# Card.voltage V+ and voltage-sensitive settings

**URL:** <https://discuss.blues.com/t/card-voltage-v-and-voltage-sensitive-settings/3440>\
**Category:** Uncategorized\
**Created:** [January 28, 2026, 3:23am UTC](https://discuss.blues.com/t/card-voltage-v-and-voltage-sensitive-settings/3440 "2026-01-28T03:23:23Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![devElert](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@devElert](https://discuss.blues.com/u/devElert)\
**Post date:** [January 28, 2026, 3:23am UTC](https://discuss.blues.com/t/card-voltage-v-and-voltage-sensitive-settings/3440/1 "2026-01-28T03:23:23Z")

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The API for [`card.voltage`](https://dev.blues.io/api-reference/notecard-api/card-requests/latest/#card-voltage) mentions

> Provides the current **V+** voltage level on the Notecard, and provides information about historical voltage trends. When used with the mode argument, configures voltage thresholds based on how the device is powered.

But there is no V+ pin on Notecard. After some hunting, I saw V+ is on Notecarrier F which is routed, together with `VBAT` and `VUSB` to `VMAIN` and then to `VMODEM_P`, so it looks like `VMODEM_P` voltage is what is driving the voltage-sensing.

The voltage-variable modes have a usb setting (like `usb:4.6` for `lipo` mode). Does the state of the `VUSB` pin (3.3-5v) play a part in setting the `usb` voltage category independently of the voltage on `VMODEM_P`?

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**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:** [February 2, 2026, 3:25pm UTC](https://discuss.blues.com/t/card-voltage-v-and-voltage-sensitive-settings/3440/2 "2026-02-02T15:25:28Z")

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Hi @devElert,

You’re right, that doc needs to be updated to state that card.voltage returns the current `VMODEM_P` voltage level on the Notecard. Thanks for pointing that out!

Regarding your other question, if a physical USB connection is detected (via the VUSB pin), the mode is automatically set to `usb`, regardless of the VMODEM\_P voltage. For example:

| VUSB Pin | VMODEM\_P Voltage | Resulting Mode |
| --- | --- | --- |
| Detected | Any | `usb` (forced) |
| Not detected | ≥4.6V | `usb` (via voltage threshold) |
| Not detected | 4.0-4.6V | `high` |
| Not detected | 3.5-4.0V | `normal` |
| etc… | | |

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<div class="post-metadata">

**Author:** ![devElert](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@devElert](https://discuss.blues.com/u/devElert)\
**Post date:** [February 2, 2026, 4:25pm UTC](https://discuss.blues.com/t/card-voltage-v-and-voltage-sensitive-settings/3440/3 "2026-02-02T16:25:06Z")

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Thanks for laying that out clearly!