Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

A couple months ago, after finishing the home-brewed power supply in the above post, I decided to make another, but this one would be different than any I had built or seen before. Part of the motivation came from the reaction I got from others who had seen the previous units. I realized there might be a market for something like this if it was built in the right manner. It struck me as a challenging, fun project that might create a bit of income on the side, from something I enjoy doing anyway.

It would be more portable, which meant wheels and a smaller overall size than I had built before. It would be weatherproof, which would require some sort of sealed case. I wanted to be able to charge or power virtually any small or medium device, which meant DC/DC converters as well as a quality (SW) inverter. I knew from experience that both area lighting and night-lighting were real handy. I wanted the versatility to plug in an I-Pod, laptop, radio, walkie-talkie, medical device, ham radio, TV, etc without fear of damaging the equipment. I also wanted this thing to be rugged, so I could rely on it working when it was really needed.

Lastly, I wanted it to be truly independent, so I would incorporate a powerful, folding solar panel and an efficient solar controller.

Well, this was quite a wish list, and frankly I wasn’t sure if all this stuff would even fit into a small case, let alone be light enough to be man-portable. With some research, I discovered that I wasn’t inventing anything at all. Our military has been using power supplies like I’ve described for years. If you can find them on the civilian market, they are anywhere from $5,000 to $9,000 apiece, normally refurbished or used.

I do have one advantage when it comes to projects like this. I can design 3D models fairly quickly in my CAD system, and am able to make a lot of mistakes in the virtual world, where they are cheap. By the time I actually start to construct something, I should have avoided most of the common pitfalls in a given project. Even with this advantage, I was surprised at the time and effort it took to get this project off of the drawing board… I was trying to fit a lot into a little package, and I needed to have all the components complement one-another in terms of their various ratings and capacities.

I logged nearly 300 hours in design and research before the first item was purchased. I guess I would do it again, but I’m surprised even now when I consider just how much time it took to work it all out. Somewhere along the way, a name for the prototype emerged: ToughPUP. My 8 YO daughter giggles at the name.

Here is a screen-shot of the nearly-final design:



Once I had the internal components roughed out in 3-D CAD, I was able to select a case. I purchased the best, toughest case I could find. Made by Pelican in California, these cases are awesome. It has ball-bearing wheels, a retractable dolly handle and two carry handles. Exterior dimensions are: 22” x 18” x 10.5

This is a picture of the case, after I dry-fitted the aluminum chassis into it:



The control panel flips up to allow access to the innards, and the aluminum plate under the lid has a fold-down shelf and is mounting platform for goodies:



Apologies for the longish posts... I need to get to the areas of specific questions, and the context will help you guys understand... more to come.

Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

The picture below shows the two 'through-hull' connections. On the right is a 110VAC male socket that connects to the AC charger. These are typically used on boats to connect to shore-power. It allows the use of a standard extension cord to plug the PUP into the wall.



On the left is another MarinCo 12 VDC socket. This is the input to the solar controller. This was a choice I agonized over some, and I think you folks might have some better suggestions... I struck out trying to find / buy a more 'standard' solar connection. As it is, I would need to wire a cigarette style plug onto the solar panel leads... not a big problem, but I still think there is maybe a better choice for this connection. weather resistance is important, because I want to be able to deploy the panel in the field, plug it into the case, and leave the case closed and rain-tight while charging. I am also real curious to get some opinions about charging the battery in an airtight case!

Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

A bit farther along:



DC fluorescent lamps, 12V 8 watts. Removable, with a 10 foot cord / tether. I modded these with strain reliefs and heavier cord.

Two DC/DC converters, selectable from 1.5 volts on up to 12 volts, with a mixture of different tips for whatever device might need to be powered. I modded these by moving the 12VDC input to a location that worked better for the install.

Two rapid NIMH chargers, AA or AAA size. I modded these by removing the 110VAC plug and wiring directly into the 12VDC input. I also added a velcro wire-wrap through the case and out the front... this serves to retain the batteries if the ToughPUP is getting some rough treatment:



Power for all of these components passes through the master On/Off switch and is then turned off / on by individual switches on the control panel.

Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

Dapdan wrote: »

A,

I definitely like the case, it is gorgeous. I especially like the fact that you did it in cad first before you did the first build. I guess I am being bias since I work alot in cad as well but for building and civil works.

Thanks, Dapdan! I doubt I could have done it without CAD... simply too much being fit into a small space... there are a few areas where my clearances were less than 1/8th of an inch in CAD, and that was borne out physically when I built. An advantage, no doubt.

Dapdan wrote: »

These are my suggestions:

1. In terms of the solar input through the case you can consider using a pair of pigtail custom made MC4 cables going through one water tight strain relief that accommodates a pair of wires similar to this one

Nice connections, but have not (yet) found an MC4 that is a female panel mount. I want to avoid a pigtail exiting the case, no matter how short it is. If I had to, perhaps I could use the 'body' of a 12vdc socket (like already installed into the ToughPUP) and replace its innards with a female MC4? Threading it might be difficult, in terms of getting your fingers in there? Looks like I need to get some and experiment. You have motivated me to take a fresh look at the MC4...

Dapdan wrote: »

2. In terms of the metering, I think you need a battery monitor so that the use can know where he or she is in respect to energy remaining like a gas meter and know as well how much and at what rate they are consuming. One like this is very good and small and does all of that and more. I have bought five recently for about $150 each. It came with all necessary parts (shunt, wires etc) and it is the smallest battery monitor out there now.

That looks sweet, though it is not cheap... please understand cost isn't really an obstacle. I am trying to build high quality and reliable. I am at cross-purposes if I 'skimp' in any area, especially meters and controls. That said, looking at the description here: http://www.jamestowndistributors.com/userportal/show_product.do?pid=51843&BASE Makes me think that one meter only measures amps in OR amps out... not both. I suppose a DPDT switch should allow monitoring of one or the other? I really like the idea of a 'fuel gauge' for the battery. Difficult, I think, to accomplish accurately, but for the average user it is more intuitive than voltage, which can be deceiving...

http://www.jamestowndistributors.com/userportal/show_product.do?pid=51843&BASE3.

Dapdan wrote: »

You may consider an optional upgrade to LifePo batteries if the person wants a 60% reduction of weight in terms of the batteries. There is a treat here on the same lithium batteries where a member was doing something similar to what you have done. Maybe on of the mods can find it and link to it.

I would LOVE to reduce the weight. I made trade-offs (of course) on weight versus capacity. I have not weighed the whole unit yet, but it is at least 80 pounds. The case handles it well, but it is hard to move if you cannot use the wheels. With the wheels and the retractable handle, on a decent surface, it is sweet. Carrying it from the house 200 feet to the shop is a pain. I do not want to wheel it across the grass and dirty things up, so I do a one-handed grunting carry.

I need to find pricing on a comparable LifePo battery... so far I am thinking they are at least 3-4 times the cost? Very nice, for sure. The weight savings would be worth the cost if you were humping this thing overland, for sure!

Dapdan wrote: »

What price point are you looking at. I might be interesting in one. It looks quite neat.

My actual cost for components and consumables is just under $1,100 right now. That does not include the 30w or 60w folding solar panel. I am expecting a retail price between $2,200 and $2,600. Add $300 - $600 for the solar panels, depending on wattage, of course.

Dapdan wrote: »

Cheers...
Damani

Thanks for the info and the food for thought!!

Az

Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

Cariboocoot wrote: »

Recessing MC4 connectors into the "cigarette lighter" sockets might make it too difficult to attach/detach; they don't come apart easily without The Tool http://www.solar-electric.com/ditoformc4co.html.

You might consider offering other designs too; ones without all the bells-n-whistles like the lights and NiCad chargers. You know: straight forward power pack with AC and DC out. Other companies make these, but they don't seem to put as much thought into the engineering as they do into the marketing.

So the question of an ideal connector for the solar panels remains unanswered... maybe what I have is allright. It is supposed to be watertight, anyway... I just wish that the end user did not have to strip wires and make their own connections if they expand the solar panels...

I like the suggestion about a stripped down version... it would certainly be cheaper and a lot easier to build! What I set out to build was a sort of electrical swiss-army knife. It is what I would want if things went dark and scary and we wanted some secure, portable power that was flexible.

All the input is great, folks!

Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

Interesting, Xringer... I see what you are layin' down!

One concern is you say 'thin sheet metal' I will have to see if there is enough engagement between the cup and thread to allow for the 0.140" or so thickness of the pelican case. I also want enough room for gasket(s) and/or silicone.

This makes me wonder about a recessed box, like a 110 vac outlet for the outside of your house? The type that has a hinged, gasketed lid? What if I installed one of those, and then had a pigtail MC4 within? You could open the door, remove maybe 4" or so of pigtail, and have an MC4 that was unmolested and factory original? Might make it hard to easily connect and disconnect, though... I would like to avoid any specialty tools. They have a habit of going gone on you when you need them!