I was not saying the charge cycles were the same, just that they do not work indefinitely. Less than 10 years life expectancy IMHO is on par with lead acid batteries.
Also, the batteries I used were 10,000 maH or 10aH ( not 10,000 aH ). For two they cost me ~$25, and they were very heavy for their size. We live completely offgrid and run our house completely off solar / a large-ish battery bank. I am not an expert per se, but have lots of hands on with this type of setup, but on a larger scale. You definitely would not want to lug one of these around to use with a BBB ( let alone 3 because they're 2v deep cycle RE's ). But the NiMH D Cells I have used in the past would probably work fine. They never corroded. Although the charge cycles is => 500 for the NiMH, which if they operate like lead acid. A charge cycle only counts once the battery is taken down below a certain charge %. Me, I'd definitely prefer to use a battery, mostly because I am very familiar with the characteristics of batteries, and writting code for an msp430 ( for conditioning a battery, and monitoring line voltage ) would be really simple. But again, I really have not spent a ton of time thinking about it. On Wed, May 28, 2014 at 12:02 PM, John Syn <[email protected]> wrote: > > From: William Hermans <[email protected]> > Reply-To: <[email protected]> > Date: Wednesday, May 28, 2014 at 11:19 AM > To: <[email protected]> > Subject: Re: [beagleboard] Re: Can the BBB get damaged due to a hard > power down? > > Batteries can be had that have a lifetime of 5+ years. Depending on the > type of battery you use. Flooded lead acid ( for RE use ) can have a much > longer life. Especially if the batteries are conditioned / charged > properly. > > You can buy Tadiran batteries that last 10 years, but they are expensive. > They aren’t real batteries either, they are a type of hybrid battery. > > http://www.tadiranbat.com > > > > I've personally bought, and used 10,000 aH D Cells that have lasted 3 > years, but failed eventually, because I was using them in a Maglite > flashlight, and had dropped it many times. The point is, where there is a > will, there is a way. > > Also, perhaps I am remembering wrongly, but I seem to recall reading that > super caps have a limited lifetime as well. Something about only having so > many charge cycles similar to a battery. > > Not true. As long as you do not exceed their maximum voltage, supercaps > charge cycles are 100x that of batteries and their life expectancy is >10 > Years. You can also charge and discharge them much faster than batteries. > Regular Lithium Iron are good for about 1,000 charge cycles and <3 year > capacity is less than 80%. > > > > > On Wed, May 28, 2014 at 11:06 AM, Dr. Michael J. Chudobiak < > [email protected]> wrote: > >> asked anyone at TI if it is OK to use the PMU like this? Perhaps you >>> should post a question on E2E. >>> >> >> From http://e2e.ti.com/support/power_management/pmu/f/200/t/185514.aspx: >> >> "The battery charger should work fine with a supercap. You'll need to >> make sure the TS (battery temp sense) pin is at a proper voltage to allow >> charging. If the supercap does not have a temperature sensor, you can >> simply put a 10k resistor from TS to GND." >> >> >> If you are charging at 440mA, it will take 50 Seconds to reach full >>> charge. What happens when the power fails before that 50 Seconds? I would >>> recommend that you monitor the supercap voltage and wait until it is >>> fully >>> charged before opening any files. >>> >> >> That is why I use full data+metadata journaling on the filesystem. >> >> If an unclean shutdown happens before the supercap is charged, the next >> boot-up will be delayed for several seconds as the filesystem is repaired >> using the full journal. That is annoying, but it is a minor cost for >> robustness. Mostly, the supercap is there to eliminate the need for the >> repair delay. >> >> >> It is an interesting concept, but I'm still skeptical if this can really >>> work. >>> >> >> Well, I do use it, so that's one data point. >> >> The other main alternative for bullet-proof power-fail robustness is to >> rely on on something like unionfs to provide a mix of read-only and >> read/write filesystems, but that's not so simple either. It's complex and >> not very well supported in general. >> >> Batteries have a fairly limited lifetime, so I don't consider that a >> practical solution (for me). >> >> I'm interested to hear how other people prevent corruption on power loss, >> though. >> >> >> >> - Mike >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- You received this message because you are subscribed to the Google >> Groups "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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