

71% (66)

I've replaced mine due to battery failure.

28% (26)

Total Votes : 92

(last vote on : 5/26/2008 8:24:51 AM)
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NiMH failures - 6/26/2007 12:30:27 PM

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From: Park Rapids, MN, USA
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While at a Fun-Fly this past weekend, a friend lost his giant scale Sig Morrissy Bravo, when his tx batteries went flat dead in the space of less then 1 minute. He was flying a new Multiplex Tx. He started with 7.5 volts and after 5 minutes of flying, the Tx started beeping and not 15 seconds later the screen went blank and the Bravo crashed totaling the plane and engine. Another friend just purchased a Multiplex TX and after the initial charge, found his Tx batteries to be flat dead after sitting idle for a few days. I have had to replace Tx batteries in my Airtronics VG6000 radio, which was little more then a year old. Another friend has had to replace his Tx batteries in his JR 9303 several times and this radio is less then three years old. These are the failures I know about, as these club members were at the fun fly and we discussed these failures. None of us are over charging, all are likely using the supplied wall chargers that came with the radios. One connection between all, is that the batteries were NiMH batteries.

I've been in this hobby off and on since 1968. With Nicads, I never had a failure such as this and got many years of service before the batteries were replaced because I just felt they had supplied me with many years of service and it simply felt like good preventive maintenence to replace them.

I am only talking about transmitter batteries, here!

So, how are your NiMH battery Tx packs holding up?

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RE: NiMH failures - 6/26/2007 2:32:25 PM

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From: Lyndonville, VT, USA
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Well I still use the tried and true Nicds, get 4 hours of Tx time with my 9Cs with a set of Sanyo 1100 Nicds.
As for your friend losing his Sig Morrissy Bravo, they are great flyers, but what was he thinking??? Taking off with his Tx at 7.5 volts

, I can't understand why his alarm wasn't going off at that point?
Pete

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RE: NiMH failures - 6/26/2007 2:35:45 PM

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From: Menahga, MN, USA
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Of the several radios I have purchased the past several years, the batteries supplied with the Transmitter are: #1: not very large in size, usually 600 or 700 Mamp, with some now including up to a 1500 Mamp Nicad battery. Of course, with the lower mamp batteries, you spend as much time charging them as you do flying, and then not many flights until the battery voltage starts to drop down quite rapidly. I have never had a transmitter battery failure, but like I've stated, I've spend a lot of time charging the transmitter in order to fly. Maybe there is just an inital drop off off the top of the battery and it maintains it's voltage more than I think.

It seems that the batteries now don't hold near as long of a charge as they used to. They are probably made more cheaply somehow, or maybe they have too long of a shelf life before a customer gets them. I've had problems charging the JR 2700 and never used it because after 13 recycles it was finally up to 2100 mamps. Other than a lot of charging, I've never had a failure but only because the battery, especially in the transmitter, is always getting charged.

But, the transmitter batteries always keep one a little nervous. My Spektrum came with a 1500 battery, and instead of always charging it, I went to a 2500 Mamp Lipo battery, so I can go flying and I have charged the transmitter once after the initial charge, and it holds it's voltage much better. I clipped the connector off, (one at a time so you don't short it out), and clipped the end off the lipo, sodered and shrink wrapped, and that was it. I'll never go back to NMH or Nicad batteries. I have actually taken that another step by putting regulators and Lithium Ion batteries in ALL of my airplanes. They are low drain, hold a charge after being charged, and between the Lipo in my transmitter, and Lithium Ion in my planes, it has taken some of the stress out of flying, and now I just go fly at the field after charging the planes at home, and don't spend a bunch of time at the field charging my transmitter or planes or worry about the transmitter starting it's "death beeps".

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RE: NiMH failures - 6/26/2007 5:13:57 PM

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i use a 1000mah Overlander NiMh in my Skysports 4, absolutely fine for a couple of flights, and a 1200Mah 6v NiMh for my Radio (about 6 months old now and has been used in cars, so its ben knocked about a lot but still works fine

but arent TX batteries 9.6v? so unless his TX was designed to run on 7.5v it seems he had a bad battery or it was sent from the factory with the wrong battery :S

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RE: NiMH failures - 6/26/2007 5:18:05 PM

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From: Whittier, CA, USA
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I replaced mine once in the Mini Inferno.

I mistakenly trusted that my peak charger would detect and charge accordingly, but it fried 'em. Not the batteries fault, it was my bad.

It charged at 3 amps and 40mV! Shoulda been 1 amp and 10mV. Oops!

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RE: NiMH failures - 6/26/2007 7:39:44 PM

GalenB

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From: Issaquah, WA, USA
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I think the issue is that NiMH batteries need to have a proper forming charge before they are fast charged. NiCds don't need this so many skip this important first step with new NiMH packs. I had a problem with an NiMH pack in my 9Z, but I had not properly formed the pack before fast charging like the previous NiCd pack. I got a new pack from NoBS, properly formed it using a Sirius forming charger, and have not had a problem since...

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RE: NiMH failures - 6/27/2007 3:04:34 AM

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From: Park Rapids, MN, USA
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quote:

ORIGINAL: pilotpete2
As for your friend losing his Sig Morrissy Bravo, they are great flyers, but what was he thinking??? Taking off with his Tx at 7.5 volts , I can't understand why his alarm wasn't going off at that point?
Pete

This is my bad! As hard as I try to get everything right when I post here on R/CU, invariably I do not. I have no idea what his battery voltage was when he began his flight. I think the crash happened on his second flight of the day. He is a very cautious flyer and I am certain he had charged sufficiently previous to going to the fun fly. When he got the warning beep, he looked down and saw he had 7.5 volts, 15 seconds later the end came.

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RE: NiMH failures - 6/27/2007 3:13:39 AM

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From: Park Rapids, MN, USA
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quote:

ORIGINAL: GalenB

I think the issue is that NiMH batteries need to have a proper forming charge before they are fast charged. NiCds don't need this so many skip this important first step with new NiMH packs. I had a problem with an NiMH pack in my 9Z, but I had not properly formed the pack before fast charging like the previous NiCd pack. I got a new pack from NoBS, properly formed it using a Sirius forming charger, and have not had a problem since...

I'm not talking about fast charging and have no idea what a "Forming Charge" is! Please explain. I understand what the initial charge of a new pack is and how this is done. If I'm supposed to have something other then a wall charger to charge my batteries, please give me my NiCads back.

Although there has only been 16 responses to this poll, as of 10:00 PM Central time on June 26th, 2007, already this poll shows a disproportionatly high number of transmitter battery failures, to people whom have not had problems.

< Message edited by Mode One -- 6/27/2007 3:59:39 AM >

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RE: NiMH failures - 6/27/2007 7:41:02 AM

GWC

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From: Tasmania, AUSTRALIA
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quote:

ORIGINAL: pilotpete2

Well I still use the tried and true Nicds, get 4 hours of Tx time with my 9Cs with a set of Sanyo 1100 Nicds.
As for your friend losing his Sig Morrissy Bravo, they are great flyers, but what was he thinking??? Taking off with his Tx at 7.5 volts , I can't understand why his alarm wasn't going off at that point?
Pete

I use a Multiplex mc4000 radio and it uses 6 subC cells. (7.2v) Straight off the charger it is 8v or thereabouts. The alarm cutoff can be adjusted and the default is 6.9v. I use NiMh 3000mAh. I know quite a few others who use the same. I have been using mine for a couple of years now with no problems.

George

(in reply to pilotpete2)

RE: NiMH failures - 6/27/2007 7:47:57 AM

GWC

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From: Tasmania, AUSTRALIA
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quote:

ORIGINAL: Mode One

quote:

ORIGINAL: GalenB

I think the issue is that NiMH batteries need to have a proper forming charge before they are fast charged. NiCds don't need this so many skip this important first step with new NiMH packs. I had a problem with an NiMH pack in my 9Z, but I had not properly formed the pack before fast charging like the previous NiCd pack. I got a new pack from NoBS, properly formed it using a Sirius forming charger, and have not had a problem since...

I'm not talking about fast charging and have no idea what a "Forming Charge" is! Please explain. I understand what the initial charge of a new pack is and how this is done. If I'm supposed to have something other then a wall charger to charge my batteries, please give me my NiCads back.

Although there has only been 16 responses to this poll, as of 10:00 PM Central time on June 26th, 2007, already this poll shows a disproportionatly high number of transmitter battery failures, to people whom have not had problems.

If you intend to rapid charge your cells (at 1C or greater), then you need to "format" or "condition" the cells first. Needless to say the cells must be designated [R] rapid charge e.g. SCHR, KR etc. You do this by cycling them at 1/10th C for 3-5 times. After that you can charge at the rapid rate. If you are using a wall charger that takes 12-14hrs to charge then there is no need to format the cells as they are not being rapid charge. You must make sure the wall charger is for NiMh cells. I wouldn't use the standard wall charger that came with your Tx unless the original cells were also NiMh.

George

(in reply to Mode One)

RE: NiMH failures - 6/27/2007 4:45:24 PM

richrd

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From: Waterford, PA, USA
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The good news most all failures can be avoided.
The bad news is the battery must be capacity tested at least before each season.
This requires the correct equipment and a log tracking the value of these packs, weak or bad packs almost always show their ugly heads during these tests. Since NiMH are a little more sensitive to over charge or abuse they will have a higher failure rate here in the hobby abusive world.
BTW I have not had a quality pack of any kind just die but cheap ones never make it long for me.
Rich.

(in reply to GWC)

RE: NiMH failures - 6/27/2007 6:08:30 PM

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From: park rapids, MN, USA
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I was there when the Bravo went in too. The pilot is more than cautious with his charging and batts............from all indications it would appear to be a bad pack......period.! My expierience with tx stock packs show they are limited in size from the get go and will fail within the first six months. This of course presumes you actually fly at a frequent level. Stock chargers, fast chargers, doesnt matter if you set the charge rate properly. The damn things just aren't cosistently reliable. A smart man would go with what works, old school nicad or new li-po. Options are out there but my advice is not to use the stock for long.........................I Saw the $700.00 Bravo hit the rock pile. That's all I got to say about that.

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RE: NiMH failures - 6/28/2007 5:54:47 AM

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I too had the unfortunate experience of watching my new 2700 NIMH pack drop voltage while I was holding the transmitter. This faq saved me:
http://www.hangtimes.com/rcbattery_faq.html. Cycled the pack, no more problems.

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RE: NiMH failures - 6/28/2007 6:25:02 AM

mrasmm

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here's the link for the previous post.... it got the period in the link somehow, but this one works
http://www.hangtimes.com/rcbattery_faq.html

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RE: NiMH failures - 6/28/2007 11:45:12 AM

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At 26 votes, there appear