I recently received two DeVilbiss CPAP’s, these units were sent to us for testing direct from the manufacturer. We did some bench testing to find out what the maximum power usage is for each machine.
The first machine we tested was the DeVilbiss IntelliPAP AutoAdjust CPAP System. We tested this system here in our office on our DC power supply. All the testing was done at 12 volts. According to DeVilbiss, all of their CPAP’s will run on a modified sine wave power inverter. The specs call for at least a 200 watt power inverter, we used an AIMS 400 watt Modified Sine power inverter for this testing. We connected the inverter directly to the battery with cables, we did not use the cigarette plug. We decided not to use a cigarette plug, for one main reason. The manufacturer specs calls for a 200 watt inverter and a cigarette plug only handles up to 180 watts, if it is fused at 15 amps. If your vehicle has 10 amp cigar plugs, you can only go 120 watts maximum.
The first test was done for about 4 hours with the heater set at 10 and the CPAP set 20 cmH2O (maximum pressure). While monitoring the usage, I observed DeVilbiss IntelliPAP AutoAdjust CPAP System with the heater set at 10, consumes just under 8 DC amps per hour, maximum. The usage actually varies between 6.0 dc amps and 8.0 dc amps. We are going to use the max usage of 8 DC amps, this will give us an accurate amount to calculate battery capacity needed. Many people may be asking how do I convert DC amps to watts, etc. I will cover this after all the testing information is covered.
The next test I did with the DeVilbiss IntelliPAP AutoAdjust CPAP System, was with the heater off. The usage is lower, between 1.8 and 2.0 DC amps. We did not observe as much fluctuation in the usage as with the heater running. This makes sense, because it is constantly working to keep the humidity water at a certain temperature, causing the usage to cycle up and down, while maintaining the water temperature. The max DC amp usage, with out the heater on the DeVilbiss IntelliPAP AutoAdjust CPAP System was 2.0 DC amps. This system actually runs at a very low usage, with out the heat and humidity, about 24 watts.
The second DeVilbiss CPAP system we tested was the IntelliPAP Bilevel S CPAP System. This machine has two functions, IPAP and EPAP. We only need to understand these functions in simple terms, it has two settings “inhale” and “exhale.” The “inhale” or IPAP pressure setting on our test unit was set at 20 cmH2O and the “exhale” or EPAP pressure was set to 12 cmH2O. As far as I understand the machine pushes more air on inhale and backs off the pressure on exhale, to help the patient breath out easier. These cycles make the machine run a little bit different than the auto adjust, it uses a little bit more power. I also tested this unit on the AIMS 400 watt modified sine power inverter. In our testing with the DeVilbiss IntelliPAP Bilevel S CPAP System, we observed the maximum usage of this system with the heater set to “10″ to be just under 10 DC amps. The actual usage varied between 7.6 and 10.0 DC amps.
The next test we did with the Devilbiss IntelliPAP Bilevel S CPAP System was with the heater set to “off”, no heater. The maximum usage without heat on the DeVilbiss IntelliPAP Bilevel S CPAP System was just under 5.0 DC amps. The actual usage fluctuated between 0.6 and 4.9 DC amps. We will go with 5.0 DC amps to be safe.
Next I want to review our maximum usage totals and make some recommendations on which power inverter and a battery to use in your mobile system.
We will make one small conversion while reviewing our data.
To convert from DC Amps to Watts, we need to multiply the DC Amps by the voltage of our system, in this case 12 Volts.
DC Amps X 12 = Watts
DeVilbiss IntelliPAP AutoAdjust CPAP System maximum usage with the heater set to “on” and at level 10 and pressure set to 20 cmH2O (maximum pressure) was 8 DC Amps or 96 watts.
DeVilbiss IntelliPAP AutoAdjust CPAP System maximum usage without the heater, heater set to “off ” and pressure set to 20 cmH2O (maximum pressure) was 2 DC Amps or 24 watts.
DeVilbiss IntelliPAP Bilevel S CPAP System maximum usage with the heater set to “on” and at level 10 and IPAP pressure set to 20 cmH20 (maximum pressure) and EPAP pressure set to 12 cmH2O was 10 DC Amps or 120 watts.
DeVilbiss IntelliPAP Bilevel S CPAP System maximum usage without the heater, heater set to “off” and IPAP pressure set to 20 cmH20 (maximum pressure) and EPAP pressure set to 12 cmH2O was 5 DC Amps or 60 watts.
Extra Testing for lower pressure settings:
DeVilbiss IntelliPAP AutoAdjust CPAP System, with a pressure setting of 12 cmH2O with heat set to “10.” The max usage was 7.5 DC Amps or 90 watts.
DeVilbiss IntelliPAP AutoAdjust CPAP System, with a pressure setting of 12 cmH2O with the heater set to “off.” The max usage was 1.7 DC Amps or 21 Watts.
We used an AIMS 400 Watt Modified sine power inverter for all of these test. I direct connected to a battery for the test. I do not recommend that you use a cigarette plug for this equipment. Even though the watts are low enough for the plug to handle the load, most cables for cigarette plugs are not thick enough to handle the load. The cables for cigarette plugs are only rated at 80 watts per UL requirements. So to prevent damage to your vehicle, power inverter or CPAP, direct connect to the battery. You will get more efficiency this way also.
If you are using a mobile battery system, for example while camping. You need to use the DC amp usage to find out what size battery is needed to run this system. Lets run over an example, if you are using the DeVilbiss IntelliPAP AutoAdjust CPAP System, with the heater, your usage is 8 DC amps. A normal nights sleep is 8 hours, you will need at least 64 amp hours (8 dc amps X 8 hrs), to cover your daily sleep requirement. Most deep cycle batteries will give you 80 percent of their power before needing a recharge. I would recommend an 80 amp hour battery for this application. On our website we sell the Lifeline GPL-24T Deep Cycle AGM Battery, it has 80 amp hours. Just make sure you have provisions to recharge the battery during the day. For this application if you had the Iota 30 Amp 12 Volt Smart Battery Charger/Converter you could recharge this battery in just over 2.5 hours.
For the entire DeVilbiss CPAP product line, I recommend the AIMS 400 Watt Modified sine power inverter, per manufacturer specs they require at least 200 watts. I chose this product because a power inverter operates more efficiently with a smaller load, the closer you are to max output the less efficient the power inversion. This AIMS product will cover your power needs and give you the most efficiency out of your batteries.