Battery-Driven Tanis

On Feb 1, 8:26 am, "BDS" wrote:
That might not work so well in an application like this. If he has the 250
watt heater and runs it for 3 hours then he has removed 750 watt-hours of
energy from the battery (plus change).

A typical solar panel charger is meant for trickle charging and they only
put out something like 10 watts or less, although I've seen some up around
20 watts. That means that it will take 75 hours of charging time at 10
watts to replace that 750 watt-hours, and that's at 100% efficiency which,
as well all know, doesn't exist.

There's a guy with a solar-power setup on the ramp but I've never been
able to run into him to pick his brain. A friend heard that he has his
thing patented so I might get little info other than a price... I
researched the solar powered thing briefly but stopped after the
numbers on the napkin hit 4-digits to the right of the dollar sign.


Most of these deep cycle cells are looking for a charge at around 20 amps
for 10 hours or so to bring them up to full charge, and then a float charge
to hold the terminal voltage around 13.8 volts.

Either a generator or a propane-fired pre-heater is the way to go here.

Yeah, I think a generator is the ideal thing. Plus, I can use it for
many different applications as well.

Marco Leon wrote:
On Feb 1, 8:26 am, "BDS" wrote:
That might not work so well in an application like this. If he has
the 250 watt heater and runs it for 3 hours then he has removed 750
watt-hours of energy from the battery (plus change).

A couple of web sites quote a 170 W BP solar panel at around $850. In
full sun this would take about four and a half hours to recharge the
battery. A 115 watt panel would take about six and a half hours and
cost $650. Add another $200 for a charge controller, wiring, etc and
another $100-$200 for the battery.

There's a guy with a solar-power setup on the ramp but I've never been
able to run into him to pick his brain. A friend heard that he has his
thing patented so I might get little info other than a price...

I am not an attorney and this is not legal advice.

The US patent system is totally broken, so it wouldn't surprise me if
such a thing was patented. If it is, get the patent number out of him,
then go look it up at Google or at the Patent and Trademark Office and
you should get a full description. If you like what you see, and the
guy isn't an attorney himself, build one of your own and don't worry
about it. He has to sue you to get anywhere, and it's pretty easy to
show prior art... look at the Bell Labs literature from the 1950s and
I'm sure you can find "hey, you could charge a battery with these
things" in no later than the third article ever written about them.

I am not an attorney and this is not legal advice.

I researched the solar powered thing briefly but stopped after the
numbers on the napkin hit 4-digits to the right of the dollar sign.

If you want to have a reasonable chance of being able to pre-heat the
next day, I'd believe it - see above.

Matt Roberds

wrote

A couple of web sites quote a 170 W BP solar panel at around $850. In
full sun this would take about four and a half hours to recharge the
battery. A 115 watt panel would take about six and a half hours and
cost $650. Add another $200 for a charge controller, wiring, etc and
another $100-$200 for the battery.

Well, it looks like they are out there and available as you've pointed out.
When I looked at websites that offered them as battery chargers I only found
the smaller ones meant to keep an already charged battery at full charge.

Still, this is much more expensive than a small generator would be, and
depends on things like sunny days and being kept clear of ice and snow. The
small generator is the way I'd go if it were me.

There's a guy with a solar-power setup on the ramp but I've never been
able to run into him to pick his brain. A friend heard that he has his
thing patented so I might get little info other than a price...

I am not an attorney and this is not legal advice.

I'm not an attorney either but I don't think you would get into any trouble
building one for yourself for your own use - who is going to hire an
attorney to sue you for $1,000 (the cost of pursuing it would be orders of
magnitude higher than that) and what attorney would be interested in such a
case? If you started manufacturing them and selling them, that would be a
different story.

BDS

BDS wrote:
Well, it looks like they are out there and available as you've pointed
out. When I looked at websites that offered them as battery chargers
I only found the smaller ones meant to keep an already charged battery
at full charge.

Those are popular because they're cheap - the solar cell itself is much
cheaper, and the control gear is much simpler - usually just a simple
diode to keep the battery from discharging through the solar cell at
night. Unless you hook one of those 10-20 W cells up to a tiny battery,
it'll never overcharge the battery, even in full sunlight at the equator
on the longest day of the year. They work pretty well for vehicles that
have to be parked in remote areas for long periods of time.

Bigger cells need a charge controller, both to regulate the charging
current to the battery, and to maximize the power output from the solar
cell. A 150 W nominal solar cell might actually give you full output
at 15 V, 10 A. If you draw 11 A you might drag it down to 13 V (143 W
output) and if you draw 9 A it might only go up to 16 V (144 W output).
The charge controller can "learn" the characteristics of the solar cell
and adjust how much power it's trying to draw. They are usually easy
to hook up - they are basically a box of electronics with terminal
strips on it and maybe a dial to adjust the battery charging rate - but
they aren't particularly cheap.

Still, this is much more expensive than a small generator would be,
and depends on things like sunny days and being kept clear of ice and
snow.

True. At the moment, solar seems to be a win if the other options are a
lot more expensive or impractical for some reason - if you have a cell
site on the side of a mountain somewhere, few people want to pay to
string a power line to it, nor do they want to pay somebody to drive a
fuel truck up there every so often. Solar cells are also quiet and have
no moving parts, which can be an advantage in some applications. Their
efficiency seems to be improving similarly to that of internal
combustion engines - probably nobody is going to triple the efficiency
of either device overnight, but with lots of work, it can get a percent
or two better a year, and if you keep at it, it gets more and more
practical.

I'm not an attorney either but I don't think you would get into any
trouble building one for yourself for your own use - who is going to
hire an attorney to sue you for $1,000 (the cost of pursuing it would
be orders of magnitude higher than that) and what attorney would be
interested in such a case?

That's why I included the disclaimer "[if] the guy isn't an attorney
himself". If his time is "free" he can sue you for fun.

Matt Roberds