The LiFePO4 Headway cell 38120P TEST REPORT inside


100 GW
Apr 8, 2007
Quebec, Canada East
I received 3 LiFePO4 38120 cell of 3.2V 8.0Ah.

I will test those 3 identicals cells with my lab equipment soon and will post some true specs. I asked 3 for having better and realistic results acuraccy.

Here are some spec from Headway:

Oem specs
300g = 85.3Wh/kg
80A continuous
160 peak

See the pics:



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This should be interesting!

Do you have a price and source for them?
I can't think of a better person to test them. :twisted:

Do you have any idea what the price on those will be?
Lately, I've been working with some 32650 'old style chemistry' LiIons rated at 3.6V 5000 mAH, /2C (4.8 AH @ < @ 5A or under and .... 3.8AH @ 12A, actual, according to my CBA) , and thought the ~$12.50 (including shipping from China) I paid for them, made them the best AH per dollar deal available,.... I have 30 now, ordered another 60 of them a month ago; (Should be here next week or so.)

Wish I'd known about these. Price is competitive; safer chemistry and better high current capacity. I sure wish I had bought 60 of these instead.

Hope they turn out to be as good as they sound!

If so, I'm afraid I'm going to spend another thousand dollars on batteries.
Where are these available commercially?

I assume that someone sent them to you for independent testing to verify their claims as they market them to the masses...but we couldn't find them available for purchase after the ZEVA reports on these cells came out. Maybe I'm not looking in the right places though.
Nice format size, and at $18.00 per cell, nice price.
Only 1000 cycle lifespan, maybe the chemistry needs a little tweeking.
Still, the cost benefit is worth overlooking some of the negatives.
I'm designing a 50A constant current load to add parallel to my cahrger that only disch to 5A.
when i will finished it i will begin the tests.

from now, i did a short test just for fun about capacity at 5A disch and the internal resistor.

i measured 8230mAh from a fully charged cell at 23 degree C at 5A down to 2.5V the nominal is 8Ah :)

Also i tested 6mohms instead of the 2.8 mohms from the nominal spec :|
Great. Thanks for the update. I have my doubts about the cells being able to handle a 10c continuous discharge, but if they could handle 5 or 6c continuous discharge that would be great. Some tests with a 50 amp load is exactly what I am interested in.

Ypedal said:
Hey Doc

When you have the time, do me a favor, put one in the oven, or heat it up to 35 celcius and do the same test for IR.. :?

In the oven?? :shock:

Ypedal.. my oven can only stabilizt starting to 70C...

I have a vetter and secure ides.. the top of a computer CRT screen or the fan output of a pc power supply when playing to need for speed underground at 1280x1024 :wink:

or maybe my Jobmate heatgun using my IR thermometer :wink:

but an oven... :!: ischhh...!
Also.. about the IR, i observed that it is not only the heat that affect it!

If you measure it immediatly after charging it, it will be higher then i you leave it few hour after charging and then measuring it!

To be valid and accurate, Capacity and IR need to be taken to a very close range of environmental and process parameter!!
that is actually the most difficult to acheive about my 360 Li-Mn Konion cells.... i measure around 15-20 a day at 5A disch but the temperature of my room affect the results...

Hey... I'm not joking. :D

You want stable temperature for at least 15min. The heating pad is hard to accurately control temperature. You can run the hairdryer hose into a clear plastic box and mix cool air into the hose while watching the temp.

That's how I would do it...
I'm testing Headway cells now 8) (I just received my CBA-II battery tester today.

First test running now;

Cell no 3/3

-10A charging terminated to 50mA
-now 8A discharging capacity test. First result: ended at 8.29Ah at 26.6degreeC :wink:

Coming next dishcarge rate: 16A, 24A, 32A, and 1A (C/8)for absulote C rating.

olaf-lampe said:
Doc, you must be absolutely fearless! Watch the last picture on top of this thread: putting a metall ruler so close to the tabs! :twisted:
How many weld-spots do the tabs have? Do they look trustworthy? I wonder if they can handle these rated amps?

they have more than 20 spot. home made style (not regular or symetric)
I had time to do some others test on the cell:

Cell no 3/3

-10A charging terminated to 50mA

-Results of 16A discharging capacity test. ended at 8.16Ah at 27.4degreeC
-Results of 8A discharging capacity test. ended at 8.29Ah at 26.6degreeC
-Results of 1A discharging capacity test. ended at 8.39Ah at 25.1degreeC (C/8)for absolute C rating.

Coming next dishcarge rate: 24A, 32A,
From now, for sure only one would be ok.

I tested this morning all 3 cells internal resistance i left them alone last night from the previous charging to stabylise.

I got exactly 6 miliohm from each of the 3 cells

Cell 1: 6 miliohms
Cell 2: 6 miliohms
Cell 3: 6 miliohms

I think that is great news from these cells.

Also what i discovered is that their no load voltage from 3.600 immediatly after i charged them droped to 3.412V 10 hours after. It seems that their nominal voltage is really 3.2V like the manufacture claim instead of 3.3 like most common LiFePo4

I will do a discharge test them at 24 and then 32 and 40A soon

I will also torture them at 60, 80 and 100A with heavy resistive load soon. bring popcorn with you next time, that will become interesting!! :wink:

Yeah ok interesting but you never said anything about prices ...the only time a saw a price was that link earlier in this thread by someone else that stated 17 something american dollar is that so or is it with the link you get would get them for by andy at 35 $
slayer said:
Yeah ok interesting but you never said anything about prices ...the only time a saw a price was that link earlier in this thread by someone else that stated 17 something american dollar is that so or is it with the link you get would get them for by andy at 35 $

That's not determined from now.