Cell internal resistance (what does it mean)

[HRTKD]

From my experience with preparing aluminum for brazing, you need to degrease the surface first. Acetone works for that. After degreasing, use a brass or stainless steel brush to remove the oxides. Do not use compressed air to clear off the dust left from brushing. I sometimes use Acetone again after brushing.

 

[ArthurEld]

Glue on the terminals definitely messes up the tester.
But I don't think I could do anything to my tester to make it show the numbers you are getting.
I doubt it is your cells if you got them from Amy

 

[Gazoo]

From my experience with preparing aluminum for brazing, you need to degrease the surface first. Acetone works for that. After degreasing, use a brass or stainless steel brush to remove the oxides. Do not use compressed air to clear off the dust left from brushing. I sometimes use Acetone again after brushing.

On my cell terminals there was no oxidation as far as I could tell and no grease. What was interesting is the majority of the gunk was on the negative terminals. There was hardly any on the positive terminals.

600 grit nail files worked great to get it off but it still took some filing. Some of it didn't come off easily. Once I was satisfied I then used acetone to make sure the terminals were clean because filing or sanding leaves a very fine powder on them. That was my experience with cleaning my terminals. I could be wrong but I believe the gunk was tape residue, and that's what the supplier told Michael it is in the group buy thread.

EDIT: Forgot to mention I did use a vacuum cleaner with a brush attached to vac the cells before I used acetone on the terminals.

 

[scott harris]

Do not use compressed air to clear off the dust left from brushing

Why not use compressed air?

 

[Dzl]

10x the readings she got, and also 5-10x the manufacturer's maximum IR spec for those cells (<= 0.25 iirc)

 

[HRTKD]

Why not use compressed air?

Aluminum oxidizes in air. Compressed air is a lot of air that promotes oxidation. It's also usually moist, unless you have a dryer device downstream of your compressor.

 

[ArthurEld]

This video talks about calibrating the YR1035+ It also goes through the menu settings. His menu is in Chinese though.

 

[scott harris]

The problem was with the calibration. The video helped a lot. The printed instructions that came with the meter; not so much. I now get 0.11 to 0.12 m Ohms for all cells.

One thing the video did not mention is that when you touch the probes the white wire should connect to the white wire and the red wire should connect to the black wire.

Thanks for the help.

 

[ArthurEld]

I'm glad that worked. Now I have to calibrate mine.

 

[crossy]

Useful thread.
The question is, is IR a reasonable measure of the life left in a LiFePO4 cell?

We have a local supplier with a "container load" of used CALB (allegedly, they are unmarked) golf-cart 200Ah LiFePO4 cells which he imported from China. He's selling them at about $50 a pop and is using a LQ1060S ( https://www.aliexpress.com/i/4000083091762.html ) to show that they are good and weed out any non-performing ones.

They are generally showing 0.233mOhm and 3.291V, worth buying or pass??

 

[HRTKD]

Seems like an inexpensive way to get into LiFePO4. The first number sounds high, but I don't keep up much with the resistance values. It would be nice to be able to run a capacity test on one before going all-in.

If I needed 600 Ah of battery, I would be inclined to purchase one or two extras, just in case. At that price, extras aren't expensive.

 

[crossy]

I bought 17 (including a spare) "on-spec".

I've got one on capacity test now before balancing and building a pack, it's at 3.245V after 100Ah @ 20A so looking pretty OK at present.

 

[HRTKD]

Now that you have yours, are you going to let the rest of us in on the deal?

 

[crossy]

Now that you have yours, are you going to let the rest of us in on the deal?

They are local to us in Thailand I'm afraid.

แบตเตอรี่ ลิเธียม CALB lithium ion Lifepo4 3.2V 12v GRADE A 200ah UPS Battery รถกอล์ฟ ระบบโซล่า คัดสรรอย่างดี | Lazada.co.th

แบตเตอรี่ deep cycle 12v 200: จะไม่ชาร์จเกินหรือชาร์จแบตเตอรี่รถกอล์ฟของคุณ battery lithium 24v 200ah: ให้พารัลเตอร์โซนกระแสไฟสูงและอัปเกรดระยะทางที่เพิ่มขึ้น แบตลิเธียม lifepo4 200ah: จะไม่ชาร์จเกินหรือชาร์จแบตเตอรี่รถกอล์ฟของคุณ แบตเตอรี่ gs 12v 200ah...

www.lazada.co.th

Not sure if international shipping is available / worth it.

Use Google or Chrome to translate.

 

[HRTKD]

They are local to us in Thailand I'm afraid.

แบตเตอรี่ ลิเธียม CALB lithium ion Lifepo4 3.2V 12v GRADE A 200ah UPS Battery รถกอล์ฟ ระบบโซล่า คัดสรรอย่างดี | Lazada.co.th

แบตเตอรี่ deep cycle 12v 200: จะไม่ชาร์จเกินหรือชาร์จแบตเตอรี่รถกอล์ฟของคุณ battery lithium 24v 200ah: ให้พารัลเตอร์โซนกระแสไฟสูงและอัปเกรดระยะทางที่เพิ่มขึ้น แบตลิเธียม lifepo4 200ah: จะไม่ชาร์จเกินหรือชาร์จแบตเตอรี่รถกอล์ฟของคุณ แบตเตอรี่ gs 12v 200ah...

www.lazada.co.th

Not sure if international shipping is available / worth it.

Use Google or Chrome to translate.

Ah, bummer for us, good for you. I hope it works out well!

 

[crossy]

Ah, bummer for us, good for you. I hope it works out well!

Yeah, we do seem to get stuff cheaper here than the US and Europe. New 330W poly panels are about USD 85 retail (just go and buy one).
Sorry drifting off topic.
Bored, awaiting the capacity test to complete.

 

[Capt Bill]

... New 330W poly panels are about USD 85 retail (just go and buy one). ...

WOW: $ 0.26 (cents) per watt. I got 6K+ worth in Northern California last year for $0.50 / watt. ... for Q-cell and REC TwinPeak panels (both high reputation brands). My first 400 watts array cost $4/ watt back inthe the 80s. ... $ 0.26/watt sound awesome. ... sorry for going off topic here.