Recording to Infinity with Audioroot

by Thomas Rex Beverly

How to Use Multiple Batteries to Power One Audio Recorder For Unprecedented Session Lengths:

In 2024 I had my first conversation with Antoine from Audioroot. I hadn’t used any gear from the company, but had their gear recommended by my contact at Gotham Sound.

What followed was the most exciting development in my field recording kit in the last 5 years: the ability to power one recorder with two or three batteries in parallel!

Gear Setup in the Field – Recording to Infinity: 

I hope you enjoy this behind the scenes video of how to set up an MKH8018, a Zoom F3, and three Audioroot batteries in parallel. 

My Old Powering System: 

Previously I’ve used Anker USB-C batteries to power MixPre-6II, MixPre-3II, F3, and F6 audio recorders via USB-C. The drop rig duration limit was always capped at the 100 Wh (26,800 mAh)  limit of these single USB-C batteries. You cannot fly on most airlines with batteries over the size of 100 Wh (but you can fly with multiple 100 Wh batteries). 

Examples of Drop Rig Runtimes (with a single 100Wh battery): 

  1. Stereo - Sennheiser MKH8020 x2 (at 48V phantom) + Zoom F3 + 26800 mAh Anker USB-C battery + 96kHz/32bit  = about 30 hours of recording time. 
  2. Stereo - LOM Usi Pro x2 (at 24V phantom) + Zoom F3 + 26800 mAh Anker USB-C battery + 96kHz/32bit  = about 60 hours of recording time. 
  3. Stereo - LOM Usi x2 (plug in power) + Sony A10 + 26800 mAh Anker USB-C battery + 96kHz/24bit   = 5-7 days of recording time. 
  4. Quad - Sennheiser MKH8020 x4 (at 48V phantom) + Zoom F3 + 26800 mAh Anker USB-C battery + 96kHz/32bit  = about 15 hours of recording time. 
  5. Quad - LOM Usi Pro x4 (at 24V phantom) + Zoom F6 + 26800 mAh Anker USB-C battery + 96kHz/32bit  = about 40 hours of recording time. 
  6. Immersive 3D - Lewitt LCT 540 S x8 (at 48V phantom) + Zoom F8n Pro + Audioroot eSMART Li-96neo + 96kHz/32bit  = about 8-10 hours of recording time. 
  7. These examples are estimates for normal temp ranges between 50-90F.

Other than the Sony A10 + LOM Usi rig I had no way of doing super long duration sessions (of more than 48 hours). I also was very limited in my ability to record with 48V phantom mics in Quad (with a limit of only 15 hours). I’ve also started recording with 8-channel immersive rigs so I need more power. With the Lewitt LCT 540 S (x8) or Sennheiser MKH8020 (x8) you can only get 8-10 hours off one 100 Wh battery.

Enter Audioroot:

Now, back to my conversation with Antoine. During our chat, he pointed out that Audioroot already made an eSmart Hotswap Dual Battery Cup to Hirose cable. This power distribution cable was not marketed for use with long-duration drop rigs, but he said it would work by draining both batteries in parallel (and can also be used to hotswap batteries)! So, all I had to do was hook two Audioroot eSMART Li-96neo batteries to that cable and then connect the Hirose connector to my Zoom F8n Pro.

I was immediately very excited, I could now record with Quad or Immersive rigs for twice the duration using two batteries!

However, what to do about all my recorders that I’ve historically powered via USB-C? Luckily Antoine is a master of custom power distribution systems. He told me that he could modify the design of the eSmart Hotswap Dual Battery Cup to Hirose, but modify the output to be USB-A&C. And the best part was that Antoine told me that you could run three batteries in parallel, not just two. 

In addition, Audioroot is turning these power distro cables into standard products! However, they are still built to order, so order well before your project begins. 

Here are the power distribution cables Audioroot designed for me. See the product pages for full descriptions and instructions on usage and device compatibility: 

  1. eSmart TRIAD Battery Cup x3 to Hirose 4
  2. eSmart TRIAD Battery Cup x3 to USB A&C 
  3. eSmart DYAD Battery Cup x2 to Hirose 4 
  4. eSmart DYAD Battery Cup x2 to USB A&C
  5. eSmart SINGLE Battery Cup to USB A&C

All those combinations opened up a whole new world of possibilities for my recording adventures. As one crazy example, you could use the eSmart TRIAD Battery Cup x3 to USB A&C to run Sennheiser MKH8020 x2 (at 48V phantom) + Zoom F3 + Audioroot eSMART Li-96neo x3 + 96K/32bit = about 90 hours of recording time

Field Testing in Hawaii: 

  1. I tested these power distribution cables (in all the configurations listed above) and all performed well in Hawaii in February 2025. 
  2. Batteries performed well in high humidity
  3. Batteries performed well in moderate temperatures

Design Choices I Love: 

  1. High build quality for the Li-96neo batteries
  2. High build quality for all power distribution cables
  3. The shake-to-wake OLED screen on the bottom of the Li-96neo batteries. No button to break in the field. The OLED screen also shows battery charge, cycles, specs, etc.
  4. Li-96neo batteries do not have a low temperature shutoff. Some of the newer Anker USB-C batteries have a low temperature shutoff, so the Anker batteries randomly shutoff somewhere between 40-55F, making them unusable for my needs in colder weather. Antoine told me that Li-96neo batteries don’t have a cold temperature shutoff (but will still be less efficient in the cold like all Lithium batteries).
  5. I can use the same Li-96neo batteries to power recorders that need Hirose or USB-C by just switching out my power distro cable!
  6. The Li-96neo batteries come with a protective cap to cover the ports
  7. Audioroot custom 3D printed some eSmart power distribution cable caps for me. I use them to protect the pins while traveling or when powering a recorder with a DYAD cable (with only one battery attached). They aren't going to sell these, but will open source the 3D printer file so you can print them yourself. 

Things I still need to test: 

  1. I have not yet tested the Li-96neo batteries in extreme cold or extreme heat
  2. The jury is still out on how this Audioroot gear holds up during long-term use, but the build quality very solid and is definitely higher than the Anker batteries I’ve been using for the past 10 years. 
  3. The ePSB - USB-C PPS power bridge adapter looks like a great way to power a Zoom F8n Pro (or any recorder that needs Hirose power) using a USB-C battery. Antoine told me the USB-C battery needs to output 15V to work with the ePSB-HRS4. I will always have some Anker USB-C batteries with me, so this ePSB-HRS4 adaptor would be a great addition to my kit. 
  4. Audioroot is even making a combining cable to run four batteries in parallel! But I haven't tested that one: eSmart BCC Power Combining Cable

Things I hope Audioroot improves in the future: 

  1. Ideally, I’d like to be able to charge the eSMART Li-96neo batteries via a USB-C charger. Something with 60-100W charging speeds would be perfect. All my other pro audio and video gear can be charged via USB-C, so I'd love to be able to charge my Audioroot batteries USB-C as well. 
  2. Lithium ion batteries should be stored at 40-60% charge. So I'd also like to have a charger that could charge (or discharge) batteries to a 60% storage level automatically when I return from expeditions.

Other Things to Note: 

  1. Battery discharge behavior: these power distribution cables will pull power from the battery/batteries with the highest charge at the beginning. Then, when the batteries equalize they will discharge evenly together (in 2 or 3 battery configurations). 
  2. Don’t store the Li-96neo fully charged (or fully discharged). That’s bad for the batteries. Store them at 40-60% charge. See the manual for more info.

Other charging accessories you might need: 

  1. eSMART Li-96neo Batteries
  2. eSMART MONO Battery Charger
  3. eSMART DUAL Battery Charger
  4. eLC-SMB eSmart Battery Charger
  5. IonGuard Fireproof Pouch

Where to Buy: 

  1. If you are in Europe you can buy directly from Audioroot (they are based in France)
  2. Gotham Sound stocks many Audioroot products in the US
  3. B&H is also an option in the US if gear is out of stock elsewhere

Disclaimers: 

  1. Do your own research when traveling with lots of batteries. Different airlines and countries have different rules. Lithium batteries can catch fire, so do your own research on how to travel with them safely. Audioroot makes an IonGuard fireproof pouch to help mitigate risk. 
  2. These power distribution setups are a non-traditional way to power audio recorders. So do so at your own risk. 
  3. Audioroot supports my recording adventures. However, all thoughts on gear are my own. You can see all my sponsors – here. 

I hope you find these new power combining cables from Audioroot helpful for your field recording adventures. Running 2 or 3 batteries in parallel has been something I’ve wanted to do for YEARS. But despite lots of searching, I couldn’t find a non-sketchy, non-DIY way to run 2 or 3 batteries in parallel. Audioroot has finally solved this problem for me (with a high quality, electrically safe solution). It was great to collaborate with Audioroot on the design of these cables and I hope they help with your recording adventure too. Have fun exploring and I hope you find some awe inspiring sounds in the natural world. 

Thanks for listening, 

Tom

 

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