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nimh or nicad

Old 02-23-2006, 10:27 AM
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Default nimh or nicad

i just got a venom 1900 6 cell pack for my savage 4.6 roto start, any way i dont have a charger and i need to know what is the battery a nimh or nicad? it does not say anything on the battery about that, i need to know this befor i get a charger, with that in mind, do i really need a charger that can charge it at different amp settings? it it absoutley necessary or can i just get a quick charger, do i need to worry about discharging befor charging again, by the way the way this battery is only going to be used for the roto start.. which charger should suffice?

thanks
Old 02-23-2006, 10:53 AM
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Default RE: nimh or nicad

man do i feel stupid it says nicd right on the front of the battery LOL, any way should i still worry about discharging,? dont nicd batteries have a memory effect?
Old 02-23-2006, 11:01 AM
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Default RE: nimh or nicad

a nicd is kinda the wrong battery for a starter unless you plan on keeping it discharged until you run or it will ruin the battery. Nicd batts need to be stored discharged or they keep the memory stored at. I would pick up a cheap nimh for your starter .
Old 02-23-2006, 12:22 PM
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Default RE: nimh or nicad

Dawman, sorry to dissagree with you but most of your information above is totally wrong. NiCd's are much more tolerant of abuse than NiMh and have twice the lifetime. If you are not pressed for room (the NiMh are less massive for an equivalent amount of energy storage) then NiCd's are far more economical in the long run. As to memory, the way we use NiCd's it is almost impossible to create any semblance of memory . For some good reliable info on batteries, check out www.rcbatteryclinic.com.
Old 02-23-2006, 12:42 PM
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Default RE: nimh or nicad

One other point in favor of NiCd used for powering a starter. Most NiCd packs have lower internal resistance than NiMh packs. The less internal resistance the more power goes to the load the less is wasted as heat. And as Rodney has already stated Nicds can be abused more and are cheaper to boot.
John
Old 02-23-2006, 01:09 PM
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Default RE: nimh or nicad


ORIGINAL: Rodney

Dawman, sorry to dissagree with you but most of your information above is totally wrong. NiCd's are much more tolerant of abuse than NiMh and have twice the lifetime. If you are not pressed for room (the NiMh are less massive for an equivalent amount of energy storage) then NiCd's are far more economical in the long run. As to memory, the way we use NiCd's it is almost impossible to create any semblance of memory . For some good reliable info on batteries, check out www.rcbatteryclinic.com.

Well , then you better tell , Novak , SMC , and Trinity they are wrong . LOL
Old 02-23-2006, 01:13 PM
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Default RE: nimh or nicad


ORIGINAL: Dawman


ORIGINAL: Rodney

Dawman, sorry to dissagree with you but most of your information above is totally wrong. NiCd's are much more tolerant of abuse than NiMh and have twice the lifetime. If you are not pressed for room (the NiMh are less massive for an equivalent amount of energy storage) then NiCd's are far more economical in the long run. As to memory, the way we use NiCd's it is almost impossible to create any semblance of memory . For some good reliable info on batteries, check out www.rcbatteryclinic.com.

Well , then you better tell , Novak , SMC , and Trinity they are wrong . LOL
Just curious what point of Rodneys do you disagree with?
Old 02-23-2006, 09:28 PM
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Default RE: nimh or nicad

Nicds get a memory if they are not stored in a discharged state. If you leave a nicd sit in the starter with some charge left in it each time you will be getting less capacity and voltage.
Old 02-24-2006, 05:59 AM
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Default RE: nimh or nicad

Dawman,
Nicds get a memory if they are not stored in a discharged state. If you leave a nicd sit in the starter with some charge left in it each time you will be getting less capacity and voltage.
I'm not trying to start a war here. All I ask is that you keep an open mind. One of the most enduring myths is that NiCd have a memory problem. They don't read more about is in Red's clinic. As far as storing them in a completely discharged state. Think about it. That's just wrong no rechargable cell wants to be stored discharged, chemically it wants to produce electricity. That's why on a good cell it will spring back if completely shorted out.

The section on Memory almost all the way down uder Basic NiCd Stuff http://www.rcbatteryclinic.com/seminar.htm

More information http://www.rcbatteryclinic.com/seminar.htm Left Side Nicd Life. A lot shorter but good reading.

Next you'll ask why believe Red. He has worked most of his adult life developing NiCd batteries in the US. A more knowledgeable or unbiased person would be hard to find.

John
Old 02-24-2006, 08:13 AM
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Default RE: nimh or nicad

Next you'll ask why believe Red. He has worked most of his adult life developing NiCd batteries in the US. A more knowledgeable or unbiased person would be hard to find.
Red has been the absolute battery expert for the thirty years that I have been flying. In addition he takes a very sensible but yet an engineering approach to problems. Red’s years of experience began before many here were born.

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Old 02-24-2006, 12:30 PM
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Default RE: nimh or nicad

I'll second Nortons comment in favor of Red. As an aside, I worked in the Design and Development area of the Mercury and Gemini area, where we spent months trying to make NiCads display a memory trait. Try as hard as we could, we never did get a NiCad to evidence any memory characteristics. After 6 months of tests, we decided they just do not evidence that characteristic.
Old 02-24-2006, 12:52 PM
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Default RE: nimh or nicad

Rodney,
Memory effect, I understand it is a sudded drop off in power at a premature point as the NiCd discharges, caused by lots of partial discharges. Is that correct? It is also meant to effect NiCds as made a few years ago than todays NiCds?

I have certainly found that cycling can restore the capacity of an old/not used for a long time NiCd. I'm sure of that but have been under the impression that this was overcoming the memory effect. Perhaps this is unrelated to memory, more of a post Xmas work out?

My perception is that NiMh do not suffer from memory effect but then I've found that cycling has the same beneficial effect on them.

Is cycling really just reforming and balancing the packs as we do when they are new and the memory bit just a red herring?
Old 02-24-2006, 01:13 PM
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Default RE: nimh or nicad

Marcellus,
Rodney,
Memory effect, I understand it is a sudded drop off in power at a premature point as the NiCd discharges, caused by lots of partial discharges. Is that correct? It is also meant to effect NiCds as made a few years ago than todays NiCds?
The section on Memory almost all the way down uder Basic NiCd Stuff http://www.rcbatteryclinic.com/seminar.htm Please read this. Please.

If cycling is done at a C/10 rate you are indeed equalizing the batteries. If the pack had a cell that was weaker than the rest charging it at a C/10 rate will equalize the pack and bring it back up to snuff.

Form charging is C/10 charging with a C/5 discharge done 3 times. It is essential to get maximum performance out of MiMh batteries.

Most of your questions can be aswered by reading Red's site. It really is worth the time.

John
Old 02-24-2006, 06:28 PM
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Default RE: nimh or nicad

I`m not questioning Red , but years ago when we raced with nicds you had to keep them discharged untill the day that you use them.
Otherwise they start loosing their edge. That is what Sanyo , SMC , Trinity , and Orion to name a few, recommended. Novak and SMC want the nimh batts kept discharged at .9 v/cell if using weekly . Or stored longer than 2 weeks with a few minutes of charge in them. We all know that every manufacture has different ways for battery care . When we used nicd back in the day , you could tell a difference if you didn`t follow that guidline and would have to do some cycling bring them back to life. It sounds like you are into planes and maybe you don`t need every little bit you can get from a battery , not sure , never had a plane. In car racing a difference of one cell having 1.157v and another having 1.199v in the same pack is a big deal.
Old 02-24-2006, 07:13 PM
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Default RE: nimh or nicad

but years ago when we raced with nicds you had to keep them discharged until the day that you use them.
Otherwise they start loosing their edge.
That is my point years ago. Batteries are better today, chargers are infinitely better, but I keep reading of practices that make no sense with todays advances and they keep on being spoken of as if it's gospel. Car guys seem to be among the worst with bulb dischargers and routinely discharging packs as if they were going to be charged with a timed charger. Maybe it's time to question some of those practices. I'm an engineer by trade. I mention that only because daily I question why things are done in the manner in which they are. In the automotive supplier business today continuous improvement is not a slogan but a reality. Isn't it time that battery packs are treated with observable fact instead of heresy?

John

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