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Building a new battery generator

 
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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.
 
Eric Hanson
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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.
 
Eric Hanson
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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
 
Eric Hanson
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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.
USB-Ports.jpeg
USB Ports
USB Ports
 
Eric Hanson
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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
 
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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
 
Eric Hanson
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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
 
Eric Hanson
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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
 
Eric Hanson
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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
 
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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...
 
Eric Hanson
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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
 
Eric Hanson
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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.
 
Eric Hanson
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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
 
Eric Hanson
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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
 
Eric Hanson
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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
 
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