Replacing batteries with USB power source

[Beast-of-Burden]

Hi all, I'm an (old) newbie here. I'm a 'jack-of-all-trades' type of hobbyist who dreams up different projects. I'm currently working with a portable item powered by two 18650 lithium batteries (in series). I want to eliminate the battery box (and batteries) and power it with a USB cable & a USB power source generally used as backup for phones. Any cautions or suggestions would be greatly appreciated.
Thanks

 

[kpatz]

18650 batteries have a nominal voltage of 3.6-3.7V each (a bit higher when fully charged and lower when discharged). 2 in series will be 7.2V or so, while a USB power adapter provides 5V. You'll probably need a boost converter to bump the voltage up from a USB charger.

How are the batteries charged in the device? Does it have a USB charger already? Or do you have to pull the batteries and charge them in an external charger? If there's a charger built in, it may have a boost converter, but OTOH, lithium cells are usually charged individually and not in series, so it might not.

What is the device, and can you post PCB pictures? It's possible the device runs on 5V or 3.3V and uses a buck converter to lower the battery voltage.

 

[Beast-of-Burden]

Thanks for the reply...It's an infrared camera & an 5" LCD monitor screen. No it doesn't have a charger it's just 2 batteries in a plastic attached box. I understand the voltage isn't the same just didn't know the tech of what I needed to get to adapt the USB power source.

 

[Beast-of-Burden]

Is this what your referring to?
DC-DC Boost Step Up Converter 4.5-32V to 5-42V 5A Adjustable Power Supply Module

 

[Beast-of-Burden]

 

[dave9]

Yes something similar, though you don't need as high as 5A since your USB supply won't be able to deliver anywhere near that.

Lower current modules are smaller, and a "little" less expensive. You ought to determine (measure with a ohm meter/multimeter) how much current the device needs, if your USB supply can even power it considering the input current is possibly going to be near double the output current.

Another thing you might try is powering the device direct from 5V... maybe you get lucky and it'll run at 5V and not need a boost module.

 

[Beast-of-Burden]

Thanks... I'm working blind now because it hasn't been delivered yet (Tuesday). I'm just getting as much figured out while I'm waiting to get it. I saw one tech sheet that listed it as 5vdc even though it obviously had the two batteries in series position. If it does in fact test out to be running on 5v then they must have a step down adapter in the battery box section (which I'll not need either with the 5v power source). I've just been 'preparing' for the worse in case.

 

[kpatz]

I'd be surprised if that camera doesn't have a USB port already on it, to download footage if not to power it without the batteries. Or at least a DC barrel jack. Do you have a product name/model number or a link to product info?

I googled "infrared camera with 5" screen" and found what appears to be the product you mention on Aliexpress (an IR night vision nightscope for a hunting rifle?). The specs are vague, but it mentions running on 3.7V, which would mean the batteries are in parallel, not series. You may need a buck converter rather than a boost one, unless the cam will work on 5V.

 

[Beast-of-Burden]

Item specifics

• weight:0.8Kg
• Model Number:FW54-YSY030
• Operating voltage:5V
• Type:Night Vision Optics Monocular
• Battery:18650(Batteries not included)
• Effective Visual Distance:100M
• Infrared Ray Launcher Type:Single Transmitter
• Magnification:1X
• Size:5inch LED

Display size: 5.0 inch

Resolution: 800*480

Scanning frequency: 60Hz

Minimum illumination: 0.0001 LUX/F1.2

Signal to noise ratio: >46dB

Operating temperature: -20℃-50℃

Adapter battery: 18650 Lithium battery

Infrared light: 850mm

Infrared lamp power: 5W

 

[Beast-of-Burden]

I've enlarged the pic & it appears the springs (for the batteries' - end) are at opposite ends of the holder so that would imply 'in series' (right?).

Oh and yes it is a night scope camera & screen attachment for a hunting scope. I guess it will be a lot clearer once It actually arrives here so I can physically examine it and know for sure the voltage. Can't wait till Tuesday's mail. Thanks for all the help.

 

[Beast-of-Burden]

OK, Update... Looks like I'm stuck using those weird 18650 batteries. It is wired in series and 5v doesn't work at all (thought I'd check & see). The monitor screen, infrared camera & built-in illuminator all are powered by those 2 batteries. Even if I rigged up a holder for 5 or 6 normal AA batteries they wouldn't have enough mAh. I'll order a couple of sets & a charger so I'll have spares in the woods. Expensive little guys but am excited to hog hunt at night with this setup.
Thanks for the feedback & help. Stay safe & happy.

 

[Beast-of-Burden]

With nothing changed it works well at night for reducing feral hogs at around 100-125yds.
But... being a tinkerer I like to modify it to do something extra.
Currently the camera is connected to the monitor screen & battery power via a 3.5mm cable. I assume it supplies the camera with power & the monitor with the camera's video. (looks like a 3-connector plug). I'd like to figure out a way that 3.5mm connection could (with a 'Y' adapter or ?) also supply the video from the camera to a recording device as well as the original monitor. If the camera could send to both (by cable or ??) maybe some Bluetooth adapter is out there. Any suggestions would be greatly appreciated.

 

[Beast-of-Burden]

 

[Beast-of-Burden]

Interesting reply but I've moved on to a different subject so I guess I should have started a new post and not continue on this existing post... my bad. I'll address my question in a new post.