Question for experts

[sadarahu]

I have 3 devices I need to charge from mobile solar panel.
1. PHONE: Samsung Note -2 (5V/2A USB)
2. TABLET: Samsung Slate-7 (DC 19V/2A DC output)
3. MARINE BATTERY (12V/4A DC output)

I bought 80W solar panel and MPPT controller to deliver 12V battery charging. USB charging worked fine but I could not charge my tablet for some reason.
The current and voltage I listed above was taken from my power supply. When I measured open circuit voltage on my tablet power supply it was 19.4-19.6V
I measure the voltage in the solar panel DC output on a bright sunny day and I have had 19.4V. With the 80W this panel can deliver 4A easily. For some reason when I plugged in my tablet it wasn't charging (and I'm sure polarity was OK).

I'm pulling my hair out to figure out what is going on. Tired to call Samsung Tech Supp fo advice but their tech supp sucks. I wonder if I should get 24V panel and use MPPT to lower it to (perhaps) 20V to see if it is working. Unfortunately panels over 20W are usually available only on-line and every return/test cost me extra $$ (as I have to pay the shipping).

Any ideas appreciated.

ARTHUR

[thastinger]

You bought an inverter that has a USB charger port? Or you're using a cig lighter adapter on the battery to charge the USB items?

[Amy@altE]

Are you trying to charge your 19V tablet from the 12V battery? Or are you trying to charge the tablet directly from the panel? Please explain your system better. Either way, the voltage isn't high enough to charge a 19V battery.

[thastinger]

http://www.amazon.com/Super-Power-Supply%C2%AE-XE700T1A-A01US-XE700T1A-A02US/dp/B00HNXTW8S/ref=sr_1_11?s=electronics&ie=UTF8&qid=1429021627&sr=1-11&keywords=samsung+series+7+charger

might work with that if you buy a 12V cig lighter adapter to wire to the battery, then plug the above into that

[sadarahu]

Thank you all who replied (I really value your time), but....

If one does not know what the MPPT controller is then should rather skip this thread.
I'm trying to charge 3 devices from the solar panel. I do have a cigarette lighter adapter but this is not an option (at all). I need this for situation when there is no car,...nothing.
I'm limited with weight as well so need this as portable as possible. The panel I have in mind has 18V 80W delivering up to 4 Amps.

Since I cannot chargge the tablet form 12V (obviously it needs 19V+) I'm trying to charge it directly from the panel. Forget about the phone and marine battery, I can handle that easily.
The question is why haveing 19.5V on the charger it charges the tablet but the same 19.5 from the panel does not ?

I think I need to measure the current on a loaded circuit to see how many Amps go from the wall charger to the tablet. I recently discovered that most of the notebooks these days use 19V so this is pretty common situation when one needs to charge the computer/tablet on the go from solar panel. Please do not suggest any battery chargers (I'm aware of this solution), as well as inverters (to inefficient and to heavy). I just need the plain panel + tablet to work.

Thank you.
Arthur

[inetdog]

Thank you all who replied (I really value your time), but....

If one does not know what the MPPT controller is then should rather skip this thread.
I'm trying to charge 3 devices from the solar panel. I do have a cigarette lighter adapter but this is not an option (at all). I need this for situation when there is no car,...nothing.
I'm limited with weight as well so need this as portable as possible. The panel I have in mind has 18V 80W delivering up to 4 Amps.

Since I cannot chargge the tablet form 12V (obviously it needs 19V+) I'm trying to charge it directly from the panel. Forget about the phone and marine battery, I can handle that easily.
The question is why haveing 19.5V on the charger it charges the tablet but the same 19.5 from the panel does not ?

I think I need to measure the current on a loaded circuit to see how many Amps go from the wall charger to the tablet. I recently discovered that most of the notebooks these days use 19V so this is pretty common situation when one needs to charge the computer/tablet on the go from solar panel. Please do not suggest any battery chargers (I'm aware of this solution), as well as inverters (to inefficient and to heavy). I just need the plain panel + tablet to work.

Thank you.
Arthur

One point that you may be missing is that you can hard wire a cigarette lighter socket (called a power port in this case) to a portable battery pack. That will let you use a car charger from the output of a battery pack to the phones or to the computer. (Two different kinds of car adapters: The USB kind drops the 12V to 5 volts. The tablet kind boosts the 12V to 19V. Look for car/airline power supply for your tablet.)
Both are better (more efficient) than using an inverter to power mains driven power supplies or chargers. Inverters will not work directly from the panels either.
There is absolutely no way that you can safely get any voltage directly from panel to tablet to work. The variable output of the panel is not compatible with the input of the tablet.
Either you use a 12V nominal panel and a DC to DC converter to get 19V (but not necessarily at the current the tablet needs!) or you use 24v nominal panels and a voltage reducing circuit (which would still not necessarily work well as the panel output changes.)

And here is one possible answer to your question:
The tablet is looking at additional signal wires from the power supply that tell it how much power the supply can deliver. With no signal the tablet does not recognize that there is a power supply there. This is the sort of thing that Apple would do.

And another answer:
The panel can produce 18V with a low enough load. But as you draw current from it the voltage drops. Once the tablet starts to draw current (and it will try to take all that it can get up to its maximum need) it sees the panel voltage drop and decides that the power supply source is broken or inadequate.

[thastinger]

Thank you all who replied (I really value your time), but....

If one does not know what the MPPT controller is then should rather skip this thread.
I'm trying to charge 3 devices from the solar panel. I do have a cigarette lighter adapter but this is not an option (at all). I need this for situation when there is no car,...nothing.
I'm limited with weight as well so need this as portable as possible. The panel I have in mind has 18V 80W delivering up to 4 Amps.

Since I cannot chargge the tablet form 12V (obviously it needs 19V+) I'm trying to charge it directly from the panel. Forget about the phone and marine battery, I can handle that easily.
The question is why haveing 19.5V on the charger it charges the tablet but the same 19.5 from the panel does not ?

I think I need to measure the current on a loaded circuit to see how many Amps go from the wall charger to the tablet. I recently discovered that most of the notebooks these days use 19V so this is pretty common situation when one needs to charge the computer/tablet on the go from solar panel. Please do not suggest any battery chargers (I'm aware of this solution), as well as inverters (to inefficient and to heavy). I just need the plain panel + tablet to work.

Thank you.
Arthur

buy one of these to hook to the battery http://www.amazon.com/Roadpro-Batter...lighter+socket

then buy the car charger I posted above

solving your problem does not require an "expert"

[sadarahu]

It seems that most of you who replied did not get what I need. Like I said I do not want to use an inverter because it is inefficient. I also do not want to convert lower voltage to the higher voltage as it is inefficient as well. I only have an option to use either 24V or 18V panel so I can use MPPT controller and drop it down to 19.5V for my tablet, 13.5V for my marine battery. Connectors and such are not problem, I can always figure out some solution. The challenge is to have my marine battery and tablet charged (even with the minimum efficiency on a cloudy day).

I called SAMSUNG to ask what is the minimum voltage/current for Samsung Slate-7. The are absolute ignorants and the tech.supp guy knows nothing, so there is not help from the company. Since most laptops and tablets operate on 19V these days I wonder if anybody have had this charging problem resolved, practically. I've got some advice from people who thought it should work but the have never been able to test it practically. I'm planing some trips in a very remote locations and need to make sure everything works as expected, therefore I need to test the hardware home at first. Also buying stuff just to find out it will notwork is no fun.

From what I know when the anel circuit is loaded the voltage drops down significantly. I do not have the 80W panel anymore (returned it) so I cannot test how muc it will drop when the tablet is connected. I'm pretty sure that if it drops below 19.1+ it will not charge. When I measured panel output on a sunny day - there was 19.6V

Onca again - is there anybody who can confirm testing solar panel charging 19V tablet or laptop ?

Thank you
ARTHUR

[sensij]

When you understand that solar panels can act as a current source, not a voltage source, the replies you have gotten will make more sense. What MPPT controller are you using? What output voltage did you have it set for?

As others have suggested, there is a non-zero chance that the charger is more complicated than a simple voltage source, preventing charging from a simple DC source, but I am not familiar enough with those devices to know for sure.

[russ]

Plan on only charging from the solar panel when you are stationary during the prime part of the day.

[sadarahu]

I will be boating, kayaking, hiking etc. The panel will be my main power source. My simple question i how to charge the laptop directly from the panel (without the batter) and of course the question is again about Volts/Amps - everything else I can manage. If one hasn't been able to practically charge the device like mine the answer will not be really reliable. I'm surprised it is so hard to find more details or demos. Several YT video presentations show panels which (as they state) are able to charge laptops but none that I've seen physically demonstrated so far charging (especially on poor sun conditions).

[inetdog]

I will be boating, kayaking, hiking etc. The panel will be my main power source. My simple question i how to charge the laptop directly from the panel (without the batter) and of course the question is again about Volts/Amps - everything else I can manage. If one hasn't been able to practically charge the device like mine the answer will not be really reliable. I'm surprised it is so hard to find more details or demos. Several YT video presentations show panels which (as they state) are able to charge laptops but none that I've seen physically demonstrated so far charging (especially on poor sun conditions).

As far as I know there are no laptop power supplies or chargers (that connect to 12V DC or 18V DC (some airplane systems)) that can work with a current limited DC source. That means that if the panels are able to produce all of the power that the charger/adapter needs, all will work well, but if panel power drops below the amount the adapter is drawing the adapter will shut down rather than just running at half speed. In the case of a laptop, the battery inside the laptop is providing the storage to keep the CPU running as its power demand goes above what the adapter is supplying that that moment, but without a battery connected to the panels on the input side of the adapter, the adapter will not be happy.
Could somebody build such a thing? Sure. Does anyone or is it a credible DIY project? No.

[russ]

I will be boating, kayaking, hiking etc. The panel will be my main power source.

Then you have no power - not what so ever practical.

Watching Youtube videos is like watching cartoons and generally just as informative.

[SunEagle]

I will be boating, kayaking, hiking etc. The panel will be my main power source. My simple question i how to charge the laptop directly from the panel (without the batter) and of course the question is again about Volts/Amps - everything else I can manage. If one hasn't been able to practically charge the device like mine the answer will not be really reliable. I'm surprised it is so hard to find more details or demos. Several YT video presentations show panels which (as they state) are able to charge laptops but none that I've seen physically demonstrated so far charging (especially on poor sun conditions).

Unfortunately there isn't any solar device that will perform as you want. Solar panels work well for certain hours of the day while they are pointed directly at the sun. They do not perform well when they are moving about.

If you want to have a portable main power source then look at some of those 20000 to 40000 mah battery systems. They can provide enough to recharge a laptop or cell phone a few times but will need to be recharged themselves from a constant power source for hours.

Some day a device you want may be invented, produced and sold but as of now the only portable solar charging systems cost a lot of money and will not perform as you want.

[sadarahu]

'I understand your point but I'm not talking about using the tablet/laptop at the same time I charge it. I'm perfectly fine with leaving the device for few hours and letting it charge. In this case more or less current won't bother unless it drops significantly below the charging range. Of course powering the laptop with no battery would make not much sense. In my case one would charge the tablet batter the same way he would charge any other bettery with the exception of charging requirements for this particular model. I do not see why this would be any problem. My only question is what is the minimum Voltage and minimum current to be in a charging range for this particular model (which seems to be pretty common) ?
If the PC says 19V what the loaded voltage/current needs to be ? It seems that what I measured on an open circuit drops down so dramaticaly that there is no enough volts to trigger charging.

Arthur