Could someone please explain?

Show and tell for your homebrew nv projects. DIY 'Stickies' here too.
baffled
Posts: 209
Joined: 08 Mar 2012, 21:30
Location: Anglesey

Could someone please explain?

Post by baffled » 07 Apr 2014, 18:15

Hi all,
Not so much a problem as something that I don't understand.

As part of my build I have a EJ230 and a generic 5" screen from that other site.

The camera and screen are both supposed to run off 12v. (+/- 10%)

My intention was to use 3x18650 to give 11.1v.

When I connected them (in a temporary manner. clothes pegs and 'lassy bands etc.) to my DC power supply and gradually increased the voltage I found that 6.8v gave me a good picture.

I then tried using 2x18650 (7.4v) and found that I get the same result.

This means that I can lose one battery from my original design which enables me to radically alter the design.

The two batteries have now been running for 1.5 hours and the voltage has dropped from 7.52v to 7.34v.

I am not unhappy with this situation but I wonder whether I am missing something or am doing some damage to some component?

Sorry if I'm being thick but I=V/R is about the limit of my electrical knowledge.

Any advice gratefully received.

Regards,
Ken.

User avatar
some bloke
TRADER MEMBER
Posts: 7492
Joined: 27 Jan 2012, 16:14
Location: Cornwall or Leicester

Re: Could someone please explain?

Post by some bloke » 07 Apr 2014, 19:34

I can't answer your question - other than to say many DC devices will tolerate a fairly wide range of volts.

This is a very interesting query - and one that has potential for me in coming builds - so I'll be watching this closely. :thumbup:
Image

User avatar
22-250jock
Posts: 2350
Joined: 07 Dec 2012, 17:53
Location: Burgess Hill, west sussex

Re: Could someone please explain?

Post by 22-250jock » 07 Apr 2014, 19:54

I'm sure Bruce will be along shortly to explain things.........................

in his usual, easy to understand terminology, that helps those of us who are less savvy, in the dark art of electrickery :lol: :lol:

cheers jock
“When guns are outlawed, only the Government will have guns. The Government - and a few outlaws. If that happens, you can count me among the outlaws.”
― Edward Abbey,

User avatar
sunndog
ADMINISTRATOR
Posts: 6478
Joined: 10 Jun 2012, 17:51
Location: buxton, derbyshire

Re: Could someone please explain?

Post by sunndog » 07 Apr 2014, 20:27

as dave say's they are designed to work in a wide voltage range, a lot of board cameras in particular work at very low voltages

if it works, it works mate...the only real problem is gonna be a shorter runtime
oslon black drivers
http://nightvisionforumuk.com/viewtopic.php?f=35&t=2333

when asking for advice, please include what n.v device and/or illumination you already have (if any) and what rifles you intend to use them on...cheers

baffled
Posts: 209
Joined: 08 Mar 2012, 21:30
Location: Anglesey

Re: Could someone please explain?

Post by baffled » 07 Apr 2014, 20:55

Many thanks for the replies so far. :D :D

I can see that reduced runtime could be a problem but I am too old
to wonder whether my batteries will last longer than me in the field. (yes they will!)

So far I am encouraged to continue with the plan and hope for the best. :)

regards,
Ken.

Snapper
Posts: 425
Joined: 14 Feb 2014, 23:23
Location: East Sussex

Re: Could someone please explain?

Post by Snapper » 07 Apr 2014, 21:38

I noticed in the spec sheet of the camera I used it said the working voltage was between 15 and 8 volts, and I assume even those voltages are ball-park figures. I tested my camera and viewfinder with a 6 v battery and it worked fine enough to test it, although the bettery was putting out a little more than 7 at the time.

I know very little about electrics but the thing I would worry about is how long the batteries will sustain the peak voltage. As they age they may not give the full voltage for the same length of time.

lightmesser
Posts: 540
Joined: 09 Jan 2014, 01:19
Location: Eastern Europe

Re: Could someone please explain?

Post by lightmesser » 07 Apr 2014, 23:40

sunndog wrote:as dave say's they are designed to work in a wide voltage range, a lot of board cameras in particular work at very low voltages

if it works, it works mate...the only real problem is gonna be a shorter runtime

2 × Panasonic NCR18650B = 6800 mah or my top pick 2× NCR18650PF with 5800 mah and they can develop up to 10A of current. So I guess runtime should not be issue here? We could even boost runtime but of course before that we got to toss all that XXX Ultra Crappy fire brands into trash where they belong because 2 4200 mah :lol: Ultrafires will not give more than 1600mah.

So I just wondered could we put this 18650 batteries in this neat little box:
Image

And then connect one pack on the camera and other pack on monitor? Stripping and soldering power wires of both before that?

We could charge batteries much faster on regular 18650(1A) charger, and just put and take them out.

User avatar
sunndog
ADMINISTRATOR
Posts: 6478
Joined: 10 Jun 2012, 17:51
Location: buxton, derbyshire

Re: Could someone please explain?

Post by sunndog » 08 Apr 2014, 00:10

course you can use a battery holder, as long as you get the pos and neg the right way round you can do whatever you like
oslon black drivers
http://nightvisionforumuk.com/viewtopic.php?f=35&t=2333

when asking for advice, please include what n.v device and/or illumination you already have (if any) and what rifles you intend to use them on...cheers

phoenix
BRUCE ALMIGHTY
Posts: 4749
Joined: 09 May 2012, 14:40
Location: Aberdeen

Re: Could someone please explain?

Post by phoenix » 08 Apr 2014, 01:17

baffled wrote:Hi all,
Not so much a problem as something that I don't understand.

As part of my build I have a EJ230 and a generic 5" screen from that other site.

The camera and screen are both supposed to run off 12v. (+/- 10%)

My intention was to use 3x18650 to give 11.1v.

When I connected them (in a temporary manner. clothes pegs and 'lassy bands etc.) to my DC power supply and gradually increased the voltage I found that 6.8v gave me a good picture.

I then tried using 2x18650 (7.4v) and found that I get the same result.

This means that I can lose one battery from my original design which enables me to radically alter the design.

The two batteries have now been running for 1.5 hours and the voltage has dropped from 7.52v to 7.34v.

I am not unhappy with this situation but I wonder whether I am missing something or am doing some damage to some component?

Sorry if I'm being thick but I=V/R is about the limit of my electrical knowledge.

Any advice gratefully received.

Regards,
Ken.

Thank you and well done!
I think you've discovered that most cameras and screens actually operate from 5 volts but have regulators built in so that they can operate from 12 volts. The reguators need a little bit of voltage to work properly so 6-7 volts is enough to get the camera or screen to work. When it comes to bateries, you may well have opened a door that many of us will want to walk through.

Cheers

Bruce
LAND ROVER - THE WORLD'S WORST 4X4 BY FAR

User avatar
some bloke
TRADER MEMBER
Posts: 7492
Joined: 27 Jan 2012, 16:14
Location: Cornwall or Leicester

Re: Could someone please explain?

Post by some bloke » 08 Apr 2014, 05:28

lightmesser wrote:
sunndog wrote:as dave say's they are designed to work in a wide voltage range, a lot of board cameras in particular work at very low voltages

if it works, it works mate...the only real problem is gonna be a shorter runtime

2 × Panasonic NCR18650B = 6800 mah or my top pick 2× NCR18650PF with 5800 mah and they can develop up to 10A of current. So I guess runtime should not be issue here? We could even boost runtime but of course before that we got to toss all that XXX Ultra Crappy fire brands into trash where they belong because 2 4200 mah :lol: Ultrafires will not give more than 1600mah.

So I just wondered could we put this 18650 batteries in this neat little box:
Image

And then connect one pack on the camera and other pack on monitor? Stripping and soldering power wires of both before that?

We could charge batteries much faster on regular 18650(1A) charger, and just put and take them out.
That holder looks a bit more substantial than the usual eblag ones - do you have a link for it please?
Image

Post Reply