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Building a pair of battery generators

 
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I have a couple of final details to add.

First off, the solar panel is on its way.  It’s not a lot—just a 28 watt unit to keep the battery topped of and maybe change on a summer day.

Secondly, I am working on an AC charger for charging on nights and cloudy days.

These two details should round out the system and leave it complete.

Eric
 
Eric Hanson
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Update,

My solar panel arrived.  It took about 1/2 hour to wire up some connectors to hook it to the battery unit (I was moving slow).  

I have lots of great things to say about the Wago connectors.  They made hooking up a piece of cake.  Also, when the panel is not in use, I stick a connector on the end to prevent an accidental short.

After hooking up the panel to the battery through the charge controller, the battery was reading 13 volts, up from the 12.8 volts earlier (I have used the battery a little bit just to test things).  So there is no doubt that the battery can charge via sunlight.

The panel is rated an a nominal 22 volts at 1.55 amps I thought that this was perfect for charging a battery and the panel is only about 12”x18” so it is not obtrusive.  More interesting, I tested the panel on our floor in a bright sunny patch.  The light passed through glass in the window made of e-glass, so some light was knowingly blocked.  But not too much as the panel read about 21.5 volts just laying on the floor.  I even took a blanket and tossed it, all crumpled up to intentionally shade, and the volt meter still read about 14 volts, so it looks like I should be able to charge on a cloudy day.

I had planned on making a little ac charger but I am wondering if this is still necessary or even desirable.  I should be able to change in daylight at pretty much anytime.

Eric
 
Eric Hanson
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Hello all,

It’s been a while since I last posted, but I thought I would comment on a couple of points.  First, much as in the previous post, I have to say that the solar panel is very handy to have.  Basically, as long as I have daylight (even through cloudy skies) I can get electricity and charge the unit.  Just make certain that when the solar panel is not in use that the power leads remain electrically separated and insulated from each other.  The panel can generate a surprising amount of electricity even without trying.  I will try to get some pictures of the attached solar panel soon.

The second point relates to a separate section of Permies.  If you are reading this and find it interesting, consider the PEP section HERE:

https://permies.com/f/412/pep-electricity

There are a number of projects detailed here that could be interesting to read, but especially might be interesting to try.  The list of projects is growing and it would be nice if we could get more people to document their projects and especially get the associated BB.  I linked this post to the electrical section but there are a number of other PEP areas as well.

Thanks to everyone who has followed this project and made commentary, it is sincerely appreciated.

Eric

 
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Great build and mini portable prewired energy system! I want to try those Wago connectors soon too.
 
Eric Hanson
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Anyone want to critique this set HERE:

https://www.amazon.com/Mighty-Max-Battery-Inverter-Outlets/dp/B01MQGXPFW

I have dropped my inverter to 1000 watts to save money and I really just don't think I will need a full 2000 watts.  I am new to both the inverter and the battery game but this looked like a good combination for the price.

Thoughts?

Eric
 
Eric Hanson
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Well,  I had my first major malfunction on my battery generator.  I believe that my charge controller failed.  Normally when I plug in the solar panel the charge controller shows a little icon of a solar panel with an arrow pointing to the battery.

I tried hooking up a power supply into the charge controller and the solar power icon would not appear and the battery would not charge.  The battery was reading 11.8 volts and 11.5 volts is considered to be reaching a danger point.  After a couple of hours of attempted charging, the battery showed no improvement in its charge and the charge icon never appeared.  I went ahead and ordered a new charge controller for about $20.

One bit to add.  I initially attempted to charge with an old printer power supply that provided a little over 12 volts at about 1 amp.  Oddly, the online directions stated to only use a solar panel and not use a “dc power supply for charging.”  I find this curious as the solar panel provides over 20 volts at a couple of amps while the modified printer power supply provided barely over 12 volts and only at about 1 amp.  I would think this would be plenty safe for charging—underpowered if anything.  I actually had to run down the battery to below 12 volts (I stopped at about 12.9 volts) just to see if the printer power supply would work.  So far it has not and the directions suggest it might be harmful but for the life of me I can’t understand why.

I am open to any and all suggestions or input.  I can believe that the charge controller was cheap and failed on its own.  But if my meager ac to dc power supply caused it harm, I would like to know how/why.  It does not make sense to me but maybe someone else better versed can provide some illumination for me.

Thanks in advance,

Eric
 
Eric Hanson
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I solved my own problem and I am embarrassed.  I bought a new charge controller for about $20.  Not terribly expensive.  I hooked it up, connected it to the solar panels and—no solar panel icon and no charging.

I thought I had some major problems till I turned the main panel upside down where I saw a disconnected wire—problem solved.

Like I said, embarrassing.

Eric
 
Eric Hanson
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Can anyone explain this?

So I was testing/using my battery box which drained the battery down to 11.8 volts.  I made a couple of DC chargers from old printer power supplies and those got me to about 12.3 volts.  Today was relatively warm and sunny so I took my battery pack and 20 volt, 28 watt solar panel outside to sit flat on the ground and soak up some sunlight.  After about 1ish hours, the voltage surged to 13 volts!  I let the system set longer, admittedly though some thin clouds and checked after a couple of hours and the voltage was 12.9 volts.  I just considered this a fluke, moved the battery to avoid some approaching shadows from a tree and placed on a slight southern incline just as the clouds broke into clear air.  I let the unit sit for a couple more hours when the wind picked up, clouds moved in and I decided to bring things inside.  This time when I checked the voltage was at 12.6 volts.  I brought everything in, disconnected everything and checked again and the voltage was 12.5 volts.

Can anyone explain to me why the voltage would spike from 12.3 volts to 13 volts only to drop back to 12.6 volts, all while attached to a 20v 28 watt solar panel in sunlight?  I hypothesized that maybe the battery had cooled off sitting on cold ground and was just not as capable of putting out the voltage like a warm one would.  But that is just my idea.

I am going to try again tomorrow if the weather is sunny and see what happens.

But if anyone has a better explanation of why a battery would discharge while under charge, I would love to hear.

Thanks in advance,

Eric
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