Page 38: of Marine Technology Magazine (March 2024)

LANDER LAB #10

Photo courtesy West Mountain Radio

Photo courtesy of Clarios/AutoBatteries.com

Figure 6

The West Mountain Radio Computerized

Battery Analyzer (CBA V) attaches to a

Figure 5 laptop by a USB-B cable, and to a battery by

Powerpole® Connectors.

Exploded view of an AGM lead-acid battery.

? Nickel-Cadmium (NiCad) batteries have a lower nom- ment System) the batteries are individually balance charged inal cell voltage of 1.2v/cell. They can be recharged up to and balance discharged on the same two-wire bus.

2,000 cycles. Self-discharge rate is 20%/month. They have a

QUANTIFYING BATTERY CAPACITY reasonably high power-to-weight ratio. The discharge curve of a NiCad battery is ? atter than other batteries. The NiCad The best way to determine a battery’s capacity is to measure battery can handle very high discharge rates, on the order of its actual performance using a computer-controlled battery ana- 15C, with no damage or loss of capacity. lyzer, such as the Computerized Battery Analyzer (CBA V), ? Nickel Metal Hydride (NiMH) batteries have high en- from West Mountain Radio (https://www.westmountainra- ergy densities, self-discharge rate of up to 30%/month, and dio.com/). The CBA V can test any type or size of battery, any display some memory effects. Their max discharge rate is 5C. chemistry or number of cells, up to 57 volts, and up to 200 watts

NiMH cells are advantageous for high-current-drain applica- continuous. A 100v version is also available. The basic model tions, largely due to their lower internal resistance. NiMH can is an affordable $189, while the Pro version is just $40 more. suffer longevity issues with deep discharge, but this may not be The CBA measures the actual amount of energy stored in a an issue if only a limited number of deployments are expected. battery, and reports that in units of amp-hours or watt-hours.

The system graphically displays the voltage-versus-time on a

There is a low–self-discharge nickel–metal hydride battery single page using a constant current load. Displayed graphs (LSD NiMH). The LSD NiMH battery, known as Eneloop, is may be saved and printed. Multiple test graphs of the same bat- currently only available as AA and AAA. tery under different conditions, or multiple batteries under simi- lar conditions, may be overlaid and compared. (See Figure 7.)

Test result labels can be printed to put on the tested batteries.

CHARGING

Dependable performance and long battery life depend upon The CBA’s intuitive software is designed to protect both the proper battery charging. Use a charger designed for the batter- CBA and the batteries being tested, providing automatic sens- ies you have. Universal smart chargers are pre-programmed ing of the battery cell count, a safety check of the test rate, and for the correct charging pro? le for the different battery fami- recommendation of a minimum safe discharge voltage.

lies. It just takes some user knowledge to set the charger for This author has also used the CBA to check the function of the right pro? le. a low-voltage cut-out (LVCO) to prevent over-discharge of a

LiPo batteries can be ganged in parallel on a two-wire volt- LiPo battery by setting the CBA cut-out voltage 0.50vdc low- age bus, as was described in Lander Lab #5, “Lithium Polymer er than the rated LVCO minimum. The LVCO was con? rmed

Batteries” (MTR, November/December 2022). Because each to work as advertised.

LiPo battery is regulated by its own BMS (Battery Manage- Primary cells may be tested and used to predict performance 38 March/April 2024

MTR #3 (34-47).indd 38 4/4/2024 10:57:30 AM