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Old Jul 01, 2001, 12:30 AM
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Cincinnati, Ohio USA
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Amp -Versus - Milliamp, How do I convert?

I'm considering buying a Duratrax Intellepeak charger. This charger has variable charge rated of 0.5 AMP to 5.0 AMP.
Whats the difference between Amps & Milliamps? if i'm charging 270 Mah Nicads for my Litestick which charge rate should I use? 0.5 Amps = ? Milliamps
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Old Jul 01, 2001, 12:42 AM
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Burnsville, MN, USA
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1000 millamps = 1 amp

270 milliamps = .27 amp

Regards,
- Razz
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Old Jul 01, 2001, 12:43 AM
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Adelaide,Australia
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metric system pretty straight forward

They all have standard prefixes for units to change their magnitude

The unit of current is Amperes, A. often shortened to amps

M=mega=X1000
k=kilo=x100
d=deci=x10

m=milli=/10
"mu"symbol=micro=/1000
p=pico=/1,000,000
n=nano=/1,000,000,000

convert from A -> mA= x1000

0.5A = 500mA

Don't you charge those batts at about 50 mA?

You'll need some else to answer that.

[This message has been edited by procrastination inc (edited 06-30-2001).]
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Old Jul 01, 2001, 12:55 AM
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razzor, the batts are 270mAh. Amp Hours are a measure of stored energy, the number of anps that 1.2v cell can deliver for 1 hour.

That's a lot more info than just current, A. The way that figure is generated, I'm not sure of. I think it's able to deliver 27mA continuously for 10 hrs, but I might have that wrong.

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Old Jul 01, 2001, 01:48 AM
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Will that 0.5 Amp charge rate be too high for my 110 Mah & 270 Mah Litestick Batteries?
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Old Jul 01, 2001, 04:01 AM
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N. Staffs, UK
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Quote:
Originally posted by mrebman:
Will that 0.5 Amp charge rate be too high for my 110 Mah & 270 Mah Litestick Batteries?
Yes. You'll kill 110 especially at that rate. If you want to charge such small batteries look for a charger that goes down to 0.1A (100mA).

Steve
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Old Jul 01, 2001, 05:25 AM
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procrastination,

I believe the correct units are:

milli (m) = 1/1,000 = .001
micro (u) = 1/1,000,000 = .000,001
nano (n) = 1/1,000,000,000 = .000,000,001
pico (p) = 1/1,000,000,000,000 = .000,000,000,001
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Old Jul 01, 2001, 05:28 AM
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Adelaide,Australia
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I stand corrected.

What was I thinking?

Got it right in the calc. though

From now on, I'll post script with.


P.S. I could be COMPLETELY wrong!
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Old Jul 01, 2001, 05:40 AM
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Somewhere in England
Joined Apr 2001
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Quote:
Originally posted by mrebman:
..snip.. Whats the difference between Amps & Milliamps? if i'm charging 270 Mah Nicads for my Litestick which charge rate should I use? 0.5 Amps = ? Milliamps
A 270mAH hour cell can in theory deliver:

270mAH for 1 hour
27mAH for 10 hours
2.7mAH for 100 hours

27A for 1/10 hour (=6mins)
270A for 1/100 hour (=0.6mins = 36 sec)

in theory, but in practice cells are not efficient at high curents and other things impose lower limits (like the thickness of metal in the cells internal construction/wiring.

The amount of current a cell can deliver for 1 hour is known as the C rating.

The standard charge current for most cells is usually 1/10th C which in your case is 27mA or 0.027A it's the same thing. It theory it should take 10 hours to charge your cell at 1/10th C but because the charge process is also inefficient it normally takes about 14 hours.

Fast charging is usually defined as anything over about 1C or 2C eg 270mA (=0.27A) or 540mA (=0.54A) in your case.

If your cells are designed for fast charging then you should be ok at 0.5A and possibly more.

At 2C your cells should take about 1/2 hour to charge. At 3C its 1/3rd hour = 20mins etc

[This message has been edited by cwatters (edited 07-01-2001).]
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Old Jul 01, 2001, 03:25 PM
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Rockingham, Perth - Western Australia
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procrastination inc ya got deci right the others though:

M=mega=X1000
k=kilo=x100
d=deci=x10

should be:

Mega=1x1,000,000
Kilo=1x1,000
Deci=1x10

each step is a division or multiplication of one thousand(with the exception of deci...a non SI unit)

As for mAh capacity, im not sure how Sanyo work their ratings but lead acid batteries made by Yuasa etc. are worked over a 20 hour period, then the Ah rating worked from that, for example a 7Ah lead-acid will deliver 350mAh for 20hours(.35x20=7) but draw 7A and the battery wont last an hour(about 30mins)
Maybe Sanyo do measure them over an hour, not sure.

[This message has been edited by MrBungle (edited 07-01-2001).]
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Old Jul 01, 2001, 04:06 PM
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Hi,

sorry folks, still not correct. So here is some help from good ol' Europe

Tera : 10^12 = 1,000,000,000,000
Giga : 10^9 = 1,000,000,000
Mega : 10^6 = 1,000,000
Kilo : 10^3 = 1,000
Hekto: 10^2 = 100
Deka : 10^1 = 10

deci : 1/(10^1) = 0.1
centi : 1/(10^2) = 0.01
milli : 1/(10^3) = 0.001
micro : 1/(10^6) = 0.000,001
nano : 1/(10^9) = 0.000,000,001
pico : 1/(10^12) = 0.000,000,000,001

Yes, the ISO system is straightforward. And yes, I love it. I think I will never really understand why some countries are stuck to lb/sqr.in, gallons, feet, inch, yards, HP and so on if you can have meters, Newtons, kg's, Watt's and all this nice stuff where you can use every physical law as it is. Just put in your data and it works. It is so easy.

Regards, Jochen
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Old Jul 01, 2001, 06:08 PM
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Oxford(ish), England
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Well, be carefull. A LOT of people have managed to confuse;

AMPERE for AMP-HOUR (Amp Hour!)

AMPERE is Olde Englishe for "Amp" (which is it's short-form) ie a measurement of power. AMP-HOUR is one amp for an hour, Ie a measurement of energy. 1 Amphour is.. one amp for one hour or six amps for ten minutes! or Sixty amps for 1 minute. Easy, but they sound similar! 2000Mah is just two thousand milli amps (thousanths of an amp) for an hour... Or 2 amps for an hour. OR 120 amps for a minute! etc etc etc.
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Old Jul 01, 2001, 06:39 PM
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Hi,

Quote:
Originally posted by gdb1973:
[B]Well, be carefull. A LOT of people have managed to confuse;

AMPERE for AMP-HOUR (Amp Hour!)
yes, you should watch for that.

Quote:
AMPERE is Olde Englishe for "Amp" (which is it's short-form)
my dictionary says:

Ampere, Andre Marie, born 1775, died 1836, FRENCH mathematician and physician, discovered magnetic fields around electric current ...

Regards, Jochen
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Old Jul 02, 2001, 05:03 AM
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I must have been REALLY tired that night, I use thes conversions EVERYDAY! Better go check what I did at work that day.
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Old Jul 02, 2001, 09:56 AM
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Vacaville, CA USA
Joined Nov 2000
355 Posts
quote:
--------------------------------------------------------------------------------

A 270mAH hour cell can in theory deliver:

27A for 1/10 hour (=6mins)

--------------------------------------------------------------------------------

I need those cells...a dream come true!!!
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