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Life of nicad batteries

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Life of nicad batteries

Old 02-26-2003, 12:47 PM
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CESSNA 421
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Default Life of nicad batteries

I have some radios on trickle charge for as much as 10 years. Theses batteries were new when installed. I recently cycled all the batteries and discovered they had lost about 30% of their rated capacity on the first discharge cycle. I have not cycled them a second time to see they rcovered any of their capacity as of this writing. Is this normal for batteries to lose this much of their rated capacity when on long term cycle?

PA28R201
Old 02-26-2003, 01:21 PM
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ethal86
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Default Life of nicad batteries

Replace them, Batterys are cheap.
Old 02-26-2003, 02:04 PM
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pcm
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Default Life of nicad batteries

Replace them, Batterys are cheap.
Yup, got to agree.
Old 02-26-2003, 06:06 PM
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CESSNA 421
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Default Life of nicad batteries

Thanks for the input. Replacing them is the correct thing to do and I will do so.

Let's get back to my original question will nicad batteries lose capacity during extended trickle charge?
Old 02-26-2003, 06:10 PM
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Geistware
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Default Life of nicad batteries

A lot depends on the amount of current during the trickle charge. If a NiCad looses 2% of its capacity a day/week/? then you need to put that much enenrgy back into the pack. WHat I have done is charge my packs with my wall wart or Einstein charger and then connect the charger to a timer that will turn on for 1 hour a day and off the remaining time. This seems to work fine.
Old 02-27-2003, 02:07 AM
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CafeenMan
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Default Life of nicad batteries

I called the guys at Sirius (I have a Sirius charger) regarding some really old batteries I had. The guy assured me that any nicad can recover with a good charger and enough cycles. I had a 500 MAh tx battery that only came up to about 120 MAh after ten charges. I threw it out. The guy said I should have kept at it and it would have recovered.

But I have to agree, batteries are cheap and to me it wasn't worth the risk. But I never put new batteries in a model until I've cycled them a couple times. Then I test fly them in an "expendable" model before risking one of my less expendable planes.
Old 02-27-2003, 11:27 AM
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Default Life of nicad batteries

I honestly don't think the "experts" completely understand the characteristics of Ni Cd batteries. I do know that a fully charged Ni Cd battery will self discharge at a rate of ~1% per day. Long term cycle may adversely affect the plates (if you will) in the battery. A Ni Cd will develop tiny bubbles on the plates that will limit the capacity of the battery. There have been times when a very quick reversal of polarity of my charger has brought "bad" batteries back but I'd NEVER use them in any of my planes.
Old 02-27-2003, 12:57 PM
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TerrellFlyer
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Default Life of nicad batteries

I've some batteries go in the trash in less than a year, I've also some batteries over a dozen or more years and going strong.If they don't hold a charge of 75% or more after recycling a couple of times I delete them.
Old 03-03-2003, 04:06 AM
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Default Life of nicad batteries

I have a 500 mah Rx pack that hasnt seen use or a charge in nearly 7 years. How many times should i cycle them to see some life back in them? do you guys recommend me using these or just buy a new pack?
Old 03-03-2003, 04:30 AM
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CafeenMan
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Default Life of nicad batteries

how much is a new 500 MAh pack vs. how much is a new airplane?
Old 03-03-2003, 07:14 AM
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dainjarouz
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Default Life of nicad batteries

well i just took it off the charger a little bit ago. It charged for about 5 hours and it went all the way up to 460mah. Does this mean anything or can the integrity of the pack still have been compromised over the long storage?
Old 03-03-2003, 12:53 PM
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Default Life of nicad batteries

Originally posted by dainjarouz
well i just took it off the charger a little bit ago. It charged for about 5 hours and it went all the way up to 460mah. Does this mean anything or can the integrity of the pack still have been compromised over the long storage?
That battery is at 92% and should be OK. If you have a cycler, put the pack on it to see how it discharges under a load. If you get 1.5 hours, or more, with a 50mah discharge, you're good-to-go.
Old 03-03-2003, 01:18 PM
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Steve Lewin
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Default Life of nicad batteries

Originally posted by ED STEFAN
That battery is at 92% and should be OK. If you have a cycler, put the pack on it to see how it discharges under a load. If you get 1.5 hours, or more, with a 50mah discharge, you're good-to-go.
Pardon me but 1.5 hrs at 50mA is only 75mAh - throw away time for a 500mAh battery. I'd be looking for around 9-10hrs at that current or 1.5hrs at >300mA. I'd cycle at least 3 times (or more likely I'd just buy a new battery).

BTW the amount of charge going IN is of very little interest. It's how much you can get OUT that tells you if the battery is any good.

Steve
Old 03-03-2003, 06:40 PM
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Kaos Rulz
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Default Life of nicad batteries

Originally posted by Steve Lewin

Pardon me but 1.5 hrs at 50mA is only 75mAh - throw away time for a 500mAh battery.
Steve
Steve,
Old 03-03-2003, 06:53 PM
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Kaos Rulz
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Default Life of nicad batteries

Steve,

You are 100% correct in the above statement. A 500ma battery would take aprox 10 hours to Fully discharge at a 50mah rate.

I failed to get into the fact that you should only discharge down to 1.1 v/ cell, or 4.4v for a 4.8v pack. This is the threshold most malefactor's consider for fly/don't fly. If you'll accept the fact the average plane drains at 50mah, you should be able to fly at least 1.5 hours before the 4.4v is displayed. This has been my experience using the LITCO battery cycler.

I may have over-simplified my first response to Dainjarouz. If that created confusion; I apologize.
Old 03-03-2003, 11:35 PM
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Steve Lewin
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Default Life of nicad batteries

Sorry Ed but you've got your terms all confused. The capacity of a battery is measured in mAh (milliAmps times hours). A charge or discharge rate is measured in mA (milliAmps).

On average a battery will have less than 5% of its capacity left by the time it gets to 1.1V/cell. A fairly normal plane in flight, i.e. with the servos active, averages somewhere around 250-300mA current though this can vary a huge amount depending on the size of the plane, servos etc. That might indeed get you around 1.5hr flying time but that's no way to test a battery.

If you are checking battery capacity you must do it with known currents. You can either use a cycler or discharge through a resistor or lamp provided you can measure the current. Just letting it run with random unknown loads is close to useless.

I suspect your cycler discharges at a much higher rate than 50mA. But if not and you really have a 500mAh battery that only delivers 75mAh to 1.1V/cell you need to throw it away. It's dead.

Steve
Old 03-03-2003, 11:51 PM
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Stick Jammer
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Default Life of nicad batteries

For anyone interested in a lot of good battery info:

http://www.rcbatteryclinic.com/
Old 03-04-2003, 02:37 AM
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Default Life of nicad batteries

ok so i dont have a cycler or discharger. any tips on what i can do to see how the pack is doing? i want to attach it to a 1157 bulb to cycle it a few times. i always forget what part of the bulb is + and which is - can anyone enlighten me please. thanks!
Old 03-04-2003, 11:52 AM
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Kaos Rulz
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Default Life of nicad batteries

Originally posted by dainjarouz
ok so i dont have a cycler or discharger. any tips on what i can do to see how the pack is doing? i want to attach it to a 1157 bulb to cycle it a few times. i always forget what part of the bulb is + and which is - can anyone enlighten me please. thanks!
In this application, observance of polarity is not needed. However, by convention the barrel is neg and the tip is pos.

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