Society of Robots - Robot Forum

General Misc => Misc => Topic started by: soninja8 on August 02, 2011, 12:53:29 AM

Title: Milli-Amp
Post by: soninja8 on August 02, 2011, 12:53:29 AM
Okay, so I have a 8.4v 1600mah battery, and then i just got a 8.4v 3000mah battery in the mail yesterday. My 1600 was suprisely small, and the 3000 is like 1.5 times its size...my question was, do batteries have to be bigger with more milli-amps?
Title: Re: Milli-Amp
Post by: Gertlex on August 02, 2011, 07:23:43 AM
Yes.  Also make sure that you get it straight that mAh == milliamp-hour, not milli-amp :).  It's yet another parallel between electricity and water... you need a bigger volume to store more water; likewise you need a bigger battery to store more energy (which is what mAh is a convoluted, but useful unit for*).  This is true within a battery type.  Different battery types (LiPo, NiCad, NiMH, PB-acid) will have different energy densities, so size for the same energy capacity will vary between the battery types.

*Actually it's not an energy unit either.  You need to multiply by the battery voltage to get milli-watt-hours.
Title: Re: Milli-Amp
Post by: Soeren on August 02, 2011, 07:50:15 AM
Hi,

[...] my question was, do batteries have to be bigger with more milli-amps?
Not to belittle Gertlex's answer, which is fully to the point, but more as a general idea of how to decide in such a case.

Take the question (any such question) to an extreme like:
"Is it possible to fit a 1,000,000,000,000 mAh battery into the same space as a 1,600 mAh battery?"
Then the answer should become quite obvious.
Title: Re: Milli-Amp
Post by: soninja8 on August 02, 2011, 03:08:16 PM
Thanks for the answers. I am now sad, but I learned it.  ;)