That was an idea for a quick portable system that can be deployed in 15
minutes. I have some 3000 mA 18650's that can deliver a lot of power. I
just don't know how to charge them using solar correctly.
http://www.amazon.com/UltraFire-300...y-Charger/dp/B004LHFU62/ref=pd_bxgy_hi_text_y
Great idea. That is a second project. May even include a transfer
switch to a circuit or two.
Think this through before you start spending money...I didn't.
I found a brand new 5KW generator at a garage sale for $100.
I couldn't pass it up.
Then I found a transfer switch for $50. Might as well get that too.
Then I found some big wire at a garage sale for $20. oooh, need that
too. Then the $15 each plugs to hook it together.
Then, I started thinking about how to do it. The electrical stuff
was trivial. But the permit to install it cost more than the generator.
And my service entrance doesn't meet current code, so there's risk
that the inspector might require a major $$$$ change there if I modify it.
My major concern was to run the furnace air handler so that the pipes
wouldn't freeze in winter. So, I'd just put a plug on the furnace
electrical wire.
Well...the electrical code forbids that. General consensus, verified by
talking to the local inspector, suggests that the "rule" is generally
ignored. But what is the fire insurance underwriter gonna say when
my furnace juice doesn't meet code and the place burned down? His job
is to DENY claims.
NONE OF THE PROBLEMS HAD ANYTHING TO DO WITH ELECTRONS.
Bottom line...anybody wanna get this generator out of my garage???
A sensible approach is to put a pair of isolation diodes and an
additional deep-cycle battery in your car or truck.
Stick an inverter adjacent to the battery and you're done.
You have a general purpose portable power source that can
supply a LOT of power for a short time. And it's always ready.
And it comes with a two-ton charging machine.
Another option is to buy a used UPS. The batteries are always
dead, but the rest often works. Make sure it's a 12V system, not all are.
Hook it up to a deep cycle RV battery and plug it in.
They're not designed to run for a long time, so you'll probably
need a fan on the heat sink.
What follows is a rant. You know where your "next" button is...
The hardest part of any project is deciding what you want to accomplish.
It's easy to lump multiple disparate objectives together and poorly
specify the desired result.
The power going out for a few days after a hurricane is a camping trip.
If you're on life support, that's an emergency.
Having a solar powered led infrastructure in your house is a hobby.
The definition of a hobby is spending WAY too much time and money on
something
that gives you pleasure, but the result is inconsequential.
Lithium batteries and solar is a fine hobby. Just expect to spend
way too much time and $$$$ on it. ;-)
If I were building a lithium standby system out of 18650 lithium
cells, I'd start by figuring out how many peak amps I'd want and
put that many cells in parallel. So, for 100W of 120VAC out of an
inverter, I'd have at least 10 cells in parallel.
If you want longer run time, put more cells in parallel.
Then I'd figure out the voltage output I wanted.
For a load that could tolerate 9V-12.6V, I'd series three.
for 12-16.8V, series 4. Notice that these numbers exceed
the requirements on one end or the other for most inverters.
So, I'd go buy 40 brand new cells from the same batch from
a reliable vendor and weld them
up in sets of 10 with high-current plugs.
Remember that random 5 year old Chinese cells reclaimed from
worn out laptop battery packs and sold on EBAY are not
what you want.
You want recently manufactured cells from a reliable source.
Those are EXPENSIVE!! Fry's gets about $13 each for 'em.
There's a reason a Tesla car costs a hundred grand.
I'd charge them to 3.8V, yes exactly the same voltage.
The optimum voltage may be different. Point is you want
40% of so state of charge.
You want the
state of charge to be EQUAL.
Then I'd stick them in the fridge at just above freezing.
One school of thought holds that at near freezing the actual
state of charge has less effect on cell life...YMMV.
When the hurricane watch goes up, take 'em out, warm 'em up
and charge each pack to 4.2V...Not about 4.2V... LESS than or equal to
4.2000V.
Notice that I didn't say plug them together and charge to 16.8V.
I said make sure the state of charge is equal and you don't
exceed 4.2V on any pack.
Plug them together and run your system.
Have a mechanism that disconnects the load when any cell pack
gets below 3V or so. Don't rely on watching a meter. Fall asleep
and you can snuff your batteries.
THESE NUMBERS WORK FOR SOME, BUT NOT ALL battery chemistry variants.
ASK THE VENDOR FOR NUMBERS and use those.
There's not much solar energy available in the wake of a hurricane,
so you don't need the solar part. IFF the cells are balanced and you
don't go overboard, you can get away with a few charge cycles without
monitoring every pack individually, but I'll deny saying that.
There's typically a pressure disconnect in each cell.
If you over-stress the system and one cell disconnects, that
puts even more stress on the others and the dominoes start to fall.
You have to balance the probability of some fault against the consequences
of that fault and how much liability insurance you have.
Then I'd look at the plan and decide that it's clear that
I should go buy a 12V lead-acid battery instead.
Garden lights make damn fine garden lights...leave them where they
belong.
18650s make horrible laptop batteries, but they're the best we can
afford. Leave them in laptops.
Are we having fun yet?