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Thread: 12v regulator or straight from 3s lipo?

  1. #1
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    12v regulator or straight from 3s lipo?

    I know people do it both ways. Is it perfectly OK to run 12v vtx and camera from a 3S lipo? I tried it and so far, so good... but am I just gambling? Am I losing range as the voltage goes down?

  2. #2
    Kiwi in Germany whakahere's Avatar
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    People generally use a regulator on a s4 system as it is a great way to add protection. Most camera and tx systems have a cut off voltage. So if you fly too far out you can milk out the last of the battery on you way home without losing battery. People recommend that you use a 5volt system if you are running on s3. I personally run a s3 system and use no reg or 5 volt system. I take the risk of not screwing up. Know your gear cut off voltage and make the judgement yourself.
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    The one thing I know how to do well with FPV - crash. All in a day of fun!
    I believe landing is a full body experience .... I do my best to aim for your body.

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    Odd. That's the first time I've read a suggestion for 4 cell. There's really no reason at all to jump to a higher voltage if you're going the regulator route... unless you're running 4s anyway I guess (but then that should only be your flight pack anyway). To me it makes a lot more sense to use a SEPIC type switching regulator and get your 12v from any input source.

    Still, I'd rather forgo the regulator entirely if the AV equipment can handle it. The suppliers put up crappy specs. They say "12v". Does that mean 12v? Or is it 9 - 12 or what? I'd like to know not only what the cutoff typically is, but what affect (if any) there is from the battery dipping below 12 on its way to "x".

  4. #4
    Kiwi in Germany whakahere's Avatar
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    it depends. My tx and rx are all running off 3.3volts or 5volts but I put in a s3 battery. the voltage is then lowered on the tx side down to 3.3volts by a internal reg. Now you normally need about 2 volts to carry this change down in voltage. For my receiver I know I can get it down to 6.5volts because the linear reg inside needs about a 1.5volt difference when it is converting it. I know my camera can get down to 9 volts before the picture starts to go.

    Using a switching bec creates noise so you will need to clean it. You will also need to have a reg that can raise or lower the voltage. All this can create more noise which could lower your effective range.

    What gear are you using might help people give you a better answer.
    Whaka's Tinkerings blog --> http://fpvlab.com/forums/showthread.php?36623-Whaka-s-Tinkering&p=631753#post631753
    Battle H Virus (home build basher quad tutorial) --> ]http://fpvlab.com/forums/showthread.php?12544-Tutorial-Battle-H-Virus
    Range record on 5.8ghz 200mw 24km --> http://www.rcgroups.com/forums/showthread.php?t=1441664

    The one thing I know how to do well with FPV - crash. All in a day of fun!
    I believe landing is a full body experience .... I do my best to aim for your body.

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    I use a small 3s to run both the camera and vtx, had a dodgy battery and its really not fun losing video when flying .

    The vtx i was using can go down to almost 9v, but the camera i used could only go down to 10v, any less and the video went purple then slowly faded away very quickly(2-3seconds).

  6. #6
    Pilot BCSaltchucker's Avatar
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    I always run a 1 battery setup, no regulator so far. The SuperHAD600 cam can run lower than I will ever run my battery, and same with the vTx I use.

    But on a couple planes I plan to go to 4S batteries. I will stick on a step down regulator or SEPIC for that, plus a ferrite.

    I run a SEPIC regulator on my ground station, where it is also critical to have stable voltage for some receivers. the RC305 especially should not be run over 12V or its onboard regulator gets hot, can blow up or at least reduce its reception performance. I set it to 11.7V and run it off a 3S (or a car battery)
    another friggin lawn dart. love it

  7. #7
    Kiwi in Germany whakahere's Avatar
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    Quote Originally Posted by BCSaltchucker View Post

    I run a SEPIC regulator on my ground station, where it is also critical to have stable voltage for some receivers. the RC305 especially should not be run over 12V or its onboard regulator gets hot, can blow up or at least reduce its reception performance. I set it to 11.7V and run it off a 3S (or a car battery)
    The RC305 will still get very warm on 11.7volts. The receiver module inside runs at 5volts and it has a linear regulator breaking down the voltage from what you put in to 5volt. higher you have it, more heat will be generated. With many linear regs, they all have a voltage overhead and from what I remember I believe the one in the 305 has a 1.5voltage overhead. This means that if the voltage drops below 6.5volts then the receiver module will be receiving less volts and then you will get less distance. I run mine at 7.4volts or on a S2. On my large ground station drop the volts to 7.4volts and I make sure that this is all shielded so less noise is put out. On my smaller ground station I just run off a S2 and that keeps the receiver cool, even in direct sunlight. What out for some switching becs. Even though you can clean the power along the power lines with a ferrite there is still noise generated that can effect the range.

    Oh fatshark goggles run on the same principles. It is just a linear reg inside and it also runs off 5volts. I generally having the googles and receiver all running off the same voltage. Only my tracker needs 12volts.

    The superhad 600 camera runs down to 9 volts. After that you will start losing picture. This is why many people run s4 systems. It becomes easier to regulate your power so if you burn your battery a little too much you are more likely to keep video even after your motor has shut down.
    Last edited by whakahere; 18th November 2012 at 08:27 AM.
    Whaka's Tinkerings blog --> http://fpvlab.com/forums/showthread.php?36623-Whaka-s-Tinkering&p=631753#post631753
    Battle H Virus (home build basher quad tutorial) --> ]http://fpvlab.com/forums/showthread.php?12544-Tutorial-Battle-H-Virus
    Range record on 5.8ghz 200mw 24km --> http://www.rcgroups.com/forums/showthread.php?t=1441664

    The one thing I know how to do well with FPV - crash. All in a day of fun!
    I believe landing is a full body experience .... I do my best to aim for your body.

  8. #8
    I Like Waffles... SENTRY's Avatar
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    I'm with Whaka. I run 3s packs and 5volt video systems with no issue. This gives me a wide range of v to play with. If I were to use a single 12v component (cam, vTx) then I'd run 4s. Per my personal taste I don't like the idea of running 12v components on 3s and using the step-ups. The RMRC "XV" line of cams is 5 - 12v, and I run the Lawmate 5v vTxs (.5 watt).

    I wonder how low you can go before the cam drops?? Probably this low...

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  9. #9
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    This gives me a wide range of v to play with.
    I think there's some confusion here on how things work. Having a higher voltage input doesn't give you more "gas in the tank", it just converts more voltage to noise regardless of what kind of regulator you're using. Switching are by far more efficient (in cases where the voltage difference is very high) or practical (in cases where the voltage difference is too low and/or variable - that's where a SEPIC comes in handy) compared to linear (which can be much more efficient in cases where input voltage is always above output but not by much) but they still convert one voltage to another and waste some energy (not voltage) in the process. You're really always better off with the closest input voltage to the output voltage possible ("possible" being determined by the type of regulator you're using). To get more operating time, use a larger capacity not a larger voltage. Its a little confusing with LiPo because of the way the curve works. We're taught that the voltage starts at X and goes to Y and then you charge, which is true... but its not linear and its not valid to think that a higher cell count gives you "more volts to play with" since its the exact same volts per cell... it just gives you more volts to waste. It also lets you use a step-down or linear where you otherwise couldn't, but that's still wasteful.

    What Whaka refers to as "voltage overhead" is the linear regulators drop out voltage. If a system runs on 5v and a regulator has a drop out of 1.5v then the battery must stay above 6.5v or you're in trouble.

    What is frustrating is how imprecise the manufacturers of these electronics are. Saying a camera is "12v" is really quite unhelpful if its not true. And its not true if people can run it off 9v. I want to know the true operating range of these devices so I can make informed power system decisions. Hense by original question.

    yes, we can test each and every component. And it seems, given the crap information we're provided, that its a very good idea to do so. But it should be fully unnecessary.

    Ah well. I doubt I'll be the one to start an accurate repository of all this stuff.

  10. #10
    Kiwi in Germany whakahere's Avatar
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    Sentry knows what he is talking about here. Going with a higher voltage has many other reasons apart from video performance. We all use one battery systems. It is all about the curve that you are playing with. On a s3 system that curve starts dropping off rapidly about 3.3volts per cell. Now knowing the drop off voltage of your gear is one of the most important things you need to find out. It is pretty easy to do too. Switching bec with variable voltage and watch what happens on the bench or open up the receiver and see which reg they are using. On most other gear it has been stated.

    The reason you use higher rated voltage is so you can have constant voltage going to your gear. The problem with s3 and running 12volt gear is the chance that they might have different operational voltages that are within the voltage slag when pushing your plane. Since FPV we generally do go outside LOS range you need every extra bit of battery to get your plane home if you be a bit of a douche and don't plan your flight (or get stuck in the wind on the way home). Some cameras will drop out at 10 volts which is pretty crappy if you are flying a copter and you push your throttle on a s3. that is a crash waiting to happen. Now with a s4 system on a 12 volt system you can push your gear and not worry as much about the voltage slag. that magical 3.3volt quick drop off won't hurt you the same and like sentry's video above will help you getting home. Oh another point is if you get a cell that drops out .... you most likely still have video

    This is not to say you have to go higher voltages. I do run 12v systems on s3 but then again these systems also have batteries in parallel and the gear will drop off at 9volts.
    Whaka's Tinkerings blog --> http://fpvlab.com/forums/showthread.php?36623-Whaka-s-Tinkering&p=631753#post631753
    Battle H Virus (home build basher quad tutorial) --> ]http://fpvlab.com/forums/showthread.php?12544-Tutorial-Battle-H-Virus
    Range record on 5.8ghz 200mw 24km --> http://www.rcgroups.com/forums/showthread.php?t=1441664

    The one thing I know how to do well with FPV - crash. All in a day of fun!
    I believe landing is a full body experience .... I do my best to aim for your body.

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