I have to replace a battery samsung 35e sd1 2g2s does it have to match exactly

I have a spare icr18650 samsung 26d sdi and a lgabd11865 n116d268af

A 26D is 2600maH and a 35E is 3500maH. You will reduce your batteries capacity by 0.90AH.

Even though you're only doing one cell, the battery capacity is determined by its weakest cell group. This cell will pull the other cells around down faster, and the group that it's in will hit the low voltage limit sooner, and shut the battery down. When you recharge it, the group will spring back to full voltage but will again be the first group to run out. The math is easy. It's 900AH lower,

What about this battery instead 6800mAh

Since, AFAIK,Samsung and other well-known battery manufacturers have a 3500 mAh max for their batteries, IMO someone at Ultra was smoking contraband when they wrote the specs for that battery.

I bought a video doorbell, and it said I had to use these batteries I bought 4 not cheap I just noticed the doorbell is dead not long since charging.
Is there an easy way to test?
It should be better than the other 2500 mah.
I have seen some test on YouTube the Chinese batteries do about half what's stated or less

I haven't had the need to test, but it's easy with the proper equipment (some use a known quantity like a light bulb to measure). Look at batteryuniversity.com or maybe DW can help.

Most Chinese put false specs on their batteries, in an attempt to sell more. They are scamming people.

Electrically, you can replace it with any battery the same voltage.

If it is one of the batteries in a pack, it is smart to use a battery with the same (or similar) amp hours or what hours, so that it discharges at a similar rate to the others.

It will probably be easier to fit physically if it is the same size.

Does anyone know what the codes on the batteries in the picture mean? They are probably manufacturing batch numbers.

Most likely the batteries are the same.

I would put a volt meter on the new one, just to check.

UltraFire has always lied about their batteries. You probably need three of them to get 3.5AH. but one will likely fail and kill the whole pack.

Probably you're correct, mostly batch-related except 1865 on one and 18650 on the other, which designate 18 mm diameter and 65 mm length.

I put the ultra fire in a cheap led flashlight left it on over night 8 hours it was very dim in the morning used another battery reclaimed from a laptop forgot about it was left on 12 hours was much brighter
Bought a doorbell camera said I must use 6800 mah I did not know anything about batteries at the time, was not easy to find such a battery I think Ultra Fire is the only company that makes them never use Chinese batteries.
Me thinking I am getting this incredibly battery not so

yeah, I've been doing this for 10+ years. I've learned to stick to name brands - LG, Panasonic, Samsung. Its too expensive to get the wrong thing (even though it is advertised as correct).

Last fall I noticed a considerable loss of range, but did nothing about it during the winter. This spring it became worse, even to the point that the system would shut down due to voltage drop under heavier loads like a long hill. It was time for new battery, but I thought maybe I could just replace a few cells. I charged the pack, took it apart and found 8 of the 40 cells were in such bad shape that they would barely register on a voltmeter. Seems like almost one whole series string was bad. Makes me suspect that there may have been an issue with the BMS rather than the cells as the remaining 32 all seemed fairly uniform.

So instead of rebuilding, I just replaced the whole pack with a new 50 cell unit with 25% more capacity. That increase sure works well on the tough hills, and the range is considerably better than the previous pack ever was.

I wound up with 32 18650 cells that all measure over 4V at full charge, so I bought a small charger for them and replaced all my old D-Cell flashlights with units that use 18650 cells - so far they seem to be performing fine, so it will be a while before I ever buy flashlight batteries again! Too bad I can't do the same with all the various battery-eating remote controls in the house.

They work great in flashlights I have a few with 18650's in

It would have been an easy job replaced those 8 with good cells then you would have had a good battery to connect in parallel

That was my original intent, but when they came from the same string it didn't just seem like a coincidence. It made me distrust the BMS, so I just replaced the pack with a unit of slightly higher capacity and eliminated any lingering doubts. Don't really need the extra range of two batteries - I got over 35 miles out of the old pack when new, and the new pack seems like it will easily meet or exceed that. It should do everything I want.