Problem with cordless spotlight

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?

Reply to
Roger Mills
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Likely the battery doesn't have enough oomph to drive the halogen. A multimeter will soon tell you whether that's where the fault is.

If the battery's not well you can try pulse charging it. 'Well above 6v' is too vague btw.

NT

Reply to
tabbypurr

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.

Reply to
Fredxx

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?

Reply to
newshound

I only use the spotlight occasionally - usually when delving around in dark attics - so I *can* manage without it. It has to be used sparingly anyway, because it soon drains the battery. The ring of LEDs produces a reasonable light - but nothing like as bright as the halogen bulb (when it's working!).

The battery is lead-acid - 6v 4Ah.

One or two people asked about actual voltages - so I've done a few measurements.

When on charge, the battery floats at just under 8v. After removing it from charge, and waiting an hour or two, it settles at about 6.65v open circuit. When either the side LED or rear flasher are on, it drops to about 6.59v. Then the front LED ring is on, it drops to about 6.51v.

When the halogen is switched on, the battery drops to 0.14v !! So, for whatever reason, the battery is no longer able to deliver the 9amps or so required to power the halogen bulb - and appears to have developed a high internal resistance.

Could that be caused by discharging it too deeply? If not, by what else? Is there any fix other than replacing the battery?

Reply to
Roger Mills

Given that a new battery (assuming NP4-6 type) is around £10 +/-2, is it worth worrying?

Reply to
Andy Burns

Those are all healthy voltages

Battery knackered, obviously. Sitting around discharged is fatal to lead acids. It might be worth a go discharging it to about 3.5v then immediately pulse charging it. A variant of that method was used a fair bit back in the 50s to get car batteries good enough to sell the car. You need a charger with recondition mode of course - or could do it the old way, but those setups tended to be a hazard.

NT

Reply to
tabbypurr

You would, IMHO, be better of just buying

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instead of a new battery.

Reply to
ARW

I bought one on Adam's recommendation and it's still fine after 3 years. I use it for all sorts including hunting through my heaps of tools in the unlit garage.

AJH

Reply to
AJH

Could be worth a try. The only charger I have is the wallwart which came with it. What is the 'old' way - manually switching it on and off? If so, at what frequency?

Reply to
Roger Mills

that certainly won't do it.

Connecting to the mains via a rectifier & current limiting lightbulb. It's not safe, don't do it. The basic idea is that excess voltage can break down some of the sulphation, which insulates & blocks ion flow. Of course that can only be applied in pulses, otherwise the battery would overheat grossly.

NT

Reply to
tabbypurr

Does it have the power of a million candles?

Reply to
Rob Morley

I once bought one for the gf as a Valentines Day present.

Reply to
ARW

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