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What charge rate is best

Old 07-17-2003, 05:44 PM
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JBoss
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Default What charge rate is best

Hello All,
I have a T-Hawk with a 400 speed electric. I use a 600 mah, 7 cell nicads. I do not know the c rate of the batteries and do not fully understand c rates.
I also have a Super Brain 959 Peak Charger. It can be set from .5 amps to 4.5 amps charge rate. By default it is at 3 but I have been doing all of my charging at .5 amps. At this rate a fully discharged battery charges to full in about 30-40 minutes and then the charger pulse charges at .1 amp for 1 hour.
My question is:
Is .5 amps the best charge rate to keep the batts at tip top,
And what is the c rate on these batteries if that is a legitimate question.

Thanks
Jim B
Old 07-17-2003, 06:44 PM
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Steve Neu
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Default Re: What charge rate is best

Originally posted by jboss
Hello All,

And what is the c rate on these batteries if that is a legitimate question.

Thanks
Jim B
1-1.2 amps should be ok. The cells should be warm to the touch after charging or around 100-110 degees F.

Steve
Old 07-17-2003, 07:25 PM
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Default Thanks

Thanks Steve,
At .5 amps ther barely get warm.

How low shoud I discharge them.
Should I hook them up to a light bulb until they are dead or just charge them after the plane cuts off the motor
Old 07-17-2003, 07:33 PM
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Red Scholefield
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Default Re: Thanks

Originally posted by jboss
Thanks Steve,
At .5 amps ther barely get warm.

How low shoud I discharge them.
Should I hook them up to a light bulb until they are dead or just charge them after the plane cuts off the motor
C= the rated capacity. For your 600 mAh cells charging at C rate would be 600 mA, 2C would be 1200 mA or 1.2 Amps

You don't need to discharge them except to check capacity once in a while, you should give them a slow charge @ 0.1C or 1/10th (60 mA) or as close as you can getof their rated capacity for about 16 hours occasionally to balance them out.
Old 07-17-2003, 07:34 PM
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Steve Neu
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Default Re: Thanks

Originally posted by jboss
Thanks Steve,
At .5 amps ther barely get warm.

How low shoud I discharge them.
Should I hook them up to a light bulb until they are dead or just charge them after the plane cuts off the motor
No need to do anything special after flying. Just put them away until next time and charge just before you plan to fly.

Steve
Old 07-17-2003, 09:30 PM
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Default That works for me

Thanks Guys That answeres my questions.
This site is great .
Where else can you get answers so quickly

JimB :sunsmiley
Old 07-26-2003, 07:17 PM
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Default What charge rate is best

Is there anybody out there that can explain in a simple way that even I can understand, what is C-rate, howis it determined and what is the difference between mah, mv and ma.
Thanks
Old 07-26-2003, 07:51 PM
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Default What charge rate is best

Originally posted by eflyer2
Is there anybody out there that can explain in a simple way that even I can understand, what is C-rate, howis it determined and what is the difference between mah, mv and ma.
Thanks
C= the capacity of the battery

Lets take a pack rated at 1800 mAh then charging it at 2C means you would charge it at 2 times 1800 or 3600 mA.

If you discharge it at C/5 this meas you would discharge it at 1800/5 or360 mA.

ma is milliamp - a mill is 1/1000 of something so in this case it is 1/1000 of an amp.

Same for the rest mv is a millivolt, 1/1000 of a volt

If we have 1 amp of current flowing for 1 hour we would have 1 amp hour or 1 Ah or 1000 mAh.

1 volt across 1 ohm of resitance (you didn't ask about ohms yet) will result in a a current of 1 amp.

OK?
Old 07-26-2003, 08:14 PM
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Default What charge rate is best

Thanks Red,

Now if I put the those ma, mv, mah, ohms the things that get crossed in a bag, tie the end up and shake the heck out of it then plug it into a wall socket ....grin.. Will my Battery be charged ?

OK- OK, let me put it this way, I have a 7.2 V 150 mah nicad, slowly now, how d I determin the C-rate and what do I tell my charger to do, charge rate, for how long.

Please don't pay any mind to my opening remarks, a bit of humor helps keep me sane.

Thanks for the help,
Old 07-26-2003, 11:26 PM
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Default What charge rate is best

Originally posted by eflyer2
Thanks Red,

Now if I put the those ma, mv, mah, ohms the things that get crossed in a bag, tie the end up and shake the heck out of it then plug it into a wall socket ....grin.. Will my Battery be charged ?

OK- OK, let me put it this way, I have a 7.2 V 150 mah nicad, slowly now, how d I determin the C-rate and what do I tell my charger to do, charge rate, for how long.

Please don't pay any mind to my opening remarks, a bit of humor helps keep me sane.

Thanks for the help,
The C rate is 150 mA. If your charger is a peak charger tell it to charge at 300 mA (2C). It will guit when the pack is full. If it is a slow charger and you can set it to 15 mA, let it charge for 14-16 hours. A bit longer will not hurt but it should be fully charged in that time, less if it had some charge remaining.
Old 07-27-2003, 01:01 AM
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Default What charge rate is best

Thanks Red,

I am begining to understand, 1-C is the capacity of the battery (mah), in milli-amps (ma), ni-cads are charged at 2-C.
Hope i'm right--

2-C @ 150 mah= 300 ma x 10 = 3 amp charge rate.

My charger is one of those 959 super brains and is ajustable for charge rates in amps, 0.5 ~ 4.5 amps.

It is also adjustable for mv from 5 ~ 70, I'm not sure what this is yet, and it is adjustable for time in minutes.

Now for NIMH batteries, do I charge at 1-C or 1/2-C, example 8.4v 730 mah, how do I find the charge rate of this one, would it be .75 amp.

I know you can't hold my hand on this but I think were getting somewhere.

Thanks again,

Eflyer
PS- the 959 charger comes with a very vague instruction sheet that tells you what the charger will do but does't tell you how to make the adjustments.
Old 07-27-2003, 10:54 AM
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Red Scholefield
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Default What charge rate is best

Originally posted by eflyer2
Thanks Red,

I am begining to understand, 1-C is the capacity of the battery (mah), in milli-amps (ma), ni-cads are charged at 2-C.
Hope i'm right--

2-C @ 150 mah= 300 ma x 10 = 3 amp charge rate.

NO, NO, where did the X 10 come from. [email protected] is 300 mA. or 0.3A

My charger is one of those 959 super brains and is ajustable for charge rates in amps, 0.5 ~ 4.5 amps.

It is also adjustable for mv from 5 ~ 70, I'm not sure what this is yet, and it is adjustable for time in minutes.

Now for NIMH batteries, do I charge at 1-C or 1/2-C, example 8.4v 730 mah, how do I find the charge rate of this one, would it be .75 amp.

For a C rate charge it would be .75 amps (or 750 mA).

I know you can't hold my hand on this but I think were getting somewhere.

If you can't hold your hand on it you are getting it to hot - Not good. (Battery humor here).

Thanks again,

Eflyer
PS- the 959 charger comes with a very vague instruction sheet that tells you what the charger will do but does't tell you how to make the adjustments.
The curse of most equipment made in the Asian rim countries.
Old 07-27-2003, 11:00 AM
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Default What charge rate is best

Red, don't go away, I'll be right back,....grin
Old 07-27-2003, 11:17 AM
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eflyer2
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Default What charge rate is best

Red, I think my biggest source of confusion is comming from the charger, you guys are feeding me the right info but the charger is talking a different language, What may be the problem is this charger was not intended to do what I need, for one thing in large writing on th box it states " For 3 ~ 8 cell NI-CADs and NIMH batteries ", in the istruction sheet in fine Print it reads " for AA and Sub-C and Glow driver batteries, It also states in even finer print " Plug and play for Sub-C and LARGER cells ONLY",

Again, it is adjustable for charge rates of 0.5 ~ 4.5 and for peak threshold of 5mv ~ 70mv.
It is not adjustable for mah rates.

Could this charger be meant to charge R/C Car batteries.

Thanks again,
Old 07-27-2003, 03:36 PM
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Default What charge rate is best

Originally posted by eflyer2

Could this charger be meant to charge R/C Car batteries.

Thanks again,
When supplying electric power Batteries are Batteries. They could care less if they are in a car, plane, boat or train. And the charger couldn't either.
Old 07-27-2003, 03:57 PM
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Default What charge rate is best

Red, does that mean that I can use my 12 volt car battery charger to charge my small e-flight batteries, you guys are telling me on one hand that the charger that I have is killing my batteries, while others are saying chargers are chargers and batteries are batteries and neither knows the other and it's all getting muddy again,

I guess it's like asking a doctor to explain whats wrong with you in lay terms, most can't do it, and the rest won't.

Thanks again for trying,

Eflyer

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