Why Won't My CPAP Run on My Battery? What to Check, in Order

If your CPAP won't run on your EXP PRO battery, check the voltage setting first. The battery has to be set to the voltage your CPAP runs on, and it's the number one thing people forget to check. If the voltage is right, the cause is usually one of four other things: the battery isn't fully charged, the DC cord doesn't match your current CPAP, the cord is in the wrong port, or (if it runs but dies early) the humidifier and heated hose are using most of the charge. Go through them in that order. None of these checks need tools.

This guide covers the EXP48PRO APEX and EXP96PRO APEX, the current batteries with the LCD screen. Both have the same output voltages and power your CPAP the same way, so every step applies to either one. If yours has four indicator lights and no screen, it's our earlier Classic model. Most of these steps still apply, but the cords are different (see Step 3).

The quick checklist

1. Is the battery set to the right voltage for your CPAP?
2. Is the battery charged and awake?
3. Is the cord made for the CPAP you use now?
4. Is the cord plugged into the right port?
5. If it runs but dies early, are the humidifier and heated hose completely off?

Here's each step in more detail.

Step 1: Set the battery to the right voltage for your CPAP

This is the check people skip most often, so start here. The LCD screen shows the output voltage the battery is set to. That setting has to match the voltage your CPAP runs on. If it doesn't, your CPAP won't run on the battery even when everything else is right.

To find the voltage your CPAP needs, look at the DC cord you use or at the power rating on your machine. For example:

• 12V: Philips Respironics DreamStation family and System One 60 Series.
• 24V: ResMed AirSense 10 and 11, AirCurve, AirMini and S9, Resvent iBreeze and React Health Luna G3.
• Breas Z1 and Z2: 15V, through the USB-C IN/OUT port (see Step 4).

If the screen shows a different voltage from the one your CPAP needs, change the setting before you plug in. The user manual shows how, or call us and we'll walk you through it. Check it again whenever you switch machines or use the battery with a different CPAP.

Step 2: Make sure the battery is charged and awake

If the screen shows the battery percentage, the battery is on. If the percentage is low, charge it before you go further.

If it's brand new: new batteries ship at roughly 10–30% charge. That's normal for shipping, but it isn't enough for a night. Charge it fully before your first night on it, and before any test night.

If the screen stays blank or the battery won't respond: try the DC charger first. That's the car-style charger that plugs into a cigarette-lighter socket. It can sometimes wake a battery that isn't responding when the AC charger doesn't.

If you charge by USB-C: use the port labeled USB-C IN/OUT, not the one labeled USB-C OUT.

If it sat in a closet all summer: a battery that hasn't been charged in months may be very low or not respond. Try the DC charger as above. For next time, store it at 40–50% and top it up at least once every three months. That recharge is part of the warranty terms, so it's worth putting on the calendar.

Only use EXP PRO charge cords. Other chargers aren't recommended and can damage the battery.

Step 3: Check that the cord matches your current CPAP

The DC cord is made for your CPAP model, not for the battery. If the cord doesn't match your machine, the battery can be fully charged and set to the right voltage and your CPAP still won't start.

The usual mistake is the cord for the wrong CPAP generation. Someone upgrades from a ResMed AirSense 10 to an AirSense 11, keeps the old "10" cord, and finds it doesn't work with the new machine. The same goes for other brands: the DS-12V cord is for the DreamStation family, including DreamStation 2, and it doesn't work with Breas machines. Check the cord against your exact CPAP model.

Second, the cord has to match your battery's generation:

• APEX batteries (with the screen) use APEX cords, with no separate converter. EXP PRO APEX power cords
• Classic batteries (four lights, no screen) need the "12V to 24V converter" version of 24V cords, such as the RM-10 and RM-11. Cords for Classic batteries with converter

If you've changed CPAPs since you bought your battery, look here first: all CPAP DC cords.

Step 4: Plug the cord into the right port

Which port your cord goes into depends on your CPAP's voltage. It's the same on the EXP48PRO APEX and the EXP96PRO APEX.

• 12V and 24V machines plug into the port labeled DC IN/OUT. That covers the ResMed AirSense 10 and 11, AirCurve, AirMini and S9, the Philips DreamStation family, System One 60 Series, Resvent iBreeze and React Health Luna G3.
• Machines that run at other voltages plug into the port labeled USB-C IN/OUT. That includes the Breas Z1 and Z2, the React Health TravelPAP and the Transcend Mini and Micro.

If your CPAP won't start and the cord is in the other port, move it. Push the plug all the way in at both ends: at the battery and at the CPAP's power inlet. A half-seated plug is easy to miss in the dark.

Step 5: If it starts, then shuts off

If the CPAP starts and then stops partway through the night, look at the screen. Check the voltage setting again (Step 1), then the percentage. A battery that wasn't fully charged will just run out sooner. If both look right, check these:

• Loose connection. Seat the cord firmly at both ends (Step 4).
• Inverter setup. Some people run the CPAP's AC cord through a pure sine wave inverter plugged into the battery. That works, but it draws noticeably more power than a direct DC cord, so the battery runs out sooner. Most CPAP makers also require a pure sine wave inverter, not a modified sine wave one. A DC cord for your CPAP will usually get you more from the same charge. Using an inverter vs. direct DC power

If it keeps shutting off with the right voltage, a full charge, the right cord and the right port, stop troubleshooting and contact us.

Step 6: If it runs, but the battery dies fast

This is the most common runtime complaint, and it usually isn't a battery defect. Make sure the humidifier and heated hose are completely off. Not turned down: off. Together they use a lot of power. With both on, the EXP96PRO APEX runs roughly one night. With both off, it runs an estimated 4–6 average 7-hour nights, and the EXP48PRO APEX an estimated 2–3.

On some machines the heated hose has its own setting, separate from the humidifier, so it's easy to turn one off and miss the other. Here's how to turn off the heated hose and humidifier on your CPAP.

Other things that affect runtime:

• Mask seal. A leaking mask makes the CPAP work harder, and that increases the power draw.
• Your pressure and mode. These affect how much power the CPAP draws. This is part of your prescription, so don't change anything to save battery. Any therapy questions go to your sleep or equipment provider.
• Your machine. Different CPAP models use different amounts of power at the same pressure.
• Temperature. Cold conditions affect runtime. If you're camping in fall weather, CPAP camping in cold weather has more.
• Battery age. All batteries lose some capacity over time.
• Inverter use (see Step 5).

Runtime figures are always estimates, because every setup is different. How long will a CPAP run on a battery? goes through the numbers.

Do a test night before you need it

The best time to find any of these problems is at home, a week or two before you need the battery. Before a trip or when storm season starts:

1. Check that the battery is set to the right voltage for your CPAP.
2. Charge the battery fully.
3. Check the cord and the port.
4. Turn off the humidifier and heated hose.
5. Sleep a full night on the battery, and check the percentage in the morning.

That tells you everything works together and gives you a realistic idea of your own runtime. If you're preparing for outages at home, plug the battery into the wall and your CPAP into the battery. In pass-through, your CPAP runs off the battery the whole time while the charger keeps it topped up, so when the power goes out nothing has to switch over. Your CPAP is already running on the battery and keeps going. How to keep your CPAP running during a home power outage walks through that setup.

Still not working? Talk to us

If you've been through every step and the CPAP still won't run on the battery, contact us at orders@exppropower.com or 360-686-7424. A real person will help you work out what's going on and the next steps. It helps to have your CPAP make and model, the cord you're using, and what the screen shows. EXP PRO batteries carry a 2-year warranty for the original purchaser.

If you're still choosing a battery, the EXP48PRO APEX bundle and EXP96PRO APEX bundle each include a CPAP DC cord. Tell us your CPAP model and we'll make sure you get the right one.

FAQ

What's the most common reason a CPAP won't run on a battery?
The battery isn't set to the voltage the CPAP runs on. Check the output voltage on the battery's screen and make sure it matches your CPAP before you check anything else.

Why won't my CPAP turn on when the battery shows a charge?
Check the voltage setting first, then the cord and the port. The cord has to match your current CPAP model. 12V and 24V machines plug into DC IN/OUT, and machines at other voltages, such as the Breas Z1/Z2, React Health TravelPAP and Transcend Mini/Micro, plug into USB-C IN/OUT.

My new battery won't power my CPAP out of the box. Is it defective?
Probably not. Check the voltage setting, then charge it fully, since new batteries ship at roughly 10–30% charge. Then check the cord and the port and try again.

My battery won't turn on or respond at all. What should I try?
Try the DC (car-style) charger first. It can sometimes wake a battery that isn't responding. If you charge by USB-C, use the port labeled USB-C IN/OUT. If it still won't respond, contact us.

Why does my CPAP battery die so fast?
The most common reason is the humidifier or heated hose being on. Turn both completely off. Mask leaks, higher pressures, cold weather, battery age and running through an inverter also shorten runtime.

Do the EXP48PRO APEX and EXP96PRO APEX connect to my CPAP differently?
No. They have the same output voltages and use the same ports.