LiFePO4 Cell Testing 0-600A (initially)
Here are some tests screen-shots to show cell testing in action. For this test the 400A run was halted due to the cell
terminals heating up. Some descriptions for the screen shot: Most of the number boxes are self explanatory, with the
possible exception of dTstep which is a loop cycle timer accuracy checkpoint. The Ah calculator used on the graph is
to see how much was consumed during the test and will serve as a good means to compare cells above 1C loads.
Recharging the cells will be with a power supply setup as CC-CV termination to the datasheet specifications, at typical
charger output currents in the range of 8 to 16A.
Initiated 8/12/10
Updated 8/14/10
Legend:
Cell Temperature
Blue (+) terminal
Grn (-) terminal
Wh is cell center



Cell Voltage
Measured under lugs
at the cell terminals


As you can see, the
terminals get real hot
dishing out 400A for
over a minute and
then some!
With many LifePO4 cell manufacturers in the market with many Ah product offerings, the need became apparent for
cell testing from a non biased -EV capable- viewpoint to see how they perform under high >1C current demands.

What is proposed herein is a win-win situation for LiFePO4 cell manufacturers and cell customers!

  • Are you a LiFePO4 manufacturer? Have your cells tested here for little out of pocket cost to you, and your
    customers get an unbiased 3rd party snapshot of your cell's performance. Click here to email Belktronix

  • Are you in the market for cell data to use in your EV project? See cell performance data for various cell types

What is the cost to do the testing?

  • A batch of cells is required and when the tests are completed the test data is published and the cells are re-
    used afterwards in various testing equipment and/or vehicles used to continue to improve EV hardware.
Left, thermocouples for each cell
terminal are placed on foam pads to
push against the underside of the
measurement terminals, right.

The measurement tabs are bus bar
OFC copper material that serves to
mate between the lugs and female
threaded power tabs of the cell.

The thermocouple for the case is on
the front face of the cell, extreme
right side of the center of the cell---->
and wrapped to limit air circulation.

A 1000A 50mV shunt handles the
current measurements from the cell.
A HP34907A multifunction module retrieves data sampled from the cell power terminals, thermocouples and current
shunt and routes it into a HP34970A interfaced to a PC running LabView. The current command is sent serially to
load modules to place the cell under a specific current -regulated load. Data is collected at timed intervals and plotted
on the screen which serves as the visual interface.
Test hardware is available to handle 600A loads is now up and running with an additional 400A parallel assembly in
the works -totalling 1000A- of load capability. The 100Ah CHP cell (1C continuous version) was evacuated from the
Scirocco and after a brief recharge, was volunteered to capture some data. More photos of the physical test setup
will follow, here's simply a first cut (preview) to show progress.
Same cell after
charging overnight,
100A discharge.

5.8Ah short of full
label rating, but not
bad considering the
cell is 2 years old

The 2.253V end of
test number is due
to the 30 sec cycle
time.
Test time = 56.5min.
Upcoming Software
Enhancements:
dT temp calculation
dT time calculation
          ----------->
With a 3rd party available to do testing, the cell manufacturer isn't spending big bucks to evaluate each product
offering for a lab to get an expensive piece of paper which will cost  the customer more in the end, and the customer
gets test results for cells being considered for use in their EV, at no cost to you. Its an affordable option for
manufacturers to send LiFePO4 cells here (essentially at cost) and let the test results speak for themselves. So what
are you waiting for? Have your manufacturer send a batch of cells here to test out, the results and test methodology
will be posted here for all to see.
Another 100Ah cell
from a different
manufacturer
Zhuhai

Running 400A
For over a minute
100A load test
Cell testing continued click here