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Power options for field recording

Filed under: live sound and recording,tools — 2013-03-03 by Richard L. Hess — Last Edit 2013-03-28 by Richard L. Hess

I had the first failure to capture an entire concert in my recording career. I had become complacent and considering that I had new (April 2012) Li-ion batteries for my Sound Devices 722 recorder, did not think twice about recording a concert on the approximately 50 Wh 6-cell packs. Well, one failed, and did so spectacularly without a warning. I did not notice the in-process warnings, because I do not wear my headphones during the whole concert. I try and take in the concert so that I can then see what’s missing in the studio. Here is what the after-the-fact results showed:

batts4a

Needless to say, I received a refund on Battery A. Oddly, Battery B was bought at the same time and I had been attempting to evenly alternate between the two. I also have a Battery D (same type as Battery C, but from a different reseller) in transit.

So, what could I have done during the recording if I noticed a battery misbehaving like Battery A?
Very little as it stood originally!

I decided to look into options. The SD 722 recorder wants at least 10 V or so on the external battery input, so you can’t just get a sled for the camcorder battery that the SD uses in its native mode.

The SD recorder came with a cable configured for a cigarette lighter to special Hirose connector (the power input). I decided to cut that cable and install a 5.5 mm with 2.1 mm centre pin plug on the half with the Hirose connector and a mating receptacle on the half that contained the cigarette lighter plug. This way, I maintain the automobile-charging capability (which I have admittedly never used), but I can also plug the SD 722 into an external 12 V pack.

I made this decision after ruling out the typical “Booster Box” as it weighs as much as the entire recording kit and I’ve not had good luck with long term stability of the $60 AGM wheelchair batteries typically found inside these heavy low-end devices.

I had spent a little time looking at external batteries prior to this experience, as I had had an instance where one of my sons was out of contact for part of a trip and I was worried, so I located some of these 20 Wh capacity USB-based batteries. Deal Extreme ships directly from China for the listed price and I have been reasonably happy with the merchandise I have purchased from them, especially considering the price. This unit charges from a USB charger (or PC) and will charge a phone or anything that can be charged via its USB port. This one must be manually shut off when the charge is complete, but it’s a fairly nice package and not much bigger than the phone. However, it does NOT have a 12 V output. I mention it as this was my introduction to the broad range of current offerings in external battery packs.

In addressing the recorder redundancy, I first purchased an Anker Astro 3 pack with 34 Wh of capacity and I really like it. I’m keeping that in my general travel accessory bag (murse?) as it can run the GPS, recharge my cell phone, and run the Sound Devices recorder for several hours. I bought it here in Canada, but it is also available in the US, the UK, Germany, and probably more locations, via the company’s website. This unit was $59.99 in Canada from Amazon.ca.

It has two USB outputs. One is plain vanilla and the other is alleged to be for iPhone and it makes my Garmin GPS think it’s connected to a PC. I have not tried it with my Android phone. It also has a switchable 9 or 12 V output and a separate charger input connector. The charger requires 12 V (plus or minus) so I found a cable with a car lighter plug to the battery pack’s input plug to charge it in the car as well. It also has auto shutoff if the load falls below about 80 mA. This “feature” needs to be watched, but I have not seen it switch off when I did not expect it…yet.

I decided to try this $34.80 rechargeable pack which has a capacity of about 50 Wh, also from Deal Extreme. It seems to perform quite well, but I have only run it for a couple of cycles. This must recharge from the included USA-type plug-in charger (which will work world-wide with simple plug adapters). The charger lights up red and when the pack is switched on and the pack is charging, a green LED glows (but the red is blinding compared to the green). When this green LED goes out, the pack is fully charged. This pack and charger are dedicated to the recorder carrying case. You must switch the pack on to charge or use it, but do not forget to switch it off. The switching is a simple, mechanical, rocker switch. This is not as well made as the Anker nor the other Deal Extreme unit, but it is adequate.

With the Sound Devices recorder, the external battery charges the internal battery or runs the unit without a battery (I don’t know if that’s really recommended). The external battery can always be used with the unit’s non-disruptive failover to the internal battery or you could opt to plug it in only when you are noticing an issue with the internal battery. I like the idea of two ways to operate. I think for the orchestra concerts where I’m not monitoring, I will use the pack and the internal battery.

(Note the term “internal” is not quite accurate as the battery is on the outside of the case, but made part of it. It is a standard Sony-type camcorder battery.)

Now I will have one fewer excuse why I did not get the recording. I may be over-reacting, but it’s the first recording I’ve lost in doing this off-and-on since about 1974 and it was because I was getting complacent.

I would recommend these units for a variety of applications, especially field recordings, making certain that you find the correct pack for the application. I suspect these could be made to work with any device that has an external power jack.



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