Solar chargers?

Thomas Wright said:

Hi

I'm looking to buy one of the above for charging two AA batteries whilst on
expedition - does anyone have any recommendations (or disrecommendations
for that matter?) I've seen one from Silva, and a foldable thing from
Coleman/ICP - has anyone used either of these?

Thanks!

Thomas,

No experience of the brands you mention but I have successfully used a
couple of Maplin cat No RR538 variable voltage charger panels to charge
my GPS NiMH AAs and a rechargeable 9V PP3 battery all spring and summer
this year. One set in use, one charging.

Maplin do sell other types.. try

http://www.maplin.co.uk/Search.aspx?criteria=solar%20battery%20charger&doy=14m9&source=15)

The variable voltage charger panel is versatile. It is fairly large,
but not overso, and is not very heavy. Size and weight may be an
important consideration for you if backpacking.

The better the charging ability, the larger area of solar cells you
need, so a small device is unlikely to recharge high capacity batteries,
like those GPS devices need, at any useful rate. They might keep already
charged batteries fully charged for emergency use but little else.

I find you really need only light cloud cover or better still direct
sunlight to really charge well. With 12 hours bright sunlight a day I
can usually recharge 2000 mAH batteries in a couple of days.

I don't think these solar chargers will be any use soon as we go in to
autumn and winter. Whether they would work for you would depend where
you are going and how much sun and daylight hours you expect.

DDM in sunny Brum with batteries charging happily.

Not much use to the OP yet, but an interesting idea that might be
be manufactured eventually : a rucksac that generates power while
the wearer is walking.

http://www.scienceblog.com/cms/node/8874/

Note that the load has to shift while walking : it's that movement
that generates the power. This doesn't sound very desirable and would
certainly make the frame more complicated / heavier. It's interesting
though that they claim it was seen to improve the wearer's gait.

-adrian

Adrian Godwin said:

Not much use to the OP yet, but an interesting idea that might be
be manufactured eventually : a rucksac that generates power while
the wearer is walking.

http://www.scienceblog.com/cms/node/8874/

Note that the load has to shift while walking : it's that movement
that generates the power. This doesn't sound very desirable and would
certainly make the frame more complicated / heavier. It's interesting
though that they claim it was seen to improve the wearer's gait.

20 to 38 kg dangling off me while climbing up a steep hill?!? That's
got to be it - I can't wait to buy one of those!
--
Rudi Winter, Aberystwyth, Wales

Thomas Wright said:

Hi

I'm looking to buy one of the above for charging two AA batteries whilst on
expedition - does anyone have any recommendations (or disrecommendations
for that matter?) I've seen one from Silva, and a foldable thing from
Coleman/ICP - has anyone used either of these?

Thanks!

If the foldable thing is the ICP iSun then I have used this for two
years and highly recommend it. Used in conjunction with the battery pack
it charges my pocket pc, phone, shaver, camera and GPS. It was used for
two months on the SWCP and that was a big saving in batteries.
It also fixes on the the handlebar bag on my bike when I am cycle touring.

--
Regards, Kenneth.
www.kmiles.co.uk

Only 2 AA's? How many recharges do you think you'll be needing? If it's
not too many, I would seriously consider skipping the whole solar
charger thing and just carrying a few extra pairs of high-capacity
batteries instead. I just finished testing a pair of Energizer e2
Lithium AA's (non-rechargeable) and I was amazed at how long they
lasted in my digital camera. I got 520 shots out of them, wheras I
normally get about 225 using my standard 2500 mAh rechargeables. Plus,
the lithium batteries are noticeably lighter.

Dan said:

Only 2 AA's? How many recharges do you think you'll be needing? If it's
not too many, I would seriously consider skipping the whole solar
charger thing and just carrying a few extra pairs of high-capacity
batteries instead. I just finished testing a pair of Energizer e2
Lithium AA's (non-rechargeable) and I was amazed at how long they
lasted in my digital camera. I got 520 shots out of them, wheras I
normally get about 225 using my standard 2500 mAh rechargeables. Plus,
the lithium batteries are noticeably lighter.

How did they make lithium AA's? As I understand it, Lithium-based cells are
3v each, but AA's are 1.2-1.5 volts. Is one a dummy (conductor) cell, and
the other one the actual lithium cell?

Where did you get them from? I've had a look in all the usual places
(jessops, mymemory, google, pricerunner) without any success. This sounds
like a viable alternative: thanks for suggesting it!

I don't know how they make them, but they are designed to replace
ordinary AA batteries. I do have to warn you that some camera
manufacturers don't approve of them. Apparently lithium batteries can
deliver so much current that they are capable of overheating the camera
if you take a large number of shots in rapid sequence.

Here in Honolulu I just picked them up in Wal-Mart. As I recall, they
cost around US $5.50 per pair. They also sold an eight-pack at a
slightly cheaper per-battery cost.

Try a Google search on "Energizer e2 lithium".

Rudi Winter said:

Adrian Godwin said:

http://www.scienceblog.com/cms/node/8874/

Note that the load has to shift while walking : it's that movement
that generates the power. This doesn't sound very desirable and would
certainly make the frame more complicated / heavier. It's interesting
though that they claim it was seen to improve the wearer's gait.

20 to 38 kg dangling off me while climbing up a steep hill?!? That's
got to be it - I can't wait to buy one of those!

It's presumably reasonable for the military who might want to run all
the mentioned kit. But note that in their trial they were generating
7W of power : the smaller Maplin chargers mentioned in this thread
produce between 1 and 2W in bright sunlight (probably less in typical
UK conditions). Other models might produce more.

So we might expect to generate a useful level of power with only a
half or a quarter of that load. 10kg wouldn't be unreasonable at all,
and it's likely that in the future the mechanical arrangements will be
refined and couple the movements more efficiently to the generator.

OK, it's not that useful yet, but it's worth watching.

-adrian

Dan said:

Here in Honolulu I just picked them up in Wal-Mart. As I recall, they
cost around US $5.50 per pair. They also sold an eight-pack at a
slightly cheaper per-battery cost.

Maplins have got them:

http://www.maplin.co.uk/Search.aspx?criteria=lithium%20aa&doy=14m9&source=15

Yet another case of 1$=1£ in Rip-Off U.K. 8^{

Jim Ford

Dan said:

I don't know how they make them, but they are designed to replace
ordinary AA batteries. I do have to warn you that some camera
manufacturers don't approve of them. Apparently lithium batteries can
deliver so much current that they are capable of overheating the camera
if you take a large number of shots in rapid sequence.

From Energizer's website, it looks like they're lithium iron disulfide,
rather than lithium manganese dioxide - I don't know enough chemistry to
understand why the latter has twice the cell voltage of the former, but the
different chemicals must explain the difference

Jim Ford said:

Maplins have got them:

http://www.maplin.co.uk/Search.aspx?criteria=lithium%20aa&doy=14m9&source=15

Thank you!

Quoted message said:

Yet another case of 1$=1£ in Rip-Off U.K. 8^{

yep, come to expect that by now but it doesn't make it excusable.

Thomas Wright said:

Jim Ford said:

Maplins have got them:

http://www.maplin.co.uk/Search.aspx?criteria=lithium%20aa&doy=14m9&source=15

Thank you!

Quoted message said:

Yet another case of 1$=1£ in Rip-Off U.K. 8^{

yep, come to expect that by now but it doesn't make it excusable.

O.T.: I've just bought a Golite Trek rucksack direct from the States.
They're around the £100 mark over here - I paid $97. The postage on top
of that was $37, so all-in I ended paying about £72!

Jim Ford