Oscar Spier
May 31st, 2009, 07:45 AM
Originally the Elphel has 48v POE (power over ethernet), but it is possible ( Modifying the camera for 12-36v mobile applications - ElphelWiki (http://wiki.elphel.com/index.php?title=Modifying_the_camera_for_12-36v_mobile_applications) )with a modified Elphel to use a power source within the 12v (9v-36v) range.
An important post on this by Sebastian:
Careful with the amps!
5W power consumption does not equal 5 Amps.
P (Watt) = U (Volts) * I (Ampere)
so I = P / U
Using a 12V battery as example:
I = 5W / 12V
I = 0.417A or 417mA
Battery capacity is rated in mAh (milli ampere hours).
So if in our example we have a fully charged 12V battery pack with
4000mAh we can estimate the camera (assuming 5W power consumption) to
last for around 9.5 hours.
This is a theoretical maximum value as you would have to consider DC-DC
losses, degree of efficiency, etc. as well.
Maybe the battery pack would last for 8 hours or less.
Regards Sebastian
5 Watt power consumption is not much at all. My EeePC draws around 15W
in idle mode and most laptops use up to 50 W.
5 W at say a battery
Right now, I've tested a 11.1v LiPo battery. It works well and they are extremely lightweight, but they are difficult to charge because they also need to be balanced so they require an expensive charger. Another issue is that you have to make your own housing with a small project box for example.
Alexandre from Elphel is testing this product which looks most promising so far: http://www.digipowersolutions.com/store/product_info.php/cPath/3/products_id/676?osCsid=d3af7ec4964ee2c9d3929b7124103a4d Here is an image with the camera: Hardware | Apertus Open Source Cinema (http://cinema.elphel.com/node/15#polto) It can be charged and used at the same time, has status LEDs on the side and also provides a 5v USB power.
An important post on this by Sebastian:
Careful with the amps!
5W power consumption does not equal 5 Amps.
P (Watt) = U (Volts) * I (Ampere)
so I = P / U
Using a 12V battery as example:
I = 5W / 12V
I = 0.417A or 417mA
Battery capacity is rated in mAh (milli ampere hours).
So if in our example we have a fully charged 12V battery pack with
4000mAh we can estimate the camera (assuming 5W power consumption) to
last for around 9.5 hours.
This is a theoretical maximum value as you would have to consider DC-DC
losses, degree of efficiency, etc. as well.
Maybe the battery pack would last for 8 hours or less.
Regards Sebastian
5 Watt power consumption is not much at all. My EeePC draws around 15W
in idle mode and most laptops use up to 50 W.
5 W at say a battery
Right now, I've tested a 11.1v LiPo battery. It works well and they are extremely lightweight, but they are difficult to charge because they also need to be balanced so they require an expensive charger. Another issue is that you have to make your own housing with a small project box for example.
Alexandre from Elphel is testing this product which looks most promising so far: http://www.digipowersolutions.com/store/product_info.php/cPath/3/products_id/676?osCsid=d3af7ec4964ee2c9d3929b7124103a4d Here is an image with the camera: Hardware | Apertus Open Source Cinema (http://cinema.elphel.com/node/15#polto) It can be charged and used at the same time, has status LEDs on the side and also provides a 5v USB power.