Battery Backup For Your Mobile DJ Rig

Apr 9, 2019 | Gear

Consider a battery backup for your mobile DJ rig

Let’s set the stage. I am getting ready to announce the wedding party in and an unexpected thunderstorm comes in. I announce them in (to the way too appropriate Back to the Future theme and Power of Love) and start the first dance. 30 seconds into the first dance, the building takes a lightning strike. The power takes a hit and everything comes down for a full second, long enough that everything resets.

Back To The Future Meme

It takes about 45 seconds for everything to come back up. So, spur of the moment, I get the crowd to continue to clap to the cadence till things come back up. Kept everyone in high spirits. The system comes back. Crisis averted. The couple could not have been more awesome about the situation, especially given their musical selection, and chalk it up to an awesome memorable moment.

As a 20+ year IT person, I knew quite a bit about UPSs, but I also knew that the devices were large and heavy that would meet the basic requirements for sensitive audio equipment. But in the past couple of years, a couple of consumer-level models came on the scene that shrunk the size and made these attainable for the mobile DJ. It’s time to examine those battery backup models.

Not all UPSs are the same

There are a lot of battery backup devices out there, and a lot of price points to consider. Most importantly, there are a lot of battery backups that would do more harm than good to your sensitive equipment. To meet the criteria needed for a mobile DJ rig, these essential elements are needed before you dive into a battery backup solution.

Ride. The. Wave.

There are numerous types of battery backups that produce a few different types of outputs. The most common is the square wave, modified sine wave (also called approximated sine wave or simulated sine wave), and pure sine wave. As shown in the picture below you can see the smooth curves of a pure sine wave, where a square wave has more of a binary up/down look. A modified sine wave tries to follow more closely the pattern of the pure sine wave, but as you can see it still has a very rigid step in its output.

Here is the problem. Finding a pure sine wave UPS tended to be in only the super heavy, super large, and super expensive server-grade equipment. However there are some gems that can be found that are not technically pure sinewave, but their output is the same. But we’ll get into that in a minute.

Automatic Voltage Regulation (AVR)

An automated voltage regulation device, well, automates voltage. In most UPS, this is done through coils of wire and a special transformer switches between the coils. Keeping the voltage consistent is a very desirable thing to have. Most UPSs now have AVRs in some way.

Switch this!

There are different designs on how a UPS switches its power from the source to a battery. The three most common are stand-by, line-interactive, and on-line. A stand-by design has a switch that detects when power is cut off and switches to the battery which can take 5-15ms depending on models. A line-interactive combines both the switch and the inverter into a single unit, in some cases cutting down transfer times. Lastly, there are on-line designs that pass all the power through the battery, converting from AC > DC > AC and is the quickest at 0ms and not coincidently the most expensive option of the three with the cheapest on-line UPS I could find on Amazon clocking in at $530 and it’s a massive server-room type device.

Stand-By Design is the oldest but the most inefficient
Stand-By Design is the oldest but the most inefficient
Line-Interactive improves on the Stand-by design, but it’s not the quickest
Line-Interactive improves on the Stand-by design, but it’s not the quickest
The On-Line Design is the quickest, but most expensive
The On-Line Design is the quickest, but most expensive

So the general thought of mind here is that the line-interactive is the best compromise to have. With the interruption published at 4ms and real-world testing having it at 4-10ms, most sensitive systems can handle that.

Watts, VA, CAPACITY!!!

So when researching for battery backups you may see an odd combination of ratings on a unit; VAs and Watts. What’s with that?

In this corner, we have the Volt-Ampere (aka VA) and this is typically described as apparent power. Then we have the Watt which represents the real power that is drawn. OK, this probably makes even less sense now. Even worse we have this expression called the “Power Ratio” which is the ratio of VA to Watts to indicate essentially efficiency.

So what does it all mean? In many of the middle-sized units you will see, you will see somewhere around 1500VA and 900W. This is a power factor of 60% and is pretty typical. Higher power factors typically have a much higher price tag involved.

As for sizing your battery right, it really does come down to investing in the largest unit you can get. The larger you get, the more battery time you get. After testing out the configuration I would be using, I was consuming in a typical 160-260W with peaks at 300W. If an outage occurred I would likely cut back a little bit to maximize my runtime, between 25-30 minutes.

What’s that noise?

While most noisy UPSs can be attributed to the type of wave output it has (a modified sine wave or square wave tends to introduce some noise in the line) you still need to be aware that many UPS models may have inferior equipment that may bring unwanted noise to the party like Electromagnetic interference (EMI) and Radio Frequency Interference (RFI). That buzzing that you would head on a speaker? That could be a combination of the power output plus EMI and/or RFI. Make sure to look for a unit that has EMI and RFI filters.

There is a battery backup that does all this?

As I noted above, the world of UPSs is pretty vast, and the past few years has seen new battery enhancements, better quality parts for lower costs, but as more UPSs are being sold to customers with home entertainment systems, desktops, and the like, they all are missing one or more key feature needed for sensitive audio equipment. But there are a pair of UPSs out there that tick off all the major checkmarks. [Note, in 2020 APC has seemingly discontinued the BR1500MS model].

One of the biggest features that both of these UPS have is that the sine wave output is as close to a pure sine wave as you can get, well without it being technically a pure sine wave. Apparently, this is a digital manufactured sine wave output but with incredible resolution in its steps. This tidbit of info can be found over at Tom’s Hardware about the CyberPower UPS:

“No digitally created wave can be a true mathematically curved analog wave. But the number of digital steps used to create the wave can be great enough that the electronics used in even the highest efficiency computer power supplies are unable to distinguish them from an analog wave. The total harmonic distortion of the output on battery is under 2% which means the output of the UPS is closer to a mathematically ideal analog wave than the powercoming out most peoples walls.

From all the videos and articles I have seen on this series of UPSs, many with oscilloscope readings, they universally have said the same thing, they cannot distinguish this from a pure sine wave and with that, the price point on this is considerably lower than anything else on the market with this capability. And to prove the point here is the oscilloscope capture of both of these units in action and comparing it to a similar APC model I have that has a stepped sine wave output.

Combine that with a line-interactive design, AVR, 1500VA/900W capacity, EMI/FRI filters, a both have a connected equipment guarantee, and a 3-year warranty, this unit hits all the right marks for use in a mobile DJ’s rig.

The practical use

Since I had a need for two UPSs (one for ceremonies, one for receptions) I decided to buy one of each, that way if one was really superior for everyday use I could gauge that, but how will I use it in my setup? To maximize the battery output for my reception rig, I am going to put one of my speakers on the surge side, while my other speaker, and the rest of my core setup on the battery side. This should net me an additional 5-10 minutes of use. In addition, I will turn off unneeded equipment.

From initial tests on real-world loads, I typically net 20-25 minutes of real-world time on my reception rig and an amazing 60+ minutes on my ceremony rig. This certainly replaces the portable batteries that I was using that were square-wave output and gave some really bad side effects of their use.

Battery backup? Absolutely!

There are a number of real-world practical reasons to consider investing in a battery backup solution for your ceremony or reception setup:

  • Provides steady power to your equipment, prolonging its life
  • Protects against brownouts, spikes, and noisy power
  • Provides 20-60 minutes of off-the-grid power
  • Can be a reasonable substitute for ceremony battery solutions that cost more or have undesirable attributes

For me, this is a no brainer. I’ve invested in a pair, and I feel far more at ease than I have incorporated a solid source of power in case of the unthinkable.

Stand-Alone Power? Really??

I have had a few inquiries about real-world testing in the way of ceremonies, specifically if they would work as a stand-alone battery. I’ve also seen a couple of comments out there that say this would not be a recommended solution. Well, the only way to figure the details out is to put it into a real-world simulation. Here are the parameters of the test.

For the test, I ran a mix of music, from classical, jazz, R&B, hip-hop; trying to mix in heavier bass notes in some tracks while others having a more rounded midrange sound. I muted for about 5 minutes and worked the microphone to simulate that kind of draw which seemed to have no increase or decrease in the battery’s output.

The end result was the following:

  • Initial load indicated 83 minutes of runtime with no sound playback after 2 minutes of power
  • 3 minutes in and the APC indicated 69 minutes of runtime with sound playing
  • 16 minutes in and the APC indicated 63 minutes
  • 60 minutes in and the APC indicated 38 minutes
  • 1:13 minutes in and the APC indicated 28 minutes
  • 1:30 minutes in and the APC indicated 14 minutes
  • 1:47 minutes in and the APC indicated 4 minutes

Again, I can’t stress enough that performance will vary depending on how much draw you have from your equipment. But in at least my case, where a pre-ceremony and ceremony lasts 60 minutes or less, this works amazingly in my situation.

Transporting Your UPSs

One difficulty to consider if you buy these UPSs is transporting them between gigs. With the cost so low, it’s hard to justify getting a 3U case or a custom-sized flight case for it. And you will likely need to replace this every year or two with the amount of use you could get out of it. In addition, this is not a standard rack size device so you have to cobble something together to make it secure in its transportation box.

I’ve tried a number of things, and the best thing I have found to date are these Geargrip “CPU Holders” that snugly secure around the UPS and have a properly angled handle to use. While this only offers minimal protection for it, this seems to be the best tradeoff of keeping it simple with getting these UPSs to and fro.

Long Term Observations

So what are my thoughts after using this for both my ceremonies and receptions for the past year? It’s nice to report that virtually all my experiences have been positive. For my receptions, it’s been nice to have that peace of mind that my system is protected. After a couple of tent-based weddings with generators, it was so very awesome to protect against a square-wave output that was noisy as all hell from one generator while another the power output was so varying that it was protecting against both overages and brown-outs.

For ceremonies, it has been absolutely solid. I had to have it in 97º baking heat and direct sunlight for one wedding and it held up strong for a 20-minute pre-ceremony and 70-minute ceremony. It truly ran to the very limits considering the run time and the heat, cutting out in the middle of the outro song, but it saw me through it all.

With my 2019 setup changes, I have added an IEM into my ceremony box, and even after 30+ ceremonies, running my Ui16, router, IEM, and 4 microphones it still runs about 1h 25m with a couple of minutes to spare. Compared to the 1h 45m run with 2 mics and a 50% load on my EV50 I’d say the battery held up quite well over the year.

I had originally planned to replace my batteries every year but it seems I might be able to squeeze more than that out of them both. When I do decide to replace the batteries the APC takes the APCRBC163 replacement battery that currently clocks in at $70 and the CyberPower RB1280X2B battery runs about $75.

Oh, yeah, there is a permanent reminder in my setup now about all of this. 🙂

1.21 Gigawatts!

Update History

  • Original Article on Battery Backup: 5/16/2018
  • 9/4/2018: I finally found some decent straps to carry around these UPSs.
  • 6/7/2018: I’ve added a real-world test of my typical ceremony solution, complete with video, that you can check out below.
  • 4/9/2019: I’ve added some long term results after using it for a full season and some other observations.

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