More battery questions, this time solar

So I was looking at some of the Goal Zero stuff and kept thinking it was way too expensive for what you get.  Certainly I can attempt to build something cheaper.

I was wondering for those Li-Ion or Lipo batteries you all are using, if charging from an unregulated 13-15V supply from a solar panel is ok?

Not all batteries are created equal.  I was looking at the Anker® Astro3 10000mAh that craig likes.  It can take an input 9-15V / 1A.  But in looking at the Anker® Astro Pro2 20000mAh Brain was looking at for his power sink, it takes 15-19V.

-Allen

It should be doable.  I know Hobie has a setup that can supposedly run the torqueedo drive at 2.5 mph forever as long as there is sunlight.

I was looking at the goal zero battery packs too, and came to the same conclusion.  Too expensive compared to other options. I do like the panels though.

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Totally doable.  The charger that comes with these things is just a 12 V wall wart plug.  The charge management chip is inside the battery, not the charger so if you can give it a steady 12 volts and your good.  I'm sure one could find a simple voltage regulator circuit for sale in the interwebs for not too much.  Or I could whip some up and sell them.     What would really be nice is to have a voltage regulator circuit that uses a buck/boost switching converter to provide a steady 12 volts, or even 15, or 19, whatever you program it to give.  That way you're not wasting any energy coming from the panel since those things have efficiencies of about 95%.  I just got done designing one for a project I did.

I was kind of wondering why the 20000 mAH one had an input spec of 15-19V.  It seemed less "standard".

-Allen

That is weird, I admit.  Maybe it has something to do with the fact that it's 20 Ah.  Maybe it needs a higher voltage so that the charge time isn't really long.   

The Goal Zero panels actually aren't that bad a deal.  It's the battery packs that they are expensive, likely because they are do-all battery packs.  They hook up to every device imaginable including 19V laptop sources.  I think I may get a 10000 mAH battery and a Goal Zero Nomad 13 and see what happens.

-Allen

I was wondering for those Li-Ion or Lipo batteries you all are using, if charging from an unregulated 13-15V supply from a solar panel is ok?

Totally doable.  The charger that comes with these things is just a 12 V wall wart plug.  The charge management chip is inside the battery, not the charger so if you can give it a steady 12 volts and your good.

Word of caution for any non engineers / geeks reading this: I think that Rawkfish is correct for these particular batteries, but I wouldn't use an unregulated source for standard lithium batteries. They like to have clean direct power. Otherwise, you could damage the cells or worst case melt through your tupperware boat.

One thought: Check out the different hobby / electrical sites for switching BECs - that might work if using unregulated lithium cells. CastleCreations had one that would probably fit the bill (up to 25V input and 9V output). If you're wanting a 12V output, I'm sure something like that exists as well. You could probably post your needs on a forum like RCGroups and get some great responses quickly.

*word of caution to my caution - I am not an engineer nor do I play one on TV. I've just tinkered a fair bit with some fun toys and have seen some of them melt. 

Allen, you might do better with the boulder series from goal 0, unless you need it to be packable.

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Allen, you might do better with the boulder series from goal 0, unless you need it to be packable.

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For the kinds of trips I do and for what I have in mind for this, I need it to be packable.

-Allen

Christmas Island will never be the same.....

"Dear Goal Zero, I'm doing this trip you see, and I'll write you a review ..."

Bam!

On my front doorstep today.  Review to come next week.   

-Allen

Score! Those look pretty sweet.  Have you used any of their products before?

"Dear Goal Zero, I'm doing this trip you see, and I'll write you a review ..."

Bam!

On my front doorstep today.  Review to come next week.   

-Allen

That's one way to answer your questions.      

OK.  I read the directions.   Yes, I did!     So I thought I'd share some first impressions.

It looks like they use 6 Lithium Ion cells in the battery pack.  Three 2.6 Ah cells in series for a 12V output.  Two of these 3-packs in parallel to make a 5.2 Ah power source.

Not that while Lithium Ion cells are 4.3V when fully charged, they spend the majority of time at 3.6V before being discharged at 3V.  This is entirely consistent with the voltage output range of 9-13.  3*3=9 and 3*4.3=13.

So I'm going to guess that the 12V output runs straight off the battery and doesn't suffer  the inefficiencies of conversion like the Anker batteries do.

Still $199 seems expensive to me just for just the Sherpa 50 battery pack.  But it does work with the rest of the goal zero stuff so no need to make plugs and adapters.  I was also sent a 110V inverter.  It plugs right into the side of the Sherpa 50 unit.

The Nomad 13 solar panel is rated 13W.  The Namad 13 retails at $159.  There are 2 physical panels, each 10.5" x 7".  It folds together like a book.  The full Nomad 13 produces an unregulated output of 13-15V sourcing 0-1 Amp.  1 Amp would be in the most direct sunlight.  Note that the spec says it takes 6-12 ours to charge the Sherpa 5 from the Nomad 13 solar panel.  So in less than ideal lighting it can be 1/2 the current (0.5A) or even less.  You could almost power a lower current fishfinder unit directly from the panel.  A neat feature is that you can chain up to 4 of these panels together to increase the current source.  The panels have plugs/ports to do exactly this.

Anyways, those are my first impressions.  More to come after I give it a good shakedown.

-Allen

I spent a few minutes with the many adapters that came with the Goal Zero and the Anker unit trying to figure out if I had the right parts to charge the Anker unit from the Solar Panel.  Unfortunately I don't have the correct adapters at this time, at least not in a straightforward manner in which I connect the 12V output of the Solar Panel directly to the input of the Anker.

I did figure out that with what I have I can connect the Solar Panel to the Sherpa 50 unit, then plug in the 110V inverter to the Sherpa 50 unit, then plug in the 110V charger for the Anker to that.  Probably a lot of inefficiencies in all the conversion going on, but it will work in a pinch.

I don't have the time to get the right connectors before the John Day trip, but once I get back, I'll get them and confirm I can charge the Anker Unit directly.

-Allen