# Notecarrier F 5 volts output on VBAT+

**URL:** <https://discuss.blues.com/t/notecarrier-f-5-volts-output-on-vbat/1804>\
**Category:** Notecarrier F\
**Created:** [November 23, 2023, 10:45am UTC](https://discuss.blues.com/t/notecarrier-f-5-volts-output-on-vbat/1804 "2023-11-23T10:45:59Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![theogrm](https://avatars.discourse-cdn.com/v4/letter/t/67e7ee/32.png) [@theogrm](https://discuss.blues.com/u/theogrm)\
**Post date:** [November 23, 2023, 10:45am UTC](https://discuss.blues.com/t/notecarrier-f-5-volts-output-on-vbat/1804/1 "2023-11-23T10:45:59Z")

</div>

Hi all,

I noticed that the notecarrier F v1.3 outputs 5 volts to the VBAT+ when the system is powered via the microcontroller’s usb port (using feather v2). I believe that could be a problem, specially when recompilling code with a lipo battery connected to the notecarrier.

Theo

---

<div class="post-metadata">

**Author:** ![RobLauer](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/roblauer/32/1567_2.png) [@RobLauer](https://discuss.blues.com/u/RobLauer)\
**Post date:** [November 24, 2023, 7:25pm UTC](https://discuss.blues.com/t/notecarrier-f-5-volts-output-on-vbat/1804/2 "2023-11-24T19:25:49Z")

</div>

Hi @theogrm,

Is your concern that you are using voltage-variable mode for your syncing cadence with Notehub, using two different power sources? If so, can you describe the scenario you’d like to address (i.e. USB power in development, but switch to LiPo mode when deploying?). For reference, there are many options that accommodate these scenarios: [Low Power Design - Blues Developers](https://dev.blues.io/notecard/notecard-walkthrough/low-power-design/#voltage-variable-sync-behavior) but I’m happy to help figure out the right solution for you.

Thanks,  
Rob

---

<div class="post-metadata">

**Author:** ![theogrm](https://avatars.discourse-cdn.com/v4/letter/t/67e7ee/32.png) [@theogrm](https://discuss.blues.com/u/theogrm)\
**Post date:** [November 27, 2023, 9:29am UTC](https://discuss.blues.com/t/notecarrier-f-5-volts-output-on-vbat/1804/3 "2023-11-27T09:29:45Z")

</div>

Hi Rob,

I just noted that with notecarrier-f v1.3 if power is fed via the microcontroller’s USB you get 5 volts at the VBAT where the LiPo are to be connected. If connected via the usb notecarrier, VBAT is the correct 4 volts.

 ![IMG20231127092000 (1)](https://us1.discourse-cdn.com/flex020/uploads/blues/original/1X/0fec4a2b52504ee9edbab2b60cd50e9a79208a25.jpeg)  
 ![IMG20231127092116](https://us1.discourse-cdn.com/flex020/uploads/blues/original/1X/654c2f2923797b8827e138f652a2852e5a7cb859.jpeg)

---

<div class="post-metadata">

**Author:** ![RobLauer](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/roblauer/32/1567_2.png) [@RobLauer](https://discuss.blues.com/u/RobLauer)\
**Post date:** [November 28, 2023, 2:24pm UTC](https://discuss.blues.com/t/notecarrier-f-5-volts-output-on-vbat/1804/4 "2023-11-28T14:24:27Z")

</div>

Hi @theogrm,

Sorry about that - I misinterpreted your first message! It is by design of the Notecarrier F that it powers the Feather via `VBAT` with ~3.8-4V, with a diode to prevent any reverse current from flowing into its supply. It is also by design of any given Feather what they push out of `VBAT` when there is no `VBAT` present. Most Feathers have a battery charging circuit, so what is pushed out `VBAT` is more often than not the Feather’s attempt to charge its own LiPo. What you are observing is the interaction between those two things.

Rob