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Need a couple quick!! Where from?
RS components etc or the Torchy the Battery Boy on Ebay.
Get UK suppliers
What fossy said.
Another vote for fossys link
Also Torchy
I've used Torchy and MTB batteries before.
I've been very happy with both, but Torchy can be slow to respond, whereas Mark at MTB batteries has possibly the best customer service anywhere, ever.
I pulled a few out an old laptop battery
Been charging and working fine in my torch
Rs. You'll pay, but they'll be on time and decent
Those old laptop cells will be unprotected.
I need one with wires and push-connector. Does that mean having to buy all the extra faff to solder and wrap? Or are there places you can get the whole shamboodle?
I use these, capacity is spot on with zero failures.
If you want branded cells for a reasonable price, look at TME.eu I ordered some Panasonic cells from them about 3 years ago, and they're still going strong.
(now in GBP)
My RSP bike light finally down to 25 mins of charge (managed 6 hrs 6 years ago) so need one of these

Short cables to male JST?
Malvern. Look at mtbbatteries, can fix anything.
I've used Torchy for smaller cells - and they have been excellent. I get all my 18650s from old laptops... usually only one of a set needs to be discarded. The ones I've kept are still good after 6+ years of use. As they are unprotected they are slightly short so I use small magnets as spacers, as well as a loop of electrical tape to give them a snug fit.
Local vape/ecig shop if you're in a rush.
Yeah, I got one from RS at the start of last winter. It might cost twice as much as ebay but I think you can trust them and have some comeback if you do get a problem.