# 10 CFR § 429.39 - Battery chargers.

§ 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 (Ebatt) in watt hours (Wh), 24-hour energy consumption (E24) in watt hours (Wh), maintenance mode power (Pm) in watts (W), standby mode power (Psb) in watts (W), off mode power (Poff) in watts (W), and duration of the charge and maintenance mode test (tcd) in hours (hrs) for all battery chargers other than uninterruptible power supplies (UPSs); and average load adjusted efficiency (Effavg) 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:

$\stackrel{–}{x}=\frac{1}{n}\sum _{i=1}^{n}{x}_{i}$

and, x
is the sample mean; n is the number of samples; and xi is the UEC of the ith sample; or,

(B) The upper 97.5-percent confidence limit (UCL) of the true mean divided by 1.05, where:

$UCL=\stackrel{–}{x}\phantom{\rule{0ex}{0ex}}+\phantom{\rule{0ex}{0ex}}{t}_{0.975}\left(\frac{s}{\sqrt{n}}\right)$

and x
is the sample mean; s is the sample standard deviation; n is the number of samples; and t0.975 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 (Pm), standby power (Psb), off mode power (Poff), battery discharge energy (EBatt), 24-hour energy consumption (E24), and duration of the charge and maintenance mode test (tcd)), where the represented value of the metric is:

$\stackrel{—}{x}=\frac{1}{n}\phantom{\rule{0ex}{0ex}}\sum _{i=1}^{n}{x}_{i}$

and, x
is the sample mean, n is the number of samples, and xi is the measured value of the ith sample for the metric.

(iv) For each basic model of UPSs, the represented value of Effavg 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 Effavg is less than or equal to the lower of:

(1) The mean of the sample, where:

$\stackrel{—}{x}=\frac{1}{n}\phantom{\rule{0ex}{0ex}}\sum _{i=1}^{n}{x}_{i}$

and, x
is the sample mean; n is the number of samples; and xi is the Effavg of the ith sample; or,

(2) The lower 97.5-percent confidence limit (LCL) of the true mean divided by 0.95, where:

$LCL=\stackrel{—}{x}-{t}_{0.975}\left(\frac{s}{\sqrt{n}}\right)$

and x
is the sample mean; s is the sample standard deviation; n is the number of samples; and t0.975 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 Effavg is equal to the Effavg 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 (Pm), standby mode power (Psb), off mode power (Poff), battery discharge energy (Ebatt), 24-hour energy consumption (E24), duration of the charge and maintenance mode test (tcd), 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]