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Old 02-23-2016, 12:21 PM   #51
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Voltage varies with the light incidence angle as well as intensity so a high voltage panel could reach >12 volts sooner than a 12v panel in theory. They also have much more surface area so it makes sense that they gather more light.
I would guess that the amps would be very low in this scenario and probably insignificant. Maybe an amp or two first thing in the morning.

Every little bit helps though...
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Old 02-23-2016, 01:16 PM   #52
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I'm wondering, if the voltage does vary, if that gives higher voltage panels a step up, by getting to a high enough voltage earlier in the day?
To charge a 12VDC battery you need a source voltage of 17Volts or more. The higher the panel voltage (30+ volts...) the sooner the charging process begins, and the longer it produces a useable charge at the end of the day. The output on a clear day (100% sunshine, no clouds) looks like the old bell curve (with a flat top) that they used to grade us in school, It starts at 0VDC moves to the VMP (Max voltage for the panel) and back down to 0VDC. So with all that, yes the higher voltage panels have a longer daily charge than the lower voltage panels. And yes it costs more because you need to purchase an MPPT charge controller to handle the higher voltage.

If you look at a graph for the output of a SOLAR panel for a normal day (clouds here and there) it looks like peaks and valleys from the morning to the evening. You will have your voltage, but your amps will be like a roller coaster ride up and down as the clouds pass over head.

Don
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Old 02-23-2016, 02:00 PM   #53
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To charge a 12VDC battery you need a source voltage of 17Volts or more.

Don
If this were true there would not be a converter alive that would charge a battery.

12.7 volts will charge a battery it will just take a very long time.

If you are referring to the input side of a charge controller then I would agree somewhat but it probably does not need 17 volts. 13+ would do it with a mildly efficient controller.

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Old 02-23-2016, 02:23 PM   #54
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If this were true there would not be a converter alive that would charge a battery.

12.7 volts will charge a battery it will just take a very long time.

If you are referring to the input side of a charge controller then I would agree somewhat but it probably does not need 17 volts. 13+ would do it with a mildly efficient controller.

Cheers
The reason you need a minimum of 17 volts is because when your battery is in need of a charge lets say it is 12.0 volts, the supply voltage will drop. If for example you have a 13VDC source, and your battery is 12.0 the source voltage will drop to somewhere between 12 and 12.5 (give or take a little). The battery being charged becomes a load on the source. It would take forever to put a full charge into that battery. To properly charge the deep cycle battery (or a car battery) you need to start at around 14.4 volts and work your way down to 13.2Volts for a float.

If you want to test this, take a 1.5 volt battery that is discharged to about .75 volts, put a fresh 1.5 volt battery in parallel and the result will be that the supply battery will drop to somewhere between 1.5 and .75 volts.

Don
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Old 02-23-2016, 02:32 PM   #55
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Originally Posted by Subaru297 View Post
If this were true there would not be a converter alive that would charge a battery.

12.7 volts will charge a battery it will just take a very long time.

If you are referring to the input side of a charge controller then I would agree somewhat but it probably does not need 17 volts. 13+ would do it with a mildly efficient controller.

Cheers

Sorry about the double post, but the screen blinked and then there were 2.

The reason you need a minimum of 17 volts is because when your battery is in need of a charge lets say it is 12.0 volts, the supply voltage will drop. If for example you have a 13VDC source, and your battery is 12.0 the source voltage will drop to somewhere between 12 and 12.5 (give or take a little). The battery being charged becomes a load on the source. It would take forever to put a full charge into that battery. To properly charge the deep cycle battery (or a car battery) you need to start at around 14.4 volts and work your way down to 13.2Volts for a float. That is why the output on a 12Volt solar system the panel VMP is usually 17 or 18 volts.

If you want to test this, take a 1.5 volt battery that is discharged to about .75 volts, put a fresh 1.5 volt battery in parallel and the result will be that the supply battery will drop to somewhere between 1.5 and .75 volts.

Don
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Old 02-23-2016, 03:21 PM   #56
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Originally Posted by Mustang65 View Post

The reason you need a minimum of 17 volts is because when your battery is in need of a charge lets say it is 12.0 volts, the supply voltage will drop. If for example you have a 13VDC source, and your battery is 12.0 the source voltage will drop to somewhere between 12 and 12.5 (give or take a little). The battery being charged becomes a load on the source. It would take forever to put a full charge into that battery. To properly charge the deep cycle battery (or a car battery) you need to start at around 14.4 volts and work your way down to 13.2Volts for a float. That is why the output on a 12Volt solar system the panel VMP is usually 17 or 18 volts.


Don
I totally agree with you. Just arguing a technicality. A higher input voltage will charge a battery faster and more efficiently than a lower one. And anything less than around 14 would be almost useless. (ie. most converters)

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Old 02-25-2016, 09:25 AM   #57
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Interesting find last night. This blogging/vlogging couple pooped up on something and, out of curiosity, I clicked.

http://www.gonewiththewynns.com/solar

While not terribly technical, I did see some things that I think are fairly valuable from an informational standpoint, even if they didn't seem to grasp the full significance.

1 - They are using 960W in 6 panels connected in series and 700 ish amp hours in lithium ion batteries.
2 - In their video on the impact of tilting, they didn't see a benefit of tilting until all 6 panels had been tilted. This confirms to me that any impact on 1 panels production will limit the rest of he panels as I have read elsewhere. They didn't seem to grasp this point.
3- They tested running the A/C off the inverter. It worked, but was sucking 75 amps, while solar was providing around 40 amps, so obviously couldn't sustain this for long periods.

Not sure if they are "keeping it simple" for the audience, our if their level of understanding is on the lower side. I found myself asking why they have 700 some amp-hrs of battery and 960 Watts of solar, but I haven't found that video yet.

Interesting to watch though.
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Old 02-25-2016, 01:25 PM   #58
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So far it looks like my max draw between genny runs has been around 55AH. That's with a few hrs of TV, LED interior lights, fridge and furnace running (cold nights in the desert). I'm in a park for a month in Desert Hot Springs now but when I was on BLM I ran the genny in the evening and again in the morning, about 6pm to 8am on batteries.
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Old 07-13-2017, 10:49 AM   #59
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Bob helped me... a lot

Only by reading HandyBob's blog, I went from zero knowledge of battery systems to being able to convert my husband's work van into a camper van with DC and a AC inverter running off a bank of four 6 volt batteries. I even mailed him a picture of my set up before I made the final tie in, just to make sure it was basically correct, and he kindly confirmed the set up. His advice has been invaluable for me.
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Old 07-13-2017, 11:26 AM   #60
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Only by reading HandyBob's blog, I went from zero knowledge of battery systems to being able to convert my husband's work van into a camper van with DC and a AC inverter running off a bank of four 6 volt batteries. I even mailed him a picture of my set up before I made the final tie in, just to make sure it was basically correct, and he kindly confirmed the set up. His advice has been invaluable for me.
WELCOME TO JOF!!!

The members here are GREAT!!! There is a lot of GREAT information to be found here. I am sure that you will have information and pictures to share with us... so please do!!

My Registry

RVing with SOLAR

--------------------------------------------------------

GREAT JOB!!!!

Tell us a little about your setup.... pictures.... we love pictures here. We also have an "RVing with SOLAR" Social Group, feel free to look it over and join in on giving some of your experiences. Unfortunately, each post will only allow for 1000 characters, so continue in a 2nd, 3rd.... post.

Where in the world did you manage to fit (4) 6 volt batteries? What type of batteries did you use? (AGM, FLOODED....). Size or your system? Ah's... type of SOLAR Charge Controller?

HandyBob's blog is a useful tool for those looking for a view on SOLAR. There are a lot of HandyBob type blogs which have good information in them ansd some that you would want to stay clear of. You just need to weed out a few things and update his thoughts with current technology.

Where in the world did you manage to fit (4) 6 volt batteries? What type of batteries did you use? (AGM, FLOODED....)

Don
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EnGenius WI-FI extender, D-Link wireless (n) modem
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