Just after some advice/help if I could. I have a kids toy that takes 4 Alkaline C batteries. Is it possible to interchange them with a rechargable battery that I can just plug in to charge up like a phone battery? If so what would be the best way to go about doing this?
Personally, my short answer is I’d look at using some C-sized NiMH batteries with an appropriate charger from Jaycar:
However, there may be a couple of LiPos that you could use, but I wouldn’t recommend trying to use them for this purpose as you’d need to make sure that:
The cell output current (including the wiring max current) is high enough
The voltage is right
The size of the pouch is appropriate for the toy
And that there’s no way that the pouch could be:
Pierced
Overheated
Shorted-out
Violently Rattled, Impacted, or otherwise damaged
Overcharged or Overdischarged
Given that you’ve got 4 Alkaline C-size batteries, that’s (assuming they’re in series) about 6 Volts (1.5 V * 4) with a capacity of around 32 Ah (approx 8000 mAh * 4), you’d also need to check what the max current draw of the toy is.
Anything around that capacity alone is a fairly large LiPo pouch you’d be looking at, which can be quite dangerous as LiPo’s tend to be fairly volatile and flammable, you may be able to make it work, but I’d suggest just going with some NiMHs such as the batteries I linked from Jaycar instead.