battery use 18650
but 18650 has 2 types, 3.6v and 3.7v
how should I choose?
battery use 18650
Not sure why they give different values.
A normal Li-ion battery don’t have different service voltages.
They all ramp-up from ~3.4V discharged to ~4.2V fully charged.
What’s really important is the claimed capacity in mAh or better in Wh. Knowing that a battery that claim a super high capacity compared to most of the other one are most likely to have a fake capacity claimed.
normal capacity for this type of battery should be around 1800mAh to 3500mAh (~6Wh - ~13Wh) every battery bellow or higher of that range should be considered suspicious.
And even in the range it can still be a fake one, but faking vendors tend to try to make their battery to look better than they are and will try to sell them with incredibly impossible capacity size. So beware.
Also there are two main type of battery, protected and unprotected. I would recommend to go as much as possible for protected one as these protection is to make sure the battery will not go hell in case of a battery charger failure.
Try to stick to well known brand.
I will choose 3.7v
I’ve tested many brands and varieties of 18650s. I’ve personally settled on the Sanyo NCR18650BL as as general electronics allrounder. These are not protected cells and so I only ever charge them with chargers specialized for charging unprotected cells… I’ve opted in this manner because I do not usually expect the drain to be so significant as to cause significant heat issues. I’m knowledgeable and experienced and I am not going to recommend others who are less wise on this matter to follow my lead… WHAT I DO RECOMMEND… is either lengthy study to find out what is best for you OR just stick with lower amp PROTECTED cells. the only time anyone ever needs batts that can output 40A is when you are vaping with potentially dangerous mech mods.