Mike, The recommended max input is 12V on that regulator but the absolute is 17V. I haven't had any issues above 12V yet but I also haven't stuck it in my car. I've mostly been using it with 1S, 2S, and 3S LiPoly packs. You are correct, voltage above 15V will eventually trip the PTC but it's nowhere near instant.
Honestly, I never thought of using the BB DC jack as an auxiliary power port! There is no reason that I can see for it not to work. The max current available from the regulator is going to depend on the input voltage. You won't get 2A unless you've got at least 5V coming in and the components should handle it (but I've only drawn just under 1.5A max so far). In boost mode, you're limited to just over 1A around 3.7V. If you're looking at the TPS63060 datasheet, check out figure 2 on page 7. I did have current measurement on the early PowerBar prototypes and I really like the INA219. But, I removed it for a couple of reasons. Cost, obviously. Then, in order to get at the I2C2 pins I had to cover the console port. I did a version that "reached around" it but didn't like it so I eventually decided to retreat from those pins all together to leave them available for prototyping and such. Eric, Agreed, the PowerBar has allowed me to run from 1S, 2S, and 3S RC batteries which is what I originally intended. I decided to tackle the charger on the PowerCape just because it seemed to make it much more useful. Although, it does impose some limitations. For example, now the DC input power must be at least 4.4V or so in order to charge the Lithium cell. And, your battery is limited to just 1S (3.7V nominal). But, on the other side the input voltage range is now greater (4-16V) since there is another regulator in front of the buck/boost circuit. The PowerBar does not have voltage measuring capability for form-factor simplicity. But, there is an INA219 on the PowerCape to monitor battery voltage and charge/discharge current. Here <http://andicelabs.com/wp-content/uploads/2014/01/PowerCapeP2s.png> is a picture of the latest PowerCape prototype. I will finish the write-up before this weekend. Thanks for the comments! -Ron On Tuesday, January 14, 2014 2:10:35 PM UTC-6, Eric wrote: > > A couple observations on designing a Li-Po (or general power supply > cape, no matter what the power source).... > > 1. the charger can be separate and it makes the design much easier. > RC Li-Po packs are plentiful as are the chargers for them just build a > cape that allows running off one of those. > > 2. Current measurement could be useful and is a good idea. > Possibly via i2c or maybe via simply using one of the analog pins. > > 3. the input voltage for such a cape ought to be roughly 9-(15-20) > volts. the low end covering a reasonably well drained 6 cell lead > acid car battery and the high being above 15 for the charging voltages > sometimes seen in the same type of battery then rounded up from there > to whatever pack voltage is for a fully charged number of Li-Po cells > in series with a voltage higher than 15 or so. that would cover many > if not most applications I can forsee. > > Eric > > On Tue, Jan 14, 2014 at 6:41 AM, Mike Bremford <mi...@bfo.com<javascript:>> > wrote: > > Hi Ron > > > > Did you cater for inputs above 14V? If powering from 12V lead-acid > > batteries, they typically charge at 14.4-15V but I'd certainly expect > spikes > > of higher and I wouldn't want to plug in anything that couldn't take up > to > > 16V safely. I see you have a 15V zener on there so the regulator won't > > receive more than that, but if this was sustained presumably your > polyfuse > > would go soon after, correct? > > > > Second, your chosen regulator will put out 2.25A - are the components > sized > > to deliver all of that, and could I tap some of it to power a USB hub? > Say > > by using the 2.1mm power socket on the beaglebone as a power source for > the > > hub? If yes to both of these then you might have a customer if my board > > doesn't work when it turns up from oshpark next week... > > > > Finally, if you're looking for other ideas, how about current > measurement > > through I2C? Nice to have rather than essential, but if you're > redesigning > > the board a spot to solder an INA219 (or something like it) wouldn't go > > amiss. If you haven't got some way to signal the BeagleBone yet that > it's > > running on LiPo, this part will also tell you about input voltage so you > > could probably deduce it from that. > > > > > > > > On 14 January 2014 04:22, Ron B. <r...@andicelabs.com <javascript:>> > wrote: > >> > >> Sorry for the late reply on this thread but it just popped back to the > top > >> of the list and caught my attention. > >> > >> I've been powering my BeagleBone from RC batteries for some time now. > The > >> most versatile method that I've been using is a buck/boost power "bar" > that > >> attaches to the expansion connections and provides a stable 5V from a > >> 3-14VDC input. It isn't fancy, but it's (relatively) inexpensive and > >> doesn't cover up the console port or I2C pins. I've released all of > the > >> files for anyone who wants to build one here. > >> > >> I'm also working on a proper Li-Ion PowerCape that incorporates > charging > >> and power control circuitry. This allows for operation as a "mini UPS" > or > >> as a battery-powered "node" that can power itself up and down. I just > built > >> up the first full prototype yesterday and will post some pictures on > the > >> blog later this week. I'd really like to get feedback on the > PowerCape, > >> especially with regards to the connectors and placement that I've > chosen. > >> > >> -Ron > >> > >> > >> On Tuesday, January 22, 2013 4:20:49 PM UTC-6, Eric wrote: > >>> > >>> I'm trying to better understand the issue with the creation of a LiPo > >>> cape for the bone. Here's my thinking: > >>> > >>> With a nominal cell voltage of 3.7v it would take a 2 cell LiPo pack > to > >>> light up the 5v rail no matter what you do. At this point you have > 7.4v. > >>> Use a buck converter and produce 5v from 7.4v (or possibly a 6-13.8v > source > >>> making it a rather useful general power supply cape useful for > powering the > >>> bone in your car as well) with decent efficiency and feed that into > the 5v > >>> line on the expansion connectors the same way that the battery cape > does > >>> now. As for charging the lipo pack I'm not sure I'd really worry > about that > >>> much, rather I'd simply supply a connector on the cape for a standard > RC > >>> type lipo pack and optionally a decent sized cap for continuity when > >>> changing batteries. The user could then choose the type and size > needed for > >>> the desired runtime. when it comes to charging, just disconnect the > LiPo > >>> pack and plug it into a standard RC charger available from any decent > hobby > >>> store where the pack was sourced from. How does this vary from the > >>> approaches previously looked at for a LiPo cape? What problems might > I have > >>> missed? > >>> > >>> Eric > >>> > >>> > >>> > >>> Eric > >>> > >>> On Tue, Jan 22, 2013 at 6:33 AM, Andrew Bradford > >>> <and...@bradfordembedded.com> wrote: > >>>> > >>>> On Mon, 21 Jan 2013 20:53:16 -0800 > >>>> Eric Fort <eric...@gmail.com> wrote: > >>>> > >>>> > Just a thought.... A large lithium pack for the bone would rock! > >>>> > >>>> Regarding the lithium battery pack idea, it's a good one except for > one > >>>> little issue with the bone where a rework is required in order to > power > >>>> down into TPS65217 OFF or SLEEP modes when a battery is connected due > >>>> to SYS voltage staying present and the way 3.3V_EXP is generated. So > >>>> long as you don't want to power off with the battery still connected > >>>> there's no issue, though. > >>>> > >>>> The existing battery cape doesn't have this problem as it's 4 AA > cells > >>>> with a regulator and that feeds into the 5V line on the expansion > >>>> connectors. > >>>> > >>>> -Andrew > >>> > >>> > >> -- > >> 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 beagleboard...@googlegroups.com <javascript:>. > >> For more options, visit https://groups.google.com/groups/opt_out. > > > > > > -- > > 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 beagleboard...@googlegroups.com <javascript:>. > > For more options, visit https://groups.google.com/groups/opt_out. > -- 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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