Internal Power for Axoloti and Midi Device

#1

I was looking into putting an internal battery and charger into my Axoloti and haven’t seen much on a working solution to power both the board and an external midi instrument. I looked into the Adafruit Powerboost 1000c which on another thread was mentioned to possibly not give enough power because it outputs 5v. I’ve seen another user use this along with a 3.7v 2000mAh battery. My question is has anyone successfully come up with a rechargeable internal battery solution that can power both the Axoloti and a midi controller?

#2

theres a few different solutions, if you want to do it without attaching wires... then you have two solutions
a) power from the USB device port, this is normal usb voltage (5v)
b) power via DC port , but this needs to 7v-12v not 5v

(if you want to hardwire, you can attach a 5v supply onto the board where the board can be split in two... theres a post about this somewhere, and it seemed to work for me )

choice is up to you...
if you just need it run a patch standalone, then you can connect your usb battery pack to usb device port

if you need it to be powered, and connect via the device port, then you can could use a usb powersuppy with a voltage converter 5v to 9v. (only reason i can think for this, is if you want to enclosure the whole thing in a case, and expose teh device port for uploading patches etc.)

anyway 3.7v is not enough, and 5v is not enough thru the DC port.

(of course, this all assumes the midi controller is usb class compliant and doesn't draw more than the normal 500mA, but I assume you've already tested this with the axo connected to a computer)

#3

Thanks for the reply, I looked it up and the midi controller takes 275mAh. If I’m getting what you’re saying correctly then the only way to have a standalone device with battery and patchability is to have it powered via the dc port or not the micro usb and then have the micro usb slot open for uploading patches. I would also like to wire some kind of charger and battery on the board to keep the unit slim and compact similar to the axocontrol but in a sturdier housing and with the addition of an internal battery and charger. How would I go about doing this? Is a board like this something that could do the job?

http://www.maglocks.com/altronix-al624-power-module-by-maglocks-com-for-34-99.html?gclid=Cj0KCQiAzrTUBRCnARIsAL0mqcxg3NKsQXS2LVAe3ylHxtIm7ULPtFQ4Rrpf6Kcj1pxPDedajeFB1PQaAh1nEALw_wcB

#4

There has been a few discussions about using power banks, and these do definitely work, I have done this myself. Use a USB cable from the power bank to the Axo micro USB input, and your done. I don't know if an internal battery system has benefits, as if you use a power bank, when it runs out, just remove it and plug in a fresh one. As for powering an external midi device, I guess it depends on the device and its power demands, and preferably it should run on 5V. There is a 5v and gnd you can tap into in the midi section of the Axo that I previously used to power and external midi device.
Here is the link, however you will notice I hacked up the midi device so I could mount it on a unit the Axo was mounted on, and it was powered by the midi section of the Axo, and could easily be powered by a power bank. In fact I could also connect another device to the USB Host which could also be powered.

But as this was not a useful setup for me, I no longer have this.
:grin:

#5

My thinking when deciding on the Powerboost was that the Axoloti is USB powered, which means it is happy with 5V and max 500mA. The Powerboost supplies 5.2V and max 1000mA, so I just assumed it would work when connected to the 5V soldering point thetechnobear mentions above. If there are problems with this approach that I haven't realised I have yet to notice what it could be.

I have no problems powering any of my USB Midi keyboards from my battery powered Axoloti. If there is anything else you want me to test, just let me know! (The reason I didn't go for a bigger battery was just that was what I had room for in the enclosure, btw.)

#6

I think you could just use some consumer smartphone powerbank and use the usb device port at axoloti. The cool thing is these powerbanks are super cheap and available everywere around the globe.

If you need more juice I made good experience with boosting the 5v of one these powerbanks to 9V and 14V for powering an axoloti, a controller and a class D amp.