Power Consumption and Battery Power Supply
Power Consumption
Elphel offers the modified Elphel 353 camera that works with 12-36V DC for additional 50$. This modification is the key to enable mobile operation. The best efficiency range is said to be at around 15V. Typical Elphel camera power consumption: 2400 milliwatts just booted 3000 milliwatts after setting image parameters 3700 milliwatts streamer on 3300 milliwatts streamer off 3800 milliwatts streamer on and somebody playing the stream 5000 milliwatts with streamer on and HD writing at full speed (dd) 5800 milliwatts streamer on, HD and USB-flash writing at full speed
If you are using an external HDD/SSD with the camera you have to provide power to this device as well. The best solution we have found so far is using an external 2.5" HDD enclosure with USB and eSATA. You can provide 5V power through USB and connect it to the camera with an eSATA to SATA adapter cable.
From our experience "general notebook backup-power batteries" also called " External Power Pack for Notebooks" work very reliable in the Apertus set-up
Tested batteries
Technical Specs: 11.1V, 4400mAh, 48.8Wh provides: 5V (USB connector), 16V, 19V It has remaining capacity status LEDs, power on/off button and can be charged while being used. Price: ~100$
When testing this battery pack we noticed a problem between the over-current (and maybe other protection circuits) detection of the Elphel camera and the Digipower battery pack which resulted in power being constantly cut and re-enabled at 16V. It worked flawlessly at 19V though.
Technical Specs: XP8000 has a listed capacity of 8000mAh and the XP18000 of 18000 mAh (they fail to tell us at which Voltage though so we can't calculate Wh) both provide 5V (USB) 1000 mA, 10.5V 2000mA, 19V 2000mA Both have remaining capacity status LEDs, power on/off button, we did not try charging them while using them. Price: XP8000 ~80$, XP18000 ~140$
We used the XP18000 one in the south Utah desert with an Elphel 353 and Intel SSD and had no bad experience with it. At the end of the day the battery was still 3 out of 4 status leds full.
Tests with LiPo battery
We did some tests with batteries actually meant to be used in RC-planes or -helicopters. LiPo batteries have the highest energy-density that is currently available, meaning for the same amount of power you need the least weight which is definitely desirable since the rest of the Apertus rig is extremely lightweight (e.g. camera: 230g). Though these batteries are also the most expensive ones and need some extra precaution as they posses the ability to light themselves on fire if not being handled properly.2000mAh LiPo using a Lipo saver LED (to avoid discharging the battery to below critical 9V)
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In our tests everything went smoothly though, batteries powered Apertus flawlessly and there were no sudden combustions ;-)
Additional External Links:
- How to choose your battery (reference for the power consumption of different cameras and manufacturers. Sony PD 170: 8 Watts Red One: 75 Watts)
- HY Research - Simple Li battery power supply (project of building a small Lithium Ion battery pack)
- http://wiki.elphel.com/index.php?title=Talk:Modifying_the_camera_for_12-... (Some more infos at elphel)
Notes/suggestions:
- Its important to have a proper mount system for the battery pack that allows battery changing without screwing and plugin in multiple connectors. Examples are the Sony V-Mount for their professional cameras or the Anton Bauer mount.
and the AXIOM project is certified Open Hardware by
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