From: Alec W. <ale...@da...> - 2006-09-08 15:11:25
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Hi all, This page: http://docwiki.gumstix.org/Batteries ..says that using four AA NiMHs is the way to go. I was under the impression that the max input voltage for the gumstix was 5v - won't this configuration give you 6v? BTW - I'm not saying at all that I think it's wrong, I just want to understand why it's OK, and why it's preferable to three batteries. Also, about a year ago, there was a thread about using a supercap in parallel with alkaline AAA batteries. I'm waaay out of my depth here, but would such a thing benefit NiMH batteries too? many thanks, alec -- Alec Waters CCNP Dataline Software Ltd Clarence House, 30-31 North Street, Brighton, BN1 1EB, UK Tel: +44 (0)1273 324939 Fax: +44 (0)1273 205576 www: http://www.dataline.co.uk IPv6: http://www.ipv6.dataline.co.uk |
From: Brad M. <bmi...@xm...> - 2006-09-08 15:47:24
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Alec > http://docwiki.gumstix.org/Batteries > > ..says that using four AA NiMHs is the way to go. I was under the > impression that the max input voltage for the gumstix was 5v - won't > this configuration give you 6v? I wrote that and I might also be out of my depth, but nimh aa batteries are 1.2v so I figured four was a better setup. > Also, about a year ago, there was a thread about using a supercap in > parallel with alkaline AAA batteries. I'm waaay out of my depth here, > but would such a thing benefit NiMH batteries too? ah yes I meant to get back with the supercap specs. I'm actually not sure about nimh. they don't have the high internal resistance that makes the supercap good for alkaline. brad |
From: Alec W. <ale...@da...> - 2006-09-08 16:01:41
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Hi Brad, > I wrote that and I might also be out of my depth, but nimh aa batteries > are 1.2v so I figured four was a better setup. D'oh! 1.2v, not 1.5v. Makes sense now :) > ah yes I meant to get back with the supercap specs. I'm actually not > sure about nimh. they don't have the high internal resistance that makes > the supercap good for alkaline. OK. thanks very much, alec -- Alec Waters CCNP Dataline Software Ltd Clarence House, 30-31 North Street, Brighton, BN1 1EB, UK Tel: +44 (0)1273 324939 Fax: +44 (0)1273 205576 www: http://www.dataline.co.uk IPv6: http://www.ipv6.dataline.co.uk |
From: Alexandre P. N. <al...@om...> - 2006-09-08 16:11:13
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Alec Waters escreveu: >Hi Brad, > > > >>I wrote that and I might also be out of my depth, but nimh aa batteries >>are 1.2v so I figured four was a better setup. >> >> > >D'oh! 1.2v, not 1.5v. Makes sense now :) > > 1.2v x 3 = 3.6v, which works but the bare minimum for gumstix is 3,4v, since nimh drops voltage fast as it discharges (as opposed as li-ion, at least), that means gumstix would shutdown when batteries still had a long way to discharge. 1.2v x 4 = 4.8v , which wastes a little extra power as heat (because of the voltage regulators), but will probably allow you to go all the way down the discharge cycle of the batteries. >>ah yes I meant to get back with the supercap specs. I'm actually not >>sure about nimh. they don't have the high internal resistance that makes >>the supercap good for alkaline. >> >> > >OK. > >thanks very much, >alec > > I remember reading some posts a long ago about that, I think I asked the same question myself, it seems like he is correct, the alkaline batts suffers if the load switches too much (the processor runs based on clocking, every clock cycle it does some work and that requires power, it idles between cycles and apparently this kind of battery doesn't appreciate that. It seems that nimh does fine). - Alexandre |
From: John A. <jal...@sp...> - 2006-09-08 17:45:53
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I'm planning to used 4xNiMH also, however I have found that I get well over 5V from 4xNiMH immediately after charging. In order to keep the supply voltage down to a better level I'm planning to use a voltage regulator to bring the supply down to 4V. I'm in the process of soldering everything up right now. The whole voltage supply aspect got me bogged down in planning my project. The main problem was the two voltages needed for the SONY LCD (3.8 and 3.0). >From the SONY datasheet, the acceptable ranges for Vcc1 and Vcc2 do not overlap, so at least for the LCD I needed to provide two voltage levels. I then decided to use a separate regulator for the gumstix so I wasn't combining higher current and lower current devices on the same regulator. I haven't seen anything to say this is necessary; however I also wanted to make the LCD modular so I could add/remove it independent of power supply considerations. I now realize, getting only this far with my project, that the power supply stuff is an important area in and of itself, and I suspect that a power supply strategy should be part of an initial project design. The MAXIM/ti websites have a bewildering number of power mgmt devices to choose from, however knowing what's appropriate for a given application is not obvious. In my case I'm trying to build a modular system where I can add/remove peripherals, which I design, without disrupting the functioning of the underlying gumstix platform. As I learn more about power supply/mgmt I plan to update my system--application specific voltage regulators, fuel gauge, etc. I'd like to hear how other gumstix'rs are designing the power supply/mgmt aspect of their projects. John Alfredo -----Original Message----- From: gum...@li... [mailto:gum...@li...] On Behalf Of Alexandre Pereira Nunes Sent: Friday, September 08, 2006 8:11 AM To: General mailing list for gumstix users. Subject: Re: [Gumstix-users] 3x or 4x NiMH AAs? Alec Waters escreveu: >Hi Brad, > > > >>I wrote that and I might also be out of my depth, but nimh aa batteries >>are 1.2v so I figured four was a better setup. >> >> > >D'oh! 1.2v, not 1.5v. Makes sense now :) > > 1.2v x 3 = 3.6v, which works but the bare minimum for gumstix is 3,4v, since nimh drops voltage fast as it discharges (as opposed as li-ion, at least), that means gumstix would shutdown when batteries still had a long way to discharge. 1.2v x 4 = 4.8v , which wastes a little extra power as heat (because of the voltage regulators), but will probably allow you to go all the way down the discharge cycle of the batteries. >>ah yes I meant to get back with the supercap specs. I'm actually not >>sure about nimh. they don't have the high internal resistance that makes >>the supercap good for alkaline. >> >> > >OK. > >thanks very much, >alec > > I remember reading some posts a long ago about that, I think I asked the same question myself, it seems like he is correct, the alkaline batts suffers if the load switches too much (the processor runs based on clocking, every clock cycle it does some work and that requires power, it idles between cycles and apparently this kind of battery doesn't appreciate that. It seems that nimh does fine). - Alexandre ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ gumstix-users mailing list gum...@li... https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: Tom G. <to...@gp...> - 2006-09-10 17:42:11
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When I charge 4xAA or AAA NiMH batteries, I get as high as 5.4v out of the chute. Is this over voltage of half a volt going to cause any problems? Likewise, is there any danger letting the unit run down - 4v, 3.5v, etc? TG -----Original Message----- From: gum...@li... [mailto:gum...@li...] On Behalf Of Alec Waters Sent: Friday, September 08, 2006 9:01 AM To: General mailing list for gumstix users. Subject: Re: [Gumstix-users] 3x or 4x NiMH AAs? Hi Brad, > I wrote that and I might also be out of my depth, but nimh aa batteries > are 1.2v so I figured four was a better setup. D'oh! 1.2v, not 1.5v. Makes sense now :) > ah yes I meant to get back with the supercap specs. I'm actually not > sure about nimh. they don't have the high internal resistance that makes > the supercap good for alkaline. OK. thanks very much, alec -- Alec Waters CCNP Dataline Software Ltd Clarence House, 30-31 North Street, Brighton, BN1 1EB, UK Tel: +44 (0)1273 324939 Fax: +44 (0)1273 205576 www: http://www.dataline.co.uk IPv6: http://www.ipv6.dataline.co.uk ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ gumstix-users mailing list gum...@li... https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: G E. <gel...@gm...> - 2006-09-11 19:52:45
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bump On Sep 10, 2006, at 10:41 AM, Tom Gonser wrote: > When I charge 4xAA or AAA NiMH batteries, I get as high as 5.4v out > of the > chute. Is this over voltage of half a volt going to cause any > problems? > Likewise, is there any danger letting the unit run down - 4v, 3.5v, > etc? > > TG > > -----Original Message----- > From: gum...@li... > [mailto:gum...@li...] On Behalf Of Alec > Waters > Sent: Friday, September 08, 2006 9:01 AM > To: General mailing list for gumstix users. > Subject: Re: [Gumstix-users] 3x or 4x NiMH AAs? > > Hi Brad, > >> I wrote that and I might also be out of my depth, but nimh aa >> batteries >> are 1.2v so I figured four was a better setup. > > D'oh! 1.2v, not 1.5v. Makes sense now :) > >> ah yes I meant to get back with the supercap specs. I'm actually not >> sure about nimh. they don't have the high internal resistance that >> makes >> the supercap good for alkaline. > > OK. > > thanks very much, > alec > -- > Alec Waters CCNP > Dataline Software Ltd > Clarence House, 30-31 North Street, Brighton, BN1 1EB, UK > > Tel: +44 (0)1273 324939 > Fax: +44 (0)1273 205576 > www: http://www.dataline.co.uk > IPv6: http://www.ipv6.dataline.co.uk > > > > ---------------------------------------------------------------------- > --- > Using Tomcat but need to do more? Need to support web services, > security? > Get stuff done quickly with pre-integrated technology to make your job > easier > Download IBM WebSphere Application Server v.1.0.1 based on Apache > Geronimo > http://sel.as-us.falkag.net/sel? > cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > > ---------------------------------------------------------------------- > --- > Using Tomcat but need to do more? Need to support web services, > security? > Get stuff done quickly with pre-integrated technology to make your > job easier > Download IBM WebSphere Application Server v.1.0.1 based on Apache > Geronimo > http://sel.as-us.falkag.net/sel? > cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users |
From: Alec W. <ale...@da...> - 2006-09-13 21:47:52
|
Hi all, Hmm... I've got 4 NiMHs, giving me just over 4.7v. Plugging this into the Gumstix yields unspectacular results - the first time I tried it, it almost completed the boot process, then it just "stopped". Every subsequent time, it barely gets a single character out to the console. The Gumstix's power LED doesn't seem as bright, either. My Gumstix works fine with 4.6v from a wall-wart - am not sure why 4.7v from some NiMHs doesn't cut it? Any suggestions welcome! many thanks, alec -- Alec Waters CCNP Dataline Software Ltd Clarence House, 30-31 North Street, Brighton, BN1 1EB, UK Tel: +44 (0)1273 324939 Fax: +44 (0)1273 205576 www: http://www.dataline.co.uk IPv6: http://www.ipv6.dataline.co.uk |
From: Brad M. <bmi...@xm...> - 2006-09-13 22:11:08
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Alec > My Gumstix works fine with 4.6v from a wall-wart - am not sure why 4.7v > from some NiMHs doesn't cut it? are you using the tweener to watch the console? I couldn't use the tweener board at all using my wimpy lipo battery. I figured it had to do with driving the serial port voltages. Things power up just fine with only the gumstix and audiostix attached and I've been logging in over the bluetooth getty. Brad |
From: Dave H. <dhy...@gm...> - 2006-09-13 22:44:21
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Hi Alec, > Hmm... I've got 4 NiMHs, giving me just over 4.7v. Plugging this into > the Gumstix yields unspectacular results - the first time I tried it, it > almost completed the boot process, then it just "stopped". Every > subsequent time, it barely gets a single character out to the console. > The Gumstix's power LED doesn't seem as bright, either. > > My Gumstix works fine with 4.6v from a wall-wart - am not sure why 4.7v > from some NiMHs doesn't cut it? Well it's 4.7v with no load. You'll probably find that the voltage is dropping quite a bit under load. 4 x freshly charged NiMH's should be around 5.5v - 6v. Measure the cells individually, and see if one of them is significantly lower than the others. NiMH batteries also lose about 1% of their charge per day just sitting idle. Normally 1v means fully discharged. Here's a chart showing the typical discharge curve: http://sackheads.org/~mayfield/battery/analysis.html http://www.zbattery.com/rechargeablenimhbatteries.html -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Alec W. <ale...@da...> - 2006-09-14 11:01:48
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Hi Dave, Brad, > are you using the tweener to watch the console? I couldn't use the > tweener board at all using my wimpy lipo battery. I figured it had to do > with driving the serial port voltages. I've got a STUART board attached. I'll try it with it detached. > Well it's 4.7v with no load. You'll probably find that the voltage is > dropping quite a bit under load. 4 x freshly charged NiMH's should be > around 5.5v - 6v. Measure the cells individually, and see if one of > them is significantly lower than the others. Will do. They were fully charged (for the first time) about a week ago I guess. many thanks, alec -- Alec Waters CCNP Dataline Software Ltd Clarence House, 30-31 North Street, Brighton, BN1 1EB, UK Tel: +44 (0)1273 324939 Fax: +44 (0)1273 205576 www: http://www.dataline.co.uk IPv6: http://www.ipv6.dataline.co.uk |
From: Alec W. <ale...@da...> - 2006-09-19 20:03:59
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Hi Dave, >>Well it's 4.7v with no load. You'll probably find that the voltage is >>dropping quite a bit under load. 4 x freshly charged NiMH's should be >>around 5.5v - 6v. Measure the cells individually, and see if one of >>them is significantly lower than the others. Yep, that's exactly what it was. Two of the cells were reading just under one volt; perhaps my charger's not quite up to task... many thanks, alec -- Alec Waters CCNP Dataline Software Ltd Clarence House, 30-31 North Street, Brighton, BN1 1EB, UK Tel: +44 (0)1273 324939 Fax: +44 (0)1273 205576 www: http://www.dataline.co.uk IPv6: http://www.ipv6.dataline.co.uk |