# 429.39 Battery chargers.
(a) *Determination of represented value.* Manufacturers must determine represented values, which include certified ratings, for each basic model of battery charger in accordance with the following sampling provisions.
(1) *Represented values* include: The unit energy consumption (UEC) in kilowatt-hours per year (kWh/yr), battery discharge energy (E<sub>batt</sub>) in watt hours (Wh), 24-hour energy consumption (E<sub>24</sub>) in watt hours (Wh), maintenance mode power (P<sub>m</sub>) in watts (W), standby mode power (P<sub>sb</sub>) in watts (W), off mode power (P<sub>off</sub>) in watts (W), and duration of the charge and maintenance mode test (t<sub>cd</sub>) in hours (hrs) for all battery chargers other than uninterruptible power supplies (UPSs); and average load adjusted efficiency (Eff<sub>avg</sub>) for UPSs.
(2) *Units to be tested.* (i) The general requirements of § 429.11 are applicable to all battery chargers; and
(ii) For each basic model of battery chargers other than UPSs, a sample of sufficient size must be randomly selected and tested to ensure that the represented value of UEC is greater than or equal to the higher of:
(A) The mean of the sample, where:
and, *x
* is the sample mean; *n* is the number of samples; and *x*<sub>i</sub> is the UEC of the *i*th sample; or,
(B) The upper 97.5-percent confidence limit (UCL) of the true mean divided by 1.05, where:
and *x
* is the sample mean; *s* is the sample standard deviation; *n* is the number of samples; and *t*<sub>0.975</sub> is the t-statistic for a 97.5-percent one-tailed confidence interval with n-1 degrees of freedom (from appendix A of this subpart).
(iii) For each basic model of battery chargers other than UPSs, using the sample from paragraph (a)(2)(ii) of this section, calculate the represented values of each metric (*i.e.,* maintenance mode power (P<sub>m</sub>), standby power (P<sub>sb</sub>), off mode power (P<sub>off</sub>), battery discharge energy (E<sub>batt</sub>), 24-hour energy consumption (E<sub>24</sub>), and duration of the charge and maintenance mode test (t<sub>cd</sub>)), where the represented value of the metric is:
and, *x
* is the sample mean, *n* is the number of samples, and *x*<sub>i</sub> is the measured value of the *i*th sample for the metric.
(iv) For each basic model of UPSs, the represented value of Eff<sub>avg</sub> must be calculated using one of the following two methods:
(A) A sample of sufficient size must be randomly selected and tested to ensure that the represented value of Eff<sub>avg</sub> is less than or equal to the lower of:
(*1*) The mean of the sample, where:
and, *x
* is the sample mean; *n* is the number of samples; and *x*<sub>i</sub> is the Eff<sub>avg</sub> of the *i*th sample; or,
(*2*) The lower 97.5-percent confidence limit (LCL) of the true mean divided by 0.95, where:
and *x
* is the sample mean; *s* is the sample standard deviation; *n* is the number of samples; and *t*<sub>0.975</sub> is the t-statistic for a 97.5-percent one-tailed confidence interval with n-1 degrees of freedom (from appendix A of this subpart).
(B) The represented value of Eff<sub>avg</sub> is equal to the Eff<sub>avg</sub> of the single unit tested.
(b) *Certification reports.* (1) The requirements of § 429.12 are applicable to all battery chargers.
(2) Pursuant to § 429.12(b)(13), a certification report must include the following product-specific information for all battery chargers other than UPSs: The nameplate battery voltage of the test battery in volts (V), the nameplate battery charge capacity of the test battery in ampere-hours (Ah), and the nameplate battery energy capacity of the test battery in watt-hours (Wh). A certification report must also include the represented values, as determined in paragraph (a) of this section for the maintenance mode power (P<sub>m</sub>), standby mode power (P<sub>sb</sub>), off mode power (P<sub>off</sub>), battery discharge energy (E<sub>batt</sub>), 24-hour energy consumption (E<sub>24</sub>), duration of the charge and maintenance mode test (t<sub>cd</sub>), and unit energy consumption (UEC).
(3) Pursuant to § 429.12(b)(13), a certification report must include the following product-specific information for all battery chargers other than UPSs: The manufacturer and model of the test battery, and the manufacturer and model, when applicable, of the external power supply.
(4) Pursuant to § 429.12(b)(13), a certification report must include the following product-specific information for all UPSs: Supported input dependency mode(s); active power in watts (W); apparent power in volt-amperes (VA); rated input and output voltages in volts (V); efficiencies at 25 percent, 50 percent, 75 percent and 100 percent of the reference test load; and average load adjusted efficiency of the lowest and highest input dependency modes.
[81 FR 89821, Dec. 12, 2016, as amended at 89 FR 82063, Oct. 9, 2024; 90 FR 43380, Sept. 9, 2025]