Post by thread:[EE] Battery suggestions?

I'm looking for a battery for a (hobby) project, and I'd be interested in any suggestions. Requirements (most are flexible): * Needs to be quite small; the usual AA/AAA are a bit bigger than I'd like. Something about the size of a CR2032 would be great, but could be a bit bigger. * Current needs are 5-10mA continuously (a small PIC and other bits), with regular short bursts of about 30-50mA (driving a 40kHz ultrasonic transducer). The battery would ideally last at least half an hour. * This project may occasionally be dropped, possibly from ~10 feet. It's not a disaster if a removable battery comes out at impact, but I'd hope it wouldn't be too damaged. * Preferably rechargeable, so I don't have to keep buying more batteries. I'd be willing to build a simple charger (eg with an easy-to-use IC) for it. * Unless it's 5-6V (regulated down for the PIC), I'll need to work out how to boost it to drive the tansducer with ~10V peak-to-peak. Now that I write it down it sounds pretty difficult to achieve! I'd appreciate any suggestions. Regards, Chris

A LiIon might be located (3.6V) that could be boosted to 5V regulated. There MIGHT be a paper-thin NiMH, but I doubt it. A CR2032 can't even deliver 10mA. A 10' drop is a very heavy drop! Not many products will survive that, except the older Fluke meters. Chris Emerson wrote: {Quote hidden}>I'm looking for a battery for a (hobby) project, and I'd be interested >in any suggestions. > >Requirements (most are flexible): >* Needs to be quite small; the usual AA/AAA are a bit bigger than I'd >like. Something about the size of a CR2032 would be great, but could be >a bit bigger. > >* Current needs are 5-10mA continuously (a small PIC and other bits), >with regular short bursts of about 30-50mA (driving a 40kHz ultrasonic >transducer). The battery would ideally last at least half an hour. > >* This project may occasionally be dropped, possibly from ~10 feet. >It's not a disaster if a removable battery comes out at impact, but I'd >hope it wouldn't be too damaged. > >* Preferably rechargeable, so I don't have to keep buying more >batteries. I'd be willing to build a simple charger (eg with an >easy-to-use IC) for it. > >* Unless it's 5-6V (regulated down for the PIC), I'll need to work out >how to boost it to drive the tansducer with ~10V peak-to-peak. > >Now that I write it down it sounds pretty difficult to achieve! I'd >appreciate any suggestions. > >Regards, > >Chris > > -- Note: To protect our network, attachments must be sent to spam_OUTattachTakeThisOuTengineer.cotse.net . 1-520-850-1673 USA/Canada http://beam.to/azengineer

> * Needs to be quite small; the usual AA/AAA are a bit bigger > than I'd like. Something about the size of a CR2032 would be > great, but could be a bit bigger How about a couple of AAAA alkaline ? 3.65V, 625mAh, can be boosted to the PIC's Vdd (do you really need 5V for that ?) and 10V-ish with a simple oscillator

On Mon, Jan 30, 2006 at 10:13:31PM +1300, Jinx wrote: > > * Needs to be quite small; the usual AA/AAA are a bit bigger > > than I'd like. Something about the size of a CR2032 would be > > great, but could be a bit bigger > > How about a couple of AAAA alkaline ? 3.65V, 625mAh, Ooh, I hadn't heard of AAAAs. They look like thinner AAAs, though, and it's the length that's the problem (which I hadn't specified earlier). It wants to fit into the smallest sphere possible, IYSWIM. You've reminded me of N batteries though, which I think are roughly half-length AA. > can be boosted to the PIC's Vdd (do you really need 5V for that ?) and > 10V-ish with a simple oscillator No, I don't need 5V for the PIC, as long as it can still drive the transducer at a higher voltage. Thanks, Chris

On Mon, Jan 30, 2006 at 01:46:26AM -0700, Bob Axtell wrote: > A LiIon might be located (3.6V) that could be boosted to 5V regulated. Hmm, a quick look through Farnell didn't show any below 20 UKP (~$30). > There MIGHT be a paper-thin NiMH, but I doubt it. It doesn't have to be paper thin (sorry for unclear specs). A half-inch-thick button-cell would be just fine, I mostly worried about the size of a sphere the whole device could fit into. > A 10' drop is a very heavy drop! Not many products will survive that, > except the older Fluke meters. Hopefully a combination of padding, potting compound, and being careful will do. Thanks, Chris

On 1/30/06, Chris Emerson <.....picKILLspam@spam@nosreme.org> wrote: > You've reminded me of N batteries though, which I think are roughly > half-length AA. If N batteries are what I think they are, then they are 12V cells which can deliver at most 10 mA. I have similar batteries at home inside professional active microphones. I once opened up an empty battery, and it contained 6 button cells with unusual dimensions. Mark

On Mon, Jan 30, 2006 at 04:59:35PM +0100, Mark Jeronimus wrote: > On 1/30/06, Chris Emerson <picKILLspamnosreme.org> wrote: > > You've reminded me of N batteries though, which I think are roughly > > half-length AA. > > If N batteries are what I think they are, then they are 12V cells which can > deliver at most 10 mA. I have similar batteries at home inside professional > active microphones. I once opened up an empty battery, and it contained 6 > button cells with unusual dimensions. No, N batteries are 1.5V alkalines. I know the 12V ones you mean, often used in security keyfobs. Regards, Chris

If you're looking for an unusual battery, Kokam makes a very small LiPol cell. This is sold by FMA Direct (http://www.fmadirect.com/) The last three at the bottom of this page may be of interest: www.fmadirect.com/products.htm?cat=33&nid=3 -- D. Jay Newman ! Author of: .....jayKILLspam.....sprucegrove.com ! _Linux Robotics: Building Smarter Robots_ http://enerd.ws/robots/ ! (Now I can get back to building robots.)

On Jan 30, 2006, at 5:26 AM, Chris Emerson wrote: > * Needs to be quite small; the usual AA/AAA are a bit bigger > than I'd like. Something about the size of a CR2032 would be > great, but could be a bit bigger There are lithium polymer cells in that size range that deliver ~100 mAH and up to several hundred mA. Expensive, but they sound spot-on to your requirements. Subject to requirements for careful charging if you don't want them to burst into flames... Representative listing: http://www.bsdmicrorc.com/products.cfm?catID=10001 BillW

On Jan 30, 2006, at 8:40 AM, William Chops Westfield wrote: > > There are lithium polymer cells in that size range > Representative listing: > http://www.bsdmicrorc.com/products.cfm?catID=10001 > There are some UK distributers as well. Here's one: http://www.indoorflyer.co.uk/index.asp?function=DISPLAYCAT&catid=31 BillW

On Mon, Jan 30, 2006 at 12:19:32PM -0500, David VanHorn wrote: > I just worked with a fun li-po cell, roughly the size of a buisness card, > and 10 mils thick. > 200mAh, and would withstand 200 mA drain without loosing too much capacity. > > Pretty soon, the battery will be the wing covering! Is it safe to say that ultra-thin and flat cells like that one are able to provide higher currents relative to their size in general? I'm assuming that they would make for higher surface areas of the reactants, but that's just my intuition. -- EraseMEpetespam_OUTTakeThisOuTpetertodd.ca http://www.petertodd.ca

N cells are short AA type cells at 1.5V. I use them in my HP41CV calculator. Larry ---- Mark Jeronimus <zombie.piclistspam_OUTgmail.com> wrote: > On 1/30/06, Chris Emerson <@spam@picKILLspamnosreme.org> wrote: > > You've reminded me of N batteries though, which I think are roughly > > half-length AA. > > If N batteries are what I think they are, then they are 12V cells which can > deliver at most 10 mA. I have similar batteries at home inside professional > active microphones. I once opened up an empty battery, and it contained 6 > button cells with unusual dimensions. > > Mark > --

On 1/30/06, Chris Emerson <KILLspampicKILLspamnosreme.org> wrote: > * Unless it's 5-6V (regulated down for the PIC), I'll need to work out > how to boost it to drive the tansducer with ~10V peak-to-peak. Can you bridge the transducer across two outputs and drive them out-of-phase? That will double the voltage the transducer sees. Regards, Mark markrages@gmail -- You think that it is a secret, but it never has been one. - fortune cookie

> > Is it safe to say that ultra-thin and flat cells like that one are able > to provide higher currents relative to their size in general? I'm > assuming that they would make for higher surface areas of the reactants, > but that's just my intuition. Pulse current yes. This one used some special electrode treatments to get more power than normal. In the end, for total watt-hours, it all comes down to what reactants you're using, and their mass.

On Jan 30, 2006, at 10:26 AM, Peter Todd wrote: > Is it safe to say that ultra-thin and flat cells like that one > are able to provide higher currents relative to their size in > general? I don't think so. In the Li-ion realm, I think even the cylinder cells are essentially wound up spools of thin ribbon-like electrodes. (that probably explains why Li-ion cells have such impressive current delivery capability, especially if you don't care about wrecking them.) (says so explicitly here: <http://www.panasonic.com/industrial/battery/oem/images/pdf/ Panasonic_LiIon_Overview.pdf>) BillW

> You've reminded me of N batteries though, which I think are > roughly half-length AA How about two of these ? http://www.rsnewzealand.com Product code 2636033 NiMH, 12mm long x 17mm diameter, 2.4V, 80mAh If this is a one-off, perhaps take something apart and use the bits - like a cell-phone battery pack ?

On Tue, Jan 31, 2006 at 10:33:09AM +1300, Jinx wrote: > > You've reminded me of N batteries though, which I think are > > roughly half-length AA > > How about two of these ? > > http://www.rsnewzealand.com > > Product code 2636033 > > NiMH, 12mm long x 17mm diameter, 2.4V, 80mAh Ooh, they look like just the ticket, and quite reasonably priced. Thanks! Chris

>> There MIGHT be a paper-thin NiMH, but I doubt it. > >It doesn't have to be paper thin (sorry for unclear specs). >A half-inch-thick button-cell would be just fine, I >mostly worried about the size of a sphere the whole >device could fit into. A replacement rechargeable battery for a PC Bios? There were a few that used small nicad cells, and IIRC some were two or 3 cell button types.