Sleep Apnea CPAP Battery Test Now Underway at Major Fleet, TMC Says
September 09, 2013
PITTSBURGH -- A field test of battery-powered CPAP devices to combat sleep apnea among drivers is now underway with the help of three suppliers and a major truckload fleet, according to a report at a task force meeting of the Technology & Maintenance Council of the American Trucking Associations.
And it appears that a single dedicated battery can effectively supply enough power to run a mask supplying continuous positive air pressure (CPAP), according to Will Watson, a consultant involved in the study. It does so without idling the tractor’s engine or running down the main chassis batteries.
CPAP masks are an effective way to combat obstructive sleep apnea, or OSA, a medical condition caused by obstructed air passages in a person’s nose and throat, said Randy Thinnes, a senior occupational health manager for ResMed Corp., a maker of masks and one of the suppliers in the study. The others are Midtronics Inc. and Trojan Batteries.
Thinnes and Watson said they both suffer from the condition, but the masks allow them to get complete nights of restful sleep. So they have a personal interest in treating OSA among commercial drivers. Daytime sleepiness is one of the prime symptoms of the condition, and drivers who have it can and do fall asleep at the wheel.
The study, which began in May, aims to outfit each of five sleeper-cab tractors with a dedicated battery to power a mask that runs on 12 volts DC, Watson explained. So far four tractors and their drivers have the equipment. Another one was installed, then removed when the driver left the company.
The battery is a Group 31 absorption glass-mat, or AGM type, mounted in a sealed box under the bunk. A smaller battery would have enough capacity, but the Group 31 is common to heavy trucks and was therefore convenient in the study. Its operation is regulated by a charge-back relay.
The most a battery has been discharged so far is to a 65% state of charge, well above an AGM’s tolerance level, Watson said. The longest a system has worked without recharging from the truck engine’s alternator is over a three-day period while a driver was waiting for a load.
The system is isolated from a tractor’s cranking batteries, and could work whether or not a tractor had shore power circuitry, he said. The 12-volt CPAP appliance is much easier and more efficient to operate than 115-volt appliances, which in a truck would require an inverter to work.
In addition to a fan to move air into a person’s passages and cause him to breathe normally through a face mask, a CPAP appliance includes a humidifier to keep his or her nose and throat moist and healthy. This is done by a heating plate that vaporizes water from a small reservoir in the appliance. Twelve volts at 4 amperes is plenty to support these functions, but not enough to seriously discharge the battery.
The study will continue for an unspecified amount of time.