Powerbank

[IDA_ML]

I didn't find 7.5 Volt power adapter in local stores, I have AC to DC adapter with 9 Volt (actual output 9.25 V) 1.5A , I used three diodes to lower the voltage to 8.25 from 9.25, after I made the dummy battery and all related work (soldering, etc..) and powering on the camera, that gave me "Change Battery Pack" message with empty battery icon, So I removed one diode and it now the voltage was ~8.55, that made the camera boots with yellow battery indicator, then I removed one more diode --> this gave ~ 8.90 Volt, now the camera showed fully charged battery icon.

I can coniform 9 Volt works fine on 700D.

Bilal,

Commercially available low-cost adapters have a pretty high internal resistance resulting in a serious voltage drop under load.  You need a steady 7,4V source with a very small internal resistance and at least 2A consumption to avoid the "low battery" warning.   This performance is readily achieved with LiIon batteries but is a challenge for power adapters.  If your camera works fine with 8,9V you shouldn't worry that something can go wrong.  This voltage will drop significantly under load.  Just monitor the camera internal temperature when recording longer clips.  If it gets too high, camera will shut down and you can add one diode.  If it is normal and does not overheat, just leave it as it is.  If something overheats or burns out, it will be the power adapter and not the camera.

I also plan to build a DIY external power supply for my EOS-M but instead of using bulky and heavy power adapters I will try connecting two powerful LiIon cells, (at least 5x the current capacity of the LPE-12 battery) in series for a stable 7.4V source.  These cells are pretty compact and not too expensive.  My concern is much more the smart charger that I will have to build to protect the cells when charging.  I'll check and see if I can find 3,7V cells with built in overcharge protection circuits inside.  If someone has used such cells, please share your experience here.

[theBilalFakhouri]

But has nothing to do with the topic of power banks, does it?

No, we are talking about 9 volt output directly to the camera, some users above are using 9 volt output from powebank to their Canon cameras, I described my experience with 9 volt output and 9 volt is related to powerbanks. I added the full story for more details.

I bought my last dummy adapter for less than 5 € in China..

Short Answer: Welcome to Syria

Extended version: I have ordered one also from AliExpress 45 days ago, and I am still waiting it I expect it to arrive after two weeks from now, but you may don't know shipping from China is quite expensive to Syria (depending on item), a 8 US Dollar USB dummy battery convertor would coast after shipping 25 USD , I felt excited and said "I don't have more time to wait" so I made DIY AC adapter from a faulty LP-E8 battery.

Directors cut: In general, ordering items from China would consume more money and time to my Country, and this would be okay if the price was already doubled in local stores for an Canon 700D AC adapter, and yeah the price is x2 (it's 53 USD for an AC adapter in local stores), I would stuck to the short answer version in this case.

note: the DIY AC adapter coast me 1 Dollar to make (fortunately, not everything is expensive here).

Bilal,

Commercially available low-cost adapters have a pretty high internal resistance resulting in a serious voltage drop under load.  You need a steady 7,4V source with a very small internal resistance and at least 2A consumption to avoid the "low battery" warning.   This performance is readily achieved with LiIon batteries but is a challenge for power adapters.  If your camera works fine with 8,9V you shouldn't worry that something can go wrong.  This voltage will drop significantly under load.  Just monitor the camera internal temperature when recording longer clips.  If it gets too high, camera will shut down and you can add one diode.  If it is normal and does not overheat, just leave it as it is.  If something overheats or burns out, it will be the power adapter and not the camera.

I also plan to build a DIY external power supply for my EOS-M but instead of using bulky and heavy power adapters I will try connecting two powerful LiIon cells, (at least 5x the current capacity of the LPE-12 battery) in series for a stable 7.4V source.  These cells are pretty compact and not too expensive.  My concern is much more the smart charger that I will have to build to protect the cells when charging.  I'll check and see if I can find 3,7V cells with built in overcharge protection circuits inside.  If someone has used such cells, please share your experience here.

I measured Original fully charged LP-E8 battery (~ 4 Years old) with multimeter and that gives 8.05 Volt not 7.40 Volt, I read somewhere on the internet LP-E8 battery could go up to 8.40 V when it's fully charged.

I made more tests yesterday, I think 8.90 Volt made the camera overheats quicker than usual, I re-added one diode to drop voltage to ~8.55 and that was fine and it doesn't overheat quickly it was normal, I will stuck with 8.55 Volt, I didn't have another issues like "voltage will drop significantly under load", I tested Still pictures with Flash ON and it was fine.

Li-Ion cells are a good option too, I thought about it today, instead I may consider good powerbank with quick charge support, this is easier than building a whole circuit with Li-Ion cells and you will need a casing for that.

I am not recommending anything I am doing, just sharing a little experience

[c_joerg]

My concern is much more the smart charger that I will have to build to protect the cells when charging.  I'll check and see if I can find 3,7V cells with built in overcharge protection circuits inside.  If someone has used such cells, please share your experience here.

I thought every 18650 cell contains a protection against overcharging and deep discharge. I once had some that definitely had this protective circuit.
After these cells were taken from me twice at the airport security checkpoint, I only use power banks.

Short Answer: Welcome to Syria

Ok then I understand…

[IDA_ML]

"I made more tests yesterday, I think 8.90 Volt made the camera overheats quicker than usual, I re-added one diode to drop voltage to ~8.55 and that was fine and it doesn't overheat quickly it was normal, I will stuck with 8.55 Volt, I didn't have another issues like "voltage will drop significantly under load", I tested Still pictures with Flash ON and it was fine."

Bilal,

Could you please measure the exact voltage in this 8.55V scenario under load, e. g. while recording a long MLV clip, and see if it drops to a lower value with recording time?  What is the current that the camera draws in this case, with Life view on?

"Li-Ion cells are a good option too, I thought about it today, instead I may consider good powerbank with quick charge support, this is easier than building a whole circuit with Li-Ion cells and you will need a casing for that."

If you can find a powerbank with adjustable output voltage (7.5 - 8V) and 2A output capability, that would be the ideal solution - powerful, compact and no casing required. You just put it in your pocket, connect it with an appropriate cable to the camera and are ready to film.  But as far as I know, these powerbanks are quite expensive.  Could you please link the one that you are considering?  Thanks.

[c_joerg]

"I made more tests yesterday, I think 8.90 Volt made the camera overheats quicker than usual, I re-added one diode to drop voltage to ~8.55 and that was fine and it doesn't overheat quickly it was normal,

Really?
I never notice this on my 6D. If I increase voltage, the current goes down.
How du you messure?

Could you please measure the exact voltage in this 8.55V scenario under load,

Is this not possible to log voltage with ML?
On my cams with CHDK I contionus log input voltage und temperature in a file.

If you can find a powerbank with adjustable output voltage (7.5 - 8V) and 2A output capability, that would be the ideal solution - powerful, compact and no casing required.

Do you read my  Reply #16 and Reply #19?
https://www.magiclantern.fm/forum/index.php?topic=21660.msg224698#msg224698
https://www.magiclantern.fm/forum/index.php?topic=21660.msg232081#msg232081

Every cheep Powerbank with Quick Charge 3.0 can do this. With Quick Charge 3.0 you can set the voltage in 0.2V steps to 7.8V and 2A.
You must only tell the powerbank, that you need 7.8V. That is what the quick charge USB tester in Reply #19 did..

[IDA_ML]

C_joerg,

Of course I read the entire thread very carefully, including your posts and there is no doubt that your solution will work without problems.  However, I think that it is not very practical.  If the step-up converter sticks out of the powerbank attached only to the USB connector, it will break very easily, especially if you move the camera around.  Powerbanks with adjustable output voltage, with the converter built in, do exist but as far as I remember, they are  quite expensive.

A much better and very cheap solution is the one linked in #22 where the guy mounts the converter inside the dummy battery.  The problem is to get one of these that can easily fit inside the battery case.

How much current does your 6D draw while video recording with Global draw ON?

[c_joerg]

If the step-up converter sticks out of the powerbank attached only to the USB connector,

Just for clarifying:
The adapter in post Reply #16 and Reply #19 is not a DC/DC step-up converter! This adapter communicates with the power bank and only tells it that the power bank should supply a different voltage. On QC 3.0 it can deliver 8.4V / 2A.

The adapter on Reply #2 is a DC/DC step-up converter and works with 5V Powerbanks. But this one only dilvers 8.4V / 1.4A which is not enough for my 6D
https://www.magiclantern.fm/forum/index.php?topic=21660.msg197698#msg197698

it will break very easily, especially if you move the camera around.

Two ways to get around it:
You remove the plug and socket of the adapter and replace it with a piece of USB cable. This is my favorite solution
You could use the adapter with a Y cable. The adapter only needs to communicate with the power bank once at the beginning until the 8.4V comes in. Then you can theoretically pull it off. But I have not yet produced that. 

Here you see other solutions with Quick charge. This adapter also prevents the power bank from being switched off in standby
https://gwegner.de/know-how/qc-powerbank-stromversorgung-kamera-slider-qccp-adapter/

How much current does your 6D draw while video recording with Global draw ONthis adapter also prevents the power bank from being switched off in standby?

I never used 6D with video. Only time-lapse.
But with the Adapter in Reply #2 the cam goes off when the mirror goes up. So 6D needs mor than 1.5A.

[theBilalFakhouri]

Really?
I never notice this on my 6D. If I increase voltage, the current goes down.
How du you messure?

Bilal,

Could you please measure the exact voltage in this 8.55V scenario under load, e. g. while recording a long MLV clip, and see if it drops to a lower value with recording time?  What is the current that the camera draws in this case, with Life view on?

I have only measured Voltage output from the dummy battery pins before attaching it to the camera, not sure how to exactly measure the current, still learning about electricity and electronics

But it's definitely overheating, even at 8.55 Volt, I made more tests today, the temperature is higher than usual (than the normal battery) it goes up to 72 C degree after ~ 25 - 30 Minutes in ~22 room temp by only setting the camera in LiveView mode. I can't re-test and apply new measurements right now, maybe I did something wrong . . I replaced the AC adapter with a 7.4 Volt Battery Pack:




Max temperature -using above battery- I got is ~62 C degree and this while recording for more than two hours and with 240MHz overclock enabled, in same room temperature and settings, I think I could record up to 3 - 4 hours with this battery before it would die. I will stuck with it in this period, good thing you don't need to play with voltage, it works out of the box.

I would back with more tests in future.

[IDA_ML]

Thanks a lot, Bilal!  The information that you are providing is really very useful to those who want to build their own external power supply for their cameras.

First of all, I think that the 7,4V NP750 battery pack solution is the perfect one - powerful, compact and no hassle with additional circuits, cables, etc..  I assume, you also have the charger for it, so if you find a way to mechanically attach the battery to the camera, then you are ready to go.  I guess, one battery charge will last for an entire day of filming.

As far as the overheating issue with your external 8.55V power supply is concerned, you could easily solve it by adding an additional Schottky diode, (less than 1$/pcs.), in series to the one that you already have.  This type of diode has about 0,3 to 0,4V voltage drop in forward direction and will give you the correct voltage for camera operation without overheating and low-battery warning. 

Current measurement is really easy.  You need to switch your multimeter in the current measurement mode, (as an ampermeter), connect the red probe to the current measurement terminal on the multimeter, then break the circuit somewhere, say at the diode, and connect the ampermeter in series to close the circuit again.  Now, when you turn the camera on, the ampermeter will measure the current that the camera draws (in A) and you can write down the current readings at different loads (camera modes).   If you happen to have a second multimeter, you could also measure simultaneously the voltage (in V) at the contacts of the dummy battery and see if it stays constant at the different camera modes (loads).  Now you can calculate the power cosumption of your camera (in W) by multiplying VxA=W and see at what power it starts to overheat.  Alternativey, you could use the current readings to calculate how long you can film with one charge of your 4400 mAh battery pack. If for example, you measure a current of 2A, your battery will last for 2,2 hours, (2 hours and 12 minutes) of continuous recording.