Re: Portable batter packs and Solar Charging?

From Wear-Hard Mailing list Archive (WH) Maintained by R. Paul McCarty

Thank you for the long and informative post. I plan to read it all
through later, just wanted to quickly respond to a couple of things:

On 7/11/06,  <> wrote:
> Are you aiming for actually running the wearable off solar cells, or
> just using them instead of a "wall wart" charger?

I wanted to explore some options. The solar backpack seems like a good
idea if you want to charge phones, PDA's, etc. But if I wanted to have
an AC source available, it didn't look like a possibility.

> I think your main trouble here might be finding an inverter that runs
> on 7.2V. With the battery pack charged, you have 2.2AH available,
> which is not bad. My current wearable is designed to use 7.2V, so it
> could run off that. The thing is, since you would be drawing from the
> battery faster than you would be recharging it, the solar cells might
> not help much.

Wasn't looking for continuous use. The idea I had in mind was to wear
the backpack, charge the battery, maybe keep some low power devices
like a phone and PDA plugged in all the time (which I think the solar
could keep up with). Then if I needed an emergency AC plug for just a
few minutes, I plugged in the inverter and I had it. When done, let
the battery charge up again till I needed another few minutes of AC
(or move to somewhere with a wall outlet, or my car with a bigger
battery ;-)

...

> That thing looks pretty cool. The line "The Powerpack has a nickel
> metal hydride (NiMH) battery you can recharge using household
> electricity or 12 V DC power from a vehicle DC outlet" makes it sound

Readying further shows it's not as simple as they make it sound on the
packaging. The battery charger runs off AC. If you need to charge it
in a car/airplane, you plug the battery charger into the inverter and
the inverter in to the car/airplane. [Since there's only one AC plug,
unless you also carry a small power strip, you can't run the laptop
off the car/plane at the same time as you charge the battery]

That also means if you're 12V supply can't provide enough current to
run the inverter, you can't charge the battery. Also, to do all that
you have to carry around several cables that take up as much space as
the battery and inverter themselves.

> like if you can supply 12V at some reasonable current, you may be able
> to charge it off solar cells. Whether you can wear a sufficient solar
> cell is another question entirely.

The concern is that a) there isn't 12V and b) even if there was, it's
not enough to power the inverter and charge the battery. And c) the
extra weight of carrying around all those cables. I would rather the
battery charged off DC, and if you wanted to charge it using AC you
use a standard wall wart to get the DC.

--
Craig

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