Backpack Portable CO2 Build

Hello everyone.

I would like to apologize if the title is slightly misleading and you thought you were going to see a fully assembled laser. Sorry! Not quite yet!

Okay let me start this thread by giving a short detail on my little project.

I recently picked up a 13W RF Excited CO2 laser from a member here. These lasers are very unique and beyond "extremely" rare for a complete setup and confirmed working/tested (For any reasonable price anyway).

Now. What I will be doing is making this laser 100% portable. Why? Well why not?

The reason for this thread is to document my progress with this build and perhaps get some feedback and suggestions on how I may improve the setup and so others who may follow in my footsteps will have a detailed build to base their work off of and modify it to their liking.

This build is not only unique because of the laser. It is unique because I will be using a method that is frequently talked about on here but I never see anyone making a practical use of. That method would be "Backpacking". Why would you want/need to backpack a laser. Well, for high energy lasers such as this one. Our usual method of using Lithium Ions could be costly and dangerous. This build will be consuming >300W of power (32V @ 10A. I believe thats correct?) That's a TON of power! So backpacking it seems like the only sensible thing.

I'd like to point out a few safety concerns I have with a build like this. Please feel free to add some concerns you may have and I'll probably add them.

Possible explosion of batteries
Class 4 laser - Possible Fire hazard
Possible burns due to overheating batteries or wires which may lead to a fire/explosion.
Blindness - Wear those damn glasses!
RF burns
Electrical shock - Please be aware of any exposed HV components/wires
Cooling of device

Okay. Now that I've rambled on about nonsense. Here is my setup plans.

Power supply - 12x 2.7V 3000F super capacitors in series
Wires - Have not decided. Perhaps some 14 gauge?
Laser - Tested 13W RF Excited CO2
Backpack - Any, you derp.
Cooling - Air cooled
Key switch? - Absolutely
On/Off Switch - Have not decided

To be updated...

I've been thinking of this very same project for a couple decades, now. Ever since I first saw the movie Ghostbusters and heard those famous words: "don't cross the streams."

Are you sure capacitors are the way to go? I feel like lead-acid batteries might work better (especially since their voltage doesn't drop with their charge).

Right now its all I have at my disposal. Since this application isn't exactly practical I would be more than happy to have a few minutes of runtime. If I get board enough tomorrow. Perhaps I'll do a little test with my caps and see how long I can run the laser for.

The problem with this specific build is the uncommon voltage the unit needs which is 28-32 VDC. Then you have the high current along with that.

I dont have any lead acids here to even attempt it at 24v and my bench top PSU only goes to 20V.

I've also thought about using a DC-DC Buck/Boost driver to get more runtime. Though the thought of fire/explosion scares me

Something like this. Though I would run two in parallel.

http://www.ebay.com/itm/271054470252

I'd also suggest the lead acid option. You could put 5 x 6 V lead acids in series to easily achieve 32 V (they are around 6.5 - 6.7 V fully charged ). They can also be very small and easily handle 10 A.:beer:

There's no high voltage in those. 32V isn't enough to shock you unless you lick it.

They're just passively air-cooled, aren't they?

I'd use either lead-acid or LiPO or LiFePO, myself. Maybe even NiMH since they're common in cordless drill packs in higher voltages like that.

Interesting project...

Some of my RC planes use way more than 300Watts of power.
Why not use an 8s Li-Po battery. It will output 29.6 volts.
just remember to use a high C rated battery to be sure the
battery can supply any running and surge currents.

I would also put a fire resistant plate in the packsack between
myself and the batteries/electronics... just in case.


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

Or some torch rags. (i think that's what they're called, its fire resistant kevlar like material I use when brazing)

Cyparagon said:

There's no high voltage in those. 32V isn't enough to shock you unless you lick it.

They're just passively air-cooled, aren't they?

I'd use either lead-acid or LiPO or LiFePO, myself. Maybe even NiMH since they're common in cordless drill packs in higher voltages like that.

Click to expand...

The reason I've mentioned HV is because I've already had the idea to power a 40W CO2 tube in the same fashion.

Yeah, This tube is passive cooled.

I've thought about lead acid cells long before this> I'm just not sure if that's what I want to make a permanent setup with. Good LIPO's are expensive and LiFePO Seem like a good idea and will likely be what I switch to if the super caps don't pan out. NiMH.. Meh They would be a PITA to charge. I'm also worried about frying the contacts on my cells.

lasersbee said:

Interesting project...

Some of my RC planes use way more than 300Watts of power.
Why not use an 8s Li-Po battery. It will output 29.6 volts.
just remember to use a high C rated battery to be sure the
battery can supply any running and surge currents.

I would also put a fire resistant plate in the packsack between
myself and the batteries/electronics... just in case.


Jerry



You can contact us at any time on our Website: J.BAUER Electronics

Click to expand...

As with cyparagon's suggestion Li-Po's can be a bit expensive. If i choose to go this route I will probably go with 26650 IMR cells or better. It would be really costly but would be a whole lot more efficient. I'm just not sure how I would go by charging all of these cells. Seems like a royal PITA. At least with these super caps they have screw terminals for easy teardown/charging.

Fire resistant plates seem like a good idea but I think if it came down to a fire... Things would be very bad which is one reason why I am a little afraid to use Lithium as a power source.

dmacrae said:

Or some torch rags. (i think that's what they're called, its fire resistant kevlar like material I use when brazing)

Click to expand...

I can get kevlar at work. Though I would rather nail down all of the rough edges and not have to even worry about a fire . Though I guess there will always be that chance.

Right, So I did not find time to test the super caps. Perhaps tomorrow.

I have been looking at LiFePO4 cells and I cannot seem to find a set that would do me <100$. I'm looking for some bigger cells and not ones that are gonna last me 30 seconds. I am gonna have to break these down to charge them.

Suggestions here? I'd preferably not like to go with Lead acid. Plus if I buy some LiFePo4 cells. I can mount them on the laser and ditch the whole backpacking thing. It would also make for easier charging.

I just ordered these for my super caps. Not specifically for this project but because I wanted em ^^ Low Z Strap 12 Pack Maxwell Super Farad Ultra Capacitor BCAP P270 K04 50UOHM | eBay

Those aluminum mounts are a bit pricy but I don't think I'd be able to get them anywhere else cheaper.


I'm also looking for that black mesh that you find on ATX psu's. What Is that stuff called? I'd like to incorporate that into this.

Idea's On how I would mount this laser head and driver? I like Hemlock_Mike's idea... However I want to try and not copy other people's ideas for once. I was thinking wood... but wood is not cool... Nerf guns are out as they do not make ones large enough that would fit inside.

Jeez, that's pretty steep. you can make your own with a hacksaw, drill, and aluminum bar from the local hardware store for like $6.

Ultracaps won't work well because the voltage drops a lot with charge level. You'd get less than a minute of run-time, and you'd use only a tiny portion of the capacity.

I have ready made some copper holding plates. I made them with a hammer, bandsaw and drill. I'm just not happy with it and don't feel like redoing it.

I've been looking at a more permanent power source. Right now I think these would be the best solution that is within my tight budget.

4 High Power LiFePO4 26650 Cell 3 2V 2500 mAh 40A Rate 8 0WH Without Tabs | eBay

interesting, reminds me of my instant car starter:

There are more to li-ion cells than just cylindrical ones, you know!

Batteries & Accessories>Li-Poly (All brands)

Also, don't be worried about fires, or explosions. Just add an appropriate li-ion cell protection circuit, and fuses.

If there's a short you'll have redundant safety to prevent the cells from exploding, or catching fire. And those li-po's can handle a LOT of current draw, trust me!

Gren used two batteries from there to build his portable x-ray machine...and I'd think that project and this project might draw around the same amount of power.

Good luck to you!

You may still consider the NiMH route. You can get 36V robot batteries for like $99. Charging isn't that hard. You just connect them to a NiMH charger and let it run. I used some NiMH RC packs to replace the rechargeable batteries in an older drill and they work great.

^ Seems like those NiMH cells might work a bit better since they have more capacity. Might add more weight but that's not really an issue is it?

Hmm... so many choices.