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. <[email protected]> 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<http://andicelabs.com/powerbar-release/> > . > > 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 < >> [email protected]> wrote: >> >>> On Mon, 21 Jan 2013 20:53:16 -0800 >>> Eric Fort <[email protected]> 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 [email protected]. > 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 [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
