Building a new battery generator

Grrrrr!  I am pretty certain the problem is both obvious and right in front of my face and I just can’t see it.  I spoke with a physics teacher at school and got him intrigued.  Maybe another set of fresh eyes will point out an simple, obvious mistake I am making.

UHHHGGGGG!!!

This week has been nothing but steps backwards and I think I had my biggest one yet.  Apparently I got a dud battery and I think that I have a bad cell.  That probably means I need to shell out another $100 for another battery.  But before I do that I think I will figure out my wiring first.

Ok, today I have very, very good news!

So my wiring problems were really vexing me for the better part of two weeks.  I was following the instructions very closely but I seemed to have two intractable problems connecting the switch to power my two USB plugs.

The first problem was that the whenever I turned on the power to power up the two plugs, my battery box (the small one I built about 18 months ago) kept faulting and shutting down.  It turns out the issue was that the battery was charged to only about 12.5 volts and the charge controller is set to shut down at just below that voltage.  The initial power up spike tripped the charge controller.  Ironically, turning the battery box off and then back on again solved the issue.  I am now charging up the battery to avoid shut-down issues.

The other issue was more trivial but even more mysterious.  The power switches for my new battery box have a tiny blue light that turns on when the switch is on.  I followed the wiring instructions to a T but the light would not illuminate, even if the switch did work as an actual switch.  I was getting ready to simply accept this minor shortcoming (I mean it still worked as a switch).  I took the whole thing over to my neighbor who is good at diagnosing these type of things but eventually he broke down and called his SIL who is an electrical engineer.  

Long story short, he was able to figure out that while the diagram may have been correct under normal circumstances, the switch itself was wired wrong.  The copper, ground terminal—normally attached by a green or yellow wire—was instead connected by a red wire and the instructions clearly indicated that red was the positive line!  

After figuring out that bit of information, wiring the rest of the USB plugs was a piece of cake.

Anyhow, I am glad to finally post a positive update for a change.

Eric

Well, it is working now, at least while on life support.  At least it shows that my basic rows of USB ports are working as expected.  And although I can’t show it in the picture, I was able to charge my phone for a bit using this setup, just to put it to the test.

Carl, I think I owe you some thanks and an explanation at the same time.

Your advice and diagrams SHOULD have been spot on and would have been had there not been for one omission due to the construction of the switch itself.  Your diagram made perfect sense to me as did the diagram that I sent in as a picture from the website.  There was one important error.  Normally, the red wire would be positive, the black negative and any other color (yellow in this case) would be ground.  Well, in this case, the red wire turned out to be not positive but ground!  Furthermore, black was positive and yellow negative!  It would be hard to make this color coded worse.  It took a discussion with my neighbor and a call to his SIL who is an electrical engineer to figure out what the problem was.  So while your diagram SHOULD have been correct, it couldn't be correct due to a pretty massive wiring color-coding mismatch.  I guess this is what you get when buying from the absolute lowest bidder from the internet.  Lesson Learned.  I how have the circuits wired "correctly", though if an engineer were to look, he/she would probably be driven nuts by the color coding.

But thanks anyways for your help and I will probably be asking for more as time goes on.

Eric

Carl Nystrom wrote:
Edit: looking at the picture again, I realize that the colored wires on there just attach with spade connectors, dont they. So they could easily have been switched. Check for a resistance between the center and one of the other legs. A value in the hundreds of ohms would be your LED circuit.

Another thing to keep in mind is that LEDs' only conduct in one direction. So if the few hundred's ohms resistance is not found, reverse the ohm-meter's probes and test again. Some multi-meters have a DIODE TEST FUNCTION, and it's helpful for finding the connections to the switch's built-in LED.

Without an ohm-meter, and if the switch wiring diagram is suspected to be in error, it can be confirmed as follows. Sometimes it is faster this way too, i.e. use a small resistor, anything in the range of say a few hundred ohms to a thousand ohms, and 1/8th watt rating will suffice.

Attach the resistor in series with a test wire (or a couple of red clip-leads) and connect one end of this to the positive terminal of a battery or DC power source.  Attach a second wire (black clip-lead) to the negative of the battery or DC power source. With the switch under test set to its ON position, randomly connect the free ends of the test leads to the switch until a combination and polarity of a particular connection arrangement is found that results in the switch's LED illuminating. This will verify or indicate the common / negative connection for the switch's LED, the terminal to which the black clip-lead is attached.

EDIT: I see this issue has been sorted out, whilst I was hammering out the above:o) Yeah, the disregard by certain overseas MFGs for proper wiring color codes is 'nuff to have one engaged in hair-pulling frustration. I've run into the same thing many times.

EDIT: typo corrections

Thanks anyways Byron.  It would have been a simple matter to swap the spade connectors to the right connections, but they were pressed on so hard I was beginning to wonder if they were welded in place!  At any case, my fingers simply could not get a decent grip on them and pliers could not fit in without potentially damaging the neighbors.  Yes, with cheap equipment I guess you get what you pay for.  Hopefully this is where the "cheapness" ends.

Eric

OK, I know that it's been 2 weeks since I posted, but in the meantime I have had some major changes.

I thought I had most of my internal wiring finished.  I got all my USB and car 12 volt plugs wired correctly despite the color coding being wrong.  Wiring up that portion took a good portion of the day.  I mounted my solar charge controller and then I realized I had made a fundamental wiring mistake.  Up till this point I had been making the battery the "heart" of the system.  What I really needed to do was make the solar charge controller the "heart" of the system.  This meant undoing a fair amount of wiring, another trip to town to get more 10 gauge wire, and a good portion of the day re-wiring the system properly which is now done.  That is all the good news.

On the down side, the charge controller and the newly installed battery meter are confounding me.  For starters, the charge controller is difficult to set up properly for a LiFePo4 battery.  The literature says it can be set up for a LiFePo4 battery and there is a setting indicating as such, but getting it properly set is difficult.  Secondly, the voltage at the charge controller is reading 12.2 volts while a volt meter at the battery indicates 13.1 volts.  A whopping .9 volt difference is a huge difference, especially with a LiFePo4 battery.

Finally, my battery meter reads all 8's, meaning that every bar in the LCD display is activated.  In the literature, this is indicates a full battery.  I deliberately put my phone on a USB plug to see if any load would bring in a change in voltage or amperage, just enough to get the battery to get a reading.  So far, this has not worked.

Right now I am charging up my battery separately on a dedicated LiFePo4 battery charger I bought just for this project.  After if charges, I might re-install the battery and try running some devices just to see if I can get a reading on the battery meter, but for the moment, the battery charger is taking its sweet time charging up the battery.

Pictures to come!

Eric

So I am really curious to know what experience others have had with LiFePo4 batteries.  I did some internet digging and found that LiFePo4 batteries are shipped at about 50-60% full (full being 13.6 volts).  Further, I was told that they should not sit around fully charged for long periods of time.  

I have a little LiFePo4 battery charger and I hooked it up and indeed, it showed the battery at a 60% charge.  The battery charged fully when the charger automatically cut off.  That was Sunday.  Today (Tuesday) I checked the voltage and it read 13.25 or about 75% full.  It seems like it dropped a lot on its own over a 2 day period, but maybe 50-60% is a sort of natural place for it to hold a long term charge.

Is anyone else familiar with this phenomenon?

Eric

Wow,  I just bought a Minkota trolling box,  put a deep cell battery in it and use the usb and power points as needed.  It's charged using a plug in electric or solar through the power point.  Not being "electrically inclined" it works for me.  Inverter plugs in the power outlet.  Can run a ham radio a long time.  Works great on field days...

Glad to hear your deep cell battery is working for you.  Is that a lead based deep cell battery?  This project was going to be my final battery box creation with a much simpler, smaller earlier DC only battery box earlier being my sort of training wheels.

I did plan my build with a 100 AH SLA battery in mind but got convinced to go with a LiFePo4 battery just before my construction began.  Really, nothing had to change aside from making certain my charge controller was safe for a LiFePo4 battery (it is) and making certain I have a dedicated battery meter.

I have been testing my little 20 AH LiFePo4 battery (I may enlarge later if I so choose--I also may go back to an SLA if LiFePo4 does not work out) outside the build.  I have charged it full with a separate charger and watched it self-discharge.  It charged fully yesterday and today it has discharged to just a little under 99% full (13.36 volts--13.4 is 99% full).  I am going to continue to monitor the self-discharge rate over the next couple of days just to see how the battery holds a charge.  The self-discharge could be a simple function of LiFePo4 chemistry or it could be the brand I am using--it was one of the cheapest I could buy on Amazon.

Even if it self-discharged to 75-80% which seems to be about where it was at before this little experiment, that would not be too bad as most batteries self-discharge a little bit on their own.

Overall, this project is proving to be one big test as opposed to a final project!  After working out the battery characteristics, I will have to figure out the charge controller and the battery meter, both of which are proving to be difficult to set.  Really, if anyone has any experience setting up a battery meter with a shunt, I would love your input--at the moment all the little LCD bars are on (reads all 8's).  The literature says this indicates a full battery but I would think it would at least read voltage.  I will try to get a picture soon.

Thanks in advance!

Eric

Update:  I am continuing to monitor the battery self-discharge.  Today, 2 days after charging to 99% or over 13.4v, the battery reads 13.35 volts.  I assume this is very near a full charge and above 90% which reads as 13.3 volts.

More updates:  I have had my battery out of my unit for several weeks now just to check self-discharge.  The battery slowly discharged to just over 13.2 volts which is about 90% capacity and has held there for weeks.  It seems that this is where the battery wants to rest at.  This is OK with me.  Now I need to get back in the groove and get some of the final details working.

It is worth noting that while I will eventually have 120v AC running from this unit, in the meantime it is basically a great big USB and 12V charging bank.  It will work very well for those functions but I do at some point want to have some AC power coming from it.  At the moment my inverter is mounted but not attached, nor is the 120v receptacle mounted.  This will happen in time.

At any rate, this is just an update.

Eric

Ok, long time and no post.  My construction has stalled on account of a battery meter that is a little wonky.  I hooked it up as described and it powers on, but every LCD bar is activated, meaning that the screen looks like a bunch of 8’s.  This is pretty meaningless data so I assume something is wrong with the battery monitor unit itself.  Fortunately it is cheap so I can replace it but I am waiting on that part.

On a secondary note I have a question about charging.  Clearly I can charge with a solar panel, but I would also like to charge with a regular ac battery charger.  I do have a battery charger designed to charge LiFePo4 batteries, and it has worked well in the past, but only when I have taken the battery out and charged it outside.  Is there any reason I can’t change one smart charger into a charge controller to charge the battery?  Would that cause any problems?

Thanks in advance,

Eric

Just solved the battery meter problem!!!  Turns out I had a bad battery meter!  

Fortunately I got this as a Christmas present, and I got a second to boot.  I just took out the old one and swapped in the new one and suddenly I got a voltage reading and the other readings sat at zero—just as they should with no load.

Why did I wait so long?!

Eric

Battery meters, Battery meters, Battery meters!

This has definitely been the hardest part of this build—getting a battery meter to work correctly.  In this case, working means getting any usable, functional information at all.

My first battery meter had power but showed no information—every little LCD was constantly lit up.  It was a shunt type meter.

The second meter—same as the first—worked as a volt meter but nothing else.  This was less than helpful.

The third meter—a little Hall effect meter—did not even power up!

Now the fourth—and final, same type as the third—finally works!!

To test, I simply connected the little meter to a 12v power supply to see if I could even power up the little device.  Sure enough, it worked.  I went downstairs, removed the old, non-functional unit, hooked up the new unit and it immediately powered on!!  A little bit of fiddling later and I was reading voltage, amperage and wattage.  This is crucial information.  I still need to calibrate it, but things are on the up-and-up.

I went ahead and took the non-functional unit upstairs, hooked it up to the power supply and discovered I had a misplaced jumper setting.  The real problem was in the poorly written (a very poor translation into English) instructions and absolutely tiny illustrations.  The new unit came with larger illustrations (though the instructions were still not worded well).  

Now I have a new, functional battery meter for my next project!

Eric

Here are a couple of images to add to the build.

I will give everyone a heads up now if you try to use one of the DROK, 0-90 volt, 100 amp Hall effect battery meters.  Getting the meter to actually read the status of the battery charge is tricky and the process is not documented in their literature.

After entering all the settings and parameters in the menu on the right, the cursor needs to be moved to the bottom setting on the menu.  Then press the “down” arrow twice.  This will make the cursor disappear.  After pressing twice, press “OK.”  This will make the battery indicator go from 0 percent to 100 percent.  Charging from there will record how many amp-hours have been used and deduct that from the 100% on the battery meter.  

This whole operation needs to be done with the battery fresh off a full charge and there are some calibration settings that need to be made in order to read accurately.  Further, the meter will not read anything below 0.6 amps.  This means that charging a single cell phone probably won’t register at all.  After 0.6 amps, it seems to read accurately at the level of every 0.1 amp.

I am still dialing the system in and I will update as things continue to improve, but getting the basic functionality out of this meter has been a huge step.

Eric

I finally got my battery generator running.

I rounded up enough items to put enough load on the battery monitor to get it to start reading reliably--that is not drawing less that 0.6 amps.  Less than that and the meter does not read, but above that figure it reads reliably.  I ended up gathering my phone and Kindle to charge.  I took my phone, opened a bunch of apps, let a YouTube video play and turned on the little flashlight--all just to add a power drain.  I also turned the brightness up all the way on my kindle.  That took the amperage draw to about 0.8 amps.

But I wanted to get a good test of the battery running at higher power so I rounded up another kindle and my daughter's gaming console.  That bumped the amperage to about 1.2-1.5 amps.  Later I plugged in the little USB lightbulb and that added another amp to about 2.5 amps.  Then my daughter saw what I was up to and grabbed her little Raspberry Pi computer and plugged it in (to USB)  That bumped the amperage to about 4.5 amps.  Finally we plugged in a little 200 watt inverter that we kept in the car and plugged in another laptop (by way of a A/C to USB mini brick) and plugged in her monitor and we were able to operate her Raspberry Pi directly from the battery box--all while charging all sorts of other things!

By this time the power draw was 14.5 amps, my daughter was eagerly looking for more ways to draw power and I had to stop her enthusiasm.  14 amps is plenty for this test, and I did draw the battery down below 80%.  It took us an hour and fifteen minutes to draw down the first 10%, then only about 20-30 minutes to draw down the second 10%.  We were adding things fast!

I have another minor modification I will make this weekend.  I am set up to charge with solar panels, but so far that is clunky and time-consuming.  I had been charging up the battery with a little LiFePo4 smart fast charger with alligator clips.  It works very quickly, unfortunately the alligator clips were cheap plastic and broke!  However, they connected to the charger with a little XT-60 electrical connector (often found on little electronic toys).  My plan is to wire a set of charging wires directly to the battery and attach them to a flush-mounted XT-60 connector on the top of the panel.  From there I will create a little set of substitute XT-60 replacement charging cords to come out of the charger.

I plan on making this new modification this weekend so I will update with new pictures then.

Eric

Another day, another problem, another opportunity!

Lately I have been charging my battery with a separate, dedicated LiFePo4 fast charger that looks like a small battery charger for a car.  It even comes with alligator clips.  I used this separate charger in lieu of solar panels for a couple of reasons.  Firstly, the charger is very fast, charging the battery up in a few minutes (it was only slightly discharged).  Secondly, I trusted the charger to get me a reliable full charge and then shut off when finished.  It works very well, but came with two built-in problems.  #1, I had to physically disconnect and remove the battery from the box to charge it. And secondly, the cheap, plastic alligator clips broke well beyond repair!

But this actually proved to be an opportunity.  The alligator clips were themselves connected to the charger by way of a little XT-60 connector.  I had a pack of these and I wired/soldered up a new XT-60 charge cable.  The “clip” end is now replaced with a little panel-mounted XT-60 female connector which itself is connected to a set up ring terminals that mount directly to the battery.  I can utilize these by turning off the battery box main switch and plugging in the external battery charger, allowing me to charge using  a/c power.  

I still have a couple of modifications to complete, but I will show pictures soon.

Eric

Finally got it installed!!

The little XT-60 connector is located in the upper right hand corner.  It is the yellow square.  That will be my a/c charging port.

On the upper left hand corner I have a little banana jack for connecting to the solar panel.  I might add in a little power pole since my solar panel is now connected via power pole, but that will have to be for another day.  At the moment, I have a working system that still has plenty of room left for expansion when I decide to do so.  Naturally, I will update again then, but I may keep this thread updated with some posts about various tests and uses.

Eric

Eric,

I ran across your battery generator build and have a couple of suggestions.

1) put a separately powered (AA battery) thermometer that uses a probe in your system. Attach the probe to the most temperature sensitive component of your system. That way you can monitor the internal temperature and prevent a potential overheating issue. A sealed box can produce a very large amount of heat.

2) Consider lowering the faceplate and/or adding a pocket to hold accessories you might need to use with the equipment. Ex: short AC extension cord, flashlight, AC LEDs and sockets, Headlamp, etc.

We built a small toolbox setup that we call the "Blackout Box". It contains a few small flashlights, 300 watt inverter, Two 9ft extension cords, 4 watt 110V LED bulbs, AC plug in sockets for the bulbs, usb charging cords, etc. This was designed to be a "Grab & Go" setup that anyone in the house could use if/when the grid power drops. (We live in a rural area so it is not infrequent). We use this to attach to out Battery Backup system for emergencies & out on farm activities where we need the comforts of AC power.

Wish you the best with you continually improving project.

Hi Harry, thanks for your input.

You make a very good point about heat building up in a sealed system.  Fortunately, although you cannot exactly see it, this system is far from sealed.  The rectangular face plate sits in an irregularly shaped box, leaving plenty of room for me to reach my fingers around to lift the plate up if I need to do so.  I had originally thought about drilling holes and placing a ventilation fan in the lower right hand corner, but honestly, there is so much ventilation around the edges that it is simply not necessary to place a fan at this point.  You are correct though about heating and I had that in mind when I started this project, but when I realized just how much space was around the edges, I realized that this was not an immediate concern.  You also make good points about making short wire runs.  I did that as much as I thought I could.  I don't have a good picture, but I am afraid that the under side is quite the spaghetti mess.  At some time I plan to put in a new battery pack that I build myself--100 amp hours!  This will be up from the present 20 amp hour battery that was intended to be a cheap way for me to get started without breaking the bank.  When I do put in the new battery pack, I will have to do some substantial re-wiring and maybe I can clean things up a bit then.

And you would think that I would have plenty of space for all the "extras" that go with one of these systems, but I am afraid that with all the wiring that I just don't have a lot of space underneath.  Also, I have an inverter in the lower space that takes up almost all of the vertical space.  This, combined with the fact that the wooden strips used as supports are attached with epoxy means that the panel level is pretty permanent.  But I did think about getting all those goodies together in a separate ammo can that would be dedicated to just this purpose.  Its not quite as convenient, but the separate ammo can storage system is still workable.

And believe it or not, I have one more system I want to build.  I want to try building something a bit smaller, but still a capacity of about 80 amp hours.  I will build the battery pack myself and importantly I will pierce the outer case instead of using an internal panel.  

At this point this is mostly a hobby, though I hope one that may be practical.

Thanks much for your feedback!

Eric