View Full Version : AB power to electronics?
03-13-2012, 09:47 PM
been doing my usual google-ing with no luck. Anybody know of some kind of voltage converter so that I can either us p tap or a AB plate to convert and use as a AC power outlet. on remote locations downloading and not having bus powered drives/not having a ups backup can be an issue. and I"m looking for something where I can use ab batteries to power a small DIT setup.
Ryan De Franco
03-13-2012, 11:03 PM
Genius. If someone figures this out I owe you and Tim both a beer.
The concern would be voltage regularity. A UPS provides standard North American 120V power from its battery. With a 12V AB brick, the voltage is going to drop from 16.0 to 11.5 quickly and you'd need a DC - AC converter that can handle the stress, or risk supplying trembling voltage to the drives. You'd definitely want a "true" sine wav inverter, one that replicates real AC power, and doesn't just pass the stress along to the drive's power supply, causing heat and timing errors within the drive. I would guess a hard drive draws more power at startup--as all motors do, and a hard drive is basically a smart motor--so you'll need an inverter that can handle these fluctuations with ease. All this leads me to think a RadioShack inverter is not the answer..
* With the Anton Bauer Cine VCLX batteries--the big bricks you'd use for 28V power on a film camera--I'd bet you could run two bus powered drives and a laptop for long enough to make a few mag transfers, one at a time.
* With a standard AB brick--anywhere from 10% to 30% of the size--I'm guessing you might be lucky to power two drives for long enough to make one transfer. I could be completely off, this is just very rough math.
**Math deleted because it's damn wrong**
A) the voltage will drop faster because you're drawing more power, so the system becomes less efficient at an increased rate; and
B) the transformer itself requires a bit of juice, usually just a few watts but more if it's got all the smart regulation systems and safety cutoffs you probably want.
Another possibility would be wiring ten 12V batteries in series to produce 120V. That's overkill, since you're looking for something more compact than a UPS. But all this is making me think either a) someone really has to figure this out or b) we're crazy and should just deal with lugging around the smallest unit APC makes.
03-13-2012, 11:44 PM
I'm not an electrical engineer but I know the biggest issue is the voltage conversion. a single 95w AB battery would however be able to power up a standard g drive for quite some time. your typical power consumption of a 3.5 spinning disc is about 3-8 watts depending on which drive you get. the laptop has its own battery, and there already is a AB voltage converter you can get for just the macbook pro. the magsafe connection does a type of conversion already. power drives and maybe a few other accessories is the key thing. pretty much like a car power inverter but using AB batteries instead of your car engine.
kind of hard to find a product like that though.
and lugging around a APC is what i always do, but I'm dealing with a situation of flight travel and want to have the smallest foot print possible. the batteries are part of the production already and could be used in this fashion. or just used in an absolute emergency.
Ryan De Franco
03-14-2012, 12:31 AM
Of course! Man I'm dumb. Drives run perfectly well off 12V--how else would they run off a laptop battery. So forget all my idiocy about inverters--that would be a ridiculous waste of the battery. We just need to wire a 12V Dtap to the standard 12V DC-in...
3-8 watts, I had no idea drives were so efficient. And is that on 120V? I was just going off the listed amp draw of my externals. I think I figured out why there's a difference though-- the power supply has the capacity to pull .65A because it draws much more when it starts, like a washing machine, hair dryer, or any other motor. Once it's up and running, it draws far less. On top of that it's cheap to source a plug-in power supply that can handle .65A, why bother with less.
Maybe we can reach out to AB and convince them to develop this, as D-Tap is their pride and joy right?
Otherwise, sounds like a job for mikegyver (http://mikegyver.com/)
03-14-2012, 07:30 PM
the additional draw in the beginning is probably from the hd spinning up. once it reaches speed it takes very little to keep it going, since, like you said, is like a washer, can keep the momentum it has going already. not sure about the pure voltage and ampage. I'm not that knowledgeable on electrical wiring, just got a good grasp on the basics. I guess there's really nothing out there that does this. the most important part is the DC to AC conversion like a power inverter for a car, but nobody has ever made anything exactly like this. shame really, and I'm not inclined to try to splice my own wiring.
if they can come out with something like this i don't see why they can't come out with what I"m talking about, maybe i'll email them after all.
03-14-2012, 08:02 PM
I have a 4 pin xlr cable for a high quality inverter so I just go AB plate to the 4 pin cable to the inverter. 300 watts. It's right handy to have portable AC. Surprisingly efficient.
03-14-2012, 08:11 PM
03-14-2012, 08:31 PM
There's no link, I just bought an inverter and wired up a 4 pin xlr cable. If you go that route, make sure the inverter you order can handle a hot brick. They can be up to 16v. A lot of cheap truck stop style inverters give an over voltage warning and shut off over 14 volts.
03-15-2012, 11:45 AM
Available from AbelCine, and many others.
03-16-2012, 12:11 PM
I asked a similar question a few weeks back about V-Mount batteries. Mitch, is there an equivalent to the AB that you linked for a V-mount plate?