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Battery Capacity Conversion

this is a great article. i was just struggling with the issue of sony presenting in wH vs mAH and this shows the conversion

only thing the article lacks is some discussion in terms of applications that says why the higher mAH lasts longer but the higher voltage is necessary to power bigger devices and the current limits of batteries available on the retail. the author probably has an understanding that he could share on the website

law
Thu, 18 Aug 2005 21:29:24 -0700

Thanks for your suggestion, law. You made some good points. So I have heeded to at least one of your suggestions by adding "Why is Battery Capacity Specified in Ampere-Hour?" to the article.

Chieh Cheng
Wed, 24 Aug 2005 11:19:23 -0700

Very useful article! i was struggling in my understanding of the relationship of "Ah" & "A". I am converting an old cordless drill to a corded one, and needed to find out the kind of adapter I'd need. I feel stupid, now :)

Karim Chakroun
Mon, 7 Nov 2005 06:24:16 -0800

I think ... Watts=Volts*Amps*0.60 which makes 1000VA=600 W !!! and not 1000Watts !!

Dan
Sun, 11 Dec 2005 09:39:32 -0800

1.The battery for my T7 camera says 1.6 wh, 3.6v.
2.Dividing the 1.6 watts for 1hr by the 3.6 volts: the current deliverd by the battery for 1 hr would be .440 amperes or 440 mili amps at 3.6 volts.
ie:440mah.

bill jones (86 yr old ww2 navy vet).
Sat, 25 Mar 2006 17:31:39 -0800

Hello Mr. Cheng
This article made by you was extremely useful for me. Actually I am mounting CCTV cameras and I needed a simple explanation for power supply wat amp conversion. Thank you again. Keep up your good work... :)

ArkeN
Thu, 13 Jul 2006 17:01:54 -0700

The real unit of battery charge is the Coulomb. mAh is a convenience for easier calculation of how long the battery will last in a walkman/camcorder.

McGyver
Fri, 28 Jul 2006 07:39:08 -0700

1mAh = 0.001A * 3600s = 0.001C/s * 3600s = 3.6C
so just multiply the mAh by 3.6 to get the real charge.

Now tell us how much charge is in an ALKALINE battery.

Jack
Fri, 28 Jul 2006 07:44:41 -0700

Your equations are not expressed correctly, since the "h" terms would cancel.

A better example of the NP-FT1 cell conversion would be:
Sony_NP_FT1_capacity = 2.4 W*h = (2.4 W / 3.6 V) A*h = 0.66 Ah
-----------------------------
A better example of Amp to Milliamp conversion would be more correct if shown as:
In a direct-current circuit, 1 W = 1 V * 1 A.
cell_capacity = 0.66 Ah = 0.66 A*h.
cell_capacity = 0.66 A*(1000 mA/A)*h = 660 mAh.

Gordon
Wed, 07 Feb 2007 18:50:01 -0800

There is a cut & paste error in my 1850 hrs post; the following was intended:
Your equations are not expressed correctly, since the "h" terms would cancel.

A better example of the NP-FT1 cell conversion would be:
In a direct-current circuit, 1 W = 1 V * 1 A.
Sony_NP_FT1_capacity = 2.4 W*h = (2.4 W / 3.6 V) A*h = 0.66 Ah
-----------------------------
A better example of Amp to Milliamp conversion would be more correct if shown as:
cell_capacity = 0.66 Ah = 0.66 A*h.
cell_capacity = 0.66 A*(1000 mA/A)*h = 660 mAh.

Gordon
Wed, 07 Feb 2007 18:55:30 -0800

you cannot simplify this as much as you did as energy (watt hour) is a multiple of voltage, current, and time. The terminal voltage of a battery is not going to stay a constant rated voltage, it is a chemical reaction that degrades overtime. So, the watt hour is more complex then amp hour as the varying voltages are taken into consideration.

Cory
Thu, 04 Oct 2007 02:10:16 +0000

Can you help me convert watts to Amp hours for a battery model HC1217W.

Minette Williams
Mon, 14 Jan 2008 18:04:02 +0000

I did a search online for HC1217W and I saw "CSB HC1217W - 12V 4.5AH SLA Battery" . . . it already says 4.5 AH . . . no conversion needed.

Chieh Cheng
Mon, 14 Jan 2008 21:07:13 +0000

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Title: light up an LED with a battery
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Excerpt: what to do for reducing ampere? i want to light up a LED which need only 25ma but every batt. is over this amp. so i have to reduce the amp. thanks mamun
Tracked: Sun, 26 Aug 2007 19:37:15 +0000

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