Hi all!
I'm building a portable camera / led matrix using a TTL camera, a Teensy 3.1 and the Adafruit 32x32 led matrix.
I'll be lowering the brightness on the display for the most part, though I'd like to plan to be able to support the max brightness level if I can. That should be around 2A, though not for very long, as I'll never have anything on the matrix for longer than about 30 seconds.
I've thought about just using a portable USB battery pack like are used for charging phones and such, but I don't want too much added weight / size. I have plenty of lipo chargers laying around, so I thought about that, but I wanted to ask around here first, since I want to drive the matrix at 5V, and all of my lipo batteries are 3.7v. I can use a boost converter, but there's just some waste in there.
Anyhoo, does anyone have a suggestion for a reasonably light, roughly 10AH battery / portable power solution for me?
Thanks!
Hi,
not a power expert, but depending on your needs, I would go for something like this:
https://www.fasttech.com/products/0/10002784/1681400-enb-2-18650-usb-emergency-charger-power-bank
Dirty cheap, available of the shelve and when you pair it with 2x3400mAH NCR18650B's like these:
https://www.fasttech.com/products/0/10001980/1141100-panasonic-ncr18650b-rechargeable-3400mah-3-7v
You pack 6800 mAh in a package just a bit bigger than the 18650s themselves... Also all your charge electronics and 5 volt voltage regulator @2.1 AMPS are taken care off...
If you want to tinker yourself, I would suggest getting at least three 18650's/LiPO's in series with a switching regulator in between...
Off-the-shelve: Search for UBEC on ebay, like this: Hobbywing 3A 5 volt UBEC. Power your Raspberry Pi from 9 or 12 volt batteries. | eBay
Regards Dennis
Pololu.com sells switched step-up voltage regulators that can handle the current, but whether your li-po's can 3-4 amps of power when you need it, I don't know. This is a step-up regulator that takes in voltage at least 2.9v and less than 5v, and produces 5v of power and up to 5 amps: Pololu 5V Step-Up Voltage Regulator U3V50F5. According to the graphs, 3.3v input tops out at 2 amps with 75% efficiency.
Note, you will generally need to worry about both the battery and the voltage regulator heating up. To quote from the product page: During normal operation, this product can get hot enough to burn you. Take care when handling this product or other components connected to it.
If you aren't sure what power source you will be using, or you want the flexibility to use li-po's, AA batteries, and 9v batteries, Pololu.com also sells step-up/step-down converters. These aren't as efficient as a step-up or step-down converter. This regulator takes power from 3v to 30v, and produces up to 2 amps: http://www.pololu.com/product/2574. However, according to the power graphs, you can only get about 1.4 amps from 3.7v.
I've bought some Pololu regulators, but so far, I haven't actually used them for serious use. I do use other pololu products and I'm satisified with them.
Also, Adafruit's new PowerBoost 1000 is generally rated for 1a, but in the text, they say they've gotten 2a from Li-po batteries: PowerBoost 1000 Basic - 5V USB Boost @ 1000mA from 1.8V+ : ID 2030 : $14.95 : Adafruit Industries, Unique & fun DIY electronics and kits. I bought their previous PowerBoost 500, but either I got a dead unit, or I messed it up via mis-soldering (unfortunately, all too likely for me), and I wasn't able to get it to work.