The Inverter Store Blog

At theinverterstore.com we recently decided to make a change in our product line we now proudly carry the Deka line of deep cycle marine batteries. The Deka line of batteries, by East Penn Mfg Company are top quality and are made in the USA. We carry two types of deep cycle marine batteries from Deka. Gel Batteries and AGM (Absorbent Glass Mat) Batteries.

These two battery types have many similarities. First, they are both designed as “maintenance free” batteries. Both Gel and AGM are sealed batteries, they are spill proof and can be operated in any position. Gel batteries and AGM Batteries are both lead acid batteries. Both types of batteries do have a break in period. Usually it takes about 10-15 charges for these deep cycle batteries to be able to take a full charge.

There are also many differences between these two types of deep cycle battery. Many resources on the web are covering this topic in much detail, I am going to do my best and keep this section simple. The first difference is in how each battery holds the electrolytes. The gel battery uses thixotropic gelled electrolytes and the AGM, uses electrolytes stored in absorbent glass mats. In cold weather the AGM battery will work better than the Gel battery in below freezing situations. This is because of the physical properties of the Gel battery. AGM Batteries are less expensive and lighter than Gel Batteries, which are heavier, but usually have more power in the same dimensional size battery.

Lets look at some applications for each type of battery. The Gel battery is better in applications that have a slow discharges and are in warmer temperatures. The AGM is a bit less touchy when it comes to temperature, you can operate the battery in warm or cold environments and get the performance you are looking for. Also AGM batteries can have a very low self-discharge rate, which means if the battery sits for a long time without being used it will hold its power. In solar or wind applications in which you are constantly charging and discharging your batteries I would recommend Gel batteries. In back up power type applications where the battery is not used constantly but is critical, I would recommend AGM battery. These batteries are perfect for this application. AGM batteries are an awesome choice for applications that require a short term high rate discharge. If you are running specialized electronics I also recommend an AGM battery. There are many variables that go into choosing the right batteries for your system, the best idea is to consult a professional before buying so you get the most out of your investment.

The applications in which the batteries are used most commonly is conjunction with a power inverter. Whether you are looking for a one battery to add to your vehicle power system or a bank of batteries to power your off-grid home. We are your one stop shop for power inverters and batteries.

We have a full line of AIMS power inverters and Deka deep cycle batteries available for you at theinverterstore.com. If you have any further questions about power inverters, cables or batteries. Please give us a call @ 888-417-8673.

Theinverterstore.com offers excellent customer support and we would be happy to answer any questions that you might have. We have a wide selection of pure sine wave and modified sine wave inverters and our goal is to make sure our customers are purchasing the right equipment the first time around.

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.

I recently was contacted by Bob Stanton from A.W.A.K.E., Truckers for a Cause.
This is a non-profit organization that is dedicated to the health of America’s Truckers. Specifically A.W.A.K.E. is a network of people helping people with sleep apnea. Bob and I were discussing the power inverter needs for a CPAP machine. He thought it would be helpful to write a blog including any information that I felt would be useful. Having experienced sleep apnea myself, I feel obligated to share what I know. I hope the information that I have gathered during a couple of testing sessions, will be useful. Sleep Apnea is a serious health issue and we here at theinverterstore.com are dedicated to providing a solution for those who need to use a CPAP on the road.

I would like to let you know up front that if you have any information regarding another type of machine, let me know I am happy to add to this post at anytime. There are so many different types of CPAP machines on the market today, this is an open forum to share your knowledge, and hopefully gain some too.

The machine that I used for testing is the REMstar Plus with C-Flex. I have had this machine for a couple of years. It has the heated humidifier unit also. the power requirements for this machine are as follows:

REMstar CPAP w/C-Flex: 1 AC amp max

REMstar Heated Humidifier: 1.7 AC amps max

I am aware that this unit does have a 12 volt outlet on the back, but I am not going to use it for this test. I am going to run this machine for 3 separate eight hour periods off of an AIMS pure sine power inverter and a couple of 6 volt batteries connected in series. According to our information the max usage of the CPAP with heat and humidity is 2.7 amps or 324 watts. I found the watts with some simple math listed below.

Amps x Volts = watts

2.7 AC amps x 120 vac = 324 watts.

I think it can sometimes be deceiving to the user how much power there CPAP is actually using. Because the two pieces are stacked together. When you look at the bottom of the unit you see 1.7 ac amps. I thought this was the number. I always double check the manual and I discovered there were two manuals one for the REMstar CPAP w/C-Flex and one for the REMstar Heated Humidifier. There is a section in the manual that clearly states what the max power needs are, usually labeled “Specifications.” The information we need is listed as “AC Power Consumption.”

I was also able to do some research on the ResMED S8, ResMED S6 and C-Series Tango machines. According to the manufacturer they will run on the AIMS 150 watt modified sine power inverter, as long as you are not using humidity. If you are using humidity on any of these units, you will need to use an AIMS 300 Watt pure sine power inverter.

Field Test Results:
I ran the CPAP here at our facility off a small battery bank. I have ran it for 6 to 8 hours for 3 days straight. The machine operates great with the AIMS pure sine power inverter I used the AIMS 600 Watt Pure Sine for this test, because of the maximum power requirement. I also monitored the watts and amps this machine was pulling with a Kill A Watt monitor. I have found out some useful information. The usage for levels 4-10 with heat and humidity on, are very low right around or below 50 watts, the only time I noticed a higher usage was during startup. What I mean when I say “startup” is the energy used when the machine is warming up, I assume the extra watts were from the heating element warming itself up to temp. The usage level was at about 115 watts during startup.

I have found that the CPAP pressure level that is set up for me, does not reach the max output usage. If your settings are higher, than level 10 the usage could be higher on your machine. If you are in a really cold environment it could take longer for your heating element to heat up. I tested the startup in our warehouse, which is around 55 degrees.

We now know enough to choose a power inverter for this application. From the research that I have done most CPAP’s require a pure sine power inverter. I am going to use the AIMS 600 watt pure sine power inverter for this test. We are just above 300 watts, but even if we were at 280 watts, I would recommend the bigger inverter. For a couple of reasons. In the future you might have another device that you want to plug into this inverter. Having more power gives you room for expansion. Also power inverters run more efficiently when the load they are pushing is not close to max capacity. Running an inverter at max capacity is ok, but you get more out of your batteries when the inverter is more efficient. By more efficient I mean that the inversion is happening with less loss of power. This is because the inverter is running with less heat, when you run a continuous load on an inverter at or near max capacity you get a lot of heat, this makes your power inversion less efficient.

I have heard of people using modified sine power inverters with CPAP’s some run with no problems.

At least that you see, but I can tell you that a modified sine power inverter can make your device run harder and hotter than its supposed too. You may shorten the life span of the device by using a modified sine power inverter. I have heard from some truckers that their CPAP burned out prematurely because of the modified sine inverter. Although, some manufacturers state that their machines will run normally on a modified sine without strain on the device. Certain ResMed, models without the humidity feature can run on a modified. Also Fisher-Paykel states it has modifed its design to allow the CPAP machine to run on a modified sine inverter.

Bob Stanton from AWAKE, Truckers for a Cause has many years experience with CPAP’s in the field. He just let me know that he ran a Respironics in his truck off the 12 Volt plug, it drained his battery below 11.78 volts. Not only would his truck not start, the data that is required for DOT compliance was corrupted and the machine was in “service required” mode.

All Aims Power inverters have an alarm that lets you know you are reaching low voltage and will shut off, before draining the batteries to low to start the engine.

Bob has also has experienced personally a CPAP failing prematurely because he was using a modified sine inverter. He owned a Fisher Paykel from 2002-2005, the first machine failed within 18 months because the motor burned out, from the modified sine inverter, running it harder and hotter then designed. Fortunately, Fisher Paykel did warranty the CPAP machine.

The difference is in the technology of the power inverter. A pure sine wave power inverter, produces a cleaner power signal, one that is very similar to the power that you get from the outlets in your home. Complex and delicate electronics and medical equipment like the CPAP need cleaner power to operate properly and reliably. CPAP machines are not cheap and they are necessary medically, so I recommend you use a pure sine power inverter. According to the information I have gathered from the US DOT, there is some data, that is collected from these machines. There have been instances of this data being corrupted, because the user was using a modified sine, so stick the pure sine. This will insure that your CPAP works dependably on the road and at home for many years.

It does not matter if you are running a 12 Volt, 24 Volt or 48 Volt system. You have probably had a conversation with someone about your battery bank. The main question that people always ask is do you keep your batteries in Parallel or Series?

For those who might not understand these terms, let me explain them for you.

Batteries in Parallel, means that the batteries in your bank are connected so that the inverter thinks they are all one big battery. Meaning if you connect four batteries 12V in parallel your inverter, still sees one 12 volt battery. Your power source is still 12 volts and your amp hours are quadrupled.

Batteries in Series, means that the batteries in your bank are connected in a way that the volts are doubled, for each series of batteries. To keep this simple, two 6 volt batteries in “series” are 12 volts. The power inverter recognizes them as a 12 volt power supply.

Now that we have a basic understanding of series and parallel. Your next question is probably which one is the better connection?

Well, that depends on your system. How many batteries are in your bank? What voltage are they?

Most battery manufactures recommend no more then 4 batteries be connected in parallel.

One point I would like to share is that if your batteries are in parallel, and one of them fails, the whole bank might stop putting out power. If the batteries are in series, if one battery fails, then just that “cell” or group of series batteries will stop producing power. So if you have a large battery bank, series is definitely the way to go.

For more information on Battery bank connections, please see our PowerPoint presentation at the link below.

Battery Connection PowerPoint

Theinverterstore.com offers excellent customer support and we would be happy to answer any questions that you might have. We have a wide selection of pure sine wave and modified sine wave inverters and our goal is to make sure our customers are purchasing the right equipment the first time around.