Before I burn up another one of these things, can I power a camera and transmitter off of a 3S LiPo battery?  The specs for the camera say 9 - 12.6v and the specs for the transmitter say 8 - 12v.

I tried using a 3S on another camera and transmitter and wound up with a small cloud of smoke and no video.  It is my understanding that the 3S produces 11.1v which should be fine.  As for AMP's, the devices will only draw what they need correct?

Figured I would ask the community before I fry this new FPV system that just arrived (I have another on order just in case).

Thank you in advance!

Views: 17701

Reply to This

Replies to This Discussion

The danger you face is that the battery voltage of a 3s should be 11.1 as you say. BUT a battery fresh of the charger could easily be over 12v. The older the battery the higher this can be. If you want to protect this then put diode in series to drop the volts a little

I always have some diodes (1N4001 // 1A // 50V Type) around to produce a voltage drop (around 0.7 V per diode). So i circumvent an extra voltage regulator.

Perhaps that is a practical tip for you as well. A fully charged 3S delivers 12.6V and even a little more. I would use 2 or 3 Diodes in serial.

Cheers Kraut Rob

Thanks for the tip...I am going to try this out and try and build a little dam to keep the voltage from killing my gear again.

Thanks for the comment...I ordered a bunch of diodes to help protect my gear.

Hi crash pilot. Exactly my solution. Just takes the extra voltage away. It also reduces the peak current on start up, win ,win

So far so good.  I was able to get the transmitter and camera running without frying the electronics.  I appreciate the comments and help!

If the device says 12V then 3S is fine. A fresh LiPO straight from the charger is 12.6V and settles at about 12.4V after resting for a short while. And there is usually at least a +-10% headroom when it comes to electronics and voltages. And most will work at even larger discrepancies. And during usage the LiPO battery will only stay at 12.xxV for a short time before it starts to drop. So in fact when you are using 3S on your device, it is more important to know that it will actually operate at a lower then 12V (~11V) most of the time.

But.. Know that while a regular wall socket power supply only delivers a couple of amps max, if something goes wrong a LiPO battery will deliver hundreds of ampers, and completely destroy the electronics.

Could always use something like this to be ultra-safe

http://www.hobbyking.com/hobbyking/store/__18787__12V_2_5A_UBEC_2_5...
Hi John , in a perfect world you are correct, but if You fast charge an older lipo you can get it to be over 13v , yes it soon drops but by then the magic smoke escapes.
Nicads would also do the same . a couple of diodes is very cheap insurance against this problem.

Yup, learned that the hard way.  Now using 3 diodes before the wire harness for the camera and transmitter to cool down the volts a bit.

This should not be the case.  Everything I have read on the subject basically says to never exceed 4.2V per cell when charging a LiPo, and to do so is potentially quite dangerous.  Fast charge has nothing to do with it; your charger should be charging at constant current until 4.2V per cell (some recommend 4.1 or 4.15 to extend the overall life of the battery), and then constant voltage thereafter.

And to make sure you don't exceed the max per cell, you need to be using balance charger.  This is where the age of the pack may specifically come into play... if one cell is degraded more than the others, you can easily overcharge a cell by only looking at the total voltage of the pack.

So, if you have a charger that is leaving your 3S LiPo at more than 12.6V, then you should probably get rid of the charger.

I actually just bought one of these (the 4.5A version) for powering 12V accessories on my quad (which is powered by a 4S pack).  By saying it can be powered by a 2S LiPo (inconsistent with the voltage range listed anyhow), the description is suggestive that this is a DC-DC converter that can step up the voltage.  It isn't, and it won't.  This device is a step-down regulator only.

It might work in the OP's case, because he will lose some voltage when using it.  But I don't see any real benefit.  Like John said above, most devices allow some tolerance in the supply voltage; the exception is usually if something says it required a regulated supply - then the tolerance might be quite small.

I also agree that putting a diode in line (size it appropriately for the current your FPV gear will draw) is probably a good solution in this case if you are concerned about whether the gear can really take 12.6V or not.

Reply to Discussion

RSS

© 2016   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service