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opinions on my off-grid system - Page 9

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Posted by Jim Wilkins on February 1, 2016, 3:14 pm
 

I can configure my solar/battery system as either 12V or 24V, to match  
which inverter I'm running. This controller adjusts to either voltage  
when the battery is connected first, before the panel.
(Amazon.com product link shortened)
I'm not promoting it over other choices but I've tested that model. It  
reduces the charge current when the battery bank reaches 13.8V or  
27.6V and can be manually programmed to equalize and desulfate old  
batteries at higher voltages, which may extend their life  
considerably. Do that only to batteries with filler caps that let you  
add water. I use separate meters to show the charge and discharge  
current and power:
Charge current:
(Amazon.com product link shortened)
Discharge, with the shunt wired into the #6 battery cables:
(Amazon.com product link shortened)
Both show total accumulated energy.

There isn't much to gain from 24V in a small system if your wiring is  
short and heavy enough. I ran easily available (stranded) 12 gauge  
house wire to the panels and 6 gauge battery cables to the inverter.

A 24V system with two 12V batteries in series will have the capacity  
of only the weaker battery, while 12V makes full use of them both.

I'm an alternate energy experimenter and was an industrial electrician  
and the electronic and battery technician at Segway so I pay close  
attention to battery voltages and currents. Otherwise the voltage  
meter on the P20L tells battery state of charge well enough for most  
users.

-jsw  



Posted by amdx on February 1, 2016, 2:55 pm
 
On 1/31/2016 8:34 PM, twnick@alaska.edu wrote:

system hooked up to it. The lights that are used are all hooked up to a  
12v car/deep cycle type of battery system.

I want to go at least 24v to make it more efficient. But the downside to  
this is, the light system it has is only for 12v.

What can I use to step down the voltage for the lights?

the generator started going overtime like it was struggling to keep on  
until I unplugged it. What can I do to fix that?

A neighbor said to install thinner power cords to the trailer but I feel  
like that won't really do much.

It sounds like to different circuits, one 12v circuit for lights only,  
and a second 120vac circuit that runs off of the inverter.
Now you have a generator that--I assume-- you plug into the 120ac  
circuit. What happens with the inverter, is it disconnected?


                               Mikek

Posted by Jim Wilkins on February 1, 2016, 3:46 pm
 
If he made that mistake he should have a local electrician check his  
system. We can't guess at what we can't see.

-jsw  



Posted by amdx on February 1, 2016, 4:39 pm
 On 2/1/2016 9:46 AM, Jim Wilkins wrote:

  That why I ask, "What happens with the inverter, is it disconnected?"
Something is loading the generator, it seems excessively.
                                   Mikek

Posted by Jim Wilkins on February 1, 2016, 5:58 pm
 
I've been studying the electrical and regulatory intricacies of  
floating or grounding a portable generator's output. A generator  
connected to house wiring through a transfer switch is supposed to use  
the breaker panel's single-point neutral to ground connection, and not  
provide a second one that would create a ground loop and  
current-carrying ground wire. When that generator is used with plug-in  
tools BOTH sides of the AC line float off ground, and light ALL the  
lights on an outlet tester. I can't tell "dim" from "lit" outdoors.
http://www.thecircuitdetective.com/outlet_tester_readings.htm  

http://oshaprofessor.com/Portable%20Generators%20and%20OSHA%20Construction%20Standards%203-05.pdf  
He doesn't mention that in many places a ground rod can't legally be  
driven without waiting for the utility companies to mark buried lines.

The result is that an accidental short from AC Hot to something that's  
grounded won't be noticed unless the generator is plugged into a  
properly grounded system. Also the inverter could load down the  
generator if it's connected to the AC wires but not turned on.

The Harbor Freight 61169 inverter genny I just bought is isolated and  
a 15K resistor is enough to pull either leg to outlet ground. This  
afternoon's project is to lower the resistance while monitoring the  
current, to see if I can safely "bond" the Neutral directly to Ground.

-jsw  



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