looking for battery operated lights
 

I am looking for standard AA or AAA battery powered front and taillights which I will be using during daytime rides. Looked around and see all the nice COB lights have USB charging and non-removable batteries. The other problem with those is that they are small, lightweight and that comes with short working times, because of small batteries. I want both lights to have daylight flashing modes which should last at least 15-20 hours. And they should be available in Europe.

Cateye sells some. Check them out.

Planet Bike
 

I won't claim expertise in thus subject area. I have not wanted more devices to charge, so I only own lights with non-rechargeable batteries. The Planet Bike Superflash taillight is on all my bikes. My most powerful headlights are from Planet Bike.

Other companies probably offer competitive products. I have not seriously shopped for a light for several years.

I have admired Planet Bikes' philosophy and advocacy.

I do not know about European availability. (though the name is "Planet ____")

Thanks for the tip, unfortunately it looks that Planet Bike has presence in US only and not in the other parts of the planet. Superflash looks cool and does what I need, at least on paper.

I was going to suggest Planet Bike, they have several versions of the Superflash that use two AAA batteries, but sounds like that is not an option. But if you wanted to contact them and ask if there is a retailer in Europe, they are at:
https://www.planetbike.com/support/#contact-us-page

The Busch & Muller lights that I have used are all dyno powered, but they might make some battery ones. It however is possible that none of theirs flash since they are made for the German market.
https://www.bumm.de/en/

It looks that Superflash (or pretty similar) is branded as "Smart" in Europe, similar run times, looks identical, I will explore those.

Cygolite still offers a couple of headlights in their Expilion series that have removable li-ion battery sticks. I have had the 700 for years, and it gets very good battery life, but I also like to have the option of swapping in a fresh battery if it is ever needed. It is also an amazingly durable light, as I have put it through the ringer!

Several companies copied Planet Bike superflash lights, I suspect the Smart is one of those.

I had a XLC brand taillight that was identical to Superflash, but leaked water in from rain, the corrosion inside killed the light. That is less likely to happen to a Planet Bike light. But the copies are cheap, go for it.

Some of the Superflash models and also some of the copies have a very tightly focused beam straight back but not much to the sides. So, be careful to aim it well so the traffic behind you sees that tight beam.

Thanks for pointing to Cygolite, funny thing - their webpage has banned access from my country, I now feel like criminal :D

One of the things I like about the Fenix BC30 V2.0 headlight is that it uses a pair of standard 18650 rechargeable batteries that are easy to swap.

I like the 50/600 lumen blinking mode for "be seen" lighting, but I don't think one set of batteries would make the 15 hours the OP was looking for, and that light doesn't offer any power-thriftier blinking modes.

What country is that ?

Latvia. This is strange because you cant even buy from their webpage, not sure what kind of scam they have received from here.

^ This.

Headlight: CatEye HL-EL135. 2xAA. Claimed to flash for 320 hours. Note: this is a 'to be seen' light. Cateye sells other 'to see with' lights that fit in the same mount.

Taillight: Cateye Tight Kinetic, Reflex Auto or Omni 5. All 2xAAA. Claimed to flash for 90+ hours.

Thanks, the headlight looks impressive, 320 hours, I have never seen running hours like this for front light and it is availble here, doesnt cost fortune so I can keep my kidneys :D

It is strange indeed. Is there any chance that you are behind a proxy ? Maybe using VPN on some weird server ?
Back to the point, i see your point about external lights, the problem is that Lithium Ion batteries are much better that NiMh (if you are planning to use rechargeable ones, which is obvious if you take into account the environmental impact of using alcaline batteries)
There are front lamps that use 16650 lithium batteries, these are rechargeable so you can have spares with you in case you are planning a very long trip. i have 7 spares that i took out from an ald laptop battery.
Lithium Tail lights are much brighter than the ones you are looking for, and they are not expensive, so you can have a couple of them in case they run out of fuel.
One thing you could also consider is that a powerbank wil charge your lights, and any other usb devices like your phone or bike computer, so that might be an option to consider.