On 21/04/2019 00:09, Fredxx wrote:
On 20/04/2019 23:32, Roger Mills wrote:
I have a Livarno Lux (Lidl) cordless spotlight - the sort with a large
diameter lens at the front, behind which is a powerful halolgen (55w)
bulb and a ring of LEDs, and with a white LED and flashing red LED at
the back.

It normally travels in the boot of my car in case of emergency, but
tends to roll around a bit - which may be related to the problem.

I recently found that it was completely dead - none of its 4 lights
would work. [You're supposed to charge it regularly since the battery
can apparently be damaged if it becomes deeply discharged. It was
working when I tested it 3 or 4 weeks ago, so it's possible that it
got turned on while rolling around (don't we all!) and flattened its
battery.]

I recharged it for over 24 hours, and the battery's open circuit
voltage is well above its rated 6v. Three of the 4 lights now work,
but the 55w halogen doesn't. I've tested the bulb on a bench power
supply, and it lights up ok - but in the lantern, nothing. It's
drawing several amps but not lighting - or even getting warm, so I
don't know where the energy is going.

55w at 6v equates to over 9amps, so the filament resistance is only
about 2/3 of an ohm when hot - even lower when cold. Any additional
resistance in the circuit will have a dramatic effect on the current,
and probably stop it lighting.

Question to those who are knowledgeable about rechargeable batteries .
. .
What sort of "damage" is likely to result from being discharged too
deeply? Is it possible that this could increase its internal
resistance? If so, is there any remedy - or is it scrap?

What's the battery volts when the halogen is turned on?

I'm thinking the battery is happy to power the LEDs but drops all its
volts when connected to a 'cold' halogen bulb with a very low resistance.

My thoughts too. Also, what sort of battery is it? Do you *actually*
need a spotlight? I reckon those "work" floodlights are usually much
more useful, they are LED and lithium ion and hence very efficient.
Could you replace the halogen with some sort of LED?