Eneloop AA battery short circuit current and other questions - Page 1
Forum section: electronics / beginners

author: dav
author_rank: Regular Contributor
timestamp: August 24, 2017, 10:43:33 am
content: I tried to measure the short circuit current of an AA Eneloop battery (1,2V 1900mA, white version, BK-3MCCE).Voltage at no load: 1,36VJust made a brief short circuit and my meters measure:voltage: 1,34Vcurrent: 440mA (about)I took a look to the discharge characteristic (datasheet downloaded here:)http://eneloop101.com/wp-content/uploads/BK-3MCC-AE.pdfand I have some questions:1) is it safe to drain 440mA from the battery? (it's the short circuit current)2) the characteristic shows a curve at 6000mA (!). Is it possible to drain more current than its short circuit current? (probably with an electronic load)3) is it safe to drain 6000mA from this battery??

author: cowana
author_rank: Frequent Contributor
timestamp: August 24, 2017, 10:55:52 am
content: Quote from: dav on August 24, 2017, 10:43:33 amThat's not a short circuit, which by definition has a voltage of zero.It looks like you applied a load of around 3 ohms (1.34 / 0.44).

author: VK5RC
author_rank: Unknown
timestamp: August 24, 2017, 11:12:01 am
content: Doesn't it appear to have an internal resistance of about 0.2, your test circuit and meter presumably added up to the extra resistance i.e. 2.8 ohms.It won't last long at 6A - after 10mins it will be below 1.0V - that is from fully charged and a new battery.

author: sibeen
author_rank: Frequent Contributor
timestamp: August 24, 2017, 11:18:44 am
content: Quote from: cowana on August 24, 2017, 10:55:52 amYou have to take into account the internal resistance of the battery,

author: sasa
author_rank: Regular Contributor
timestamp: August 24, 2017, 11:33:39 am
content: You have to find the "C" value of specific battery series...For 3th generations of Eneloop battery I have and use (last produced by Sanyo), if remember correctly, safety drain limit is up to 1A (I would check if you want) in order to retain maximum predicted life of charge/discharge cycles. Probably similar for the 4th and 5th generations as well.If you need more capacity and more current to drain, perhaps better choice are the "black" series (radically less charge/discharge cycles, however higher capacity and probably the "C" value).

author: tszaboo
author_rank: Super Contributor
timestamp: August 24, 2017, 11:54:12 am
content: Look at the discharge characteristics of the battery. There are several curves. One with 6A discharge curve. So is it safe? Yes, if you keep the battery in the 0°C - 50°C range.So you need to realize, that you did not measure the short circuit current properly. Maybe the burden voltage of the meter is the issue, maybe the leads, maybe you are using it on a wrong range.Ni-Mh batteries are much much safer than Li-Ion. Hovewer:Quote

author: wraper
author_rank: Unknown
timestamp: August 24, 2017, 12:45:37 pm
content: Quote from: sibeen on August 24, 2017, 11:18:44 amIf the battery is not dead, it's internal resistance in negligible compared to that.

author: dav
author_rank: Regular Contributor
timestamp: August 24, 2017, 02:33:23 pm
content: Thanks to all for replies.Battery was not dead and, during the "short", doesn't overheated.No, I don't need to drain 6000mA.I just would like to try some experiments (induction, electromagnet...) with coils.On youtube a lot of guys simply direct connect an AA battery to the coil, with no resistors for limiting the current.For safety reasons first I checked (for approx. 4-5 seconds) how many high should be the short circuit current of the battery (I used a short piece of wire and 2 meters).Then I removed the DMM used as voltmeter and current seems to be the same (440mA).So the question is: is it safe do direct connect the battery to a coil for some minutes?

author: IanB
author_rank: Super Contributor
timestamp: August 24, 2017, 02:43:01 pm
content: Something is wrong. The short circuit current from an AA Eneloop will be well over 10 amps. The internal resistance of the cell should be from 25 to 50 milliohms, producing a peak current of around 1.2 V / 50 milliohms = 24 A. The wire you use to make the short may get red hot, and the battery will get hot too. Don't do this with a good battery.Note: I sometimes test the short circuit current of an alkaline cell using the 10 A range on a multimeter (it will be several amps). But I won't do this with an Eneloop as it might blow the fuse.If your battery is only giving 500 mA something is wrong. Either your battery is damaged or the resistance of your test setup is too high.

author: IanB
author_rank: Super Contributor
timestamp: August 24, 2017, 02:45:39 pm
content: Quote from: dav on August 24, 2017, 02:33:23 pmYou can do this with an alkaline battery. Don't do it with an Eneloop unless the coil has a reasonable resistance (0.2 ohms or so).

author: Audioguru
author_rank: Super Contributor
timestamp: August 24, 2017, 03:04:19 pm
content: My Energizer and Duracell Ni-MH AAA (700mAh) and AA cells (2300mAh) have the same "comes pre-charged and charge lasts for one year" chemistry as Eneloop cells. When fully charged and not worn out they deliver 4A to 5A to my Fluke multimeter (0.3 ohms with leads). When an old cell cannot deliver more than 1A when shorted with my meter I call the manufacturer and have it replaced under warranty if it is less than 5 years old.Cheap Chinese AAA Ni-MH cells (300mAh) in my solar garden lights deliver 3A to 4A when new. They do not have Eneloop chemistry and do not work anymore after about 1 year but have no warranty.Your battery holder and electromagnet coil have resistance that limits the current so that your cell under test is not shorted.

author: sasa
author_rank: Regular Contributor
timestamp: August 24, 2017, 04:08:54 pm
content: A 1900mA rated NiMH battery cells usually cannot store more energy than Ultra Power alkaline battery (Duracell or similar). I would not waste fresh Eneloop battery for similar test which obviously can damage it badly. If NiMH battery overheat, cells will be permanently damaged. If initially was shorted without testing is it overheated, probably is damaged.I use 4xAA 1900mA Eneloop batteries for digital camera and with display on and using flash easily can be make more than 200 photos (never tested more actually, without flash once was 800), however, after 10 or 15 in a row, the container with batteries is notable hot.