BACtrack C6 review of a fuel cell tester for your keyring

The C6 is built for people who want a check available wherever they are, such as at a dinner out or after a work event, without carrying a separate case. Standalone Mode gives a quick reading on the device itself, and App Mode adds history and a ZeroLine estimate of when your level returns to 0.00% if you want to look back at patterns later.

It suits occasional to moderate personal use. Households that run many tests a week will burn through AAA batteries faster than with a larger Pro Grade unit, and anyone who wants a maker stated tolerance should look elsewhere in the lineup.

Keychain testers are easy to lose and easy to knock about, so think about where it will live. The maker's published size and weight figures are not consistent with each other, which is a small point but worth knowing if you are comparing it with other keychain models by weight.

The range stops at 0.300% BAC, lower than the 0.400% BAC listed for several other BACtrack units. For personal screening this ceiling rarely matters, yet it shows the C6 is aimed at casual use rather than professional settings. The maker publishes no C6 specific DOT, NHTSA or FDA 510(k) statement.

Small does not mean less careful. The same pre test wait applies as with any tester, and readings taken too soon after a drink can run high. Our piece asking are keychain breathalyzers accurate looks at the limits of this size class in general.

BACtrack lists the C6 on its send in calibration service, which runs mechanical, air flow and accuracy checks and returns most units in about 10 to 14 business days under the standard option. No interval specific to the C6 is published, so follow the brand's general advice of at least once every 12 months, sooner if you test daily. There is no user calibration and no replaceable sensor module.

Because the C6 is not part of the Pro Grade group, do not expect it to hold calibration as long as the S80 or Trace. Our guide to calibrating a breathalyzer explains how to tell when a unit is drifting.

Its closest relative is the BACtrack C8, which uses the same BluFire sensor family in a slightly larger body. Within the keychain class, the BACtrack Go keychain breathalyzer costs less but uses a semiconductor sensor with a much shorter battery rating. See our keychain breathalyzer category for models from other makers, and the fuel cell vs semiconductor breathalyzer page for why the sensor difference matters.