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2600ma Power Stick 88% off at Staples — Parallax Forums

2600ma Power Stick 88% off at Staples

PublisonPublison Posts: 12,366
edited 2015-05-07 18:28 in General Discussion
Nice little accessory for very little price. Could power a QuickStart or Project Board:

http://www.staples.com/Acesori-Powerstick-2600mAh-Portable-Power-Bank-Assorted-Colors/product_SS3891349?cmArea=home_box1

$6.99. Not sure they are available in store or Internet shopping only.

Comments

  • ercoerco Posts: 20,256
    edited 2015-05-05 11:10
    Sweet! Will see if any are at my local store.

    Between Jim & CuriousOne posting these smoking deals, it's gettin' hard for old erco to keep up!
  • PublisonPublison Posts: 12,366
    edited 2015-05-05 11:36
    You keep inventing super secret robots; we got your back. :)
  • ercoerco Posts: 20,256
    edited 2015-05-05 11:49
    Wish I could share them, they are pretty nifty and making me up my game!

    You may see some of them next year at NYTF. One for sure.
  • User NameUser Name Posts: 1,451
    edited 2015-05-05 21:03
    Publison wrote: »
    Nice little accessory for very little price. Could power a QuickStart or Project Board....

    The problem I have with this idea is that the recharging packs I've used turn themselves off if the current being drawn from them drops below a specific level. I have not tested this particular unit from Staples, so it could be different. If it is, please let me know and I'll pick one up!

    Meanwhile, with the power packs I already have, the QS board does not draw sufficient current to meet this stay-on threshold. I could always add a resistor straight across the power pack's 5V output, but that wastes a significant percentage of the stored charge.

    So I had an idea I'd like to test: Instead of imposing a constant stay-alive current with a resistor, I want to see if a low-duty-cycle load would keep the pack on. (Something like a 20 mA load of 50 ms duration every 5 seconds, probably accomplished with a CMOS 555.)

    Has anyone already tried this?
  • xanaduxanadu Posts: 3,347
    edited 2015-05-05 23:06
    User Name wrote: »
    The problem I have with this idea is that the recharging packs I've used turn themselves off if the current being drawn from them drops below a specific level. I have not tested this particular unit from Staples, so it could be different. If it is, please let me know and I'll pick one up!

    Meanwhile, with the power packs I already have, the QS board does not draw sufficient current to meet this stay-on threshold. I could always add a resistor straight across the power pack's 5V output, but that wastes a significant percentage of the stored charge.

    So I had an idea I'd like to test: Instead of imposing a constant stay-alive current with a resistor, I want to see if a low-duty-cycle load would keep the pack on. (Something like a 20 mA load of 50 ms duration every 5 seconds, probably accomplished with a CMOS 555.)

    Has anyone already tried this?

    No, but I know what you mean. It reminds me of when aftermarket LED lighting went into cars and the cars would report bulbs out when they weren't. It's a system designed for one thing doing another. USB spec might not be flexible enough to be certified at low current. I have a 1S lipo charger that is USB and I've been through a lot of these USB chargers and the best one was a Tenergy 2200mah I bought at Fry's. It would stick with the charger all the way down to the peak of a 1S lipo charge. You would need to reboot it before the charger would work again after that, but as long as there was some draw it stays on.
  • ercoerco Posts: 20,256
    edited 2015-05-06 05:44
    I'd just hack into the pack and connect directly to the internal LiIon, bypassing the regulator & shutoff functions. Adding an external regulator or boost circuit is quick easy & a buck or less.

    But leave the USB charge circuitry in place.
  • User NameUser Name Posts: 1,451
    edited 2015-05-06 08:40
    erco wrote: »
    I'd just hack into the pack and connect directly to the internal LiIon, bypassing the regulator & shutoff functions. Adding an external regulator or boost circuit is quick easy & a buck or less.

    But leave the USB charge circuitry in place.

    I'm willing to bet you are better at taking things apart and putting them back together than I am, erco. I always break a few things upon disassembly, but it's the putting back together that really screws things up. :\

    Since an external solution is the only solution that fits my limited skill set, I undertook a few minutes ago to find out what it would take to keep my Tenergy pack alive - the one that Curious One brought to our attention in January. (I selected it because it has the highest capacity of the packs I have, and is the one I'd most like to use if I could.) I'd previously determined (on 1/21/15) that a 50 Ohm load was enough to keep the unit on, but that an 85 Ohm load wasn't.

    So, starting from that point I used a QS board and an MPS2222 to turn a 50 Ohm load on and off. Long story short, what I determined is that a 100ms on-time every 4 seconds is enough to keep the unit on indefinitely. So the wasted current (to keep it on) has now been reduced 40x, to effectively 2.5 mA.

    Now I can design a timer circuit to mimic this action...
  • CuriousOneCuriousOne Posts: 931
    edited 2015-05-07 06:39
    Some Motorola smartphones and power banks have such feature - it detects the compatible hardware upon connection, so batteries are just hooked in parallel - avoiding unnecessary energy loss on up/downconversion.
  • tonyp12tonyp12 Posts: 1,951
    edited 2015-05-07 09:42
    Here is a 6,000mAh Power Bank $39.99+FS
    http://www.amazon.com/dp/B00UCP6HKK/ref=nosim/?tag=fatwalletcom&linkCode=as1&ascsubtag=ebs2d-1d1d1431016903765sbe&sourceName=forums&sourceId=1441192
  • User NameUser Name Posts: 1,451
    edited 2015-05-07 11:33
    tonyp12 wrote: »
    Here is a 6,000mAh Power Bank $39.99+FS
    http://www.amazon.com/dp/B00UCP6HKK/ref=nosim/?tag=fatwalletcom&linkCode=as1&ascsubtag=ebs2d-1d1d1431016903765sbe&sourceName=forums&sourceId=1441192

    Same capacity as the Tenergy but 4x more expensive. :(
    OTOH, the Tenergy won't jump-start your motorcycle. :)
  • CuriousOneCuriousOne Posts: 931
    edited 2015-05-07 11:33
    U can't touch this:

    http://www.ebay.com/itm/Tenergy-6600mAh-6-6AH-Power-Bank-w-Micro-USB-for-iPad-iPhone-Mo-bile-/390449318860?pt=LH_DefaultDomain_0&hash=item5ae897cbcc

    6600mAh for $9.99 + FS :)
  • ercoerco Posts: 20,256
    edited 2015-05-07 15:28
    That IS a smoking' deal, CO!

    Do not tempt erco!

    Weak, hoarder erco...
  • User NameUser Name Posts: 1,451
    edited 2015-05-07 18:28
    A few additional notes on the Tenergy unit that CuriousOne links in post #12:

    Since there are two output ports, one rated at 1A and the other at 2A, I realized that I probably wouldn't have to make a custom cable to accommodate the keep-alive timer. Instead I simply put the intermittent load (in the form of a small dongle) on the 1A port and use the 2A port to power whatever it is I want to power. I tested this notion and it works great.

    Curiously enough, it doesn't work the other way. If I put the intermittent load (re: post #8) on the 2A port, it doesn't keep the power pack alive. Presumably it requires a bigger dummy load. But why bother with that??

    Finally, I found that the 100mA keep-alive load can be applied as infrequently as every 7 seconds and still keep the power pack from turning off. This represents an effective current load of just 1.4 mA, a drop in the bucket for a 6600 mAh power pack. ;)
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