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Looking for clarification on Trinket pro back pack charger
Moderators: adafruit_support_bill, adafruit

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Looking for clarification on Trinket pro back pack charger

by blicken on Wed Nov 30, 2016 9:38 pm

I just got some trinket pro, and trinket proback pack to charge my batteries via usb.
the pins on the backpack read:bat,G,5v.

the Trinket pro reads:
bat,G, Bus. and 5v is the next one over.

Do I connect "5v" pin of the Back Pack, to th e "Bus" pin of the pro trinket?

I read the tutorial, but it was not clear to me.

***Secondary Question****
is it imperative to jumper the 100mA contact to charge batteries over 500mAh?

***tertiary Question***
will a backpack with the 100mA contact joined damage a battery under 500mAh?
(fire risk, reduced life, etc..)

***tertiary Question2***
I have some trinkets, (not the pro variety) and I want to connect the backpack. does the bcakpack 5v connect to the 5v of the trinket?
I wired this, and it seems to be doing something funny. when it is plugged in, it illuminates "charging" although the battery is charged.
when the USB cable is unplugged, both lights (CHG, DUN) glow dimly. should I have connected the 5v pin of the backpack to the USB pin of the Trinket?

This is the tutorial I am referring to:
https://learn.adafruit.com/adafruit-pro ... k/overview

blicken
 
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Re: Looking for clarification on Trinket pro back pack charg

by blicken on Wed Nov 30, 2016 10:36 pm

From the tutorial:
"Ideally, this backpack is for use with the 3.3V Pro Trinket, so that the battery voltage (3.7V-4.2V) will get regulated down to 3.3V on the Pro Trinket board. "


I find it confusing that right below this line, is a 5volt trinket, and that the backpack is also labelled 5v. if its 3v, for 3v systems, why is 5v labelled on the backpack?

blicken
 
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Re: Looking for clarification on Trinket pro back pack charg

by adafruit_support_bill on Thu Dec 01, 2016 7:06 am

The 5v pin on the backpack connects to the BUS pin directly below it on the Pro Trinket. The BUS pin is connected to the USB bus power which is always 5v (even on a 3.3v Trinket).

The BUS/5v pins are only powered with 5v when the Pro Trinket is plugged into USB. This is an input to the charger backpack. It is not a source for 5v power when running from the battery.

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Re: Looking for clarification on Trinket pro back pack charg

by Jabrwock on Mon May 13, 2019 7:17 pm

I have the backpack hooked up to a 3.3V pro trinket. Both LEDs on the charger glow faintly when the battery is the only source of power (trinket runs fine). How much current are they drawing? I'm trying to make a low power audio device and hopefully they're not too much of a drain...
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Re: Looking for clarification on Trinket pro back pack charg

by adafruit_support_bill on Mon May 13, 2019 7:25 pm

Both LEDs have 1k current limiting resistors in series. Powered from 3.7v, there would be about 2.5mA current draw per led.

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Re: Looking for clarification on Trinket pro back pack charg

by Jabrwock on Tue May 14, 2019 12:16 am

adafruit_support_bill wrote:Both LEDs have 1k current limiting resistors in series. Powered from 3.7v, there would be about 2.5mA current draw per led.

I'll have to de-solder them once my design is complete. Thank you for the info.
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Re: Looking for clarification on Trinket pro back pack charg

by Jabrwock on Tue May 14, 2019 2:04 pm

I just did some quick measurements, and I think I'll be fine.

I thought they'd be pulling 2.5mA all the time, but when BUS/5V is connected and USB is unplugged (so both CHG and DONE are glowing faintly), they're only drawing 0.02mA each, which is the same as what my ProTrinket is drawing while in deep sleep (since I de-soldered the PWR LED).

With my current battery that's a year's worth of endurance, which is way more than I need.
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Re: Looking for clarification on Trinket pro back pack charg

by adafruit_support_bill on Tue May 14, 2019 2:25 pm

Sounds good. There must be some additional current limiting internal to the charge controller chip.

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Please be positive and constructive with your questions and comments.