Using Li-Ion batteries.

How much time goes between last recharge and when you find it flat? Lithium based batteries should have a much longer self discharge rate compared to NiMh ones. This may indicate che battery is either crap or defective. The safety circuit also may be eating power for no reason.

Lots of information here.

That shouldn't happen. The self-discharge of LiIon batteries should be measured in years. At the PPoE, after four years on the shelf we found "new" batteries still had over half charge.

Cycling LiIon batteries is often recommended but not so much to condition the battery as to reset/calibrate the charging circuit. Laptops, in particular, track the charge of batteries and the charger needs to learn a "new" battery. The cells themselves don't need any "reforming" or anything.

They're really pretty simple to use but don't take gross abuse well. It sounds like you have a defective battery or perhaps more likely, a defective appliance.

Maybe 2-3 weeks, I'd expect the battery to stay up a lot longer than that!

The instructions warn to disconnect the wall-wart from the lamp when not charging, to prevent discharge - but when its not brought in for charging, the lamp is in the lock up garage far from the wall wart.

It says 3 yr warranty on the box and I'm well within the statutory 1 yr, if having cycled the battery shows no improvement, I can decide to return it or write off the loss & indulge in a bit of reverse engineering.

The instructions say its protected from overcharging - but nontheless shouldn't be left charging for long periods after the charge indicator LED changes from red to green.

When I cycled the battery - towards the end of discharge I could hear the oscillator whine getting lower, AFAIK there is no indicator of excessive discharge, I didn't continue the discharge to see if there's an automatic UVLO, as I understand that Li-Ion won't recharge if over discharged.

Or a defective battery charger

I think the wall wart is the same as supplied for that store-chain's "stick" type LED worklight with NiMh batteries - AFAIK all the electronics for controlling charge to the Li-Ion are in the lamp.

Yes, it should be definitely more than that. Is the battery easily replaceable without voiding the warranty?

Huh? I would expect at least a diode in series to protect the wall-wart and/or the battery. If they had to save one diode they probably went also for a cheap safety circuit. Just speculation, though it would explain something.

I would return it too.

Is the battery removeable? For a flashlight I'd guess yes.

The behavior and danger of overcharging and overdischarging depends on whether the cell has a protection circuit. If it's a cylindrical cell, it's easy to tell as it's a thin metallic disc shrink-wrapped on the end of the cell.

Even if the cell or charger protects against overcharging, it is not a good idea to leave it charging indefinitely as the heat generated will eventually degrade the cell. Conditions of high temperature and high voltage are the most harmful to LiIon cells.

Protection against overdischarging is necessary because below ~1v or so the copper electrode will go into solution. If such a cell is charged again, the copper then turns back to metal within the electrolyte, forming shunts that act as short-circuits leading to explosion.

The over-discharge behavior depends on whether there is a protection circuit. A protected cell will typicially cut off at ~2.5V and go to sleep; a "smart" charger will refuse to charge it until the protection circuit is awakened by force-charging it momentarily at low current. Of course, by doing that you assume all risk if the cell's voltage is really much lower than 2.5V.

An unprotected cell will keep putting out juice for longer, leading to an over-discharged cell that is dangerous to charge again.

Learning usually comes at a cost - I could write off the loss and see what I could learn reverse engineering the inverter.

A 3W LED would also be a welcome addition to the junk box - not a cost effective trade in this instance, but I do get the reflector & mounting thrown in.

I still have the option to return it, but if I get a lithium fire, I'll definately be having words with the retailer!

Audibility of a charger is a fair indication of defect in either the charger or load.

RL

A few good points to take noteof there.

Its a pistol grip lamp with a 3W LED main beam plus a low power ring of LEDs around the rim of the reflector & a panel of LED on the side for "map reading".

None of the internal parts are accessible without voiding the warranty.

Well it run for longer than the claimed endurance when I tried cycling the battery, so there can't be that much wrong with the charge circuit or inverter.

Discovering whether self discharge takes a decent length of time - takes a decent length of time!

What type of battery is it. cyl 18650? I have several flashlights that use

18650. 1000 lumens to 6000 lumens. None of the batteries discharge whatsoever. Many of these flashlights use an LED voltage controller (driver ) It may be defective draining the battery, but the battery should not be connected if the switch is off..!!! I purchased mine from a china market and they will hold voltage for at least a month with a Vdrop of less than 10 percent Will the battery go flat if not in the flashlight? If so bad battery or the built in battery charge controller is bad. Ben

Haven't opened it to have a look - presumably it will eventually deteriorate to not very long running time.

Allegedly, it has a 3-yr warranty and I still have the box it came in, but its a Lidl stores weekly offer that I'd have to wait for them to come around again.

It has a 2200mAh battery which it claims should run the 5W LED spot light for 2-hrs.

If you have a voltmeter charge up the battery for the normal charge time. Measure the voltage. It should measure about 4.22 vdc. If it doesn't there is something wrong with the charger or the battery. After a week it should measure about 3.7v. The Chinese ones I purchased hold 3.4 after one month and I have heard that they are seconds from major manufacturers, but thet work well in my high power flashlights. Also I use the special dual cell charger that they come with. If you have a multimeter you can remove the end cap switch and measure the current the flashlight. One of the flashlights I have has a slide switch which allows an infinite number of brightness settings. If I turn off the flashlight with the slide switch the battery will run down because a small amount of current is flowing. So I have to unscrew the tail cap when I shut off the light. Then the flashlight does not discharge the battery

On Sun, 8 Jun 2014 20:28:14 +0100, "Ian Field" wrote as underneath :

Id write to the warrantee people, Lidl are very good about genuine complaints in my experience, they might just send you another one FOC without requiring return, say you cant open it to find what the problem is because of warrantee void! C+

Its 3yr warranty hasn't expired yet so I'm resisting the temptation to open it up.

It was on the Lidl store weekly offers, so I have to wait for them to come around again to get a replacement rather than refund.

For the time being, the battery stays up as long as its left on the charger, and I get a reasonable run time when using it - if it stops doing that before they come round again (or the warranty expires) I'll probably open it up and see what can be done.