Update on USPS Global Priority (Airmail)

Laurence Dodd said:

I received my new Cateye Stadium 3 bikelight system from Bikeman.com

It only cost Aus$611.33 and that includes US$40 for freight and insurance,

You ... spent ... $600 ... on a bike light !!!????

Don't you think there is something a little obscene about that?

And it uses a NiMH battery! Isnt that a bit like getting a porsche
and finding it has solid rubber tyres?

Fer christ sake, ditch the el-cheapo boat-anchor battery and get a
LiIon. About $200 for a 8-cell 60WHr model.

$200 for a battery, that's obscene :-)

Funnny how different people have different priorities. You have to
smile when Mike criticises a bloke for spending $600 on lights, then
suggests he spends another $200 :-)

John L

Mike said:

You ... spent ... $600 ... on a bike light !!!????

Don't you think there is something a little obscene about that?

And it uses a NiMH battery! Isnt that a bit like getting a porsche
and finding it has solid rubber tyres?

Fer christ sake, ditch the el-cheapo boat-anchor battery and get a
LiIon. About $200 for a 8-cell 60WHr model.

John L said:

$200 for a battery, that's obscene :-)

Funnny how different people have different priorities. You have to
smile when Mike criticises a bloke for spending $600 on lights, then
suggests he spends another $200 :-)

For the humour/irony impaired: :-) :-) :-) ;-)
I hate having to use smileys.

Those metal-halide lamps really are impressive technolgy though.
I believe they are rougly as efficient as florescent lights,
but its awfully hard to focus a floro.

I just wanted to say:
a) it seems an awful lot of money, when 10-20W halogens work just fine.
But as you say, thats just my priorities.
b) it does seem odd to not use LiIons with that kind of budget,
considering the emphasis many cycling accessories put on weight.
I guess its just too new, and we will see LiIon in more places soon.

Quoted message said:

b) it does seem odd to not use LiIons with that kind of budget,
considering the emphasis many cycling accessories put on weight.
I guess its just too new, and we will see LiIon in more places
soon.

The latest crop of NiMH have about the same energy density by volume
as Li-ion, at a`fraction of the cost. Of course, by weight, Li still
wins, but they suffer a range of other issues (discharge cycle life,
low maximum discharge rate, deep discharge intolerance, special
charging need, explosion/fire risk).

"Glen F" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

b) it does seem odd to not use LiIons with that kind of budget,
considering the emphasis many cycling accessories put on weight.
I guess its just too new, and we will see LiIon in more places
soon.

The latest crop of NiMH have about the same energy density by volume
as Li-ion, at a`fraction of the cost. Of course, by weight, Li still
wins, but they suffer a range of other issues (discharge cycle life,
low maximum discharge rate, deep discharge intolerance, special
charging need, explosion/fire risk).

Best energy density I could find in NiMH was a Sanyo 4/3FA, 18mm dia by 67.5
long, and 62g, for 4500mAh at 1.2V.
http://www.master-instruments.com.au/browse/Model/HR_4_3FAU.html

That works out to 87 Joules/kg, and 314 Joules/litre (assuming you can pack
them 100%, which you can't because they're round).

In Li-Polymer, I found the following:
http://www.master-instruments.com.au/browse/Model/SLPB526495.html which is
95mm x 64mm x 5.4mm, and 64g, for 3270mAh at 3.6V

That works out to a whopping 184 Joules/kg, and 359 Joules/litre.

If I were shelling out $600 for a light, I know which I'd go for. Just
think, 2 hours of 20W light in 250g...

As for charging difficulty and explosion risk, they're perfectly happy in my
notetoy.

Regards,

Suzy

Quoted message said:

Best energy density I could find in NiMH was a Sanyo 4/3FA, 18mm
dia by 67.5 long, and 62g, for 4500mAh at 1.2V.
http://www.master-instruments.com.au/browse/Model/HR_4_3FAU.html
That works out to 87 Joules/kg, and 314 Joules/litre (assuming you
can pack them 100%, which you can't because they're round).

In Li-Polymer, I found the following:
http://www.master-instruments.com.au/browse/Model/SLPB526495.html
which is 95mm x 64mm x 5.4mm, and 64g, for 3270mAh at 3.6V

That works out to a whopping 184 Joules/kg, and 359 Joules/litre.

Which is about the same volume energy density as your NiMH figure -
as I said. Also, we were comparing Li-ion (which ARE round), not
the newer Li-Polymer flat cells.

For info, the latest "Energiser" NiMH AA claims 2100mAh at nominal
1.2V = 2500mWh (actually that will be a bit less due to the voltage
depression during discharge). That is about 2.5 x 60 x 60 = 9000J.
The package is about 50mm x 14.5mm dia = 0.008L, so we have 1100kJ/L
Suggest maybe check your math...

"Glen F" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Best energy density I could find in NiMH was a Sanyo 4/3FA, 18mm
dia by 67.5 long, and 62g, for 4500mAh at 1.2V.
http://www.master-instruments.com.au/browse/Model/HR_4_3FAU.html
That works out to 87 Joules/kg, and 314 Joules/litre (assuming you
can pack them 100%, which you can't because they're round).

In Li-Polymer, I found the following:
http://www.master-instruments.com.au/browse/Model/SLPB526495.html
which is 95mm x 64mm x 5.4mm, and 64g, for 3270mAh at 3.6V

That works out to a whopping 184 Joules/kg, and 359 Joules/litre.

Which is about the same volume energy density as your NiMH figure -
as I said. Also, we were comparing Li-ion (which ARE round), not
the newer Li-Polymer flat cells.

For info, the latest "Energiser" NiMH AA claims 2100mAh at nominal
1.2V = 2500mWh (actually that will be a bit less due to the voltage
depression during discharge). That is about 2.5 x 60 x 60 = 9000J.
The package is about 50mm x 14.5mm dia = 0.008L, so we have 1100kJ/L
Suggest maybe check your math...

On ebay at present, there are some bulk lots of batteries:

48 2100mAH AA (currently $240)
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=3051203036&category=31581

20 Nokia lipo batteries (currently $150) (3.6V about 900mAH)
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=3052297418&category=31581

A possibly cheap way of making a few lighting system packs?

Tim

Quoted message said:

On ebay at present, there are some bulk lots of batteries:

48 2100mAH AA (currently $240)
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=3051203036&category=31581

That's ~$5ea - they are cheaper retail at some sources,
and you don't have to buy 48! Ebay can be very odd...

Quoted message said:

20 Nokia lipo batteries (currently $150) (3.6V about 900mAH)
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=3052297418&category=31581

A possibly cheap way of making a few lighting system packs?

The Li's only if you know EXACTLY what you are doing. There
are several rather serious issues, not least the explosion
risk.

"Glen F" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Best energy density I could find in NiMH was a Sanyo 4/3FA, 18mm
dia by 67.5 long, and 62g, for 4500mAh at 1.2V.
http://www.master-instruments.com.au/browse/Model/HR_4_3FAU.html
That works out to 87 Joules/kg, and 314 Joules/litre (assuming you
can pack them 100%, which you can't because they're round).

In Li-Polymer, I found the following:
http://www.master-instruments.com.au/browse/Model/SLPB526495.html
which is 95mm x 64mm x 5.4mm, and 64g, for 3270mAh at 3.6V

That works out to a whopping 184 Joules/kg, and 359 Joules/litre.

Which is about the same volume energy density as your NiMH figure -
as I said. Also, we were comparing Li-ion (which ARE round), not
the newer Li-Polymer flat cells.

For info, the latest "Energiser" NiMH AA claims 2100mAh at nominal
1.2V = 2500mWh (actually that will be a bit less due to the voltage
depression during discharge). That is about 2.5 x 60 x 60 = 9000J.
The package is about 50mm x 14.5mm dia = 0.008L, so we have 1100kJ/L
Suggest maybe check your math...

Math is ok, units are up the creek. Units are actually Wh/kg and Wh/litre.

Converting to Joules, we have 313kJ/kg and 1130 kJ/litre for the NiMH, and
662kJ/kg and 1300kJ/litre for Li-Poly.

Your comment about Li-Ion and Li-Poly being an explosion risk is specious,
IMHO. Just because you can't charge them with a plug pack and a series
resistor doesn't mean they're difficult to use. All you need is a simple
(relatively accurate) current limited and voltage limited power supply, and
you're made. In fact, fast charging Lithium chemistry batteries is
considerably easier than NiMH and NiCd, as you don't need thermistors or a
peak detect cct.

As for discharge, a simple comparator and power fet is all that's required.

Regards,

Suzy