++++++++++++++++++ From: "Don Brown" To: "Steve Jackson" , "Elecraft" Subject: Re: [Elecraft] AA primary cell (K1 related) capacity Date: Wed, 19 Jun 2002 07:44:45 -0500 Hi >From the Eveready website the standard AA bunny battery is 2850 mah and t= he e2 AA battery is 3135 mah =20 Don Brown KD5NDB ----- Original Message ----- From: Steve Jackson Sent: Wednesday, June 19, 2002 7:23 AM To: elecraft at mailman.qth.net Subject: [Elecraft] AA primary cell (K1 related) capacity Does anyone know what a modern alkaline AA-size primary cell is rated for= , in Ampere-hours? Ttrying to do some back-of-an-envelope comparisons betw= een 1800 mAh NiMH cells and Duracell/Energizer class cells. TIA 73 Steve KZ1X/4 K1#1181 K2# 771 +++++++++++++++ Date: Wed, 19 Jun 2002 08:43:53 -0400 From: "Mark J. Dulcey" To: Steve Jackson Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] AA primary cell (K1 related) capacity Steve Jackson wrote: > Does anyone know what a modern alkaline AA-size primary cell is rated for, > in Ampere-hours? Ttrying to do some back-of-an-envelope comparisons between > 1800 mAh NiMH cells and Duracell/Energizer class cells. One site I checked claimed 2800 mAh. Other sites seem to give numbers in the same neighborhood. However, alkaline batteries aren't nearly as good at handling high current rates as NiCd or NiMH, so the capacity drops faster at high discharge rates. Here's a page with a link to a chart that shows the effect: http://www.greenbatteries.com/documents/Battery_FAQ.htm The net result is that an alkaline pack would probably outlast a good NiMH pack by about 50% in receive-only use, but might actually last LESS time if used for a session that included a lot of transmitting. +++++++++++++++++++++ From: "Rod N0RC" To: "Steve Jackson" , Subject: Re: [Elecraft] AA primary cell (K1 related) capacity Date: Wed, 19 Jun 2002 06:50:28 -0600 Steve, ANS: ~2.5 mAh (for Energizer A91 AA) Source: http://data.energizer.com/ follow the data sheet link. Cells from other manufactures are similar. The actual realized capacity is a function of discharge profile, (continuous vs intermittent use for example). The major battery manufactures have a wealth of detailed technical data on the websites. Follow technical/engineering/OEM links. 73, Rod N0RC ++++++++++++++++++++ From: "Rod N0RC" To: "Steve Jackson" , Subject: Re: [Elecraft] AA primary cell (K1 related) capacity Date: Wed, 19 Jun 2002 07:01:40 -0600 Folks, The Duracell people have a thorough tech bulletin (13 page PDF format) available at: http://www.duracell.com/oem/Pdf/others/ATB-full.pdf Everything you could possibly want to know about their alkaline manganese dioxide chemistry batteries. You can view it on line in HTML format at: http://www.duracell.com/oem/Primary/Alkaline/alkaline_manganese_tech.a sp 73, Rod N0RC ++++++++++++++++++++++ From: "Don Brown" To: "Elecraft" Subject: Re: [Elecraft] AA primary cell (K1 related) capacity Date: Wed, 19 Jun 2002 09:30:00 -0500 Hi Yes you are correct about alkaline batteries and high currents. Here is a= site that goes into great detail on the testing of batteries in high cur= rent demand applications. Note how the alkaline batteries compare to the = NiMh. =20 http://www.imaging-resource.com/ACCS/BATTS/BATTS.HTM The performance of NiMh batteries is also very dependant on the charger u= sed. The Maha c204f is the one I use and it works very well although it w= ill only charge 4 at a time in about 3 hours. At only $23 each you could = buy two. The ultimate is the Maha MH-C777+ this charger will charge just = about any battery pack up to 12 cells NiCad NiMh NiLion. http://www.mahapowerex.com/maha-mh-c204f.htm http://www.mahapowerex.com/mh-c777plus.htm Don Brown KD5NDB ++++++++++++++++++++ Date: Wed, 19 Jun 2002 11:26:21 -0500 To: From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: Re: [Elecraft] AA primary cell (K1 related) capacity Check out: http://www.mrnicd-ehyostco.com/ for 2000mAH AA NiMH cells and they have a new charger, too! http://www.mrnicd-ehyostco.com/new_page_2.htm At 09:30 AM 6/19/02, Don Brown wrote: >Hi > >Yes you are correct about alkaline batteries and high currents. -- snip -- ++++++++++++++++++++ From: "Steve Jackson" To: "Mark J. Dulcey" Cc: Date: Wed, 19 Jun 2002 13:08:47 -0400 Subject: [Elecraft] AA primary cell (K1 related) capacity planning ----- Original Message ----- From: "Mark J. Dulcey" > ... alkaline batteries aren't nearly as good at handling high > current rates as NiCd or NiMH, so the capacity drops faster at high > discharge rates. The net > result is that an alkaline pack would probably outlast a good NiMH pack > by about 50% in receive-only use, but might actually last LESS time if > used for a session that included a lot of transmitting. Now, we're on to the heart of the matter, Mark. Here goes: My K1 on RX is in the vicinity of a 60 mA load. Battery cost aside (a tradeoff for portable convenience) ... for receive purposes, it seems as if the alkaline cells make the best choice. Now, certainly, I'll try and transmit, too! Figure I have the K1 set to 3 Watts, for example. I am guessing the draw at this power level (at 12VDC) is about a half-amp. That's much less than a digital camera draws, and in a less onerous duty-cycle. The advantage again may well tilt towards the alkalines. My NiMH charger does a GREAT job, but handles only 4 AA cells at a time. If it takes, say, 2 hours to charge one set of 1800 mAh NiMH cells, that's a minimum of 4 hours to bring two sets back from the discharge state. Eight new NiMH cells of this rating would cost me about $25 at a hamfest, 2x that mail order. Duracell AA size costs about $1 each at discount retail; that's $8.50 with tax for an 8-cell pack that may well last 30% longer than an equivalent NiMH charged set. Not counting the sunk cost of the 4-cell NiMH charger I already have, and discounting the inconvenience factor (and the environmental impact of many dead alkaline cells), I see the apples-to-apples breakeven point at about 4 use cycles. While this seems like a good argument for rechargeables, I'm still not 100% convinced. Am I missing some key coefficient here, guys (& gals)? Battery power is an issue for QRP operators everywhere, so I appreciate the only slightly tangential bandwidth this thread is using up. Nowhere else can you find an assembly of the sort of analysis brainpower that this reflector brings to bear. Steve KZ1X/4 ... looking at my K1 which has a fresh set of Energizers in it, but no antenna hooked up +++++++++++++++++++ Date: Wed, 19 Jun 2002 10:56:10 -0700 From: Wayne Burdick Organization: Elecraft To: Steve Jackson Cc: "Mark J. Dulcey" , elecraft at mailman.qth.net Subject: [Elecraft] AA primary cells: NiMH vs. Alkaline Steve, When we first started demonstrating the K1 with the KBT1, we were using Alkalines. We'd get maybe one full day out of a fresh pack. Then we switched to NiMH cells, and we'd get three days! The problem with Alkalines, as alluded to earlier, is that they have a sloping discharge curve. They'll drop to the K1's regulation threshold--about 1.05 volts per cell (8.4 V total for the pack)--long before they are fully discharged. In fact the mAHr rating on Alkalines is usually based on discharge to 0.9 volts per cell! Below 1.05 volts/cell they'll be nearly useless for transmitting, because their internal resistance will have increased significantly. There will be a large voltage drop when you try to transmit. NiMH cells, in contrast, will sit between 1.125 and 1.25 volts per cell for about 90% of their charge life, and even up to the 95% discharge point they'll be usable on transmit because their internal resistance stays low. This translates to more operating time. This alone would favor the NiMH cells, but when you factor in 500-1000 recharge cycles, they're much more cost effective, too. Besides your K1, you can use them in most consumer products, HTs, etc., so the initial expense of the cells and charger will quickly be reclaimed. Over a year ago I bought 16 NiMH cells and the Radio Shack 8 cell AA fast-charger, and I haven't purchased a single AA cell since. So in my opinion, there's no comparison: if you're using 8 cells, as with the KBT1, the NiMH cells win. Alkalines are OK if you're in a hurry and need some charged cells quickly, or perhaps as a backup pack. 73, Wayne N6KR ++++++++++++++++++++ Date: Wed, 19 Jun 2002 21:12:57 +0000 To: elecraft at mailman.qth.net From: Larry Cahoon Subject: Re: [Elecraft] AA primary cell (K1 related) capacity planning At one point I was doing some direct comparisons of the NiMN and the alkaline batteries. These were mostly in the Rx mode over several days. They came out pretty much even with that type of use. So I'm convinced that with more TX time the NiMH are the way the go. You do have to make sure they are freshly charged. Let them sit for a couple of weeks and lose some of their advantage. The battery page is at http://www.wd3p.net/qrp/batteries/battery_index.htm That page reflect my feeling on batteries in general. There are two links there to the actual results of the testing. There is also a link to AE5X's page there. He has also done some battery testing in the field. If you go to my home page there is a link to what I did in the NA QSO party last January using a set of NiMH batteries - 200+ QSOs running 2 or 3 watts with a K1, K2, and a Sierra. 73 de Larry.........WD3P in MD http://www.wd3p.net/ ++++++++++++++++++ Date: Wed, 19 Jun 2002 15:39:04 -0700 From: Wayne Burdick Organization: Elecraft To: Phil Wheeler Cc: "Wallace, Andy" , elecraft at mailman.qth.net Subject: [Elecraft] Re: AA primary cells: NiMH vs. Alkaline Phil Wheeler wrote: > >Note that we recommend using 3-4 watts when running from internal > >battery, because best PA collector efficiency at 9 to 10 volts occurs at > >a lower power level than at 12-14 V. > > > > I often use a battery pack which has 10 NiMH AAs in series. Would a > different power recommendation apply? Best efficiency would be somewhat higher with 10 cells rather than 8, but still, the lower the power output, the longer the batteries will last. You can drop power during a QSO if you think it won't impact readability. Wes Hayward is a big fan of the 0.5-watt level, although to do that efficiently with a 5-watt class transmitter you'd have to bypass the PA stage and run from the driver. > Also, aside from the cost, would Lithium AAs work well for this > application? The thrust of the question is there are situations (e.g., > backpacking) where the weight savings and the low-temp characterisitics > of Li cells can make them worth the cost. The weight saved by using Lithiums would be at most a couple of ounces. Since the rig, antenna, key, log, and batteries weigh upwards of 32 ounces, this probably isn't a good tradeoff. More likely someone trying to reduce weight to a minimum would start with a completely stripped, optimized monobander such as the Wilderness SST, *and* use lithium or LiIon batteries. Such rigs routinely finish at the top of the heap in the ARS "Spartan Sprints," proving that they're effective for communication despite their lack of frills. (Non-Impartiality Alert: I designed the SST :) Wayne ++++++++++++++++ Date: Wed, 19 Jun 2002 22:16:56 -0500 To: Phil Wheeler From: Dave Gingrich K9DC Subject: Re: [Elecraft] Re: AA primary cells: NiMH vs. Alkaline Cc: elecraft at mailman.qth.net At 15:04 6/19/2002 -0700, Phil Wheeler wrote: >Also, aside from the cost, would Lithium AAs work well for this >application? The thrust of the question is there are situations (e.g., >backpacking) where the weight savings and the low-temp characterisitics of >Li cells can make them worth the cost. Yes. I use 8 energizer L91 Photo Lithium AA. Voltage on these guys is high, over 13v if new, and they last forever Rated 2.9 ah. They can supply up to 1.4 amps so well suited to the K1. Except the cost as you mentioned. Best price I've seen is about $10 per 4-pack at Wal-Mart. ================================================ Dave Gingrich, K9DC - Indianapolis, Indiana USA ++++++++++++++++++ From: kevinrock at earthlink.net To: elecraft at mailman.qth.net Date: Fri, 21 Jun 2002 13:05:17 -0600 Subject: [Elecraft] Battery Information I am reposting this from the QRP-Solar list : This link is to a very interesting web site for a book by Isidor Buchmann. "Batteries in a Portable World A Handbook on Rechargable Batteries for Non-Engineers, 2nd Edition" http://www.buchmann.ca/default.asp 72, Kevin. +++++++++++++++++++++