Timer Switch for wallwart chargers

[Davidm]

I'm looking for a timer switch that I can use with wallwart chargers - press to switch on, automatically turns off after a delay. Have googled but the best I can find is

which I could mount in a suitable box, with a 13a socket (for the wallwart) and a flying lead to plug in to a normal wall socket.

However: it's a bit over rated for wallwarts, 13a when I don't need more than 2a (and maybe the price refects this), and I'd really like the delay to be selectable up to 5 or 6 hours.

Anyone come across such an item?

[Andy Burns]

To save power, or for other reasons?

Does the timer have lower standby consumption than the charger?

[GB]

[GB]

Sorry, I meant to add that the timer ought to have no standby consumption, once it's switched off as it doesn't need to do anything. That's assuming that whatever button you press to start the timer latches the PSU back on again. Just as likely, they won't have designed that in, so yours is a very good question!

[Andy Burns]

e.g. this one hasn't

[alan_m]

I once looked into automatically turning off a 10W LED light during daylight hours. Many if the cheap stand alone photo electric switches on Ebay had a normal operating power of 3 to 5W irrespective of the switch being on or off :(

[Dave Plowman (News)]

I made one for my charging station. Originally for basic Ni-Cad chargers so set for 14 hours (IIRC) But it also saves others being left on longer than that.

[Dave Plowman (News)]

Mine uses a one shot timer which activates when you power up the 13 amp socket strip. An LED shows when mains are going to that, and there is a neon in the on off switch. So zero power consumption when not powered.

These days more for safety - no point in having things powered up when not needed. Of course if you used it every day - like say for a phone - it might just get left on all the time. But it's in my workshop and just used for charging power tool etc batteries. I really should shorten the on time since I don't often charge Ni-Cads with a simple charger these days.

[Davidm]

It's not about consumption, it is about not leaving the batteries (Lithium) on charge for extended periods. It's for a battery powered vacuum cleaner which will only get used 2 or 3 times a week, maybe less.

[Andrew Gabriel]

If it's a lithium battery, the charger *has* to cut out completely when the battery is charged, or it would kill the battery on first charge. There may be other reasons to disconnect the charger, but not that one in the case of a lithium charger, as it has to do that internally anyway.

[Dave Plowman (News)]

Can't remember last time I saw any charger which doesn't switch off when the battery is charged. That sort of thing dates back to very early cheap power tools.

I have a small Lidl cordless vacuum - ideal for hoovering up crumbs etc. That isn't worried about being left on charge. The warning light even tells you when it is charged.

[T i m]

I have used time switches for such but nowdays an Arduino nano might be handy (especially with a preset time).

Press the button that energises a mains relay which then supplies the power to the Arduino and the output, keeping the relay engaged (triac?). Arduino program / timer runs out and drops the feed to the triac and everything is depowered ;-)

Cheers, T i m

[PeterC]

The one for my 'phone eventually goes cold after charging and I can't see any drain on W, VA or even PF other than 1, so I guess its consumption is SFA. Somewhere I've a diagram for a delay-off timer (fits in an octal base) that's turned on with a 2-way pull switch and goes off and completely de-energised at the set delay. Comes on again with a single pull.

[The Natural Philosopher]

Bear in mind the original premise is completely false.

Lithium ion battries can be charged indefinnitely at a cell terminal voltage of 4.2V. They simply will not absorb charge at this voltage once fully charged,

In this respect they are like lead acid.

And completely different from nickel based chemistry where the fully charged condition has to be detected by a voltage *drop*, and the charger switched off.

[Andy Burns]

My Lithium charger switches from constant current to constant voltage mode as charging reaches completion, at which point there is a "maintenance charge" of a couple of mA

[Brian Gaff]

I was just wondering this, unless its for multiple wall warts but then ould they all be in the same place in any case. What you really want here is some kind of device that is operated by radio to isolate everything. This then poses the problem as below about consumption of the switch against what it is switching and if safety is the goal, I'd imagine a plug in switch is just as likely to go bang as a wall wart. Not really an answer just more problems. Perhaps this is where smart meters come in. Brian

[The Natural Philosopher]

That is how the best ones work.

[Dave Liquorice]

FFS, technollogy for technologies sake!

Get a mechanical ie motor driven time switch. Open it up and move the wire to the motor from the live side of the switch to the switched side.

Set the pins or plastic flippy bits to be on for the required charge time. Plugin, set it to on at the begining of the time period. Runs until it switches off. Simples.

[Dave Liquorice]

A modified mechanical one yes, when it's off, it's off off.

[Davidm]

Now that's what I call a diy'ers answer - top man! *****