Battery Pack Testing & Review - Omni 20+ & Omni Mobile 25,600

During your Black Friday sales, I purchased both an Omni Mobile 25,600 and an Omni 20+ unit which I plan to use to power my ResMed AirMini CPAP machine during a flight or when camping.

In doing my research on battery solutions, I discovered the hot topic on Reddit about the choice of cells used for in the Omni products, and though I read through this information, my concerns are primarily reliability and performance. If the product performs reliably and safely as advertised, I do not care who's cells they choose to use.

With that being said, I set about testing the two battery packs and found some interesting results that give me confidence in using both of these devices for travel CPAP power.

For reference, my testing was conducted using a Junsi iCharger 406 DUO battery charger / discharger. I set this device up to discharge at a constant current until the voltage dropped below a threshold. This discharger is intended to monitor battery voltage and stop discharging when the voltage drops below a set point, but in this test, the Omni battery DC output simply cuts power when the internal battery is empty.



During this discharge process the iCharger logs the mAh and also provides the instantaneous W rate and Voltage. Using this I can calculate the Wh pulled from the battery packs.



For both batteries, I discharged at 12v and at 24v using the DC barrel connector. The Omni+ is capable of greater rates of discharge than the Omni Mobile, but I conducted two similar tests to simulate high load and medium load.

Starting with the Omni 20+, this is a beautifully designed product. It features an OLED screen with information about the outputs enabled, the instantaneous W pulled from the cells, a battery percentage etc.



The Omni 20+ also has a lot of different inputs and outputs:

• 110 v AC / 150 v HVDC (100 W max)
• USB C (In 45 W max and Out 60 W max)
• 2 x USB A (18 W max each)
• DC Barrel Jack
  - Input 4.5 v to 36 v (45 W max, suitable for Solar Charging)
  - Output configurable between 5v and 25v (5A / 100 W max)
• Qi 10W wireless charging

The 110 v AC output and high power output capability make this battery slightly larger than others of a similar capacity, and I’d have loved to have seen a 100 Wh version available for extra capacity whilst still OK for in flight use. Omni does make a larger battery, but it is over the 100 Wh limit for in flight use at 142 Wh

The DC port is what's needed for ResMed CPAP machines, and cables are available online to connect to the AirMini, the AirSense and the S9. DC ports are rare on these sorts of battery packs, which makes these Omni products quite unique.

Perhaps most importantly, the Omni 20+ can charge and discharge at the same time, effectively acting as a UPS. You can charge using the USB-C or DC port. We're using the DC port for CPAP, so USB-C it is, and a MacBook or other USB-C laptop charger works great. Also interesting is that you could use another, cheaper USB-C battery pack to extend the run time of the Omni 20+... There are many options possible.



So on to my capacity tests…

Omni 20+ @ 12 v, 4 A (48 W):
- During discharge, the voltage remained steady at 11.9 v
- During discharge the iCharger indicated an instantaneous power consumption of 47.3 W and the Omni 20+ indicated an instantaneous power consumption of 51.5 W, suggesting an efficiency of 91.8%
- The iCharger indicated a total capacity of 5,386 mAh when the Omni 20+ switched off, giving a total usable capacity in this configuration of 64.1 Wh (5,386 mAh x 11.9 v)
- If we take the efficiency calculated above, this suggests a total pack capacity of 69.8 Wh
- If we assume the pack capacity is 71.040 Wh as stated, this gives a discharge efficiency of 90%
- If we assume the total pack capacity is in fact 69.8 Wh, this calculates to 6 cells of 11.63 Wh, or 3,144 mAh (@ 3.7 v)
- Omni states the capacity as 71.040 Wh +/- 5%. 71.040 * 0.95 = 67.488 Wh. My calculations suggest that at this medium rate of discharge, the capacity is within tolerance, and equal to 71.040 - 1.7%

Omni 20+ @ 24 v, 4 A (96 W):
- During discharge, the voltage remained steady at 23.87 v
- During discharge the iCharger indicated an instantaneous power consumption of 71.6 W and the Omni 20+ indicated an instantaneous power consumption of 75.3 W, suggesting an efficiency of 95.1 %
- The iCharger indicated a total capacity of 2,631 mAh when the Omni 20+ switched off, giving a total usable capacity in this configuration of 62.8 Wh (2,631 mAh x 23.87 v)
- If we take the efficiency calculated above, this suggests a total pack capacity of 66.0 Wh
- If we assume the pack capacity is 71.040 Wh as stated, this gives a discharge efficiency of 88.4%
- If we assume the total pack capacity is 66.0. Wh, this calculates to 6 cells of 11 Wh, or 2,973 mAh (@ 3.7 v)
- Omni states the capacity as 71.040 Wh +/- 5%. 71.040 * 0.95 = 67.488 Wh. My calculations suggest that at this high rate of discharge, the capacity is slightly lower than this, and equal to 71.040 - 7%

I also tested the Omni 20+ running my AirMini overnight. I run in APAP mode 7 ~ 12, and 8 hours of use left me with 55% battery remaining in the morning. It might be tight, but 2 nights should be possible.

The Omni Mobile 25,600 is a costed down battery pack, but with many of the same features of the Omni 20+, and a larger capacity. Both the Omni 20+ and the Omni Mobile 25,600 use 18650 cells, with the 20+ using 6 and the Mobile 25,600 using 8. Despite the additional capacity, pricing is also lower for the Mobile 25,6000 at just over half the cost of the 20+.

The Omni Mobile 25,600 features a metal enclosure which feels sturdy, and makes do with 4 LEDs instead of the OLED screen on the 20+. While it’s certainly not ugly, it’s not as elegant as the Omni 20+.



Although the Mobile 25,600 features a DC jack, it has limitations compared to the Omni 20+, not that these will be a problem for CPAP use. The main limitation is that you must choose from 4 preset output voltages (12, 16, 19 and 24) as opposed to the Omni 20+ DC output which can be configured in 0.1 v steps. The Mobile 25,600 also has a current limit of 3 A, and a maximum power capacity of 72 W. Interestingly, if you try to draw 3.5 when the DC output is set to 24 v, the unit will lower voltage to stay within the 72 W capability bringing the output down to 20 v. As you can see from my testing below, the unit had no problem supplying 3.5 A at 12 v even though this is beyond the specifications. The Omni Mobile 25,600 does not feature the current limiting functionality of the 20+.

The Omni Mobile 25,600 has the following inputs and outputs:

• USB C (In 40 W max and Out 60 W max)
• 2 x USB A (18 W max each)
• DC Barrel Jack
  - Input 4.5 v to 36 v (40 W max, suitable for Solar Charging)
  - Output selectable (12 v, 16 v, 19 v, 24 v - 3A / 72 W max)
• Qi 10W wireless charging

So in terms of functionality, you don’t give up much from the Omni 20+. Capacity is greater, price is lower, and the most significant thing you loose is the 110v AC output, which is inefficient and takes up space in the product! Personally I love the design of the 20+, and appreciate the data that the OLED screen provides, I just wish there was an 8 cell 100 Wh version. Ideally I’d like the capacity and size of the Omni Mobile 25,600, with the design and functionality (minus the 110v) of the 20+!

On to the capacity testing then:

Omni Mobile 25,600 @ 12 v, 3.5 A (42 W):
- During discharge, the voltage remained at 11.9 v
- During discharge the iCharger indicated an instantaneous power consumption of 41.6 W; the Omni Mobile 25,600 does not have a display, so it is not possible to calculate an efficiency
- The iCharger indicated a total capacity of 6,863 mAh when the Omni Mobile 25,600 switched off, giving a total usable capacity in this configuration of 81.9 Wh (6,863 mAh x 11.93 v)
- If we be kind and take the lowest efficiency calculated for the Omni 20+ as an example (91.8 %), this suggests a total pack capacity of 89.2 Wh
- If we assume the pack capacity is 92.160 Wh as stated, this gives a discharge efficiency of 88%
- If we assume the total pack capacity is 89.2 Wh, this calculates to 8 cells of 11.1 Wh, or 3,013 mAh (@ 3.7 v)
- Omni states the capacity as 92.160 Wh +/- 5%. 92.160 * 0.95 = 87.6 Wh. My calculations suggest that at this medium rate of discharge, the capacity is within tolerance, and equal to 92.160 Wh - 4%

Omni Mobile 25,600 @ 24v, 3A (72 W):
- During discharge, the voltage held steady at 24.09 v
- During discharge the iCharger indicated an instantaneous power consumption of 72.3 W; the Omni Mobile 25,600 does not have a display, so it is not possible to calculate an efficiency
- The iCharger indicated a total capacity of 3,343 mAh when the Omni Mobile 25,600 switched off, giving a total usable capacity in this configuration of 80.5 Wh (3,343 mAh * 24.09 v)
- If we be kind and take the lowest efficiency calculated for the Omni 20+ as an example (91.8 %), this suggests a total pack capacity of 87.7 Wh
- If we assume the pack capacity is 92.160 Wh as stated, this gives a discharge efficiency of 87%
- If we assume the total pack capacity is 87.7 Wh, this calculates to 8 cells of 11.0 Wh, or 2,963 mAh (@ 3.7 v)
- Omni states the capacity as 92.160 Wh +/- 5%. 92.160 * 0.95 = 87.6 Wh. My calculations suggest that at this high rate of discharge, the capacity is just within tolerance, and equal to 92.160 Wh - 5%

So overall the Omni 20+ and Omni Mobile 25,600 devices appear to perform a little under, but close to the specified capacity.

I was asked how long these batteries would last at 16cm H2O in another thread about my AirMini modifications, so I did some testing. I'm re-posting here because it's relevant to this thread as well:

The testing I conducted was to run the AirMini from a battery pack, but this was only done because I could then use the 24v DC power cable with barrel connector end. I have male and female barrel connectors for another project, and I used this to put a Fluke 87V multimeter in series measuring current. The Fluke was set to average and I took measurements whilst laying down breathing normally over a 2 minute duration. I tested at 5cm, 10cm and 16cm (for @woot) with every combination of masks and tubing setups I have.

The first thing I discovered is that Bluetooth adds about 10mA of load to the power supply / battery pack. That's not a lot, but you might want to turn it off to eek out some additional run time.

The next thing I discovered is that the silencer system doesn't add any additional load. I didn't really expect it to, but thought I'd test that just in case.

Finally, the HumidX, which is optional for the DreamWear Nasal Cushion how I have it set up, does increase load, and how much depends on the pressure. I've therefore included data with and without the HumidX for the DreamWear Nasal Cushion.

On to the results:


It's pretty interesting to me that the N20 gives the least amount of load at 10cm H2O, but not the least at 5cm. This is probably due to measurement error, and the reality is that it's very close. The DreamWear Full Face mask uses quite bit more at 16cm, but this is mostly due to it leaking a little bit. I don't think this is a good mask for high pressures. At lower pressures it's pretty comparable in load to the other masks.

As for run-time, the Omni Mobile 25,600 will get you two 8 hour nights with all masks up to 10cm H2O, but not at 16cm. You should easily get 1 night out of either battery pack at 16cm, as long as you don't have many leaks.

If you need two nights, the Pilot 24 might get you there at 95 Wh capacity, but it's likely to have similar performance to the Omni Mobile 25,600 and might not at 16cm H2O.

I saw one of these batteries pop up on sale. Remembering this post, I grabbed one. But I'm having a hard time tracking down the DC to AirMini cables.

Can you share more info on exactly where you got one? I see that Mediastrom certainly did make an AirMini cable kit, but on 10+ CPAP online stores it says out of stock or discontinued. I'm not sure they make these anymore. I have also seen your photo of your travel kit and it appears you have a while DC>AirMIni cable which I haven't seen in my searching.

Can you point me in the right direction?

Thanks!