Recently we have bought a few portable gardening battery operated machines
which require the battery to be charged for a set time otherwise the battery
overheats and can be suffer damage, one is 8 hrs the other 5hrs.
I assume they have constant current chargers, the charging current not being
dependant on the back voltage of the battery.

I require a timer which would plug into a 13A socket which has a simple 10
or 5 position rotary switch on the front graduated in say 1 to 10 hrs with
a big button on the top which will switch it on, it will then count down
and switch off.

At the moment SWMBO is leaving bits of paper with time-off reminders all
over the house and I would like a more elegant solution.
There are plenty of cheap standard on/off timers about but has anyone come
across a countdown timer as described and where can I get one.

Don

In message , Donwill
writes
Recently we have bought a few portable gardening battery operated machines
which require the battery to be charged for a set time otherwise the battery
overheats and can be suffer damage, one is 8 hrs the other 5hrs.
I assume they have constant current chargers, the charging current not being
dependant on the back voltage of the battery.

I require a timer which would plug into a 13A socket which has a simple 10
or 5 position rotary switch on the front graduated in say 1 to 10 hrs with
a big button on the top which will switch it on, it will then count down
and switch off.

At the moment SWMBO is leaving bits of paper with time-off reminders all
over the house and I would like a more elegant solution.
There are plenty of cheap standard on/off timers about but has anyone come
across a countdown timer as described and where can I get one.

Don



If you feel adventurous and competent then.

When I needed something similar years ago I modified a 24 hour
mechanical time switch, the sort with lots of little push pegs to set
1/4 hour slots. This was modified to run through itself so that once
started it would run until it was time for it to turn off and then it
would disconnect the load and itself from the mains. It maybe possible
to do it with the newer digital readout timers but I found the
mechanical ones quite adequate
--
Bill

On Sun, 13 Jul 2008 10:59:37 UTC, "Donwill" popple @diddle .dot wrote:

Recently we have bought a few portable gardening battery operated machines
which require the battery to be charged for a set time otherwise the battery
overheats and can be suffer damage, one is 8 hrs the other 5hrs.
I assume they have constant current chargers, the charging current not being
dependant on the back voltage of the battery.

I require a timer which would plug into a 13A socket which has a simple 10
or 5 position rotary switch on the front graduated in say 1 to 10 hrs with
a big button on the top which will switch it on, it will then count down
and switch off.

I use one of the cheap rotary mechanical on-off timers for this purpose.
NOt quite as elegant as what you describe, but it does the job.

This is the kind where you press in segements for the time you want. I
have a block of 4 hours pressed in. It's permanently plugged in, but the
socket is usually 'off'. When I want to charge, I turn it on, rotate the
dial until it goes click, and I get four hours. Come back next day and
turn it off. Now, if you don't come back, in another 20 hours it will go
on, but I can live with that.

I'd probably just use 2 of those in adjacent sockets.

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

In article ,
Donwill popple @diddle .dot wrote:
Recently we have bought a few portable gardening battery operated
machines which require the battery to be charged for a set time
otherwise the battery overheats and can be suffer damage, one is 8 hrs
the other 5hrs. I assume they have constant current chargers, the
charging current not being dependant on the back voltage of the battery.

I require a timer which would plug into a 13A socket which has a simple
10 or 5 position rotary switch on the front graduated in say 1 to 10
hrs with a big button on the top which will switch it on, it will
then count down and switch off.

At the moment SWMBO is leaving bits of paper with time-off reminders all
over the house and I would like a more elegant solution. There are
plenty of cheap standard on/off timers about but has anyone come across
a countdown timer as described and where can I get one.

This might do:-

http://www.jaycarelectronics.co.uk/p...Max=&SUBCATID=

--
*Time is the best teacher; unfortunately it kills all its students.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
"Donwill" popple @diddle .dot writes:
Recently we have bought a few portable gardening battery operated machines
which require the battery to be charged for a set time otherwise the battery
overheats and can be suffer damage, one is 8 hrs the other 5hrs.
I assume they have constant current chargers, the charging current not being
dependant on the back voltage of the battery.

I require a timer which would plug into a 13A socket which has a simple 10
or 5 position rotary switch on the front graduated in say 1 to 10 hrs with
a big button on the top which will switch it on, it will then count down
and switch off.

At the moment SWMBO is leaving bits of paper with time-off reminders all
over the house and I would like a more elegant solution.
There are plenty of cheap standard on/off timers about but has anyone come
across a countdown timer as described and where can I get one.

If these are standard sealed lead acid batteries, then I suggest
you get a proper microcontroller-based charger for them, and ignore
the crap charger they came with (it's only the really crap chargers
which have to be disconnected after a certain time). A collegue bought
one of those jumpstart-with-inverter units with a 17Ahr SLA battery in
it. A few weeks later, he accidently charged it for several days, and
that was the end of it. I also have one (but with a compressor). I
charge it with a proper SLA charger, and not the crap wallwart it came
with which has no regulation or timing circuitry in it at all.

Aldi had a very nice charger for SLA batteries a few months back. It
was £12 or £14. Sadly, they don't have it anymore, and it's more
like £50 anywhere else.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Sun, 13 Jul 2008 13:06:34 +0000, Andrew Gabriel wrote:

Aldi had a very nice charger for SLA batteries a few months back. It was
£12 or £14. Sadly, they don't have it anymore, and it's more like £50
anywhere else.

The thing to look for is a charger that switches to 'trickle charge' or
'maintenance mode' once the main charge is done.

To answer your original question, you should be looking for 'one shot'
timers, such as the DMB51CM24, £14.00 from http://cse-distributors.co.uk/
controlgear/timers.htm, datasheet at http://www.carlogavazzi.co.uk/.

On Sun, 13 Jul 2008 11:59:37 +0100, "Donwill" popple @diddle .dot
wrote:


I require a timer which would plug into a 13A socket which has a simple 10
or 5 position rotary switch on the front graduated in say 1 to 10 hrs with
a big button on the top which will switch it on, it will then count down
and switch off.

http://www.homeenergysaving.co.uk/pl...kly-timer.html not
quite what you wanted but once you set a countdown time it remembers
it and pressing a button activates it.

or DIY :-) http://www.quasarelectronics.com/3141.htm

"Bill" wrote in message
...
In message , Donwill
writes
Recently we have bought a few portable gardening battery operated machines
which require the battery to be charged for a set time otherwise the
battery
overheats and can be suffer damage, one is 8 hrs the other 5hrs.
I assume they have constant current chargers, the charging current not
being
dependant on the back voltage of the battery.

I require a timer which would plug into a 13A socket which has a simple 10
or 5 position rotary switch on the front graduated in say 1 to 10 hrs
with
a big button on the top which will switch it on, it will then count down
and switch off.

At the moment SWMBO is leaving bits of paper with time-off reminders all
over the house and I would like a more elegant solution.
There are plenty of cheap standard on/off timers about but has anyone come
across a countdown timer as described and where can I get one.

Don



If you feel adventurous and competent then.

When I needed something similar years ago I modified a 24 hour mechanical
time switch, the sort with lots of little push pegs to set 1/4 hour slots.
This was modified to run through itself so that once started it would run
until it was time for it to turn off and then it would disconnect the load
and itself from the mains. It maybe possible to do it with the newer
digital readout timers but I found the mechanical ones quite adequate


The old Smiths timers had pegs you inserted.. you just inserted an off peg
when you wanted it off and forgot about it.
It would never switch on again unless you put an on peg in.

on 13/07/2008, Andrew Gabriel supposed :
A collegue bought
one of those jumpstart-with-inverter units with a 17Ahr SLA battery in
it. A few weeks later, he accidently charged it for several days, and
that was the end of it. I also have one (but with a compressor). I
charge it with a proper SLA charger, and not the crap wallwart it came
with which has no regulation or timing circuitry in it at all.

Mine has a rather good relay operated charge circuit. Each time it is
powered up, it brings the battery voltage up to a set point then the
relay drops out with the battery fully charged.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Donwill formulated on Sunday :
At the moment SWMBO is leaving bits of paper with time-off reminders all over
the house and I would like a more elegant solution.
There are plenty of cheap standard on/off timers about but has anyone come
across a countdown timer as described and where can I get one.

For my chargers which include a proper means of control, I have in my
garage a time clock which powers a 4 outlet strip. That is set to come
on for an hour or so each day.

I recently put my compressor on a one shot circuit. Reset it runs for 5
minutes then shuts off - that way my compressor is never left on and
forgotten. The one shot is just an electronic relay with a dial on the
front to set how long it runs for. You can get these in ranges able to
be set for seconds, minutes, or hours from places like Farnell, RS and
CPC.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In article ,
Andrew Gabriel wrote:
A collegue bought
one of those jumpstart-with-inverter units with a 17Ahr SLA battery in
it. A few weeks later, he accidently charged it for several days, and
that was the end of it. I also have one (but with a compressor). I
charge it with a proper SLA charger, and not the crap wallwart it came
with which has no regulation or timing circuitry in it at all.

My awfully cheap Lidl one switches off when charged.

--
*The statement above is false

Dave Plowman London SW
To e-mail, change noise into sound.

On Jul 13, 11:59*am, "Donwill" popple @diddle .dot wrote:
At the moment SWMBO is leaving bits of paper with time-off reminders all
over the house



Buy her a 'parking timer' keyring?

cheers,
Pete.

On 13 Jul, 11:59, "Donwill" popple @diddle .dot wrote:
Recently we have bought a few portable gardening battery operated machines
which require the battery to be charged for a set time otherwise the battery
overheats and can be suffer damage,

They _don't_ require a set time, that's just the easiest way to warn
against over-charging. An intelligent charger, usually sensing the
battery EMF, sometimes temperature as well, is always a better idea.
For one thing, this "ideal" time varies widely depending on conditions
such as state of charge, battery age and temperature.

They're not expensive these days. I've just bought a couple this
weekend: lead-acid gel for a tenner, NiCd / NiMH for 15. Doing on a
simplistic timer is obsolete.

Andy Dingley wrote:
On 13 Jul, 11:59, "Donwill" popple @diddle .dot wrote:
Recently we have bought a few portable gardening battery operated machines
which require the battery to be charged for a set time otherwise the battery
overheats and can be suffer damage,

They _don't_ require a set time, that's just the easiest way to warn
against over-charging. An intelligent charger, usually sensing the
battery EMF, sometimes temperature as well, is always a better idea.
For one thing, this "ideal" time varies widely depending on conditions
such as state of charge, battery age and temperature.

These are integrated chargers - you plug the device into the charger.
And yes, they do, as a simple resistor is cheaper than the pound or so
of stuff that'd be needed to do a proper charger.

"Dave Plowman (News)" wrote:
In article ,
Andrew Gabriel wrote:
A collegue bought
one of those jumpstart-with-inverter units with a 17Ahr SLA battery in
it. A few weeks later, he accidently charged it for several days, and
that was the end of it. I also have one (but with a compressor). I
charge it with a proper SLA charger, and not the crap wallwart it came
with which has no regulation or timing circuitry in it at all.

My awfully cheap Lidl one switches off when charged.

I note that teh surprisingly good 1.99 12V battery charger of a couple of
years back was 12.99 this year.

In article ,
Ian Stirling wrote:
"Dave Plowman (News)" wrote:
In article ,
Andrew Gabriel wrote:
A collegue bought
one of those jumpstart-with-inverter units with a 17Ahr SLA battery in
it. A few weeks later, he accidently charged it for several days, and
that was the end of it. I also have one (but with a compressor). I
charge it with a proper SLA charger, and not the crap wallwart it came
with which has no regulation or timing circuitry in it at all.

My awfully cheap Lidl one switches off when charged.

I note that teh surprisingly good 1.99 12V battery charger of a couple
of years back was 12.99 this year.

Do you mean the 5 amp SMPS car one? Which goes to a maintenance charge
after the fast one? Never saw that at 1.99 - it's excellent value at 13
quid. Other places charge 3 times that for the same thing.

--
*Therapy is expensive, poppin' bubble wrap is cheap! You choose.

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote:
In article ,
Ian Stirling wrote:
"Dave Plowman (News)" wrote:
In article ,
Andrew Gabriel wrote:
A collegue bought
one of those jumpstart-with-inverter units with a 17Ahr SLA battery in
it. A few weeks later, he accidently charged it for several days, and
that was the end of it. I also have one (but with a compressor). I
charge it with a proper SLA charger, and not the crap wallwart it came
with which has no regulation or timing circuitry in it at all.

My awfully cheap Lidl one switches off when charged.

I note that teh surprisingly good 1.99 12V battery charger of a couple
of years back was 12.99 this year.

Do you mean the 5 amp SMPS car one? Which goes to a maintenance charge
after the fast one? Never saw that at 1.99 - it's excellent value at 13
quid. Other places charge 3 times that for the same thing.

Yes.
I swore loudly next year, as I was intending on getting 5.
I hadn't imagined that it could be that good at 2 quid, so I diddn't
examine it closely at the time.

In article ,
Ian Stirling wrote:
Do you mean the 5 amp SMPS car one? Which goes to a maintenance charge
after the fast one? Never saw that at 1.99 - it's excellent value at 13
quid. Other places charge 3 times that for the same thing.

Yes.
I swore loudly next year, as I was intending on getting 5.
I hadn't imagined that it could be that good at 2 quid, so I diddn't
examine it closely at the time.

I keep a close eye on Lidl stuff via their website - and never saw it
advertised at that low price. As it was I bought several as Xmas presents.

--
*Learn from your parents' mistakes - use birth control.

Dave Plowman London SW
To e-mail, change noise into sound.