Amp -Versus - Milliamp, How do I convert? - RC Groups
Jul 01, 2001, 12:30 AM
Registered User

# 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
 Jul 01, 2001, 12:42 AM Registered User 1000 millamps = 1 amp 270 milliamps = .27 amp Regards, - Razz
 Jul 01, 2001, 12:43 AM Registered User 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).]
 Jul 01, 2001, 12:55 AM Registered User 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.
 Jul 01, 2001, 01:48 AM Registered User Will that 0.5 Amp charge rate be too high for my 110 Mah & 270 Mah Litestick Batteries?
Jul 01, 2001, 04:01 AM
Registered User
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
 Jul 01, 2001, 05:25 AM Triad of Fun 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
 Jul 01, 2001, 05:28 AM Registered User 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!
Jul 01, 2001, 05:40 AM
Registered User
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).]
 Jul 01, 2001, 03:25 PM rebmeM roineS 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).]
 Jul 01, 2001, 04:06 PM Registered User 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
 Jul 01, 2001, 06:08 PM Senior Member 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.
Jul 01, 2001, 06:39 PM
Registered User
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
 Jul 02, 2001, 05:03 AM Registered User I must have been REALLY tired that night, I use thes conversions EVERYDAY! Better go check what I did at work that day.
 Jul 02, 2001, 09:56 AM Registered User quote: -------------------------------------------------------------------------------- A 270mAH hour cell can in theory deliver: 27A for 1/10 hour (=6mins) -------------------------------------------------------------------------------- I need those cells...a dream come true!!!