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Gear / Technical Help => Remote Power => Topic started by: Bdifr78 on April 18, 2011, 12:19:09 PM
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Hi Guys,
I haven't run gear at a festival in around 3 years :'( so I haven't had to worry much at all about batteries. So my knowledge is very hazy and I wanted to get a refresher/ask a few questions pertaining to my 722. Since there is a good chance this info is already available please point me in the right direction if need be.
1. What kind of power draw difference (run time more specifically) is there between running the 722 and recording to:
A. Both HD and CF
B. Just HD
C. Just CF
For one nighters I run to both, but what would be most efficient for festy. I have enough CF to record the full fest, and of course enough hard drive. So to add to the question, what is most efficient and uses the least power? How can I quantify this for run time?
2. How will running P48 vs. not running P48 impact battery life?
3. One of my 722 batts will only charge to 7.5V and the rest will charge to 8.2V or 8.3V. Does this mean this battery is on it's last leg? How will this effect run time?
Thanks so much guys.
I was a heavy duty taper for a few years and now have been relegated to extreme light duty and as mentioned my knowledge is way hazy/rusty. Superball IX will be my first fest I have taped since All Good 08.
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Hi Guys,
I haven't run gear at a festival in around 3 years :'( so I haven't had to worry much at all about batteries. So my knowledge is very hazy and I wanted to get a refresher/ask a few questions pertaining to my 722. Since there is a good chance this info is already available please point me in the right direction if need be.
1. What kind of power draw difference (run time more specifically) is there between running the 722 and recording to:
A. Both HD and CF
B. Just HD
C. Just CF
For one nighters I run to both, but what would be most efficient for festy. I have enough CF to record the full fest, and of course enough hard drive. So to add to the question, what is most efficient and uses the least power? How can I quantify this for run time?
2. How will running P48 vs. not running P48 impact battery life?
3. One of my 722 batts will only charge to 7.5V and the rest will charge to 8.2V or 8.3V. Does this mean this battery is on it's last leg? How will this effect run time?
Thanks so much guys.
I was a heavy duty taper for a few years and now have been relegated to extreme light duty and as mentioned my knowledge is way hazy/rusty. Superball IX will be my first fest I have taped since All Good 08.
1) CF only uses the least. Sound Devices published a series of stats (http://www.sounddevices.com/notes/recorders/powering/power-draw/) related to the 7 series power draw that you might want to take a look at.
2) As far as P48 is concerned, it does impact draw, but I don't have that handy in terms of hours and stuff. Unless their chart is off, SD says it draws like 0.3W (depending on the ma draw of the mic as well).
3) Recycle the bad one and keep the rest. I just baught a new Lenmar 7800mah off of amazon for $50. I've been able to get my bottom batteries to charge to 8.2, but they will shut off early if I'm not careful. That's the first sign for age as best I can tell. I have an older one which is about 2, maybe 3 years old and it charges to 8.2-8.1 while it dies at about 7.2v now (where as in my experience, brand new large capacity batteries charge to 8.2 and die around 6.9 or 6.8). Lithium Ion naturally loses it's ability to hold a charge as it ages.
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Thanks Page. How much time do you find you typically get from a battery in good condition? Looks like most of my batts are 7.4v 6900 mah. Isn't there a chart somewhre to help calculate?
Anyone else have input or want share personal experiences?
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Based on SD table, a 722 consumes about 20 watts during record, with phantom power on, recording to the HDD. Your KM140s draw about 2 ma each which is lower than many condenser mics, so 20 watts is a reasonable number. You batteries supply 7.4v * 6.9 Ahr = 51 watt hours. 51 Whr / 20 W = about 2.5 hours. In my experience, 2.5 hr is a low estimate for a 6900 mAhr battery, but it depends on the particular battery.
However, there is no reason to guess or estimate battery life since it is an easy test to find out the life of a particular battery. Just set up you 722 with mics attached and phantom power on, connect a fully charged battery, and hit record. Obviously, the 722 will stop recording when the battery is dead (the 7xx recorders are good, but they still require power). Then check the length of the recording. You may end up with more than one file depending on how long the battery lasts since FAT32 has a max file size of 4 gig. You probably should set the file size to 4 gig (menu item 35) and you may want to record at a lower sample rate and at 16 bits to keep from generating multiple files during the test. Or record a FLAC or MP3 file to keep the size down. You get the idea. After the test, just write the time on the battery. Don't do this test too often since Li-ion batteries do NOT like to be deeply discharged.
In practice I never approach the endurance of my batteries since I NEVER run the 7xx boxes with just one battery; I always use an external power source along with the internal battery. Dual power sources is one of the great features of the 7xx boxes. I used to connect to AC if power was available, but now I use an external battery.
I have two types of external batteries. The first is two 7.4 V Sony mount batteries in series which is 14.8 volts. I built a battery sled that holds the two batteries. The advantage of this is it uses the same batteries that mount on the recorder.
The second battery I use is this:
http://www.batteryspace.com/waterbottlelifepo4battery128v6800mah8704whforhidhalogenbikelighttrial-techfemaleplug.aspx (http://www.batteryspace.com/waterbottlelifepo4battery128v6800mah8704whforhidhalogenbikelighttrial-techfemaleplug.aspx)
Since I am a bicyclist also, I actually bought this battery as part of this bicycle light kit: http://www.batteryspace.com/trailtechsinglehidhelmetlightwith128v64ahlifepo4waterbottlepacksmartcharger--2000cyclelifeforbattery.aspx (http://www.batteryspace.com/trailtechsinglehidhelmetlightwith128v64ahlifepo4waterbottlepacksmartcharger--2000cyclelifeforbattery.aspx)
(This is a really nice bicycle light, in case you care about such things.)
Anyway, that bad boy battery will run a 7xx box for 8 hours easy, and will charge the internal battery as well.
The biggest problem with using an external battery is building the cable. Soldering to the Hirose 4-pin connecter that SD uses is not an easy task, particularly for these old eyes.
Based on email correspondence with a SD engineer, do not exceed 18 V with an external power source. I mention this because many nominal 18 V batteries can have a much higher voltage when fully charged.
One more comment: I always record to both the HDD and CF. The HDD does not draw that much more power and being able to record to dual media is a great feature. A long time ago I was using a 702 without an external drive. The 702 recorded just fine, but when I transfered the recording from CF to my laptop, Windows f-uped the CF. I had to use a hex editor to extract the data, and I delivered the recording about a week late. I HATE going to a client to try to explain "technical difficulties". At least I was able to recover the recording. So the moral is: always record to dual media.
That's my experience.
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Based on SD table, a 722 consumes about 20 watts during record, with phantom power on, recording to the HDD. Your KM140s draw about 2 ma each which is lower than many condenser mics, so 20 watts is a reasonable number. You batteries supply 7.4v * 6.9 Ahr = 51 watt hours. 51 Whr / 20 W = about 2.5 hours. In my experience, 2.5 hr is a low estimate for a 6900 mAhr battery, but it depends on the particular battery.
Yeah, that's low in my experience. On a brand new 7600mah battery, P48, dual media, and backlight off (LEDs on low) I've gotten around 6hrs of recording. Maybe a touch more, but thats about it. I remember it got down to uncomfortably low levels (but was still on) after that.
However, there is no reason to guess or estimate battery life since it is an easy test to find out the life of a particular battery. Just set up you 722 with mics attached and phantom power on, connect a fully charged battery, and hit record. Obviously, the 722 will stop recording when the battery is dead (the 7xx recorders are good, but they still require power). Then check the length of the recording. You may end up with more than one file depending on how long the battery lasts since FAT32 has a max file size of 4 gig. You probably should set the file size to 4 gig (menu item 35) and you may want to record at a lower sample rate and at 16 bits to keep from generating multiple files during the test. Or record a FLAC or MP3 file to keep the size down. You get the idea. After the test, just write the time on the battery. Don't do this test too often since Li-ion batteries do NOT like to be deeply discharged.
agreed (especially on the deep discharge).
fire everything up, run it dead and look at the wave file time (flac's are all or nothing, beware...), knock off about 30-45 minutes for safety and that is your running time for the rest of the summer season.
In practice I never approach the endurance of my batteries since I NEVER run the 7xx boxes with just one battery; I always use an external power source along with the internal battery. Dual power sources is one of the great features of the 7xx boxes. I used to connect to AC if power was available, but now I use an external battery.
Ditto, I now run two, a tekkeon at 11v and a jumbo 7.4v.
The biggest problem with using an external battery is building the cable. Soldering to the Hirose 4-pin connecter that SD uses is not an easy task, particularly for these old eyes.
Best $50 I spent was having Ted do it for me (inc the supplies).
One more comment: I always record to both the HDD and CF. <snip> I HATE going to a client to try to explain "technical difficulties". At least I was able to recover the recording. So the moral is: always record to dual media.
On mission critical jobs, I agree, and since I do stuff on guestlists or other type events every now and then I keep the 722 over a 702 for that very reason. I've had an hdd in a recorder die before, so I always viewed the 722's dual media feature as a precaution against that. While possible, it's less likely to lose both mediums in a single recording event.
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I record to JUST CF Card at festies and get about 2 more hrs compared to running INHDD or INHDD+CF Card
I use 3x7.2v 4500mah rc batteries for each "battery" in my setup, so essentially a 7.2v/13,500mah battery ;) I can get around 10 hrs running MIC-IN, and around 15-20hrsd running LINE-IN :)
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Awesome info. Thanks guys. I certainly remember getting at least 5 hours per batt when put to the test. I also know that 2.5 is way low because I never have to change batteries foe a show with opener and 2 set headliner. Of course that is while not running p48 and using v3 instead. Will spl make a difference in power draw?
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Will spl make a difference in power draw?
I don't have any data, but I doubt it. I've have run some test with the LEDs on vs LEDs off, and that makes little difference. This is to be expected since LEDs require very little power. I was running the LEDs at their lowest brightness, so maybe if they were cranked all the way bright there would be more of a difference between on and off.
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I also run my 722 w/ the backlight ALWAYS LIT UP, because there is miniscule difference between them ON vs. OFF ;)
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Great thread guys. I appreciate all the info supplied here.
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Great thread guys. I appreciate all the info supplied here.
It was good meeting you Charlie :)
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Great thread guys. I appreciate all the info supplied here.
It was good meeting you Charlie :)
Yeah, it's been fun meeting everyone.