Register to reply

Li-ion protection breakdown voltage?

by Artlav
Tags: breakdown, liion, protection, voltage
Share this thread:
Artlav
#1
Nov10-13, 12:20 PM
P: 145
Li-ion cells come with undervoltage protection circuits - little integrated thingies that open up the circuit when the voltage across the cell drops below 2.7V or so.
What sort of a switch is that?

I've been thinking, if a cell is inside a large series pack - a dozen of cells for a hobbyist, or a hundred cells for an electric car - won't that switch be subjected to the entire voltage of the pack upon it's opening for the weakest cell?

If so, what is the breakdown voltage of these switches, i.e. in 18650 cells, where can i look it up?
If not, how does that protection work?

I never seen such figures given in battery datasheets, so maybe i've missed the big idea?
Phys.Org News Partner Engineering news on Phys.org
Tiny UAVs and hummingbirds are put to test
Britain to trial driverless cars from 2015
NIST corrosion lab tests suggest need for underground gas tank retrofits
meBigGuy
#2
Nov10-13, 05:26 PM
P: 1,074
You do not just stack Li-Ion batteries with single cell protection systems. You need to use a multi-cell over voltage and under-voltage protection system. There are IC's and systems to do this.

http://cds.linear.com/docs/en/articl...%20LTC6802.pdf
http://www.ti.com/lit/an/slua434/slua434.pdf
http://www.intersil.com/content/dam/...n13/an1333.pdf
Artlav
#3
Nov13-13, 12:31 PM
P: 145
Nice. So that is how you do it right.
But if you just stack a set of common, single-protected cells - what would be their limit?

meBigGuy
#4
Nov13-13, 11:18 PM
P: 1,074
Li-ion protection breakdown voltage?

Don't.

I've never considered it. The protection circuit design assumes you won't do that.


Register to reply

Related Discussions
Breakdown voltage and electric field Engineering, Comp Sci, & Technology Homework 1
Effect of Humidity on Breakdown Voltage Electrical Engineering 1
Breakdown voltage Engineering, Comp Sci, & Technology Homework 11
Breakdown voltage Engineering, Comp Sci, & Technology Homework 2
Breakdown voltage of capacitance network Introductory Physics Homework 5