12v battery charging from an 18v portable solar panel?

[inetdog]

...Worst case scenario and a decent size panel its possible, better than nothing. I know if I was in the wilderness and only had a 40 watt panel I would try it.

I would try almost anything if I found myself in the wilderness with no other options. I would even try McGyvering.
But I would not go into the wilderness in the first place planning to use that as my main backup.
And I might find better uses for the weight and expense during that planning process. Maybe a lithium battery jump start pack for example. (Not planning to use that pack for routine loads, although it would be capable of that too.)

[russ]

I know if I was in the wilderness and only had a 40 watt panel I would try it.

Better off to spend that time hiking to where you can get assistance. What you suggest is peeing into the wind.

[Jeff-oh]

Your posts seem more condescending than constructive. Which is pretty surprising coming from a "moderator". I'm not sure why you'd talk down to me just because I'm not as well versed in solar technology as you.

I'm with you Dave, I too was very surprised. Particularly since your question seemed fair.

40W /17V is ~2.25A thus it would take a long time to charge a 60 Ah battery at 5 hours per day... i.e. a week or so... but stranded in an emergency it could be your only option, if not ideal.

FYI this exact situation happened to me. We were fishing in the back woods of N. Ontario about 60 Km from the nearest town. I did not fully latch the back cab window and a dome light was left on all day. Dead battery. Your idea would have been ok. We could have easily placed the battery and panel in full sun all day for several days as needed.

As we did not have that option we canoed a series of 5 lakes to the Rail line then hiked the line until we came across a work crew. They gratefully placed the canoe in the back of their truck (F350 with the Railroad wheels) and drove backwards down the line to their bunk house where we called the local garage man who came and picked us up and took us back to the camp.... A day long adventure.

[russ]

I'm with you Dave, I too was very surprised. Particularly since your question seemed fair.

40W /17V is ~2.25A thus it would take a long time to charge a 60 Ah battery at 5 hours per day... i.e. a week or so... but stranded in an emergency it could be your only option, if not ideal.

FYI this exact situation happened to me. We were fishing in the back woods of N. Ontario about 60 Km from the nearest town. I did not fully latch the back cab window and a dome light was left on all day. Dead battery. Your idea would have been ok. We could have easily placed the battery and panel in full sun all day for several days as needed.

As we did not have that option we canoed a series of 5 lakes to the Rail line then hiked the line until we came across a work crew. They gratefully placed the canoe in the back of their truck (F350 with the Railroad wheels) and drove backwards down the line to their bunk house where we called the local garage man who came and picked us up and took us back to the camp.... A day long adventure.

Foolish person! To go where you did and do something dumb like that? You deserved what you got. I can easily think of a few hundred other things you could also carry in case of emergencies that would be more likely to be of use.

[PNjunction]

Dave - why don't you look at what I do when camping light with a dinky panel, but still need to have the assurance of being able to jump a car to get off the mountain fast:

http://www.solarpaneltalk.com/showthread.php?18771-NOCO-Genius-Boost-GB30-lithium-jumpstarter

This is a far more reliable solution. Use the dinky panel to charge the NOCO lithium jumpstarter if needed. Mine charges from empty to a full charge in about 3 hours with nothing but a 14w Anker panel. It does double duty as the cellphone / tablet charger, and charges in hours or less instead of days. There are similar products out there, but you may want to make sure it has a usb charging jack to make it convenient for use with the typical folding camping panels.

While I might like to justify waiting days for the vehicle battery to charge directly from the camping panels, my buddies want to leave NOW.

[Bucho]

I can currently use it to charge my portable powerbank to keep my phone charged. There are times when I'm several miles into a state forest or something and could potentially be stranded if my car battery failed.

So I gave one of these little panels a try when I hiked the Appalachian Trail, turns out there's not much sun in the woods. I've been wondering about this: http://sectionhiker.com/npower-peg-k...aaron-lemieux/

[bcroe]

When I was a kid, my bicycle lights at around 6 W were powered by me, via a generator
against the wheel. It didn't slow me much. Seems to me, someone needs to figure how
to connect a "generator" to a hiker and grab several watts. Bruce Roe

[Bucho]

Seems to me, someone needs to figure how
to connect a "generator" to a hiker and grab several watts. Bruce Roe

That's what the device I linked to is.

[bcroe]

That's what the device I linked to is.

OK, my oversight. If it will consistently deliver 2.5 watts, it will be hard to find a competing
PV solution. Unless you are hiking in the desert. Works all the time, all weather. I'm
guessing its on the heavy side, to absorb that much power. I hypothesize, a lower power
version could be proportionately lighter.

Looks like battery storage and regulation to a USB is all worked. Bruce Roe

[russ]

OK, my oversight. If it will consistently deliver 2.5 watts, it will be hard to find a competing
PV solution. Unless you are hiking in the desert. Works all the time, all weather. I'm
guessing its on the heavy side, to absorb that much power. I hypothesize, a lower power
version could be proportionately lighter.

Looks like battery storage and regulation to a USB is all worked. Bruce Roe

Even in the desert you either have to constantly adjust a panels direction - I guess you could place the panel on top of a treking pole that you twist and turn to keep it aimed at the sun - seems a bit silly.

14 oz. is not light weight for long trips where every oz. is considered. To that you have to ad the weight of the assorted electronics that the hiker could now carry. Maybe better to just camp out in the back yard.

It would be interesting to see the evaluation of an independent user as to how much power is estimated. This is far in excess of what a bike or tread mill can generate.

[Bucho]

14 oz. is not light weight for long trips where every oz. is considered. To that you have to ad the weight of the assorted electronics that the hiker could now carry. Maybe better to just camp out in the back yard.
generate.

Considering I carried around 25lbs on my thru hike, yeah 14oz is a lot but I don't think solar would be lighter. So considering that all the gear stores seem to have solar panels some people must be willing to carry the weight.

[russ]

Considering I carried around 25lbs on my thru hike, yeah 14oz is a lot but I don't think solar would be lighter. So considering that all the gear stores seem to have solar panels some people must be willing to carry the weight.

Stores will sell anything some sucker will buy - good, bad, legal, illegal, useful or useless.

We used to count every oz - carrying heavier packs for longer though.

[Bucho]

Stores will sell anything some sucker will buy - good, bad, legal, illegal, useful or useless.

The point being there clearly must be a market.

We used to count every oz - carrying heavier packs for longer though.

We were keeping track down to 1/10th of an ounce when I hiked the AT. That said the average thru hiker still carries at least one thing they really don't need.

[bcroe]

We used to count every oz - carrying heavier packs for longer though.

Seems like with so many people addicted to their "personal devices", this
power source is a solution to the power problem, at a weight cost. I'm guessing
the battery serves as both the inertial weight for the generator and the storage
medium.

With success, I can imagine development of an improved model. The weight
would become the actual pack, and the generator would be built into the frame
supporting the pack. Storage might be reduced if the generator primarily fed
energy into the devices instead of its own energy bank. Bruce Roe