Wind up Torch from ASDA

[Skvez]

I saw this wind up torch in ASDA (late Aug 2011) for only £3.50
   

It's certainly not the best quality product in existance but it works and it is both brighter and longer lasting than my previous wind up torch while being more compact. (Tests were done giving each torch 20 winds at as close to the same wind-speed as I could manage)
Each push of the button cycles between, Off, 1 LED, OFF, 3 LEDs

Certainly worth £3.50 especially if you want to give your children a torch in a grid down scenario without having to worry about them wasting batteries.
While I don't expect it to last forever in use it should outlast your batteries on a shelf.

[maddog]

this is one time where it is better to have several cheap items as well as one expensive one

[grumpy old man]

kids are a good way to test things?
if it last then worth having, not everyone can afford the best for everyone in their family and the kids can have fun as well?
glow sticks are good for power cuts, safe to use and cheap.

[Skvez]

Last night (1st Sept 2011) I took the ASDA wind up torch apart to see what the rating on the capacitor used to store the electrical charge between winds was and got rather a shock to discover that there wasn't a capacitor, it was using a Lithium Ion (rechargeable) battery.
       
Unfortunately Li+ batteries have a limited shelf life, I had expected the life expectance of the torch to be affected by use (since it's using plastic gearing and no proper overcurrent protection of the LEDs) but have a fairly good shelf life, making it reasonable for prepping but the Li+ battery changes this considerably.
The Li+ battery probably has a half life (time to loose half its capacity) of 2 or 3 years and that's assuming it gets charged nicely (which it isn't) and not overly discharged (a distinct possibility in this application).
I then took my other wind up torch apart and found it too used a Li+, it actually has a bigger battery so its poorer performance is probably due to it being over a year old already (other possible causes are a less efficient generator or LEDs).
I withdraw my recommendation to buy this as a prep.

[Skean Dhude]

Interesting.

Is it possible we could replace these batteries with capacitors? I would have though the rest of the circuitry would be the same.

[Skvez]

(2 September 2011, 10:19)Skean Dhude Wrote: Is it possible we could replace these batteries with capacitors?

Absolutely, in fact I intend to get another one for butchering and see just how well that goes but exchanging them will require some soldering and possibly the addition of over-Voltage protection to avoid damaging the Capacitor if the torch is wound (with the LEDs off).
Also the sort of Capacitor required is a memory back-up capacitor, available from places like RS (Radio Spares) and Farnell but not generally available to the average prepper.

[Skean Dhude]

Cool. A nice compact project. Why don't you document it, with pictures, and we can all learn.

[maddog]

i wonder how many other wind up items use batteries that we will find out after it is to late

[Skean Dhude]

Good point. I have a few wind up tools, radios and lights mainly. I will check them. It will be a pain if they are the same.

[grumpy old man]

i have a few wind up things, guess i won't be buy any more and letting the kids play with the ones i do have. unless i can change them from battery