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

AzaziahAzaziah Registered Users Posts: 15
Hello, everyone! First, I LOVE this forum and the knowledge represented here. I really appreciate all the excellent help and information that is represented. Thank you for letting a previous lurker read & learn. :D

I have been working on a project, and wanted to share and get some input on a couple specific points that have me scratching my head. This is not a typical solar project, although it has solar elements.

By way of introducing the concept, please understand that I am a bit of a tinkerer, have been all my life, and I have always had an interest in alternate power. One of the projects I have played with over the years, is a portable power supply. The first units were made mostly from scrounged or scavenged materials. In the simplest form, the components are a battery, AC charger, inverter, and 12 VDC powerpoints. The purpose is to have a source of power either in a short grid-down situation or for camping / remote applications. Not a new concept, I realize.

My DW and I have a son who has Down Syndrome. He is doing great, but still receives a large portion of his daily (nightly) nutrition via a mechanical feed pump that delivers liquid via a G-tube (small port surgically installed into his stomach). The feed pump runs on 110AC and has a mediocre back-up battery. This is the sort of circumstance that can motivate a parent to have back-up power, of course. The most recent unit I have finished is the one that currently sits in my study, always charged, and ready to help us through a brief period of power loss (we live on-grid).

Here are a couple photos:

DSCN2550.JPG


DSCN2552.JPG

Main components:

Salvaged oxygen tank cart
Two Group 30 AGM batteries
3-bank, 20 amp, charger / maintainer
1500 watt Xantrex inverter, MSW
100 watt inverter
Old solar controller as regulated 12-volt power supply (harbor fright unit)
two DC compact-fluorescent bulbs, fixtures, and long cords
Automotive-style 12 volt receptacles
Mag-light w/ mounting clips
A pile of scrap 3/4" plywood from other projects.

We are very happy with the way this thing works, and have taken to calling it the PUP (Portable Universal Power supply). ;) It is very heavy, of course, well over 200 pounds, but it is pretty easy to move around thanks to the dolly wheels. If we had an interruption of the grid, this would certainly help my son's medical needs as well as some other uses. I do have some solar panels that would be pressed into service for this unit if the grid was down for any extended period of time.

Any way, all of this to come to the real reason for this post...

Comments

  • AzaziahAzaziah Registered Users Posts: 15
    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:

    pup_iso.jpg

    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:

    DSCN2580.JPG

    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:

    DSCN2584.JPG

    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.
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    In the picture below, you see the beginning of the build:

    DSCN2596.JPG

    On the left is a NOCO AC charger. 3.5 amps, and a pretty slick example of an 'automatic' charger. I think I should have gone with one of higher amperage, and NOCO does make this one: http://www.impactbattery.com/brands/genius/noco-genius-g7200-12-24v-smart-charger.html which is 7.2 amps and would be a better match for the battery I shoe-horned into the case.

    In the middle is an AIMS pure-sine inverter. 300 watts constant, 600 surge. Two cooling fans that are load-sensing, all in a pretty compact package. If you look close you can see that I have removed the 110 outlets... they will be remoted to the control panel, along with the on/off switch for the inverter. This is one specific area I have a question about, and will ask it later when it becomes clearer...

    On the right, sorta hard to see, is a Morningstar 10 amp sun-saver with LVD. Sweet little unit, love the simple, rugged design.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    Interesting reading so far. :D

    One suggestion; ditch the AIMS inverter in favour of the Morningstar 300; no cooling fans.
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback
    Interesting reading so far. :D

    One suggestion; ditch the AIMS inverter in favour of the Morningstar 300; no cooling fans.

    Agreed. The MS 300 is awesome. Too pricey for me at the moment, but it would be a better choice from a mechanical standpoint. Maybe the next ToughPUP will have one? 8)


    A better view of the Solar controller:

    DSCN2625.JPG

    In the foreground you can see the leads from the NOCO charger. This thing comes with some nice extras. One of which is a battery-clamp style connector that snaps into the plug you see. This allows the charger to be connected to another battery than the one you might have the lugs screwed onto. I opted to pass this connection outside of the chassis and then back in. This lets me disconnect the NOCO from the internal battery, connect the clamps, and hook it to a different battery real easily.

    Another view:

    DSCN2626.JPG
  • JESSICAJESSICA Solar Expert Posts: 289 ✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback
    Interesting reading so far. :D

    One suggestion; ditch the AIMS inverter in favour of the Morningstar 300; no cooling fans.

    Is yours a Crusade against the infidels at AIMS? (Just kidding!)
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    The beginnings of the control panel:

    DSCN2646.JPG

    The master on/off switch is by Blue Sea Systems. Intended for marine applications. Very nicely made. 300 amp rating.

    The 12 VDC 'cigarette' power points are Marinco. They are (theoretically) watertight when paired with a MarinCo plug, and have a neat bayonet locking feature: Insert plug, give it a quarter-twist, and the connection is secure. Not cheap, but pretty cool.

    I opted for circuit breakers instead of fuses to protect the power points in the panel. More expensive but much more reliable and field-ready. Who wants to hunt for a fuse because the Boss plugged her hair dryer in? Ayup. Not me!
  • AzaziahAzaziah Registered Users Posts: 15
    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.

    DSCN2590.JPG

    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! :blush:
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    The beginnings of the 'guts' of the control panel:

    DSCN2648.JPG

    I am keeping both the AC and the DC grounds isolated. See if you can spot my newbie mistake along those lines in the pictures above and below:

    DSCN2652.JPG

    Anyway, the grounds are isolated from the aluminum chassis and from each other. I know there is much to understand about this subject, and I hope to hear opinions. For example: if the inverter is not grounded, what are the concerns? This of course means that a three-prong 110 VAC plug, plugged into the control panel, has an unused ground prong. And the extension cord that plugs into the wall has a grounded prong that doesn't even connect to the inverter...

    DSCN2704.JPG

    Man, I was surprised at just how much wire, connectors, heat-shrink, zip-ties, screws, and busted knuckles can be squeezed into a small space!
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    Grounding is a big debate starter. :p

    Normally a pure sine inverter will have the case grounded as well as the negative DC and the neutral AC. But since there is no actual Earth ground for this portable unit, I'd say you'd be better off treating it all as "double insulated" or "floating ground" like a portable generator. Others may disagree.

    As for charging batteries in a closed space ... either AGM's or gels should be fine so long as the current isn't too high. Heat dissipation will be a problem for everything, even with the lid open.
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback
    Grounding is a big debate starter. :p

    LOL. Yup.
    Normally a pure sine inverter will have the case grounded as well as the negative DC and the neutral AC. But since there is no actual Earth ground for this portable unit, I'd say you'd be better off treating it all as "double insulated" or "floating ground" like a portable generator. Others may disagree.

    So... "double insulated" or "floating ground" is what I have now, right? By isolating both?
    As for charging batteries in a closed space ... either AGM's or gels should be fine so long as the current isn't too high.

    Yes, this is my understanding. I managed to squeeze a group 24 AGM into the chassis. It actually fits real sweet. The battery I am using is this one:
    1721421453.jpg

    Specs:
    Voltage: 12V
    Amp-hour: 75
    Watts/cell: 270
    Length: 10.2 in.
    Width: 6.6 in.
    Height: 8.3 in.
    Weight: 52.8 lbs.
    Terminals: T9, threaded, .236 inch diameter
    Warranty: 2 Years
    Price: $173.15


    Heat dissipation will be a problem for everything, even with the lid open.

    Agreed. Especially in the environments where something like this might be needed or wanted. Hot, sticky, sandy, humid... cranky people, kids with suckers... madness!

    Both ends of the chassis are open, allowing air to circulate a bit more than otherwise. I also have a bent flange of aluminum that the inverter fans blow across, in an attempt to force air up and out of the chassis, therefore pulling it in from the opposite end, and across the components:

    DSCN2626.JPG
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    A bit farther along:

    DSCN2700.JPG

    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:

    DSCN2632.JPG

    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.
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    This is a decent shot of the control panel after completion - it is shown removed from the pelican case.

    You can see the two analog amp meters, one shows the draw, or power being used. The other shows the power coming into the PUP, via the AC charger, solar controller, or both. This should make it easy to tell if you are running a deficit or a surplus at any moment by comparing in versus out.

    DSCN2767.JPG

    The digital display in the middle top is the real-time voltage of the battery.

    Anderson power-pole connectors on the left, two binder posts on the opposite right.

    Main power off in the center (big rotary switch).

    (6) LED switches, - these control the lights, DC chargers, AA chargers, and charging for the LED flashlight.

    Two 5-volt USB ports in the middle.

    12 VDC 'cigarette' style ports.

    All the power points have a 10-amp circuit breaker adjacent. Superior to fuses. More expensive, and more work to install, but real nice when you are having trouble and are flipping a breaker for some reason.

    In the middle at the bottom, the two 110 VAC outlets with power switch.

    Next photo, chassis removed from case, panel open:

    DSCN2763.JPG

    You can see the AGM battery installed. There is very little play between the battery and the chassis... this is deliberate, as the battery is almost 52 pounds, and I don't want it shifting at all if the PUP is being tossed around, dropped, or transported.

    The wiring looks a bit messy here, I had some retention clips removed to access other stuff. It is nearly complete though (wiring) in this photo.

    BTW, I ran the charger today with the case closed, for about 4 hours. It was in bulk mode the whole time, and ambient outside temps were in the high eighties. Upon opening, the interior was noticeably warmer. at least ten degrees warmer. Not enough to worry me, at this point...

    A couple closer shots showing how the battery is secured:

    DSCN2762.JPG

    DSCN2761.JPG

    DSCN2764.JPG
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    analog meters!:confused: i thought those went out years ago. you probably could've put more accurate digital in there for about the same cost and maybe even less. one thing about them you have to be aware of is that you can destroy the meter movement with the kind of jarring you battened down the battery for.
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback
    niel wrote: »
    analog meters!:confused: i thought those went out years ago. you probably could've put more accurate digital in there for about the same cost and maybe even less. one thing about them you have to be aware of is that you can destroy the meter movement with the kind of jarring you battened down the battery for.

    DRAT!!


    But I like the old-school meters...

    Allright. And this is hard to take back, considering the hole size and shape needed for the analogs.

    Dagnabbit. Well, the next one goes digital. This one maybe I could graft in a plate in each opening, and put digital in, but it would look a bit goofy.

    Double-drat.

    Ah well, okay.

    This brings up a related question... what about some of the smart meters (like Dr. Watts, etc.) to replace all the meters? I checked into them, and they seemed to be intended for a single circuit, not a bunch of loads like I have?

    Oh, and thanks, Niel. No, really. ;)

    Better that this gets caught now, and corrected before I build one for sale...
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    i was thinking of simpler digital panel meters, but some of the other ones like trimetric and such can be put in too even though much more costly.
  • DapdanDapdan Solar Expert Posts: 313 ✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    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. 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

    wind-sun_2161_61906452

    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.


    51843.jpg

    3. 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.

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


    Cheers...
    Damani
  • AzaziahAzaziah Registered Users Posts: 15
    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

    wind-sun_2161_61906452

    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.

    51843.jpg

    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
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    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.
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback
    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!
  • XRingerXRinger Solar Expert Posts: 529 ✭✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    If you wanted to install a recessed MC4 socket & plug, the bottom section
    screws together and could be mounted on thin sheet metal. (At the bottom of your connector cup).

    As for the locking feature, I don't think that would really be required in this app.

    Cut off those spear barbs. And open up the outside strap, on the slots. (barbed spear receivers)
    MC4-Solar-Connector-RO-1--2355447118.jpg

    Then your rig would be able to easily accept PV power and unplug without tools.

    Because this type of connector will be damaged if plugged or unplugged while under power,
    I recommend that Velcro straps or some other method be used to secure the PV panel's connector to the case.
  • AzaziahAzaziah Registered Users Posts: 15
    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!
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback
    Azaziah wrote: »

    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!

    Az

    The advantages of the LiFePo battery go beyond simply weight. They will last probably twice as long as lead, AND the gigantic advantage is that they can be deeply cycled, where the lead battery really must be only cycled to 50% for any lifespan.

    There are lithium cells advertised for $1.075/ah, for 3.3V, which is an extremely good price. Of course, you'll have to add shipping too. They are for sale here: http://www.alliancerenewableenergy.com/Thunder-Sky-LiFeYPO4-Batteries_c3.htm Also, to clarify, I have no affiliation with this company, and I have never ordered anything from them, nor have I heard of anybody who has ordered anything from them.

    So then you could use 4 batteries of 60 ah, for a cost of $258. That is more than the $173.15 for the 75 ah battery (really 37.5 ah usable though), but with 54 ah usable (90%), the price really starts to look better. You might need a BMS, which would add some to the price, but that is another debate, and with only four cells it might be possible to skip. You could drop down to the 40 ah batteries, which would be a less money, but then you would not have the absolute emergency reserve of your chosen lead battery.
  • XRingerXRinger Solar Expert Posts: 529 ✭✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback
    Azaziah wrote: »
    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!


    The strain relief shell needs to be screwed down tightly, to compress the
    rubber doughnut down on the wire. (To be watertight).
    But, since those cables aren't going to be yanked on (inside the casing),
    the shell/nut should work.. If the metal isn't too thick.


    If you install a big pigtail(4") cup, you should go ahead and hack the MC4s
    so they don't latch.
    At least one of the connectors can be of the Finger-Release type.

    (The bottom connector. Squeeze the tabs and unplug it. :cool:
    mc4%20pair.JPG
    $2.99 Ebay item 320594843356
  • AzaziahAzaziah Registered Users Posts: 15
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback
    The advantages of the LiFePo battery go beyond simply weight. They will last probably twice as long as lead, AND the gigantic advantage is that they can be deeply cycled, where the lead battery really must be only cycled to 50% for any lifespan.

    There are lithium cells advertised for $1.075/ah, for 3.3V, which is an extremely good price. Of course, you'll have to add shipping too. They are for sale here: http://www.alliancerenewableenergy.com/Thunder-Sky-LiFeYPO4-Batteries_c3.htm Also, to clarify, I have no affiliation with this company, and I have never ordered anything from them, nor have I heard of anybody who has ordered anything from them.

    So then you could use 4 batteries of 60 ah, for a cost of $258. That is more than the $173.15 for the 75 ah battery (really 37.5 ah usable though), but with 54 ah usable (90%), the price really starts to look better. You might need a BMS, which would add some to the price, but that is another debate, and with only four cells it might be possible to skip. You could drop down to the 40 ah batteries, which would be a less money, but then you would not have the absolute emergency reserve of your chosen lead battery.

    Excellent info! Okay, so the batteries alone are not prohibitively expensive:

    LiFePo, 54 usable AH, equals $4.77 / AH
    AGM, 37.5 usable AH, equals $4.61 / AH

    And the weight!!:

    LiFePo, 5.51 lbs x (4) cells = 22.4 lbs
    AGM, 52 lbs

    And the size!!:

    LiFePo: 8.5" x 2.4" x 4.5" or a bank of approx 8.5" x 10" x 4.5", or 383 cu in.
    AGM: 10.2" x 6.6" x 8.3" or 559 cu in.

    That is all awesome until you confront the BMS. Do you really need a $200+ Battery Mgmt. System? If so, OUCH. If not, then COME TO POPPA!

    Oh, and shipping is an issue... 6-8 weeks on a boat? ummm, okay...

    But the specs are simply fantastic.

    NICE.
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback

    On the MC4 tool, just attach it inside the case with a lightweight chain, heavy string or lightweight steel rope - permanently attached to the tool and case. Secure it inside by bundling it up with a small velcro strap like you have on your AA battery charger. Then you can use stock MC4s and be sure the tool is always there. I like the idea of sticking with MC4s so you can use off-the shelf PV.

    Thinking outside of the box - literally - I would suggest you divide up the project into 2 smaller boxes. One with all of the output electronics/connections, the other for the battery and both chargers. Easier to lug around in 2 parts, ability to just take the battery box outside for solar charging or to attach to a neighbor's genset 3 houses away, ability to easily add (sell) modular battery capacity.

    The last is a biggie, its the one achilies heel to the whole thing with only 52 amps available at 70% depth of discharge (70% is reasonable for an emergency power system, where power NOW is more important than long-term battery life). You sell them one battery box now, then your customer realizes they need 3 times as much run time so you sell them 2 more battery boxes. All they have to do is plug them into each other in a chain which internally you have wired in parallel. Which leads to one more selling advantage, you could offer more than one battery chemistry to the same user without duplicating the output electronics. Just provide more than one input on the "main" box with different connectors for each chemistry and isolate them electrically so they can't back-feed the others. With the chargers already in the battery boxes you just match the charger and battery at the factory, the user just daisy-chains like chemistries as needed.

    Someone already mentioned lithium, there is also flooded NiCad which has several advantages over lead acid. Yes there is the issue of keeping them upright but since the battery cases would be separate you could clearly mark them "this end up at all times". Flooded NiCad is lighter, can be completely drained to 100% DOD (and stored that way!), lasts up to 5 times longer than lead acid, doesn't loose much capacity when cold, and its compatible with lead-acid chargers if necessary. Here is one manufacturer: http://www.sbsbattery.com/subpage_index.php?_subp_=142
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Wanted to Share an Interesting Project - Looking for Input, Advice, & Feedback
    Azaziah wrote: »
    Excellent info! Okay, so the batteries alone are not prohibitively expensive:

    ...

    That is all awesome until you confront the BMS. Do you really need a $200+ Battery Mgmt. System? If so, OUCH. If not, then COME TO POPPA!

    Oh, and shipping is an issue... 6-8 weeks on a boat? ummm, okay...

    But the specs are simply fantastic.

    NICE.

    OK, I thought the website said the batteries were in stock and ready to be shipped. But I don't know definitely.

    The BMS is really the debatable aspect. Here is somebody who, while somewhat controversial, states that no BMS is needed: http://jackrickard.blogspot.com/ . Of course, the people that make the BMS say he's crazy. Now, many of these projects use 80 or 100 batteries. With 4 batteries I don't know that a BMS is really necessary. You only have to make sure that no battery gets overcharged or undercharged. So you could possibly be safe with the 90% full and never discharged under 10%, and just occasionally checking individual cells if there's only four.

    One person had a BMS for PbA batteries that essentially equaled the cost of the batteries! I never saw how that could possibly be worthwhile. Even when you calculate that you can use a BMS with another set of batteries years later when the first set dies.
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