Panasonic D-54 Batteries Powering Odyssey 7Q - Electric Experts Wanted

Ted Herod

Ted Herod

Active member
Hi all,

We're using an A/B -> D-Tap setup as our primary power source for the 7Q, however we've got a load of Panny D54s hanging around, and we're trying to figure out a spare-parts method to power the 7Q in a more mobile/light-weight environment.

Now obviously, the only spare part we didn't have was a 7Q power cable... so we bought an OD-Flying. Meanwhile, we have the batteries, and we have a battery plate. Seems like a match? Not quite. In very short order the batteries drop to 6.5v and the 7Q becomes very unhappy.

These D54s are: 7.2V 5400 mAh 39Wh

They are in great shape. They're powering an LED light that's 7.2V 9Wh at full power for about 4 hours, and then on a slightly lower power (still 70% output) running for another hour. So they're working just fine.

What I finally realized is that the plate we have was designed to run a BlackMagic (specifically a HyperDeck Shuttle 2) at 12V. Therefore, there's a little bit of circuitry in there working some Voodoo to run up the battery's output to 12V. I'm wondering if somethings going amiss in that conversion process that's dropping the battery's volt output.

This is all coming down to my final question: My instinct is to bypass the circuit board and wire directly into the battery. I also don't desire to destroy our 7Q, so I'm asking anyone out there with electric expertise (and I feel as though there are a few of you) to please let me know if this is a bad idea or a simple solution.

Best,
Ted

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As an engineer that designs circuits and circuit boards for a living, I will throw in my opinion.

The 7Q can run off of 7.2v but it's on the low side of ideal. If the 7Q gets 7.2v from a perfectly stable source there would be no problem, but in the case of a battery the voltage is always changing as it is either loaded or discharged. I am not sure what the cutoff of the battery is, but it is probably lower than the 6.5v cutoff of the Odyssey. This means that the 7Q is not able to fully discharge the battery in an ideal scenario. In reality there is even more working against you, including the resistance of the battery itself and the total of all the wires and connections from the battery cells to the power supply input on the 7Q. The odyssey doesn't need much power but it is enough of a load to drop the voltage just by being turned on.

If you were able to measure the voltage at the input of the 7Q you will see the difference when you turn it on. It could be a little or a lot depending on the various connections or circuits in the middle. If you are using a 7.2v battery - I would make as direct a connection as possible to get the most out of the batteries.

If that adapter indeed makes 12v, that might not be a bad option as it is right in the middle of the voltage range the 7Q is looking for. From what I see in the picture, the circuit board looks like it is not big enough to be a good boost converter and there is no room for filtering. This means that if it does make 12v it is probably not very efficient and is probably making some really rough power with tons of switching noise and ripple. If it were me plugging in a recorder to capture the days work - I would be looking for very clean power. The cleanest available is from a battery source.
 
Thank you Carlos! That sounds about right. I realize the D54s are not ideal for running the 7Q, we have the A/Bs for most normal work, but every once in awhile a situation arises where you don't want to rig up in the way one needs to to run off the A/Bs, and then for short periods of time, I'm hoping the D54s will do. They're pretty comparable to the Sony batteries used in the FS, the ones people seem very intent on using with the 7Q. I have to believe these are fully capable of running for more than 20 minutes above 6.5V, which they are not at the moment. I was also hopeful the 12V adapter would be a benefit, but I think you're right... there's an inefficiency here that must be causing an overall loss in power flow.

In your expert opinion, you're saying there shouldn't be anything wrong with directly wiring that OD-Flying onto the two prongs coming directly out of the battery plate (fully bypassing all circuits)? I've done this before with other batteries, but not with a 7Q on the line, so I'm just making double sure. Thank you so much for your time and expertise Carlos.
 
Two comments:
1-The BMD 12v adapter takes 14v and maintains a steady 12v. It CANNOT take 7vdc and make 12vdc. In order to do this, you'd need a transformer and oscillator, which is not what the BMD batter adapter has.
2-The only practical way to make your Panny batteries work is to hook them up in series, then supply the 7+7 = 14v to the BMD 12v adapter, or straight into the O7Q, since it will regulate this voltage itself. If you supply higher than 14vdc to the O7Q you need to be very careful you don't exceed the O7Q capacity to regulate that voltage. I'm pretty sure the O7Q has over/under voltage protection, but, don't take MY word for it.
 
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cuervo said:
Two comments:
1-The BMD 12v adapter takes 14v and maintains a steady 12v. It CANNOT take 7vdc and make 12vdc. In order to do this, you'd need a transformer and ascillator, which is not what the BMD batter adapter has.
2-The only practical way to make your Panny batteries work is to hook them up in series, then supply the 7+7 = 14v to the BMD 12v adapter, or straight into the O7Q, since it will regulate this voltage itself. If you supply higher than 14vdc to the O7Q you need to be very careful you don't exceed the O7Q capacity to regulate that voltage. I'm pretty sure the O7Q has over/under voltage protection, but, don't take MY word for it.
Click to expand...

Hi Cuervo, a couple of questions:

1-The "adapter" in question is actually not a BMD made piece, so I just want to make sure I'm understanding you correctly and we're both talking about the same equipment. It's a piece made specifically to fit a single D54 battery that runs at 7.2V, and up convert it to 12V in order to run a BMD device. Here's an example of a similar unit: http://www.bhphotovideo.com/c/product/900544-REG/ikan_BMC_PWR_PW_P_Blackmagic_DV_Top.html

My understanding is that in order to increase the Voltage draw it's going to lower the Watts output to the device.

2-I considered running a series, and it's certainly a viable option, though I'm a little confused as to why these D54s will not function as everyone seems to be making single Sony NP plates, which have the same Volts and similar mAh capacities. Initially I thought perhaps people would be making dual (series) Sony plates, but there seem to be single unit ones designed for the 7Q.

Thanks Cuervo!

Best,
Ted
 
cuervo said:
Two comments:
1-The BMD 12v adapter takes 14v and maintains a steady 12v. It CANNOT take 7vdc and make 12vdc. In order to do this, you'd need a transformer and ascillator, which is not what the BMD batter adapter has.
Click to expand...

Settles that ;-) Almost all boost converters use switching architecture which (in easy talk) essentially pulses a coil and uses a solid state switch to make use of the resulting spike in voltage. It is a very very delicate process that happens very fast. A transformer would be very big, heavy and inefficient at boosting a voltage.


Yes, I would connect your cable directly to the output of the battery and see of it helps coax more energy out of the battery. I am not sure what protections the 7Q has for reverse polarity, so be exceedingly careful the + and - are matched. The only thing missing here is protection from short circuits. I am fairly confident that the panny batts have a catastrophic over current protection so they wont catch fire, but you should probably have a thermal fuse in there that breaks at about 2-3 amps to keep it safe.
 
Ted Herod said:
Hi Cuervo, a couple of questions:

1-The "adapter" in question is actually not a BMD made piece, so I just want to make sure I'm understanding you correctly and we're both talking about the same equipment. It's a piece made specifically to fit a single D54 battery that runs at 7.2V, and up convert it to 12V in order to run a BMD device. Here's an example of a similar unit: http://www.bhphotovideo.com/c/product/900544-REG/ikan_BMC_PWR_PW_P_Blackmagic_DV_Top.html

My understanding is that in order to increase the Voltage draw it's going to lower the Watts output to the device.


Ted
Click to expand...

OH, no we're talking about different power supplies, sorry. Generally, converting the output to higher voltage will reduce the available current out of the device, since watts needed have to stay the same. If the device requires more current than the battery can provide, something will give, like a fuse, or if the device can't get the current it needs, it won't work.

So, the O7Q needs 15 watts, max at 12v, which is 15/12 = 1.25 amps. The D54 supplies 7.2 v at 15 watts, that's 15/7.2=2 amps plus the inefficiency of the converter, so something like 2.25 amps needed out of the D54. If that amperage is available, everything should work. If the D54 can't supply that current, it will overheat, it's output voltage will drop, and the O7Q won't work.
 
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Wire your cable straight to the battery contacts on the plate. Or buy the Panasonic version of our battery plate for $75 as that is exactly what it is. Done.

The Odyssey7Q can accept voltage from 6.5-34v, so I don't know where this 12v max info is coming from. We can accept a huge range of power. And yes, the most efficient way to deliver it is straight from the battery with no additional boosting or regulation. If those batteries are in as good a shape as you say they are, I would think you would get at least a couple hours out of each if not double that.
 
Mitch...

The OP said they were running lights off of the D54 batts, that I ass_umed needed 12v.
My whole point is that you can't get something for nothing, i.e. raising the supply voltage won't get you more battery life. You are quite correct to say that a 38 Wh battery will last a couple of hours at 18 watts, which is the max wattage specified for the O7Q. My experience is that these batteries don't recharge to their full capacity as they get old. So, that two hours duration specified for a brand new battery is less as the batteries age. Running these batteries and having to change them out every 1-2 hours sound problemmatic to me, but, it's the users choice. But, connecting two batteries in series or parallel will double the life. If 12-14vdc is needed, connecting in series is the solution.
 
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Thanks Mitch! Can you tell me, does CD's plate use a fuse, or is the Odyssey protected enough that it doesn't need one?

Cuervo, I'm sorry for not being clear, the LED light was actually just an example of the condition of the battery. It pulls natively a 7.2V battery. While I get your concern for 1-2hrs of run time, that's why we have the Anton Bauers for, we're looking for the D54s as a super-light option that doesn't require fully rigging up the camera.

And Carlos, thanks again for helping! It does drive me nuts that the specs on those plates don't seem to tell you anything at all about what they're actually doing.
 
Ted, not sure why the adapter that you have does not work - need a hands on test to figure it out. We offer a plate that should work for you - just cut out the plug and wire directly to the CD cable.
Hope this helps
 
cuervo said:
No problem, Ted. Just trying to be helpful. Sorry if I confused the matter.
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Hey, no problem! I appreciate the help. Just making sure everyone is on the same page in case anyone else has a similar problem and finds this thread. Thanks Cuervo!
 
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