Hi all,
I bought a cheap RC car in China for the kid and found out it had 3xAA NiCd batteries. Needless to say, they didn't last long, took long to charge, and then there's the memory effect thing.
So, you might be outraged, but I'm not a EE (I am a IET member, but I'm actually a mechanical engineer), so I opened my bin of recycled electronics stuff, found a Li-Ion battery I salvaged from the battery bin at work, connected it to the car via a charging board (I think they were 5 for like £2 off eBay from China), and it works great.
Feeling like an experienced EE now, I thought "right, next I have this fabric shaver the wife also bought when we were in China", and when I opened it, low and behold, it uses AA NiCd batteries too. I'm not sure how they still manage to procure those, maybe they found an old stock in a warehouse from the 80's.
Anyway, to the point (finally):
- I saved more Li-Ion batteries from the battery bin at work.
- I've got more charging boards.
- BUT the shaver uses 2 AA batteries, so about 2.5V ish, and of course my Li-Ion battery that is small enough is 3.7V.
So I need to drop the voltage. What I thought was to use a diode (on the load side obviously, not on the charging side), and I checked google:
- I found a thread on Stack Exchange with pretty much the same question. In the guy/gal's case, it's to drive a ESP, so maybe he/she needs a more reliable way to drop the voltage, and indeed the consensus it to use a low drop regulator.
- In my case, it only lights up a power LED and run a small DC motor akin to a toothbrush, so I presume that I can go low tech.
- I'd also like (if possible) to have quite an efficient solution, so I'd rather use a diode than a resistor based voltage divider.
- I don't have LDOs.
- I do have a couple of buck converters from eBay too, but again, I'm thinking that might be overkill.
So would the diode do the trick in this low-tech situation, or do I need something better (I suppose a buck DC step down or a LDO, but I'd have to buy some of the latter)?
Thanks!
*EDIT* I've got 2 DC step down buck converters from eBay, but they are rated for 4.5-28V input, so I don't suppose I can use them either, bugger
