I'm fairly new to this. I've been looking for a couple spare 14500 protected cells that will fit my AA Tool V2. Seems to be lots of variance of OAL between manufacturers, and I don't want to waste money on batteries that are too long. I've been checking Orbtronics daily hoping the 1000mAh units (advertised as 51.5mm) would come back in stock. My other option would be the Nitecore NL1475R (49.5mm), but its rated 3.6V as opposed to 3.7V. My question, albeit maybe an ignorant one, is there any significant difference in .1V for practical purposes? I'm certainly open to other options, but it's difficult to find sources for decent batteries.
3.6V vs. 3.7V 14500 cells...does it matter?
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DIWdiver
Flashlight Enthusiast
There's no significant difference. That is only a 'nominal' voltage. It's something like the average voltage as the cell discharges.
Most LiIon chemistries are fully charged at around 4.2V. As you discharge them, the voltage drops. It crosses 3.6-3.7V somewhat near mid-discharge, and depending on a lot of things not much related to the cell chemistry, we call it fully discharged somewhere between 3.2 and 2.5V.
All of these numbers are rooted in the cell's behavior, but are also somewhat arbitrary. Charging to 4.1V instead of 4.2V gets you only a slight reduction in capacity, but also an increase in cell life (number of cycles). Charging to 4.0V would give you a greater reduction in capacity, but also a greater increase in cycle life.
The same thing happens at the other end. The lower you go in voltage before stopping the discharge and charging the cell, the more capacity you get, and the fewer cycles.
The one chemistry that is significantly different is Lithium Iron Phosphate, AKA LiFePo4, or LFP. The voltages are significantly lower for this chemistry. Fully charged is around 3.5V, discharged is around 2V. These are often referred to as 3.2V cells.
We do occasionally see LiIon cells referred to as 4.1 or 4.2V cells. This is typically just specsmanship. You also see 5000-9000 mA-H 18650 cells. This is just a lie. These same people could refer to an LFP cell as a 3.6V cell. To avoid these issues, stick to reputable suppliers and avoid places like Amazon, Banggood, etc. Unless you are careful and lucky, it's easy to get ripped off on sites like that.
Most LiIon chemistries are fully charged at around 4.2V. As you discharge them, the voltage drops. It crosses 3.6-3.7V somewhat near mid-discharge, and depending on a lot of things not much related to the cell chemistry, we call it fully discharged somewhere between 3.2 and 2.5V.
All of these numbers are rooted in the cell's behavior, but are also somewhat arbitrary. Charging to 4.1V instead of 4.2V gets you only a slight reduction in capacity, but also an increase in cell life (number of cycles). Charging to 4.0V would give you a greater reduction in capacity, but also a greater increase in cycle life.
The same thing happens at the other end. The lower you go in voltage before stopping the discharge and charging the cell, the more capacity you get, and the fewer cycles.
The one chemistry that is significantly different is Lithium Iron Phosphate, AKA LiFePo4, or LFP. The voltages are significantly lower for this chemistry. Fully charged is around 3.5V, discharged is around 2V. These are often referred to as 3.2V cells.
We do occasionally see LiIon cells referred to as 4.1 or 4.2V cells. This is typically just specsmanship. You also see 5000-9000 mA-H 18650 cells. This is just a lie. These same people could refer to an LFP cell as a 3.6V cell. To avoid these issues, stick to reputable suppliers and avoid places like Amazon, Banggood, etc. Unless you are careful and lucky, it's easy to get ripped off on sites like that.
hsa
Flashlight Enthusiast
^ Good information as usual and much appreciated DIWdiver.
LTO is another oddball, much lower nominal
Which is midpoint 50% SoC resting OCV
For the "normal" LIs, usually rounded to 3.6V I think rounding up is just marketing.
Although among the dozens of specific chemistries in that range, maybe some are actually a bit higher than others, but not an indicator of "better" even if so.
Which is midpoint 50% SoC resting OCV
For the "normal" LIs, usually rounded to 3.6V I think rounding up is just marketing.
Although among the dozens of specific chemistries in that range, maybe some are actually a bit higher than others, but not an indicator of "better" even if so.
LTO batteries are normally 2.3 volts, aren't they?
I have some LTO's out of a car that I use to run a trolling motor.
I charge mine to 2.6 volts but they will take 2.75 volts.
They have some great characteristics but do not have the energy density that most other chemistries have. For deep cycle use they are great. No thermal runaway, can be charged at any amperage and will fully charge in 30 minutes if you have the charge rate to do it. They will also last 20k charges.
What are some of the best 14500's out right now? I am in need of a few more.
I have some LTO's out of a car that I use to run a trolling motor.
I charge mine to 2.6 volts but they will take 2.75 volts.
They have some great characteristics but do not have the energy density that most other chemistries have. For deep cycle use they are great. No thermal runaway, can be charged at any amperage and will fully charge in 30 minutes if you have the charge rate to do it. They will also last 20k charges.
What are some of the best 14500's out right now? I am in need of a few more.
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