How does rechargeable torch recharge?

[ss]

What I mean is I have a rechargeable torch whereby there is a plug that goes in to the wall socket and the torch sits on it for recharging, it is one of those that is all plastic so no metal contacts (I dont know what you call this type of charging) The torch has dimmed now (LED) and needs charging however it does not appear to be charging, it is just a cheap torch (£9) but was useful.

If possible before I bin it I would prefer to open it up in the hope it is repairable.

How do these things work (re charging) and could it be a simple repair?

[tabbypurr]

Inductive charging. If you can access the battery terminals with a multimeter you can find out what's going on.

NT

[T i m]

Sounds like what we have several of.

I think I tried with the torch bit but ended up destroying it in the process.

I believe it's magnetic induction. A powered coil in the 'socket' generates a magnetic field and is received by similar in the torch and turned into a charging voltage / current.

I have at least two bases that have failed (and one torch) with two different designs of such a torch (one round one flat, tested by putting the torch on a different base and it charges ok).

Cheers, T i m

[Dave W]

Yes it's most likely the socket that's at fault as it's on for all hours of all days, with or without the torch.

[Brian Gaff]

Usually inductively with a coil in both bits. The efficient ones use quite a high frequency for efficiency. The question is which bit has died? Brian

[Brian Gaff]

Yes I'd expect the base unit to be the weak link in the same way as some chinese wall warts that are switch mode die due to a mains spike. It might be fixable but you can tend to destroy it trying to get inside. if you can find an identical torch, get one and see if the old one charges on it, it could be handy to charge one while using the other. Brian

[ss]

I think this image answers the question, this is the plug that goes in to the wall, now is that repaireable?

[Andy Burns]

Can you read the part number on the knackered capacitor? (it might be the same as the others) if so replace them all if you can solder.

[ss]

Yes I have the number so will give it a go, not the best at soldering but it looks doable for me, so will give it a go.

[ss]

Image below: As far as I can make out it is CBB22 400v 224J The others are: CBB22 664J 400v CBB22 474J 400v CBB28 125 OV 5623

[Bob Minchin]

[newshound]

Except that at that price it might well have a rubbish battery

[tabbypurr]

which is 220nF 400v

Maybe use a site that works.

NT

[Andy Burns]

0.22uF 400V Metallized Polypropylene Film capacitor +/- 5%

e.g.

that's a +/- 10% part, but I doubt it's critical.

[Dave W]

Assuming that 664J means the no of pF expressed as 66 with 4 zeroes (J = 5%), i.e 660nF, I think it's probably 564J which is a preferred value.

[Roger Hayter]

Or 680.

[Rob Morley]

+1

[Roger Hayter]

I don't think a high voltage low loss capacitor could easliy be damaged by another fault in that sort of circuit, but it might have *caused* other damage.

[Rob Morley]

That sort of failure is outside my limited experience - I don't think I've ever seen an exploded high voltage plastic capacitor IRL.

[Roger Hayter]

They're usuallly supposed to be self-healing. Film defects vaporise a small region of the metallisation near them.