Building a pair of battery generators

Hello everyone,

So lately I have become fascinated with the idea of building a battery inverter power supply, sometimes known as a battery generator.  I could just go and buy one, but they are expensive and some have serious reliability issues.

I am planning on building two devices.  The first one is really an experiment to see if I can make a working model before I build the big one.

The first model is based on a plastic .50 cal ammo can (a black plastic case) and a 12v 15ah SLA battery.  I have found a build on YouTube, complete with step-by-step instructions and a parts list ( I already bought the ammo can case just to get an idea of how big it is).  The device will mainly be dedicated to USB and 12v car outlets.

I have yet to decide on the specs for the larger model, but in addition to USB and 12v, it will additionally have 120v AC and possibly a buck converter (a device that lets me dial up whatever DC voltage I want).  Both should be capable of charging via either solar panels or 120v ac.  The larger one will probably be based on a rolling tool case.

At any rate, I am wondering if anyone else has tried one of these projects or general thoughts.

Thanks in advance,

Eric

So my project has just begun—Sort of.

I did go ahead and order the ammo can case.  This .50 cal case is nice, having a rubber gasket in the lid, making it at least mildly waterproof.  The insides is just big enough so that it’s interior is as wide and tall as a dvd case, which gives the case a nice backup role if my project fails.

As I said earlier, this is a sort of training/learning project for me before I make a 100ah battery version in a rolling tool case.  I expect the small version to be able to charge up cellphones, tablets, perhaps a computer and other small odds and ends.

If anyone else had tried this I would love to know how it went.  If you have some experience with any of these types of projects, I would love to hear your thoughts as well.

Thanks in advance,

Eric

I am following this with interest.  I am currently playing with solar.  I am exploring putting a wheel on the spillway of my pond.  As you know, here in southern Il we have indirect lighting from December through Feb.  Some years we can include Nov and March.  Anyway, my spillway runs when the sun doesn't.  Finally,  I am looking, also, into the possibility of a methane operated generator.  

John,  

I will definitely keep this updated.  Right now I have the ammo can and charge controller.  The actual battery is around $35 or so and is the most expensive part.  I still need to get the battery, power face-plate ($17) and the rest are basically $3-$4 pieces.  This should be an easy build.  Initially I plan to use a car battery charger, but eventually I will switch to a solar panel system.

The real fun will be 100ah system.  That will be a much bigger and more complex build.

So out of curiosity, why the methane generator?  I mean natural gas is basically methane and those generators are easily available.  At times I have been interested in a wood gas generator.

Eric

Hi Eric,  

In philosophy this is called equivocation.  What I meant to communicate was that I am looking into a means of generating methane that can be used to run an lp generator to produce electricity.   Of course, the methane could also be used with our kitchen range.

John,

Ahh, I understand now.  Yes, being able to generate methane could be very useful.  On a similar note, I have an interest in a wood gas generator for much the same purpose.

Eric

When you say wood has, I am assuming you mean as in the production of charcoal.  Am I correct?

John,

Yes, most wood gas generators can be easily modified to optimize either charcoal or wood gas production.  A simple TLUD design is a sort of non-optimized way to produce both charcoal and wood gas (which is immediately burned off).  I have watched some YouTube videos where people make dedicated wood gas generators deliberately for running an electrical generator.  There was even a commercial design called the LEAF generator, meaning Low Emissions Altrernative Fuel.  Those were a bit expensive, but with even just s small amount of metalworking skills one can build one to one’s own specifications.

I did see one that was spectacularly constructed and ran a generator just fine.  However, it was designed to run on wood pellets and not scrap wood, meaning one would need to store wood pellets and they could run out, just like gasoline.  If I were to make one, it would run on sticks, twigs, and the type of debris one would find after a storm—exactly the time one would need such a device.

There was one time in my adult life when one of these would have been very helpful.  Back in 2009, in the immediate aftermath of the May 8th storm, I was without power for about a week.  A wood gas generator would have been great then.  We had an over abundance of wood fuel and no power and little likelihood of getting gasoline for some time.  How did the May 8th storm affect you?  I do have a generator and regularly keep 10 gallons of gasoline on hand, but the thought of a wood gas generator still has an appeal.

I could go on but I think you catch my drift.

Eric

John, everyone,

My first build is only a 12v 15 amp hour unit.  This would ideally give 180 watt hours of output.  This will be great for charging phones, tablets and such.  While designed and set up to charge via solar, I will simply charge via 120v ac to start.  I am building this on the cheap so I will forgo solar panels at first.

Don’t worry, I will add in solar panels in time, I just want to build a small prototype unit from scratch just to get some basic skills and ideas for the second, much larger build.

I will add solar panels to the setup sometime after the finishing the first unit and before building the second unit.

The second unit will be based on a contractor job box for portability and decent interior volume.  While I don’t have exact specs for the larger one, my goal is to base it on a 100 ah battery, have USB, 12v DC output, along with 120v AC output, and a DC buck converter.  The buck converter allows me to basically dial up a precise voltage for a specific application.  Off hand, I would like to power a laptop which requires about 20 v, an atypical voltage setting.

At any rate, I will keep this updated as I go.

Eric

Hi Eric,

I love DIY projects!  

Would you please post some pics?  

And by the way, most of the electronic device builders I know create the electronic device first and then look around for a case to hold it.....but if you know your exact dimensions from your paper design -more power to you!

I did the easy thing and purchased an inverter, so I'm interested in seeing your work; looking forward to pics!

Orin,

I will definitely post pictures.  I am doing this on the cheap right now so I am only getting parts one at a time.  The reason I got the case first was two fold.  First, I am basing my build on a design I saw on a YouTube video.  The guy was knowledgeable and even had a clickable parts list from Amazon.

The second reason for going with the case first was simply to see how big a unit I was going to build.  Fairly prosaic reasoning here.  As it stands, the battery fits the width so perfectly that I almost don’t need to secure it as the battery friction fits almost perfectly.  Almost.  Don’t worry, I will fix it into place.  I was actually thinking about using hot glue.  Hot glue will be tacky/sticky and combined with the already excellent friction fit, it should go nowhere.  And if for some reason I need to take it out later, I can do that too.

I have a couple of more expensive pieces to acquire (not really expensive—$27-$35 apiece) and a handful of cheap ones and I should be ready to go.

I am going to hold off on building it as I spoke with my father and he urgently wants to be a part of the building process, so I will wait for him.  This will also allow me to take some pictures during construction.

I will update this as I go,

Eric

This fellow went BIG, he went step by step and kept improving it.

Hi. Jd

Thanks for the photo.  It pretty well speaks for itself.

JD,

Looks like an impressive build!

Eric

Sorry it’s been so long without a post!

I had been acquiring my components piece by piece, but I am not presently certain what to do.  Some of the parts won’t come for about a month and given current events I am not certain this is a priority right now.  The device will only power small devices and charges via a battery charger.

Please don’t get me wrong, I plan to build this device and when I do I certainly will post pictures.  At the moment all I have are a plastic .50 cal ammo can and a charge regulator.

Orin, you wanted an idea of how big the build is.  The ammo can is sized such that I can perfectly fit a dvd case vertically inside the can.  I could probably place 25-40 dvd cases stacked vertically in the container.  I hope this description helps.

Eric

One way to get a good inverter is use an old inverter from a trailer, I have really big one in my 30 foot travel trailer.  I picked up the trailer for $300 many years ago, I believe this inverter is rated at like 2,500 watts.  It is quite large and heavy maybe 16 inches by 14 inches wide by 14 inches tall or so and weighing in at around 40 pounds or so, not exactly portable, but it works crazy well.

You might consider looking for an old one like that in a trailer, not terrible expensive and very good powerful units.

Thanks Roy,

Actually the main goal of this project is simply to build the inverter box.  This is much the same reason I prefer to do my own oil changes on my tractor.  True, I do save some money, but really I do this to better understand my tractor.  Likewise I want to have a better feel for how my battery generator will work.

Eric

Update,

So out of claustrophobic boredom, yesterday I browsed through my parts list on Amazon.  I am basically building a near perfect copy of a build I found on YouTube that included a parts list.  In recent days the parts kits either went very expensive or had a delivery date sometime in May.  But as I searched around I found near identical components that would deliver within a week and are are actually cheaper than the parts list.  And when I say near identical I mean the item itself is identical, but some writing is slightly different—basically a different branding of the same product.

So I wet ahead and ordered a battery and the power-out plate,  all I need now is the wiring, connectors and fuse holder.  I think I will acquire these components soon and begin within a week or so.  I will also upload some pictures just to get an idea of the size of build we are talking about.

Eric

Further update,

So this morning I ordered my electrical connectors.  Typically I would just use wire nuts, but this build introduced me to Wago lever nuts.  Basically you just strip the end of the wire and stick the wire into a little connector.  The wire (up to 5 wires depending on the actual connector) is held in place by a little lever.  This means no twisting to mate up two wires under a wire nut.  Also, if I need to change the wiring, I can simply release the lever and pull out the wire—no untwisting, straightening and re-twisting.  I am looking forward to trying these little connectors out for real.

Eric

Hi Eric

I am interested in hearing how the connectors work.

John,

I am interested also.  I have never used them before, but they seem much more efficient that a wire nut.  I went ahead and found a picture of them so that you could see a couple wired together.

Can you post a parts list of what you are trying to build. I find this topic very interesting.
It sounds like you are building a 'pre-wired Power Center', with easy to attach/detach Loads, Storage and Source (Solar/Grid/Generator), making it very mobile


Source (AC Grid/Generator and DC Solar/etc)
Charger (MPPT and AC-DC charger)
Storage (SLA or LiFePO4)
Output Converter (DC-AC Inverter, DC-DC Converter)

What size Storage are you envisioning, whats the cost associated with it. Below is what I am thinking about for my setup, each component is rated for 10+ years of 24/7 usage.

$750 Solar Panel 1000W and 4KWH/day https://www.wholesalesolar.com/1977433/astronergy-solar/solar-panels/astronergy-chsm6612p-hv-345-silver-poly-solar-panel
$250 Charge Controller 50A https://www.wholesalesolar.com/2940165/victron-energy/charge-controllers/victron-energy-smartsolar-mppt-100-50-charge-controller
$2000 Battery 4000W https://www.batteryspace.com/lifepo4-rechargeable-battery-12-8v-100ah-1269-7wh-100a-rate-with-bluetooth-option---un38-3-passed.aspx
$1000 Inverter 4000W  https://www.wholesalesolar.com/2923535/cotek/inverters/cotek-sp4000-124-inverter
Total Cost = $4000

I wonder if $4,000 is expensive. I would like to get 3 more solar panel to double the production to 8KWH/day from just 4KWH, and a 100A Charge Controller, for a combined extra $1000.

S,

So I really plan on building two of these devices.  The first is really a fairly cheap test/practice build.  I can probably get you a parts list (or at least a partial parts list) fairly shortly.  I am actually following a build I found on YouTube.  This first build will be based on a simple 12v 15ah battery and output 12v and USB charging.  So this one needs no inverter which is fine as this is largely a relatively cheap practice build.

The second build will be much more substantial.  It will also have USB & 12v output in addition to 120v ac via a 2kw-4kw inverter and a buck converter so I can dial up a specific voltage (say 20v for a laptop).  It will be powered by a battery in the 100ah range.  I wish I could give you a parts list, but I have yet to even design the contraption.  I have decided that I will house it in a large rolling tool case.  Beyond that I just don’t know yet as I hope to incorporate some of the knowledge I acquire from building the small unit.

I will keep this updated as I go.

Eric

Case
Battery $30 https://www.amazon.com/15AH-180W-Sealed-Lead-Battery/dp/B00ANT0PFI
Output 12V + USB $12 https://www.amazon.com/Ginsco-Cigarette-Lighter-Splitter-Motorcycle/dp/B01B79F8CW
Output 12v-50V 5A $17 https://www.amazon.com/WHDTS-Converter-Display-Adjustable-Constant/dp/B07L5KNBCN
Fuse/Switch $9 https://www.amazon.com/Nilight-NI-FH01-Automotive-Holder-10-Warranty/dp/B07426WCLM

John, everyone,

I just found a 100 watt solar panel for under $100.  I figure this is about the optimal price point for a small, portable solar panel.  I might start with one of these panels for my small unit and maybe expand to two units for a larger unit.  I will try to get a link and picture up soon.

Hopefully the rest of my components will come later this week and I can start to build the unit.

Eric

I have a quick link to a potential solar panel HERE:

https://www.amazon.com/HQST-Watt-Monocrystalline-Solar-Panel/dp/B07QW8B6ZF/ref=wsdps_3?cv_ct_pg=detail&cv_ct_wn=woodstock-mobile&linkCode=oad&cv_ct_id=ws&pf_rd_r=MKNKWPHH8NSWQVEC0ETS&pd_rd_wg=KiAqH&pd_rd_w=R1lEt&pd_rd_r=c79b817d-583a-400f-b521-9e8b1f6ef51f

The short version is that it is a framed 100watt solar panel for just a little over $90.

Eric

Just to give an idea of the size of the build I am including a couple of pictures of the ammo case itself.  It is pretty straightforward, but I put a DVD case in the ammo can just for scale.  Actually, this would not be a bad way to store old DVD cases that you don't really use that often but also don't want to get rid of yet.

Eric

John, everyone,

I just received two components.  I have the plate for the power outlet.  It comes with USB, 12v power, a volt meter, and a power switch.  It’s actually a nice little package.

I also received the Wago connectors—a whopping 50 of them!  My build only requires 3, but my next build will surely require more and buying 50 was cheaper than buying only 10.  

The Wago connectors are not terribly big, about the length of the top length of my thumb.  Each connectors has 4 ports.  The little levers are snappy little things!  If you are not careful they can snap fingers in the wrong place!  But I still want to actually get them into action.

My battery is scheduled to come by Thursday.  I still need to get a fuse port, ring terminals and of course, wire.

Hopefully I will be building by this weekend.

Eric  

This is pretty exciting news Eric, looking forward to see it all come togather.

S,

In this particular build I make no perforations of the case, which is nice as it is a good, solid case.

Instead the components mount to a thin sheet of plywood mounted inside the case.

At any rate, when I start, I will be certain to get some good pictures.

Eric

S, John, everyone,

So I just had a palm-to-face moment.  I had one last component to order—banana jacks.  I placed the order, but it won’t be here till the 28th.  I will still do what I can in the meantime—I can at least mount some components.

Eric

Ok, I just got back from the hardware store.  Illinois is theoretically on lockdown, but the list of “critical services” is surprisingly expansive.

Anyhow I bought a couple of my final pieces to the project—some ring terminals and of course the wiring.  The wire was surprisingly expensive—$15 for 25 feet!  That was the smallest available in 12 gauge wiring.  So $15 for one each of red and black and now wiring is one of the most expensive items on my list!

But like the dufus I am sometimes, I forgot the 1/8” plywood which was right at the same store (It was a big box store).

I guess tomorrow I will get the plywood and at least cut that to proper dimension.

Pictures coming soon,

Eric

Hi everyone,

So I think I have all almost all of my components--I am still waiting for a pair of battery connectors, but I have enough to at least begin construction.  

The first step I took was to locate the battery approximately center in the case so that it feels fairly level while in hand and not terribly lopsided or unbalanced.

The next step involved me measuring out a 6x8" piece of plywood and then dry-fitting the components into place.  I tried fitting all components into place with the battery at exact center--7.5", but there just was not enough room to mount the hardware and leave a little gap for the wires to feed into the charge controller.  By moving the battery 1/2" to the side gave me the room I needed.  This is why the plywood has two parallel lines side by side.  offset by 1/2 inch barely affects the battery balance at all.

I have a couple more measurements to make, but I should be able to get out a jig saw and start cutting later today.

I went ahead a took some pictures so far

Eric

A couple more pics.

In the first I marked the outline for the charge controller at the top and I have a 1/4 by 1/2 inch rectangle in the middle that will be drilled out in order to make room for the wiring to come up from the battery and outputs and fit into the charge controller.

How will the wires leaving the charge controller affect the cigarette lighter outlet?
I know that when I have a regular surge protector extension outlet, once I plug in a bulky keyboard plug it blocks the adjacent port where there isn't enough space.

Hey S,

There should not be an issue with the 12v leaving the charge controller.  As it is set up, the battery sits in the middle of the ammo can, under the charge controller.  This leaves a pocket on the other side of the charge controller for a few odds and ends (I plan to have: 12v-USB adapter, USB light, maybe a 12v light and an ac charge unit.).

As it sits, there is ample room under the plywood to fit any wiring.  I will send pictures as I get there.

Eric

Here is a quick dry fit set of pictures

Eric

I have to take a little break on the project as I forgot to add spade connectors.  I actually had them in my Amazon cart but forgot to actually buy.  I ordered this morning and they should be here by Friday.

But the parts mounted on the wood panel pretty well.  Now I have a very good idea of how the panel will mount and how much storage space I will have.

Eric

Hello everyone,

All my parts finally came and I got to it.

Well I got started wiring up the components.  I followed the instructions in the video closely.  I had a couple of extremely minor changes I made, basically amounting to me giving myself more wire to work with than I actually needed.  This in turn required me to use a couple of extra Wago connectors.  The Wago connectors are a GREAT way to splice wires together, and when I go to make my next, larger unit, Wago connectors will definitely be a part of the build.  Basically you just strip the ends of the wires, push them into the slots and lower the lever and the wire is LOCKED solidly into place.  I was using connectors that could connect up to 4 wires together, but mostly I only used 2 wires--a splice in essence.  On one of the connectors I did use all 4 connectors to wire in parallel.

The way this unit is set up I made no piercings or perforations of the actual case which means that in order to use the unit I need to open the lid.  This is nice because it retains the integrity of the case.  The wiring connections actually had two different videos detailing the work.  The first, more simple video showed a setup in which the charge controller was always on which would of course eventually drain the battery and possibly kill it.  The second video showed a wiring setup where the little switch on the output panel became the master switch and turned everything on or off, thus saving the battery.

I included two pictures.  The first shows the unit in a finished condition with the panel nicely resting in place.  The second I took the panel out and turned it upside down outside of the case to show the wiring detailing.  I know it is a bit of a jumbled mess, but it at least gives an idea of how the Wago connectors work and how the unit is wired together.  Just for reference, when looking at the second picture, at the bottom of the backside of the panel, the top two components are the USB and 12 volt outputs.  at the bottom right is the volt meter and on the bottom left is the switch.

Eric

I will give a few specs on this system.  It is powered by a 12v 15ah battery which is heavy, but not terribly.  This gives 180 watt hours of out.

The build is chargeable by either an AC wall outlet or solar DC panel.  The system can output to USB, 12v car output or to a universal banana jack output.

Eric