Jump to content
dzbum

Power regulator question.

Recommended Posts

As a frequent lurker of this forum I find I can usually find the answers to my questions without asking them, but I finally have one to ask.

I have just put together my first “proper” UAV / FPV setup. I have ground tested all the components separately and they all work well. I am intending on putting all of the equipment into a trainer I have kicking around. The TX and Camera will be mounted wing with the Nav equipment in a similar place on the opposite wing.

My question is around power for all the various voltages required.

Equipment list.

1w 2.4GHz Lawnmate TX (12v)

420 line Board Camera (12v)

Gecko 201 (3v)

RCAP2 (6v- 12v?)

FMA Copilot FS8 (standard RX 4.8v-6v)

I intend on adding.

GPS Overlay Board

Video source switch

Digital still camera

RS232 Modem on the Audio channel sending NMEA string back to the ground station.

This is probably going to be in a bigger airframe.

I already have 7.4v LiPo’s that I use in my son’s Easystar, I had intended on using them with a DC-DC boosting regulator to give me the needed 12v for the Video system. (Shown here in MR-RC Cam’s project http://www.rc-cam.com/dc-dc.htm ) This would also allow me to also just use the video system to the Easystar if I needed to.

I want to keep the power source for the Video (given that it is the highest current draw) isolated from the RCAP and receiver. I also intend on running my Gecko from an external power source, (See this thread http://www.rcgroups.com/forums/showthread....light=gecko+201 ) for which I will also need 3v regulator. I think for simplicity I will attach this vreg to the RCAP for ease of feeding the Gecko from the same connector as the RS232.

I am currently leaning towards buying a 11.1V LiPo and use it to power the Video without a regulator. (This is within tolerance as far as am aware) And using a 7.4V LiPo with a 3V vreg for the RCAP and the Geko.

Does anyone have any advise on this?

Share this post


Link to post
Share on other sites

Will you use a seperate battery for all electronics stuff or do you intend running all gear from the main battery (motor as well) ?

Share this post


Link to post
Share on other sites

That is my question. I want to have a dedicated battery for the video TX as its the highest current device. Should I also use that for nav?

Share this post


Link to post
Share on other sites

if you plane is electric powered ??

I simply suggest a few switchmode converters to give you all the different voltages you need, Directly from the main power battery, they are also lighter weight compared to having several more batteries,

and then only one battery to charge and maintain.

Another fine detail is if you add the OSD board from Intelligent flight,

it has power meter on screen, so you can see exactly how many mAh you have used.

Remember to carefully range check your radio equip when using switchers,

some of them are generating noise that can limit your range.

Share this post


Link to post
Share on other sites

Thomas,

the plane that I am going to use is not electric powered, however I do have an eclectic plane that I would like to use just the video TX and Camera with that runs on 7.4v LiPo's. I had intended on using the same LiPo's to run all my gear when they are in my gas powered plane. I am starting to think that I should just but another 11.1v LiPo to run the video and use Vregs step down to the voltages I need for the rest. That is my main question, should I power everything from one 7.4v battery and step up to 12v for the TX or run the video off a 11.1v LiPo and use a second power source for the GPS and RCAP for safety?

Share this post


Link to post
Share on other sites

I got reminded the other day that powering everything off the same battery has another disadvantage than potential interference too: When it's dead, it's dead.

A guy at the field was flying a motor glider. He noticed his motor had gone a bit weak but thought it was because the lipo was a bit old and wouldn't give enough current. There were good conditions, so he continued to fly with natural power. A few mins later, we hear "RADIO GLITCHES" and see his glider going down to earth way too quickly with servos moving totally erratically. Reason: 3s lipo was down to 3V. And that was with only the radio drawing on the battery.

Now, add a bunch of electronics that will draw 500mA-1A. You'd better NEVER get close to having your battery discharged, as with the discharge curve of some batteries once your ESC stops the motor it could be a matter of seconds until you have no more control and video. If you use a separate battery you'll have all the time in the world to glide down safely should you run out of motor juice.

Share this post


Link to post
Share on other sites

Kilrah,

totally agree. I have several 7.4V LiPo's. I think I am going stick with them and add a DC-DC boosting regulator to bring it up to 12v for the Video. Everything else will run off 6v with 3v for the GPS. I use the Easy star either with 1 x 3000mah or 2s x 2100mah packs. I can divide these two packs and use one for video. Anyone have any do's and don'ts when using DC-DC regulators with LiPo's?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×