Larger capacity DeWalt 14.4V Li-Ion batteries?

I don't think you'll find Li-Ion in the same sort of physical size as NiMH which are usually sub-C size in power tools.

I only need to get 4 cells into the battery case so there shouldn't be a problem - question is really where to get decent cells at a sensible price

Wholesale quantities only:

If they will fit, you can use 4S 18650s with a BMS board like:

Theo

IME finding cells of decent quality that work out less than the cost of a new OEM battery is actually quite difficult.

It's not super efficient, but there are Li-Ion in a size that would fit in the space of a Sub-C (which is roughly 22430 as a lithium size):

Also bear in mind one Li-ion is worth 3 NiMH in voltage terms, so some

Theo

Perhaps one of the most common - so good value - Li-Ion types is the

They are used in vaping devices so made for pretty heavy use. Plenty on Ebay.

But you'll also need a new charger.

And a suitable safe charger no doubt. Brian who thinks we have been round this mulberry bush before quite recently here.

This is where some ebay batteries come from ('Ultrafire' etc):

I'm sure you could buy rubbish ones elsewhere too. usual thing applies - if it looks to be too good a price to be true, it probably is.

However, easier to get your money back from Ebay than some suppliers, if the goods are poor.

I'm wondering whether it's worth cannibalising a laptop battery, but I don't know whether they use cells that are optimised for self-discharge (e.g) rather than having a low impedance, or whether all 18650s have similar characteristics ... ?

I'm fairly certain there are several different 18650s, as the stated capacity varies. And then there would be things like peak current. If that varies too, ones for a laptop would be unlikely to need a high current delivery?

Ultrafire lithium batteries?

I think I've heard tales about them. I thought it was a fault, not a brand!

Andy