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madspaniard
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PostPosted: Wed Jun 11, 2014 7:15 am    Post subject: Reply with quote

I don't understand your rationale. You said at the beginning that you don't want to mount the panel on the roof. Then you say you don't want foldable because it might get damaged by kids etc on the ground. How are you planning to use your non-foldable 100w panel and why you couldn't do the same with a foldable one?

By the way, the reason I got rid of my 135w panel is because I got tired of moving it in and out of the van or around camp, too heavy. I used to have it on the roof but more than once I found out my camping spot was in full shade for most of the day. The foldable panel is so much easier to handle and it fits in many places inside the van.
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PostPosted: Wed Jun 11, 2014 8:56 am    Post subject: Reply with quote

Checkout the below link. 2 50w removable panels on 50 foot cords so you can chase the sun while the van stays in the shade. I am the new owner of the van and love the solar panel setup. He did a great idea for mounting the panels and locking them yet making it easy to take off.

http://patrickbrown.org/2013/02/18/solar-panels-on-a-westfalia-luggage-rack/
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PostPosted: Wed Jun 11, 2014 9:08 am    Post subject: Reply with quote

WestyDreamer wrote:
Ohooooo you guys are driving me insane. Guess my brainfart of trying to go small say 50 watt panel just ain't going to be practicable.

So looks like I have to take your advice Luke and look into the larger 100 gig-a-watt Panels. Problem now becomes transporting and storage of the larger panel the one I'm looking at is est size 47"x21" which should just fit across westy cargo box. Wish I could find one slightly smaller say est 46x19 as it would drop down inside of the Cargo box.


The 75-80 watt panels fit the size you need and provide adequate power. You can figure out a removable mounting system and make yourself happy by having it on the van or remote in the sun. All the below are good options.

75 watt - 38x23 $93 - 4.28 amps

http://www.solarblvd.com/Solar-Panels-&-System..._info.html

80 watt - 34x26 $116 - 4.65 amps

http://www.solarblvd.com/Solar-Panels-&-System..._info.html

85 watt - 47x21 $125 - 4.78 amps

http://www.amazon.com/HQRP-Solar-Panel-Monocrystal...olar+panel

100 watt - 47x21 $149 - 5.29 amps

http://www.amazon.com/RENOGY-Monocrystalline-Photo...olar+panel
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PostPosted: Wed Jun 11, 2014 9:28 am    Post subject: Reply with quote

Keep in mind that every foot of wire from the panel to the battery will lead to increased voltage drop. Patrick did a great job of making an easy to use extension cord for his setup, but with 16AWG wire, the voltage drop from 50' of extension cable will be considerable.

If frame color is a major deciding factor when choosing panels, stop by the auto parts store and get some high quality masking tape, primer and spray paint. Aluminum is easy to paint and the whole job should only take a couple hours.

The voltage that the charge controller will put out has no relation to its maximum amperage capacity. Most PWM chargers put out 12-15V depending on temperature and sun exposure. For more efficient charging, an MPPT charge controller is the way to go for most people. Prices range from $50.00 for no-name brands on Ebay to well over $500.00 for well known brands like Morningstar.

Size your charge controller based on the wattage of your panel. Since Amps = Watts x Voltage, take the wattage of the panel you purchase and divide it by 12 to come up with a ballpark figure for the controller you will need. If you think you might want to add another panel at some point, plan ahead and go bigger on your controller now.
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WestyDreamer
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PostPosted: Wed Jun 11, 2014 9:42 am    Post subject: Reply with quote

Surferboy120 wrote:
Checkout the below link. 2 50w removable panels on 50 foot cords so you can chase the sun while the van stays in the shade. I am the new owner of the van and love the solar panel setup. He did a great idea for mounting the panels and locking them yet making it easy to take off.

http://patrickbrown.org/2013/02/18/solar-panels-on-a-westfalia-luggage-rack/


I've seen that "Kiss me I'm Patrick" Solar setup on you tube several times.
He's my Hero and especially appreciate his creative Thule Locking system.

http://patrickbrown.org/2013/02/18/solar-panels-on-a-westfalia-luggage-rack/

When Patrick built his system Panels were more expensive and less choices he used dual 50W panels but If I'm forced to go larger I'd do the 1 pieces larger 100W panel 47"x21" and I'd probably use his creative build idea.

But then again the Madspaniard may twist my thoughts about a portable unit Laughing
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PostPosted: Wed Jun 11, 2014 10:01 am    Post subject: Reply with quote

thatvwbusguy wrote:
Keep in mind that every foot of wire from the panel to the battery will lead to increased voltage drop. Patrick did a great job of making an easy to use extension cord for his setup, but with 16AWG wire, the voltage drop from 50' of extension cable will be considerable.

If frame color is a major deciding factor when choosing panels, stop by the auto parts store and get some high quality masking tape, primer and spray paint. Aluminum is easy to paint and the whole job should only take a couple hours.

The voltage that the charge controller will put out has no relation to its maximum amperage capacity. Most PWM chargers put out 12-15V depending on temperature and sun exposure. For more efficient charging, an MPPT charge controller is the way to go for most people. Prices range from $50.00 for no-name brands on Ebay to well over $500.00 for well known brands like Morningstar.

Size your charge controller based on the wattage of your panel. Since Amps = Watts x Voltage, take the wattage of the panel you purchase and divide it by 12 to come up with a ballpark figure for the controller you will need. If you think you might want to add another panel at some point, plan ahead and go bigger on your controller now.


I agree with your comments in regards to the cord length. When mounted on the Van he put in a short 2 foot cord and you only use the 50 footer for when taking the panels off to put into the sun. Panels work great and keep all three batteries happy with no issues.
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PostPosted: Wed Jun 11, 2014 12:05 pm    Post subject: Reply with quote

thatvwbusguy wrote:
Keep in mind that every foot of wire from the panel to the battery will lead to increased voltage drop.


Correct me if I am wrong, but this only really applies to the run between the controller and the battery, correct? The raw voltage from the panels should be in the neighborhood of 20V. So if the controller is mounted close to the battery, and you see some voltage drop from the panel to the controller, down to even, say 18V, the controller will still be putting out the same charging voltage of 14.7V (or whatever it is set to).

But, maybe I am thinking about this wrong.
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Love My Westy
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PostPosted: Wed Jun 11, 2014 1:59 pm    Post subject: Reply with quote

When I purchased wire for running my solar panels from Northern
Arizona Wind and Sun, they recommended 10 AWG wire to run the 60 feet that I wanted to go. I am reading 22.5 volts at the charge controller which is the same as at the panel. No loss.
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madspaniard
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PostPosted: Wed Jun 11, 2014 2:01 pm    Post subject: Reply with quote

WestyDreamer wrote:

But then again the Madspaniard may twist my thoughts about a portable unit Laughing
.


Sorry, I don't mean to be pushy or have an agenda about foldable panels, just trying to help and offer my experience. We all have different needs when it comes to solar panel power. You really need to take a hard look at how you camp (lenght of stay, power needs, sun/shade) and then come up with the simplest solution so that you don't spend the whole weekend worried or anoyed by your power system.

My first approach was roof rack-mounted 135w panel. That worked great for a while until I camped in Yosemite in full shade for more than 2 days. From there I tried to use the 135w panel as something I could temporarily remove from the roof rack and deploy in a sunny area near my van (uff, too heavy and bulky). From there I went to keeping the panel inside the van in the upper bunk and deploying the panel upon arrival to campsite (ufff, still heavy and I'm hitting every single piece of cabinetry in the van trying to get it out). From there I got tired of it all, sold my 135w panel and got the 120w foldable one - easy, it is a two-60w-panel arrangement that folds in the middle so small footprint, comes with handles, corner bumpers, and a fabric case, this I can handle while camping. The only downside is I don't have a panel permanently wired to my battery so you need to watch your aux battery for voltage drop in between camping trips but my battery is very healthy and I drive it at least once a week (usually one weekend day). Before I give it that weekly drive I check the voltage and it is usually sitting at 12.6v after a week of no action. I have a circuit breaker that I keep in the off position to fence off parasitic charges from radio, inverter, etc. One advantage, no need for the roof rack unless I bring the roof top box.
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Last edited by madspaniard on Wed Jun 11, 2014 2:03 pm; edited 1 time in total
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WestyDreamer
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PostPosted: Wed Jun 11, 2014 2:03 pm    Post subject: Reply with quote

Altoona wrote:
thatvwbusguy wrote:
Keep in mind that every foot of wire from the panel to the battery will lead to increased voltage drop.


Correct me if I am wrong, but this only really applies to the run between the controller and the battery, correct? The raw voltage from the panels should be in the neighborhood of 20V. So if the controller is mounted close to the battery, and you see some voltage drop from the panel to the controller, down to even, say 18V, the controller will still be putting out the same charging voltage of 14.7V (or whatever it is set to).

But, maybe I am thinking about this wrong.


Ha Ha-aaaaaa even I think I can answer this one..

Nope the longer the distance current has to travel the more loss. Think someone mentioned trying to stay under 20-30 foot for best performance. Also the longer the distance the heavier the gauge of wire that should be used..

Where the Heck is that Crazy VWBUSGUY when we need him Laughing
.
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madspaniard
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PostPosted: Wed Jun 11, 2014 2:36 pm    Post subject: Reply with quote

WestyDreamer wrote:
Altoona wrote:
thatvwbusguy wrote:
Keep in mind that every foot of wire from the panel to the battery will lead to increased voltage drop.


Correct me if I am wrong, but this only really applies to the run between the controller and the battery, correct? The raw voltage from the panels should be in the neighborhood of 20V. So if the controller is mounted close to the battery, and you see some voltage drop from the panel to the controller, down to even, say 18V, the controller will still be putting out the same charging voltage of 14.7V (or whatever it is set to).

But, maybe I am thinking about this wrong.


Ha Ha-aaaaaa even I think I can answer this one..

Nope the longer the distance current has to travel the more loss. Think someone mentioned trying to stay under 20-30 foot for best performance. Also the longer the distance the heavier the gauge of wire that should be used..

Where the Heck is that Crazy VWBUSGUY when we need him Laughing
.



His queestion is a bit different, he is already assuming a voltage drop due to wire resistance from the remote panels to the controller and that everything would be fine as long as the voltage drop still keeps the voltage above what the controller puts out so you really would have to worry about voltage drop from the wire running from the controller to the battery.
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Altoona
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PostPosted: Wed Jun 11, 2014 3:38 pm    Post subject: Reply with quote

madspaniard wrote:
WestyDreamer wrote:
Altoona wrote:
thatvwbusguy wrote:
Keep in mind that every foot of wire from the panel to the battery will lead to increased voltage drop.


Correct me if I am wrong, but this only really applies to the run between the controller and the battery, correct? The raw voltage from the panels should be in the neighborhood of 20V. So if the controller is mounted close to the battery, and you see some voltage drop from the panel to the controller, down to even, say 18V, the controller will still be putting out the same charging voltage of 14.7V (or whatever it is set to).

But, maybe I am thinking about this wrong.


Ha Ha-aaaaaa even I think I can answer this one..

Nope the longer the distance current has to travel the more loss. Think someone mentioned trying to stay under 20-30 foot for best performance. Also the longer the distance the heavier the gauge of wire that should be used..

Where the Heck is that Crazy VWBUSGUY when we need him Laughing
.



His queestion is a bit different, he is already assuming a voltage drop due to wire resistance from the remote panels to the controller and that everything would be fine as long as the voltage drop still keeps the voltage above what the controller puts out so you really would have to worry about voltage drop from the wire running from the controller to the battery.


Exactly, thanks for presenting that more clearly, madspaniard.
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Howesight
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PostPosted: Wed Jun 11, 2014 4:38 pm    Post subject: Reply with quote

Altoona wrote:
thatvwbusguy wrote:
Keep in mind that every foot of wire from the panel to the battery will lead to increased voltage drop.


Correct me if I am wrong, but this only really applies to the run between the controller and the battery, correct? The raw voltage from the panels should be in the neighborhood of 20V. So if the controller is mounted close to the battery, and you see some voltage drop from the panel to the controller, down to even, say 18V, the controller will still be putting out the same charging voltage of 14.7V (or whatever it is set to).

But, maybe I am thinking about this wrong.


You are wrong. Long wiring runs reduce voltage and current. Essentially, a long wiring run with small gauge wire will make the power to the charge controller equivalent to the power supplied by a much smaller solar panel. If your controller is the MPPT style, you are doubly cursed because they convert higher voltages to extra current using a transformer and a lot of fancy electronics. It never ceases to amaze me how much people are willing to pay for the panel, controller, etc., etc., and how little they are willing to pay for proper wiring.

The reasons there is an emphasis on short runs from the controller to the battery are twofold:

1. Most people do not shell out for a battery temp sensor which most intermediate to high quality charge controllers are designed to accept. These controllers typically have a built-in temp sensor that can be a proxy for battery temp if the battery and controller are in fairly close proximity.

2. More importantly, your battery is designed and tested by the manufacturer to have its best charging performance at specified charging voltages. Any reduction of the specified voltage slows charging and may prevent full charging. Failure to fully charge a deep cycle battery can quickly ruin it. So, even a 3% loss will be very significant. If the specified charging voltage is 14.8 volts and a long or undersized wiring run from the charge controller to the battery causes a 3% reduction, voltage supplied at the battery is a mere 14.36 volts. This will NOT fully bulk charge my lead-acid Trojan battery. Even if the loss were only 1%, you have a charging voltage of 14.65 volts. Charging time will be increased significantly.

Here's what "HandyBob", a solar guru says:

"VOLTAGE: For the sake of simplicity, I am only going to talk about the requirements of standard flooded wet cell lead acid batteries, which is what most of us use. The major points apply to all types of batteries, but the actual numbers will vary. It is very important for you to research the charging requirements of your batteries if you are using any other type and make sure that your charging system provides what they need, or you could end up damaging them by over charging or never getting them fully charged, which will also damage them. Battery manufacturer’s specifications say that a standard 12 volt wet cell battery needs to be charged to between 14.4 to 14.8V and then held there for some time before it will be fully charged. The Trojan Battery company says 14.8V daily charge (at 77 degrees F) and Interstate will tell you over 15V. Trojan’s 2010 Users Guide has a new chart that shows you should actually vary the voltage depending on the amps you supply for charging and even higher voltages are recommended. Of course they recommend temperature regulation. So all of those out there who are telling you 14.8V is too high do not know what they are talking about. How long it takes to get the charge in depends on how far it was discharged. Trojan says to keep charging until a hydrometer test shows that the battery is charged and not one charger available today can do this. The best chargers can do a reasonable guess at state of charge by providing constant voltage and watching the amps taper as the battery fills to tell them when the battery is full. However, they rely on whatever the designer or programmer gives them for guidelines and are only as good as that data. Many do no work worth a hoot. A fully charged battery can be maintained at a full state by applying a 13.2 – 13.6 volts “float” charge. All of the talk about how many amps a charger puts out means nothing. It is the volts (pressure) that you need to push the amps (volume) into a battery. VOLTS, VOLTS, VOLTS!! Also, the amps pushed into a battery at a higher voltage contain more power than those at a lower voltage. Remember, volts times amps equals watts, so amps pushed at 10% higher volts give you 10% more watts. Therefore, the power stored in the upper range of a battery’s charge is greater, so it is very important to get a full charge. Low voltage DC is not easy to get through wire without losing power due to voltage drop or resistance. It is huge problem in an RV. Use big wires and short wiring runs to get around this. It is good practice to use one or even two sizes bigger wire than recommended to limit voltage drop. This charge voltage has to actually reach the battery, not just the output terminals on a charger. If you cannot get your batteries up to 14.4 volts (14.8 is better & faster) with whatever charging system you have and then keep them there while pushing amps in for more than an hour or two, your batteries will never be full."

You can use long wiring runs from the panel to the controller, but only if you use sufficiently large gauge wire. Here's a link to a transmission-loss calculator that Northern Arizona Wind and Sun has on their website:

http://www.windsun.com/Hardware/Voltage_Calc.htm

For the OP's parameters, I used the above calculator, entering the following data:

- Single phase
- copper wire
- overhead installation
-Voltage: 18v (average highest power for 12V nominal panel in full sun)
- 3% maximum voltage drop (many installers aim for lower losses)
- 50 feet of cable run: Remember that a 25 foot distance from panel to controller involves 50 feet of cable run as this is DC and the circuit requires the current to travel through 50 feet of wire! Many people forget this!
- Current: 2.77 amps (derived from rated 50W panel at 18 volts: 50Watts/18volts = 2.77amps)

The calculator result is as follows:

"Results:
1 conductor(s) per phase utilizing a 12 AWG Copper conductor will limit the voltage drop to 2.67% or less when supplying 2.77 amps for 50 feet on a 18.0 volt system.

For Engineering Information:
•20 Amps Rated ampacity (NEC) of selected conductor
•1.9029 Ohms Resistance (Ohms per 1000 feet)
•0.054 Ohms Reactance (Ohms per 1000 feet)
•0.54 volts maximum allowable voltage drop at 3%
•0.48 Actual voltage drop loss at 2.67% for the circuit
•0.9 Power Factor"

Now, if you want to use all the same parameters but limit the voltage loss to 2%, then the following result is given:
Results:
1 conductor(s) per phase utilizing a 10 AWG Copper conductor will limit the voltage drop to 1.61% or less when supplying 2.77 amps for 50 feet on a 18.0 volt system.

For Engineering Information:
•30 Amps Rated ampacity (NEC) of selected conductor
•1.1417 Ohms Resistance (Ohms per 1000 feet)
•0.05 Ohms Reactance (Ohms per 1000 feet)
•0.36 volts maximum allowable voltage drop at 2%
•0.29 Actual voltage drop loss at 1.61% for the circuit
•0.9 Power Factor

And another thing . . . you have to configure your charge controller. It has pre-sets that are quite likely to be wrong for your battery(ies). If your charge controller is not configurable, throw it away - - it is a mere excuse for a charge controller. If possible, you need to configure the charging time for bulk charging as some controllers are pre-set to short-change the needs of some batteries and either bulk charge for a limited and defined time or reduce the charge rate to float too early, based on sensing and estimating current flow into the battery.

Charge controllers are like Facebook - - if you don't take care of your settings, prepare to be screwed.
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PostPosted: Wed Jun 11, 2014 5:10 pm    Post subject: Reply with quote

And another thing . . .

In the research I have done on solar power and how to make it work, the most helpful comment I read to understand intuitively the relationship between volts and amps in charging your battery is to think of the analogy of filling up a flat tire. Amps represents the amount of air going in. Volts represents the pressure of the air.

When the tire or the battery is flat, the resistance to the flow of air is low and the amount of air/electricity admitted by the tire/battery at a given pressure/voltage is high. As the battery fills, more voltage is needed to continue to push the same amount (or any amount) of current into the battery. Thus, when a battery is being charged, the closer to a full charge, the higher the voltage needed to continue to provide the same amount of amps into the battery. Since batteries continue to provide greater resistance to flow as the level of charge increases, current into the battery declines as the battery reaches towards a full charge. The battery must remain at the "absorption" voltage (usually the same as the "bulk charge" voltage for a sufficient period of time to completely fill.

This is why volts matter so much in a solar charging system. This is also why that "long" drive home still won't fill up your deep cycle battery if your alternator only puts out 13.5 volts.
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PostPosted: Wed Jun 11, 2014 6:01 pm    Post subject: Reply with quote

As long as we are talking controllers....for an entry-level panel (100w poly) and an AGM battery (sears platinum 65), what is a good-enough-to-get-by controller? I'm really trying to keep this project/budget from running away...its on the bubble as is. I've read the benefit of MPPT really only becomes meaningful when installing bigger systems (>400w) and I've been convinced elsewhere that decent PWM is the way to go.

Not trying to win the solar install prize, just something that helps me run a fridge for a day or so between drives.
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PostPosted: Wed Jun 11, 2014 6:33 pm    Post subject: Reply with quote

WestyDreamer wrote:
Ohooooo you guys are driving me insane. Guess my brainfart of trying to go small say 50 watt panel just ain't going to be practicable.
Guess I'll have to get creative and make the 100 watt Panel tiltable to capture sun angle. Or even removable / extendable with a length of jumper wire to capture the best sun.

.


This is what I did. I have a 100 watt panel mounted to the back of the Westy top with quick releases so I can easily remove it and use an extension cord to prop it up in the sun off the bus when needed. Best of both worlds.... Very Happy
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PostPosted: Wed Jun 11, 2014 8:40 pm    Post subject: Reply with quote

Howesight - Thank you for the very comprehensive post and after posting that I thought about it and realized I was wrong....but also (kind of) right, depending on what you're talking about.

I was wrong if you are thinking that charging would not be impacted at all by the long run, of course there is no such thing as a free lunch, clearly, the power goes somewhere.

But I was right, because my original concern when I was thinking about it, was how the charging voltage the battery was seeing was impacted. For instance, if the controller was putting out 14.7V but the battery was only seeing 13.8V due to a long run of thin wire between the controller and the battery, my battery would not be getting a full charge. By putting the long run of thin wire between the panel and the controller, the charging voltage would not be impacted, but the current would. So my battery would receive a full charge, it would just take longer to get it.

Of course, ideally, the wire would sufficiently sized to keep any losses to an acceptable level, but even so, if you have a choice between putting the long run between the panel and the controller (like most portable panels that have the controller attached to the panels) or the controller and the battery (like installs that have the controller permanently mounted inside the van), it should be between the panel and the controller, so at lest there is no risk of decreased charging voltage, just amperage. Which, in my mind is the lesser of two evils.
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PostPosted: Thu Jun 12, 2014 2:48 am    Post subject: Reply with quote

From Solar Blvd. Your panels may be getting more expensive soon.

Dear Friends,

On Tuesday, June 3rd 2014, The United States Department of Commerce successfully imposed increased duties of approximately 21.89 percent to importers of solar panels, asserting that foreign manufacturers had benefited from unfair subsidies.

The decision, in a long-simmering trade dispute, addresses one of the main charges in a petition brought by the manufacturer SolarWorld Industries America. While it is preliminary, the ruling means that the United States will begin collecting the tariffs in advance of the final decision, expected later this year.

What does this mean to you as a customer? Since you are not the importer on file, you will not be directly taxed for your solar panels. There will, however, be an increase of about 15 percent across the board on all solar modules in the next coming months.

Our goal at Solarblvd is to remain competitive. So, we will continue to offer you great pricing and unprecedented service in the coming years!

Thank you for your continued support.



Solarblvd
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WestyDreamer
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Joined: December 22, 2011
Posts: 156

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PostPosted: Thu Jun 12, 2014 7:25 am    Post subject: Reply with quote

OK..
Since this topic has taken on so many variables and so many expertize has spoken and given there suggestions.

Another Question now has come to mind about standing Battery Voltage?

It was posted that a Solar Panel should provide Charge Voltage between 13.5 to as Hi as 14.8 Volts..

But after charging what should we see on a normal wet cell 12V Deep Cycle Battery? After I unplug my battery maintainer mine usually reads about 12.4 - 12.7 Volts. My charge volt meter usually reads 13-14 Volts but once disconnected the Battery Voltage drops to a steady 12+ volts. Is this Wrong.

I just don't understand how you squeeze 14 volts into 12

Just wondering if I should invest in a 14V Battery Laughing
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Altoona
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Joined: November 14, 2011
Posts: 478

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PostPosted: Thu Jun 12, 2014 8:12 am    Post subject: Reply with quote

WestyDreamer wrote:
OK..
Since this topic has taken on so many variables and so many expertize has spoken and given there suggestions.

Another Question now has come to mind about standing Battery Voltage?

It was posted that a Solar Panel should provide Charge Voltage between 13.5 to as Hi as 14.8 Volts..

But after charging what should we see on a normal wet cell 12V Deep Cycle Battery? After I unplug my battery maintainer mine usually reads about 12.4 - 12.7 Volts. My charge volt meter usually reads 13-14 Volts but once disconnected the Battery Voltage drops to a steady 12+ volts. Is this Wrong.

I just don't understand how you squeeze 14 volts into 12

Just wondering if I should invest in a 14V Battery Laughing
.
.


The short answer is, this is normal and correct. Charging voltage is higher than resting voltage. A fully charged 12V battery should read about 12.7 at rest. Depending on the battery chemistry, the charging voltage should be between 14.2 and 14.8.

Note: this is a simplified explanation, there are many good 12V battery tutorials on the web that explain the physics and chemistry behind it in great detail.
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