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Huge wrote:
On 2017-09-13, Tim Watts wrote:
On 13/09/17 14:31, Bill Wright wrote:

Why people buy battery tools to use at home I really don't know.
Ignorance of the customer plus the vendor's sales hype I guess.
Thinking about it, I bet a lot of people who buy a battery drill
have never used an electric drill before, so they won't realise how
limited their new toy is.

Bill


I can counter everything you've just said

10.8V Blue Bosch driver, drill and impact driver are small, light and
surprisingly powerful for their size and I've used mine for years.

36V Bosch garden tools are equal in calibre to mains tools of a
similar size - hedge cutter, lawn mower and strimmer.


The bloke who fitted our kitchen did it entirely with battery tools,
including most impressively, core drilling a 110mm ventilation duct
through a 9" brick wall with a battery drill.

Don't worry - Bill doesn't know anything about anything other than
being a racist bigot.


Bill is cleverer than you.


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On 13/09/2017 20:50, Mr Pounder Esquire wrote:
John Rumm wrote:
On 13/09/2017 19:25, Mr Pounder Esquire wrote:

I felt like Arnold Schwarzenegger when I used it. Me and him look
very similar.


What, old, grizzled, and past it? ;-)


This was in 1999.
These days I am still a man of steel.


Rusty and past it?


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On Wed, 13 Sep 2017 18:25:36 +0100, Tim Watts
wrote:

On 13/09/17 16:49, TMH wrote:

You need to buy some decent kit like Makita.


I have never seen the owner of battery Makita kit moan


I have , he had just found out it had been nicked.

Diverting the thread a bit some battery powered things like lawn
mowers are claimed by their manufactures to be as powerful as petrol
ones eg
https://www.bosch-professional.com/s...n-tools/gb/en/
though craftily they don't say exactly which petrol ones.
Wonder what it would be in watts if it were mains, if over 1000 Watts
would it be possible for an enterprising firm to make a cordless
vacuum of that rating but because it could be charged from a charger
less than 1000 watts it would get around the EU restriction, or have
they sewn that up legally.

G.Harman
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On Wednesday, 13 September 2017 17:58:40 UTC+1, Bill Wright wrote:
On 13/09/2017 16:39, John Rumm wrote:


Many tools don't require more than a few hundred W - even in mains form.


Well, it's always good to have power in reserve, and anyway I'm really


No it's not, that's part of the whole point of battery tools. I have SDS and SDS max mains tools, and rarely would I even consider picking the max one. Extra power is far from always good to have.

Battery tools are great when you don't need the extra power and are willing to pay the price of shortish life for the time & effort saving. When you're not, stick with mains. For some jobs battery wins hands down, for some mains does.


NT
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On 13/09/2017 19:25, Mr Pounder Esquire wrote:

Got to admit that in 1999 I used this huge very heavy Bosh cordless drill.
Cost £400 apparently. I was informed that if I lost it I would be beaten up.
It was Magnificent! It had these lights that came on when it was being used.


Yes I used to use drills like that. They used to help with my erections.

I felt like Arnold Schwarzenegger when I used it. Me and him look very
similar.


You must look like me then, but less rugged maybe.

Bill



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On 13/09/2017 19:57, John Rumm wrote:

These days you can get the 36V cordless ones (which use two 18V batts)
and they will do 1200 RPM and hit with 2.5 Joules, which is pretty much
on par for a basic 2kg mains SDS.


Yes I have to agree they're pretty good. Our Paul has one and it's
impressive. Not quite as good as my mains one though.

Bill
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On 13/09/2017 20:28, John Rumm wrote:

I used to have problems on flats complexes fixing aerials onto masonry
(8 holes per aerial) when I was working my way along a row of small
blocks. Used to recharge from the van. Sort of OK.


The fact that you did not go to the faff of taking a mains drill and
extension lead up there, suggests that the overall experience with the
cordless was still preferable though?


It was marginal because of the weight of the cordless, but in fact I had
no choice because of H & S. In the days before H & S it did used to be a
problem sometimes getting a mains supply to the job. I used to use a
genny, then later an inverter in the van running from its own battery.
Cordless tools were crap in them days though. I bought one of the first
cordless drills and it was a ****ing joke. Wouldn't drill a 7mm hole in
wood more than once per charge.

Bill
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On 13/09/2017 20:22, Andy Burns wrote:
Bill Wright wrote:

I've just bought a mains Makita recip saw and I think it's great. Really
good design, especially blade changing.


I bought an 18V makita recip saw (to use with the batteries I already
have) and also think it's great.

If I'd only used it for the intended job of removing window frames I'd
have been happy, but it's chopped a couple of small trees and some oak
sleepers too.


This morning my bleary peer out of the window detected that a tree
branch had fallen and smashed a fence. Not very far from the mains
socket in the chicken shack so I was able to use the new toy without
taking the genny up there. Magic! Very quick and easy it cut away the
smashed bits and cut the new bits to fit, and then cut the branch up so
I could drag it to the bonfire heap.

Bill
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On 13/09/2017 18:24, Tim Watts wrote:

I can counter everything you've just said


Argument is an intellectual process. Contradiction is just the automatic
gainsaying of anything the other person says. (Python)


10.8V Blue Bosch driver, drill and impact driver are small, light and
surprisingly powerful for their size and I've used mine for years.


Yes they're very good. I have two old ones and they'll do almost owt.
Paul has the same thing but a newer type and that's the same.

Bill



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On 13/09/2017 18:27, Huge wrote:

Don't worry - Bill doesn't know anything about anything other than being
a racist bigot.


I do then! Here's a list of some of the things what I know.
The route to Morrisons
The route to alcoholism
The route to the clitoris
Which way it is to 28E
How to deal with faecal impaction
How to do CPR
To never to go to London
To always to drive on the left in Scotland
How to weld
Never to tell a big woman she's a big woman
What a mux is
Never to get up on stage with the turn after ten pints
How to hot wire a Cortina
How to make a bomb
How to spell diarrhoea
How to make a good dovetail joint
How to clean diarrhoea up
How to point mortar
How to dress a wound
How to answer the telephone
How to tie shoelaces
How to solder
How to use a knife and fork
How to calm down an angry or upset child
How to give carrots to a horse
When to love and when to scold
How to work at heights
How to re-tune channel filters
How to reverse park
How to get splinters out
How to confuse a dog
How to ruin an enemy's lawn
How to exploit depth of field
How to bypass an electric meter
How to change a nappy
How to set out a paved surface
How to turn it off and then on again
How to get free calls on a Button A/B call box
How to erect a suspended ceiling
How to get banned from Asda
How to mount a TV set on a wall
How to blur my fingerprints
How to concrete
How to use Photoshop
How to erect a catenary
How to clean a paintbrush
How to mourn
How to celebrate

I also know what a racist is, and I know that if you throw 'racist'
about as a loose term of abuse against people who aren't at all racist
you do great harm to the noble cause of anti-racism.

Bill


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damduck-egg wrote:

would it be possible for an enterprising firm to make a cordless
vacuum of that rating but because it could be charged from a charger
less than 1000 watts it would get around the EU restriction, or have
they sewn that up legally.


rechargeable vacuums are excluded from the .eu power ratings
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Jethro_uk wrote:
Unless I've missed a trick, the most obvious problem with battery tools
is the lack of in-car charging solutions ....

Surely tradesmen would find charging between jobs a handy feature ?


Cordless tool manufacturers don't seem to have (yet) discovered the
cheap 'buck' converters you can get to step up (as well as down) DC
voltages. I use these extensively on my boat (12 volt system, like a
car) to provide efficient supplies for running several 9 volt devices
like routers and switches (that's networking stuff, not woodworking)
and also 19 volts and 20 volts for charging laptops.

Most cordless are now 12 volts so need a step up from the car's 12
volts.

You could use an inverter to provide 230 mains and then the cordless
mains charger but it's almost certainly less efficient. Also you
probably need a pure sine inverter for many switch mode chargers, I've
killed big modified sine inverters with tiny switch mode supplies.

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Steve Walker wrote:
On 13/09/2017 17:22, Brian Gaff wrote:
Well I only have a mains drill of quite a vintage. I guess battery
screwdrivers can save a lot of blisters, but for those awkward screws,
never
seem to fit in the gap you need them to. I personally think battery tools
have their place. How about a battery angle grinder for that wheel
clamp, or
a battery powered chainsaw to annoy the neighbours with?


I happened to drive past a guy removing a wheel-clamp with a petrol
powered grinder last night

SteveW

Aldi battery powered angle grinder is quieter even if weak and slow.
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Huge wrote:
On 2017-09-13, Tim Watts wrote:
On 13/09/17 14:31, Bill Wright wrote:

Why people buy battery tools to use at home I really don't know.
Ignorance of the customer plus the vendor's sales hype I guess. Thinking
about it, I bet a lot of people who buy a battery drill have never used
an electric drill before, so they won't realise how limited their new
toy is.

Bill


I can counter everything you've just said

10.8V Blue Bosch driver, drill and impact driver are small, light and
surprisingly powerful for their size and I've used mine for years.

36V Bosch garden tools are equal in calibre to mains tools of a similar
size - hedge cutter, lawn mower and strimmer.


The bloke who fitted our kitchen did it entirely with battery tools,
including most impressively, core drilling a 110mm ventilation duct
through a 9" brick wall with a battery drill.

Don't worry - Bill doesn't know anything about anything other than being
a racist bigot.



People that put up large metal sheds do almost the whole job with
battery tools.


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On 14/09/2017 08:48, Chris Green wrote:
Jethro_uk wrote:
Unless I've missed a trick, the most obvious problem with battery tools
is the lack of in-car charging solutions ....

Surely tradesmen would find charging between jobs a handy feature ?


Cordless tool manufacturers don't seem to have (yet) discovered the
cheap 'buck' converters you can get to step up (as well as down) DC
voltages.


You mean like:

https://www.amazon.co.uk/Makita-LXT-.../dp/B001UGMC9U




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John.

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On Thu, 14 Sep 2017 07:51:07 +0100, Andy Burns
wrote:

damduck-egg wrote:

would it be possible for an enterprising firm to make a cordless
vacuum of that rating but because it could be charged from a charger
less than 1000 watts it would get around the EU restriction, or have
they sewn that up legally.


rechargeable vacuums are excluded from the .eu power ratings


Ta, I wonder if those who decided the regs thought that rechargeable
vacuums would always be those lightweight things promoted at the
moment.
So it be could be possible for a manufacturer to make one using 36volt
batteries like mower ones and promoted it as being more powerful than
you can get from a mains one, whether they would have sufficient sales
to make it worthwhile is debatable .

G.Harman
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On Thu, 14 Sep 2017 06:07:21 -0000 (UTC), Jethro_uk
wrote:

Unless I've missed a trick, the most obvious problem with battery tools
is the lack of in-car charging solutions ....

Surely tradesmen would find charging between jobs a handy feature ?


Quite a few tradesmen by the very nature of their skills and work will
have been aware of inverters that could be fitted to vehicles many
years before the general public became aware of them and they reached
the shelves of Halfords etc.

I think it was the early 80's when I purchased my first , 200 watt
peak ISTR . Can't remember now if it was square wave or modified .
If you wanted a real sine wave some firm was making a rotary converter
device ,possibly called Redline or similar.
My last van had an 800 watt one, as batterys had got better I rarely
needed it for charging but it ran a couple of infra red heat lamps
nicely positioned to act as a hair dryer and give instant heat on cold
mornings and warm aching neck muscles on the way home.

G.Harman
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On Thursday, 14 September 2017 03:55:12 UTC+1, Bill Wright wrote:

I do then! Here's a list of some of the things what I know.


How to spell diarrhoea


dire rear


NT
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On Thu, 14 Sep 2017 13:39:46 -0000 (UTC), Jethro_uk
wrote:

On Thu, 14 Sep 2017 11:44:52 +0100, damduck-egg wrote:

On Thu, 14 Sep 2017 06:07:21 -0000 (UTC), Jethro_uk
wrote:

[quoted text muted]


Quite a few tradesmen by the very nature of their skills and work will
have been aware of inverters that could be fitted to vehicles many years
before the general public became aware of them and they reached the
shelves of Halfords etc.


Sledgehammer, nut though ? Stepping up to 230V just to step down to
9/12/18 ?????


No horses for courses,
Although step up step down is not the most efficient way of using
electricity unlike a battery charged with a solar panel or windmill in
a van you can easily keep enough power available by running the engine
though normally charging between jobs was enough, and the firm was
paying the fuel cost so that wasn't a consideration.
Besides as I said this was before such things were common and to
return to the theme of this thread cordless tools had even less power
and run time than they do now.
Having found the small Inverter was practical I soon replaced it with
a bigger one and sometimes used it to run a mains tool in the back of
a van rather than right on the site where some **** of a painter will
be painting everything you want to get by.
A couple of times I used it to power a submersible pump to lower
water in a cellar where the mains had tripped.

Now with cordless being more powerful and batteries lasting longer
coupled with some makers supplying chargers designed for a 12V DC
supply that may be the more practical way to go.

G.Harman


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On 13/09/2017 21:52, Mr Pounder Esquire wrote:

Don't worry - Bill doesn't know anything about anything other than
being a racist bigot.


Bill is cleverer than you.


Argh! Damned with faint praise!

Bill
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On 14/09/2017 14:39, Jethro_uk wrote:
On Thu, 14 Sep 2017 11:44:52 +0100, damduck-egg wrote:

On Thu, 14 Sep 2017 06:07:21 -0000 (UTC), Jethro_uk
wrote:

[quoted text muted]


Quite a few tradesmen by the very nature of their skills and work will
have been aware of inverters that could be fitted to vehicles many years
before the general public became aware of them and they reached the
shelves of Halfords etc.


Sledgehammer, nut though ? Stepping up to 230V just to step down to
9/12/18 ?????

It's just very convenient to be able to use any mains charger in the
van. It doesn't matter about the inefficiency since the engine will be
running.

Bill
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On Thu, 14 Sep 2017 08:48:14 +0100, Chris Green wrote:

====snip====

Cordless tool manufacturers don't seem to have (yet) discovered the
cheap 'buck' converters you can get to step up (as well as down) DC
voltages. I use these extensively on my boat (12 volt system, like a
car) to provide efficient supplies for running several 9 volt devices
like routers and switches (that's networking stuff, not woodworking)


I'm not sure whether you're referring to the fact that pretty well all
such IT kit utilises buck converters to provide the internal 5 and or 3.3
volt rails from their supplied wallwarts and as such can be powered off
any DC voltage from 6 to 15 volts (or even as high as 25 volts in some
cases) regardless of their nominated DC input voltage ratings in the 7.5
to 15 volt range, including 12 volts, on condition that the substitute PSU
can supply the required volt amps, or whether you're simply stating that
you use a 9v buck converter powered by the 12 volt supply to power your
collection of 9 volt IT kit. Hopefully, it's the former rather than the
latter interpretation. :-)

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On Thursday, 14 September 2017 11:55:46 UTC+1, wrote:
On Thursday, 14 September 2017 03:55:12 UTC+1, Bill Wright wrote:

I do then! Here's a list of some of the things what I know.


How to spell diarrhoea


dire rear


I like that, it gives both the emotion and direction and reminds me of listening to dire straits too.



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On 15/09/2017 03:44, Johnny B Good wrote:
On Thu, 14 Sep 2017 08:48:14 +0100, Chris Green wrote:

====snip====

Cordless tool manufacturers don't seem to have (yet) discovered the
cheap 'buck' converters you can get to step up (as well as down) DC
voltages. I use these extensively on my boat (12 volt system, like a
car) to provide efficient supplies for running several 9 volt devices
like routers and switches (that's networking stuff, not woodworking)


I'm not sure whether you're referring to the fact that pretty well all
such IT kit utilises buck converters to provide the internal 5 and or 3.3
volt rails from their supplied wallwarts and as such can be powered off
any DC voltage from 6 to 15 volts (or even as high as 25 volts in some
cases) regardless of their nominated DC input voltage ratings in the 7.5
to 15 volt range, including 12 volts, on condition that the substitute PSU
can supply the required volt amps, or whether you're simply stating that
you use a 9v buck converter powered by the 12 volt supply to power your
collection of 9 volt IT kit. Hopefully, it's the former rather than the
latter interpretation. :-)


I get the impression he was thinking of the slightly more elaborate
inverter style DC/DC converters, rather than the more common buck
regulator which is only really capable of stepping down a voltage rather
than say generating something that can charge a 18V battery from a 12V
car supply.


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John.

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On 15/09/17 13:38, John Rumm wrote:
On 15/09/2017 03:44, Johnny B Good wrote:
On Thu, 14 Sep 2017 08:48:14 +0100, Chris Green wrote:

====snip====

Cordless tool manufacturers don't seem to have (yet) discovered the
cheap 'buck' converters you can get to step up (as well as down) DC
voltages. I use these extensively on my boat (12 volt system, like a
car) to provide efficient supplies for running several 9 volt devices
like routers and switches (that's networking stuff, not woodworking)


I'm not sure whether you're referring to the fact that pretty well all
such IT kit utilises buck converters to provide the internal 5 and or 3.3
volt rails from their supplied wallwarts and as such can be powered off
any DC voltage from 6 to 15 volts (or even as high as 25 volts in some
cases) regardless of their nominated DC input voltage ratings in the 7.5
to 15 volt range, including 12 volts, on condition that the substitute
PSU
can supply the required volt amps, or whether you're simply stating that
you use a 9v buck converter powered by the 12 volt supply to power your
collection of 9 volt IT kit. Hopefully, it's the former rather than the
latter interpretation. :-)


I get the impression he was thinking of the slightly more elaborate
inverter style DC/DC converters, rather than the more common buck
regulator which is only really capable of stepping down a voltage rather
than say generating something that can charge a 18V battery from a 12V
car supply.


the difference between buck and boost is almost semantic, with very
similar curcuitry being able to do either.

Or in this case, the same.

https://www.dimensionengineering.com/products/anyvolt3


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guns, why should we let them have ideas?

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The Natural Philosopher wrote:
On 15/09/17 13:38, John Rumm wrote:
On 15/09/2017 03:44, Johnny B Good wrote:
On Thu, 14 Sep 2017 08:48:14 +0100, Chris Green wrote:

====snip====

Cordless tool manufacturers don't seem to have (yet) discovered the
cheap 'buck' converters you can get to step up (as well as down) DC
voltages. I use these extensively on my boat (12 volt system, like a
car) to provide efficient supplies for running several 9 volt devices
like routers and switches (that's networking stuff, not woodworking)

I'm not sure whether you're referring to the fact that pretty well all
such IT kit utilises buck converters to provide the internal 5 and or 3.3
volt rails from their supplied wallwarts and as such can be powered off
any DC voltage from 6 to 15 volts (or even as high as 25 volts in some
cases) regardless of their nominated DC input voltage ratings in the 7.5
to 15 volt range, including 12 volts, on condition that the substitute
PSU
can supply the required volt amps, or whether you're simply stating that
you use a 9v buck converter powered by the 12 volt supply to power your
collection of 9 volt IT kit. Hopefully, it's the former rather than the
latter interpretation. :-)


I get the impression he was thinking of the slightly more elaborate
inverter style DC/DC converters, rather than the more common buck
regulator which is only really capable of stepping down a voltage rather
than say generating something that can charge a 18V battery from a 12V
car supply.


the difference between buck and boost is almost semantic, with very
similar curcuitry being able to do either.

Or in this case, the same.

https://www.dimensionengineering.com/products/anyvolt3

Yes! :-)

I was using 'buck' rather loosely to include 'boost'. In reality they
are very similar in implementation. If you look to buy one on eBay
the only visible difference between a buck and a boost is usually the
IC used.

I use buck converters on my boat to supply 9v and 5v devices and boost
converters to provide the 19 or 20 volts required by most laptops.

What I was saying originally was that few cordless tool manufacturers
seem to take advantage of the cheap boost converters to allow charging
of (for example) 18 volt cordless tools from a car battery.

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On Fri, 15 Sep 2017 14:51:17 +0100, Chris Green wrote:

The Natural Philosopher wrote:
On 15/09/17 13:38, John Rumm wrote:
On 15/09/2017 03:44, Johnny B Good wrote:
On Thu, 14 Sep 2017 08:48:14 +0100, Chris Green wrote:

====snip====

Cordless tool manufacturers don't seem to have (yet) discovered the
cheap 'buck' converters you can get to step up (as well as down) DC
voltages. I use these extensively on my boat (12 volt system, like
a car) to provide efficient supplies for running several 9 volt
devices like routers and switches (that's networking stuff, not
woodworking)

I'm not sure whether you're referring to the fact that pretty well
all
such IT kit utilises buck converters to provide the internal 5 and
or 3.3 volt rails from their supplied wallwarts and as such can be
powered off any DC voltage from 6 to 15 volts (or even as high as 25
volts in some cases) regardless of their nominated DC input voltage
ratings in the 7.5 to 15 volt range, including 12 volts, on
condition that the substitute PSU can supply the required volt amps,
or whether you're simply stating that you use a 9v buck converter
powered by the 12 volt supply to power your collection of 9 volt IT
kit. Hopefully, it's the former rather than the latter
interpretation. :-)

I get the impression he was thinking of the slightly more elaborate
inverter style DC/DC converters, rather than the more common buck
regulator which is only really capable of stepping down a voltage
rather than say generating something that can charge a 18V battery
from a 12V car supply.


the difference between buck and boost is almost semantic, with very
similar circuitry being able to do either.

Or in this case, the same.

https://www.dimensionengineering.com/products/anyvolt3

Yes! :-)


A buck/boost converter won't be quite as efficient as a buck or boost
only type. The difference is only a matter of an extra one or two percent
loss in the best efficiency buck/boost designs compared to the best
efficiency versions of the buck or boost only types which, iirc, could be
in the region of 97 to 98 percent efficient depending on voltage levels
and power requirements.

Even way back in the late 70s, early 80s, there were boost converter
chip drivers and powerFET devices that could raise a few hundred
milliwatts' worth of 5 or 6 volt power from a single NiCad D cell
replacement to a 4 or 5 AA cell NiCad battery pack at better than 90%
efficiency. Although the 10% loss of battery energy more or less
cancelled the 10 to 15% gained in substituting a full capacity D cell for
a set of 4 full capacity AA cells, the big deal in this case was the
elimination of the reverse charge syndrome inherent to any string of
rechargeable NiCad cells made up with more than two cells in series.

At a stroke, you eliminate the inevitable chucking away of a bunch of
still serviceable cells for the sake of the weakest in the bunch being
destroyed by reverse charging. If you could use each cell independently
of the state of the other 3 cells in a purchased pack, you'd be getting
the full value out of each one in spite of a 10% variation in usable
capacity between them that would otherwise accelerate the demise of a 4
cell battery made up of those cells (even if they had been precisely
matched capacity-wise in the pack of four, it doesn't take too many
charge/discharge cycles to upset the balance before the issue of reverse
charging rears its very ugly head once more).

These days, the concept of "The Single Cell 'Battery'" has been
resurrected in the form of the 3.7v Li-Ion 'batteries' as used in mobile
phones (smart arsed or otherwise) and some P&S digital cameras.

Unfortunately, when it comes to allowing them to be totally discharged,
unlike the case with NiCad and NiMH cells which can be left stored in
this state indefinitely, this is a complete No no! Indeed, if you let a
Li-ion cell drop below 2.4 to 2.9 volts the Lithium metal will plate out
onto its internal structure, creating an unwanted discharge path as well
as compromising the cell chemistry. However, rather than use a switching
converter to generate higher voltage to power a 2 watt UHF transmitter in
a mobile phone, the designers have simply used UHF power transistors
optimised for lower voltage higher current working allowing an endpoint
voltage of 3.5 or so to still permit 2 watts of transmit power to be
raised.

I suspect that the only form of voltage stabilisation being used is of
the buck converter persuasion since the laptop originated 3.3v
alternative to the 5 volt standard of TTL is both below the 3.5 to 3.6
endpoint voltage of a Li-Ion cell and sufficient to allow the Tx circuit
to produce the required watts to maintain the up-link path to the cell
tower node. Since, contrary to all appearances (allowing a smart arse
phone to become bogged down with energy sapping apps), battery life *is*
still a prime consideration, hence the avoidance of the slightly less
efficient buck/boost switching converter in mobile phones (I presume).


I was using 'buck' rather loosely to include 'boost'. In reality they
are very similar in implementation. If you look to buy one on eBay the
only visible difference between a buck and a boost is usually the IC
used.

I use buck converters on my boat to supply 9v and 5v devices and boost
converters to provide the 19 or 20 volts required by most laptops.


Boost converters to generate the tightly specified 18.0, 19.0, 19.5 or
20.0 volts typically used to charge modern day notebooks and tablets
eliminates the extra conversion stage involved in running a mains
inverter to power the original or replacement charging brick which simply
has to supply a steady DC voltage to the charging port, leaving the
notebook or tablet to manage the battery charging for itself.


What I was saying originally was that few cordless tool manufacturers
seem to take advantage of the cheap boost converters to allow charging
of (for example) 18 volt cordless tools from a car battery.


Although Li-Ion battery chargers utilise switching converter technology
to control the charging voltage and current, there's also a charge
management controller included, tuned to the requirements of the battery
pack or range of battery packs it was designed to charge. Li-Ion
batteries are 'very picky eaters' of electric charge compared to pre-
Lithium battery technologies.

Designing a charger for a single cell Li-Ion "battery" (3.6v) is pretty
straight forward but once you have two or more cells corralled into a
battery pack, things become more complicated, usually demanding the use
of chargers matched to a particular two or three (or more) celled battery
pack, largely, it has to be said, on account of the many inventive ways
the battery manufacturer can choose to monitor individual cells or
achieve charge balancing.

As others have mentioned, some battery tool manufacturers do offer such
in-car chargers for a price. However, don't expect such chargers to be
priced like a basic boost converter since they're a lot more
sophisticated than that.

The point I was originally trying to make was that, with the obvious
exception of 5 volt devices intended to be powered via a handy USB port
or USB mains charger, pretty well all SoHo network kit intended to be
powered from a wallwart designed to supply a DC voltage in the region of
7.5 to 15 volts, will quite happily work off a nominal 12 volt DC supply
thanks to the use of buck switching voltage regulator technology to
generate the stable 5 and 3.3 voltage levels typically required to power
the logic chips used in such IT kit.

The lower limit on input voltage will typically be a little over the 5v
mark[1] to give the buck switching converter a small margin to provide a
stable 5v output whereas the upper limit is typically set by the voltage
rating of the input filter capacitor, typically an electrolytic of either
16 or 25 volt rating.

I don't recall seeing 10v rated caps ever being used for the input
filter but I suppose it's a remote possibility if the supplied wallwart
output voltage is less than 10vdc regulated. Quite frankly, you're
unlikely to see an input capacitor of less than 16 volt rating being used.

If you're entertaining the elimination of an 8 to 10v smpsu based
wallwart in favour of powering such a piece of kit directly from a 12v
battery supply, you can always pry open the casing (it's *always* plastic
clip together casing on cheap commodity SoHo networking kit[2]), and take
a peek at the capacitor's voltage marking to confirm your expectations
(that it will almost certainly a 16 or possibly even a 25 volt part).

If, incredibly, it turns out to be a 10v rated cap, there's still the
option of upgrading it to a 16 or 25 volt rated one if you're possessed
of soldering skills, a soldering iron (a 25 to 35 watt Antex should
suffice) and good old fashioned tin/lead multicore solder... oh, and a
replacement cap! :-)

[1] Purely of academic interest in this case, but if the kit only uses
the laptop based 3.3v standard for its internal logic, it may even still
function perfectly fine off of a single 3.6 volt Li-Ion cell.

[2] Eliminating an expensive metal case required to heatsink an analogue
voltage regulator chip was *the* whole rationale behind the use of (at
the time) the more expensive switching regulator technology option, along
with being able to get away with a lower (cheaper) VA rated wallwart
supply to boot.

--
Johnny B Good
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