Solar Charging

[RDW]

Btrayfors, So what happens to the volts out of a solar panel when shaded?
I do have a multimeter. It was part of stating the question.
Thanks for your help. It was most gracious.
rdw

[travellerw]

Originally Posted by hellosailor

traveler-
They SHOULD be using 25v rated components, that would be what a good engineer would normally choose. However, you know ICOM, the radio company? They lost a lot of ICOM 706-series fans because the main caps across the power input, which are always connected, were 15V rated parts.
And now that so much stuff, especially the cheap DC-to-DC power supplies, is coming from "cheapest shop in Shenzhen! Promising You!" I expect that even more parts will be spec'd at 15V for "12" volt use. Saturn car owners had a series of ECU failures because of poor quality electrolytics. The computer industry lost a lot of motherboards that way...what was it, 15 or 20 years ago?
When I see a "12v USB adapter" on sale for less money than it would cost me to post it to the source of origin....I have to ask, how can they sell it so cheap? Kinda like the problem with counterfeit and no-name lithium batteries for call phones and other gizmos catching fire, because so many companies cheated on their specs.
Mind you, I LIKE fire. I just don't appreciate it coming as a surprise.

I agree %100. Even quality manufactures are guilty of this.

Not to side track too much, but the design and manufacture process is to blame here. Its common practice for a device to be designed by a competent engineer, then be sent to an "economizer". So originally the product was a solid well spec'ed design (even in China), but was bastardized to save a few pennies. It was Dell that got burned by this. Proper spec'ed Caps but using a shady Cap manufacturer with a stolen electrolyte recipe (that was known to be bad).

On the plus side, Caps make a satisfying POP and SMOKE when they splode!

[Nicholson58]

Originally Posted by zboss

No, those devices use a lower voltage than the panels provide. You would have to use a converter to convert the voltages down to whatever you needed.

So... generally Panels>Charge Controller Load output>Inverter>Device Plug>Device.

There are special solar panels with built-in controls for laptop and cell phone charging. We bought one that folds up like a small portfolio but can run a laptop.

You could get an alternate charge controller for your panels or a dc-dc converter for the correct voltage.

[Zven]

Nobody commented on the lead pencil idea...
That could work, but you would need to measure and calculate carefully, to get the resistance right.
Probably not worth the risk and trouble...!

[Maine Sail]

Originally Posted by RDW

I have solar panels on my boat. If I were to get into a bad situation where I lost my boat electrical system like my batteries blowing up etc., could I hook my solar panel directly to cell phones, computers and Ipad type devices so I could use them to navigate.
I know this is off the wall question but it is an interesting concept.
RDW

Not "directly" but you could cobble something together using a controller, a 12V outlet and a USB charger socket... They also make dedicated solar chargers for iPhones etc..

Course you could just open the chart table and pull out the dividers, stopwatch, sextant, hand bearing compass, charts, note book etc. and not need any iToys...

[RDW]

Originally Posted by Zven

Nobody commented on the lead pencil idea...
That could work, but you would need to measure and calculate carefully, to get the resistance right.
Probably not worth the risk and trouble...!

My question was a "what to do in an unusual situation". I have enjoyed the responses. Using a multimeter, could you just slide the wire down to different points on the pencil until you got near the right voltage.? From the little I know there could be a big range of input into a USB or cigarette outlet.
One other "source" stated that if the controller still worked, the energy coming out of it could be used.
Yes you are right to suggest celestial navigation which I am prepared to do but just think of how much better I would feel and my crew would feel if I were able to get a GPS fix!!!!!!
thanks
rdw

[Maine Sail]

Originally Posted by RDW

Yes you are right to suggest celestial navigation which I am prepared to do but just think of how much better I would feel and my crew would feel if I were able to get a GPS fix!!!!!!
thanks
rdw

A small Garmin hand held in a Faraday box and a small Tupperware container full of Lithium AA batteries will get you many, many, many hundreds of GPS fixes and could conceivably give you well in excess of a two months worth of 4X - 6X per day GPS fixes with DR taking up the in-between times.... My little Garmin will run 18 hours straight on two standard AA batteries, considerably longer with AA Lithium. Running it 4X- 6X per day just to get a lat - lon and you might even be able to go six months on a small supply of Li AA's... Probably the most simple and water proof...

[socaldmax]

Originally Posted by RDW

Btrayfors, So what happens to the volts out of a solar panel when shaded?
I do have a multimeter. It was part of stating the question.
Thanks for your help. It was most gracious.
rdw

You're on the right path. Most laptop power supplies put out about 19v. A lot of older solar panels put out 18 - 21v. If you hooked up the output of the panel(s) to the laptop and monitored the voltage under load, you might end up at 18-19v without having to do any McGyvering. If the voltage is too high, you can always lay a towel over a small section and gradually adjust the voltage up or down, with a small loss in current. But hey, at least you're getting what you can out of it.

Newer solar panels might be putting out higher voltage, possibly between 28 - 65v, in which case I'd adjust the open circuit voltage to 19v, then readjust it back up to 19v under load.

Then just use the laptop's USB ports to charge up whatever USB devices you want.

I also have a very small solar charger with a battery and 2 USB ports, it's exactly the same size as my Samsung Note 2 phone. The battery is rated something ridiculous like 10,000 mAH, but in reality, it's about the same as my phone's battery cap. One side is completely covered in solar panel, and small LEDs tell you if it's charging or discharging. They're kinda handy and cheap on Ebay, about $10-20.


What you can achieve is limited only by your own ingenuity. I once reattached the front 1/2 of the siding of an RV in a huge wind and rain storm by detaching the truck, using the bed rails as a step stool and using a large number of screws and a cordless drill. I also reattached a guy's shocks onto his vehicle with a roll of duct tape, then won the $20 bet from the owner when we got home and his shocks were still attached. LOL

You have to take care to think things through, Murphy's law is always in effect, as I learned when I used a coat hanger to strap down a battery in an old Chevelle when I was 18. It wasn't that tight, and when I turned across oncoming traffic at 55, the battery slid over, positive post hit the metal hanger and the car died instantly, right across both lanes. I was lucky the other drivers all avoided hitting me!

I learned a lot from that lesson! I've made other emergency type repairs since, but much better thought out, and repaired properly as soon as possible.

[newhaul]

Why not throw something like this AGM battery in the cage with the backup GPS hook solar panel to it then hook to chargers for electronic toys.
AP-1290 - Amstron 12V / 9Ah Sealed Lead Acid Battery w/ F1 Terminal hard to not suggest this option kiss

[zboss]

Originally Posted by RDW

The white plugs that come with the apple products are not technically chargers but are voltage regulators which take the voltage down to 5V. QUOTE
The white plugs convert AC to DC and then to 5 volt, 2, or 2.4 volt,,,,,,, I think.
rdw

Exactly.

Originally Posted by Nicholson58

There are special solar panels with built-in controls for laptop and cell phone charging. We bought one that folds up like a small portfolio but can run a laptop.

You could get an alternate charge controller for your panels or a dc-dc converter for the correct voltage.

Yes, I've always wanted to get one of the solar panel backpacks.

http://www.voltaicsystems.com/