Post by thread:Battery rate data and sale, was "Formula previousl

A few helpful comments (Pseudo battery expert...FWIW) In the recent postings I have noticed that the AA cells are underated, For Alkaline in recent and past tests this cell to 0.9V/ cell using 4 of them for 3.6 volts min and 6.2 volts max 1.55 V cell start. These consistently provide 1.7 Amphours. at 12 mA drain rate, the low dropout 3.3v regulator really helps. If they are "older" shelfed for 6 months this is 1.6AHr. Industrial NiMH AA cells provide 1.4 and 1.5 AHrs (buttoned) and solder tabbed, I have these and they really pour out the storage and the Ultra High Watts/Litre. Most folks do not know that the "A" fat cell (18mm dia and 57mm long) made by Sanyo (NiMH) has a whopping calculated 390 Watts/Litre... There is the little brother the 17 mm diameter that has a 3.8 AHr rating that is commonly used in Laptops in last 3-4 years. L ion is lighter has less cycles and not that much advantage in volume, only by weight. I do have 12 of these 17mm dia cells with solder tabs that have never been used (5 months old). If any piclister is interested they are 4$/per and the /schematic and charge circuit is at MAXIM using the MAX2003 or MAX713 in NiMH setting for voltage. They have 900 typical full cycles and really pour out the power for those that use PIC to control "physical things". The Industrial AA NiCad provide 850-1000mAHr rating. The Alkaline 9V Battery provides 300-200 mAHr of power. This is scaled from AAAA is 1/2 of AAA is 1/2 of AA. I like Alkaline D cells and F cells best bang for buck in primary cells. Eriuc Borcherding

Most folks do not know that the "A" fat cell (18mm dia and 57mm long) made by Sanyo (NiMH) has a whopping calculated 390 Watts/Litre... Isn't that 4/3A ? At least, they're about twice the length of the 2/3A lithium camera batteries? L-ion is lighter has less cycles and not that much advantage in volume, only by weight. By Amp-hour, or watt hour? Don't forget that the Li-ion cells have 3x the voltage of a NiCd. From an electronics perspective, the output voltage (from a single cell) is enough to power many circuits directly, which is quite nice... BillW

>In the recent postings I have noticed that the AA cells are underated, For >Alkaline >in recent and past tests this cell to 0.9V/ cell using 4 of them for 3.6 volts >min and >6.2 volts max 1.55 V cell start. These consistently provide 1.7 Amphours. at >12 mA drain rate, the low dropout 3.3v regulator really helps. If they are >"older" >shelfed for 6 months this is 1.6AHr. 1700mAh? Am I reading this wrong? AA batteries? My 3.6 Li-Ion battery for my minidisc outputs 1700mAh... Or is it the NiMH AA's you're talking about? Slightly confused, -greg ----------------------- Greg Cormier, age 17 Canadian living abroad in Kathmandu, Nepal Digital electronics, programming, computer interfacing, microcontrollers Local time : GMT + 5h30m spam_OUTgcormierTakeThisOuTwlink.com.np ICQ # : 565465

unsubscribe * netwide end -----Original Message----- From: Greg Cormier <.....gcormierKILLspam@spam@WLINK.COM.NP> To: PICLISTKILLspamMITVMA.MIT.EDU <.....PICLISTKILLspam.....MITVMA.MIT.EDU> Date: Monday, February 01, 1999 5:23 PM Subject: Re: Battery rate data and sale, was "Formula previously" >>In the recent postings I have noticed that the AA cells are underated, For >>Alkaline >>in recent and past tests this cell to 0.9V/ cell using 4 of them for 3.6 volts >>min and >>6.2 volts max 1.55 V cell start. These consistently provide 1.7 Amphours. at >>12 mA drain rate, the low dropout 3.3v regulator really helps. If they are >>"older" >>shelfed for 6 months this is 1.6AHr. > >1700mAh? Am I reading this wrong? AA batteries? My 3.6 Li-Ion battery for >my minidisc outputs 1700mAh... Or is it the NiMH AA's you're talking about? {Quote hidden}> >Slightly confused, >-greg > >----------------------- >Greg Cormier, age 17 >Canadian living abroad in Kathmandu, Nepal >Digital electronics, programming, computer interfacing, microcontrollers >Local time : GMT + 5h30m >EraseMEgcormierspam_OUTTakeThisOuTwlink.com.np >ICQ # : 565465

The NiMHs are A long, A short, and A fat (only in long) as a common reference. The dimensions were given. Try to buy some rechagable L ion cells and you will have to arm wrestle (serious, like give us charger design and prove to us you are worthy like you have the liabilty insurance necessary when they blow up) William, Look into the cost by power density volume and cycles and NiMH clearly still wins. Try to get a L ion to match a 4 AHr NiMH in a single cell or power balance paralled L ions (a no no). Nicads in the F Cell range still carry the highest consumer reachable single cell power storage and can last over 10 years and 2000 cycles I have designs that are running from 1989 with this cell - it is quite the champ. Match that with L ion - NOT POSSIBLE. for less than >10K; this cell is 24$. The 4/3 A cell has the >same power as a L ion cell. 1.25V x 4A vs 3.6V x 1.35A or 5 to 4.86 and much cheaper. Eric Borcherding

Try to buy some rechagable L ion cells and you will have to arm wrestle (serious, like give us charger design and prove to us you are worthy like you have the liabilty insurance necessary when they blow up) I'm dumpster-diving Li-ION battery packs from laptops. When you work at a company with a couple thousand laptop users, and mandated recharhable battery recycling, it's pretty easy to find a couple packs if you make the rounds and look. I was betting that Li-ION packs were like NiCds, and that a dead pack still contains some usable cells. So far, this seems to be true. Many of the cells in a pack still have 4V on them. One pack in particular had three sets of 3 A-long cells in serial/parallel configuration, with ONE set "reverse charged" to actual negative voltage, while the other sets still showed 4V. One cell from the bad set seems to have CC charged (~100mA) to a reasonable capacity. Try to get a L ion to match a 4 AHr NiMH in a single cell or power balance paralled L ions (a no no). BTW: standard configuration for these packs is 10.8V at 3.4AH, in the above mentioned 3x3 wiring scheme, with assorted amounts of electronics. The parallel wiring is hard - spot welded metal strips (I didn't think you could do that with rechargables either!) Looks like there is electronics in the series wiring, though. I understand that I won't get great life, and probably not full power, out of such "recycled" cells. However, you can change your way of looking at things when you're getting the batteries for free. Thanks for the info on NiMH. I believe you that the power density is higher, I just wasn't sure. I really dis-like NiMH's self-discharge behavior, and LiIon does very much better in that area. BillW

>I'm dumpster-diving Li-ION battery packs from laptops. When you work at a >company with a couple thousand laptop users, and mandated recharhable >battery recycling, it's pretty easy to find a couple packs if you make the >rounds and look. I was betting that Li-ION packs were like NiCds, and that >a dead pack still contains some usable cells. You know the charge voltage has to be set to 1% tolerance, right?

You know the charge voltage has to be set to 1% tolerance, right? I have heard that (actually, I think I heard 0.5%) At the moment I'm mostly looking at chip sets. I fully believe that for maximum charge in minimum time, and for maximum cell lifetime, you have to follow some very stringent charging regimes. I'm not sure what you can get away with if you're willing to settle for a partial charge overnight (already, someone here has claimed that you can charge them at C/10 indefinately) or reduced cell lifetime. In any case, I'm being quite careful. It seems quite unlikely that a 10-50mA charge current would cause a 4/3A cell to explode or even burst into flames - you'd have to have some an internal catastrophy to get "access" to the cell charge, since 200 mW or so won't even heat that size of a package appreciably... BillW

If you overcharge the cells and do not have proper pack protection they can fail rather spectacularly. At the Microchip Masters conference one of the engineers mentioned they had a pack explode rather violently when they intentionally defeated the protection circuits and overcharged a pack in a test. I have designed a charger for a client of mine and the tolerances are tight to get the maximum energy out while not reducing the cycle life. All the cells are in packs with protection circuits built in. At 12:17 AM 2/2/99 PST, you wrote: {Quote hidden}> You know the charge voltage has to be set to 1% tolerance, right? > >I have heard that (actually, I think I heard 0.5%) At the moment I'm >mostly looking at chip sets. > >I fully believe that for maximum charge in minimum time, and for maximum >cell lifetime, you have to follow some very stringent charging regimes. I'm >not sure what you can get away with if you're willing to settle for a >partial charge overnight (already, someone here has claimed that you can >charge them at C/10 indefinately) or reduced cell lifetime. In any case, >I'm being quite careful. It seems quite unlikely that a 10-50mA charge >current would cause a 4/3A cell to explode or even burst into flames - you'd >have to have some an internal catastrophy to get "access" to the cell >charge, since 200 mW or so won't even heat that size of a package >appreciably... > >BillW > > Larry G. Nelson Sr. L.Nelsonspam_OUTieee.org http://www.ultranet.com/~nr