Some LiFePO4 Battery Testing Results Manual and Automated

Some updates;

- I was lent a Bioenno BLF-1209WS purchased in Jan 2019. Tested and ran for 8.8h.
- Updated my Arduino automated tester by adding an "LCD Keypad Shield" display to allow monitoring of the testing. The updated code has been uploaded..
- Created a new XLS spreadsheet to parse the automated testing results and create a graph from them
- Added pictures of my test rig.

Find all this, and more, at http://aviation.derosaweb.net/batterytest.

John OHM Ω

On Thursday, May 2, 2019 at 5:11:13 PM UTC-4, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
Some updates;

- I was lent a Bioenno BLF-1209WS purchased in Jan 2019. Tested and ran for 8.8h.
- Updated my Arduino automated tester by adding an "LCD Keypad Shield" display to allow monitoring of the testing. The updated code has been uploaded.
- Created a new XLS spreadsheet to parse the automated testing results and create a graph from them
- Added pictures of my test rig.

Find all this, and more, at http://aviation.derosaweb.net/batterytest.

John OHM Ω

I get 404 not found at http://aviation.derosaweb.net/batter...g_Template.xls and the other two as well. I do see the SOARING reprint, though.

On Thursday, May 2, 2019 at 4:27:06 PM UTC-5, Dan Daly wrote:
On Thursday, May 2, 2019 at 5:11:13 PM UTC-4, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
Some updates;

- I was lent a Bioenno BLF-1209WS purchased in Jan 2019. Tested and ran for 8.8h.
- Updated my Arduino automated tester by adding an "LCD Keypad Shield" display to allow monitoring of the testing. The updated code has been uploaded.
- Created a new XLS spreadsheet to parse the automated testing results and create a graph from them
- Added pictures of my test rig.

Find all this, and more, at http://aviation.derosaweb.net/batterytest.

John OHM Ω

I get 404 not found at http://aviation.derosaweb.net/batter...g_Template.xls and the other two as well. I do see the SOARING reprint, though.

Dan - You might just need a web page refresh as I had been actively updating the web page around the time of your 404. Let me know if it still fails.

On Friday, May 3, 2019 at 12:33:46 AM UTC-4, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
On Thursday, May 2, 2019 at 4:27:06 PM UTC-5, Dan Daly wrote:
On Thursday, May 2, 2019 at 5:11:13 PM UTC-4, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
Some updates;

- I was lent a Bioenno BLF-1209WS purchased in Jan 2019. Tested and ran for 8.8h.
- Updated my Arduino automated tester by adding an "LCD Keypad Shield" display to allow monitoring of the testing. The updated code has been uploaded.
- Created a new XLS spreadsheet to parse the automated testing results and create a graph from them
- Added pictures of my test rig.

Find all this, and more, at http://aviation.derosaweb.net/batterytest..

John OHM Ω

I get 404 not found at http://aviation.derosaweb.net/batter...g_Template.xls and the other two as well. I do see the SOARING reprint, though.

Dan - You might just need a web page refresh as I had been actively updating the web page around the time of your 404. Let me know if it still fails.

John - it now shows the "updated" banner, and I can download. Thank you! Your page is a great resource!

You may remember last spring that I did some testing under load of my (and others) LiFePO4 batteries. After a year's worth of soaring I tested my two batteries again. Below is an update and comparison.

Tested was done with a 1A load and after just coming off the charger to when the battery has discharged to 12Vdc.

2015 Stark - Model SP-12V9-EF
April 2019 - 5.71h
October 2019 - 5.49h (loss of 13.3mins or 3.8%)
2017 Bioenno - Model BLF-1209WS
April 2019 - 8.83H
October 2019 - 8.85h (loss of 12.0mins or 3.2%)

I also updated my Arduino based testing rig's display. Previously, I used a simple 2 line by 16 character LCD B/W display. Now I am using a 240x320 pixel LCD touch sensitive color display. Oooooo, cool (and surprisingly cheap).

The new display allows me more room to display information during testing and to create a real time graph of the data. Displays are more fun than necessary but what the heck. There is amazingly inexpensive open-source hardware available for the Arduino system. The O'Reilly "Arduino Cookbook" leads you by the hand to create some powerful cool tools.

Information can be found at http://aviation.derosaweb.net/presen...s/#batterytest.

On Thursday, May 2, 2019 at 2:11:13 PM UTC-7, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
Some updates;

- I was lent a Bioenno BLF-1209WS purchased in Jan 2019. Tested and ran for 8.8h.
- Updated my Arduino automated tester by adding an "LCD Keypad Shield" display to allow monitoring of the testing. The updated code has been uploaded.
- Created a new XLS spreadsheet to parse the automated testing results and create a graph from them
- Added pictures of my test rig.

Find all this, and more, at http://aviation.derosaweb.net/batterytest.

John OHM Ω

Congratulations on building a battery tester (I wouldn't bother, myself).

But here are the shortcomings of your tester:
1. It has no discharge cutoff. It keeps discharging the battery until totally discharged. This can damage the battery, and is certainly not good for it. I would not test a battery w/o this.

2. It does not discharge at a constant current. The current decreases as the voltage drops. Modern battery testers will do this.

3. It does not discharge at a constant wattage. This is a more typical scenario where avionics will increase current as the voltage drops.

That said, it is better than sitting down for 6 to 10 hours and recording meter readings. I have switched my avionics battery from a Pb to a LiFePO4 partly because I don't want to buy a new battery every 2 years.

Tom

On Wednesday, 16 October 2019 05:44:35 UTC+3, 2G wrote:
On Thursday, May 2, 2019 at 2:11:13 PM UTC-7, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
Some updates;

- I was lent a Bioenno BLF-1209WS purchased in Jan 2019. Tested and ran for 8.8h.
- Updated my Arduino automated tester by adding an "LCD Keypad Shield" display to allow monitoring of the testing. The updated code has been uploaded.
- Created a new XLS spreadsheet to parse the automated testing results and create a graph from them
- Added pictures of my test rig.

Find all this, and more, at http://aviation.derosaweb.net/batterytest.

John OHM Ω

Congratulations on building a battery tester (I wouldn't bother, myself).

But here are the shortcomings of your tester:
1. It has no discharge cutoff. It keeps discharging the battery until totally discharged. This can damage the battery, and is certainly not good for it. I would not test a battery w/o this.

2. It does not discharge at a constant current. The current decreases as the voltage drops. Modern battery testers will do this.

3. It does not discharge at a constant wattage. This is a more typical scenario where avionics will increase current as the voltage drops.

That said, it is better than sitting down for 6 to 10 hours and recording meter readings. I have switched my avionics battery from a Pb to a LiFePO4 partly because I don't want to buy a new battery every 2 years.

Tom

1. BMS does the cutoff inside battery anyway
2. Voltage does not drop much with LFP
3. How is this relevant, most just want to know if their battery capacity is 10Ah or 7 Ah, not 9.998 Ah.

On 10/16/19 4:05 AM, krasw wrote:
On Wednesday, 16 October 2019 05:44:35 UTC+3, 2G wrote:
On Thursday, May 2, 2019 at 2:11:13 PM UTC-7, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
Some updates;

- I was lent a Bioenno BLF-1209WS purchased in Jan 2019. Tested and ran for 8.8h.
- Updated my Arduino automated tester by adding an "LCD Keypad Shield" display to allow monitoring of the testing. The updated code has been uploaded.
- Created a new XLS spreadsheet to parse the automated testing results and create a graph from them
- Added pictures of my test rig.

Find all this, and more, at http://aviation.derosaweb.net/batterytest.

John OHM Ω

Congratulations on building a battery tester (I wouldn't bother, myself).

But here are the shortcomings of your tester:
1. It has no discharge cutoff. It keeps discharging the battery until totally discharged. This can damage the battery, and is certainly not good for it. I would not test a battery w/o this.

2. It does not discharge at a constant current. The current decreases as the voltage drops. Modern battery testers will do this.

3. It does not discharge at a constant wattage. This is a more typical scenario where avionics will increase current as the voltage drops.

That said, it is better than sitting down for 6 to 10 hours and recording meter readings. I have switched my avionics battery from a Pb to a LiFePO4 partly because I don't want to buy a new battery every 2 years.

Tom

1. BMS does the cutoff inside battery anyway

Unfortunately, not all LFP batteries have a BMS, and of those that do,
not all have low-voltage cutoff. Of all the misinformation that gets
spead about on LFP's, that right at the top of the list.

Given how easy it is to add a low-side power switch, I wonder why you
would build an automated, computer controlled tester that lacks this.
Adding it would make it useful for a wide range of batteries.

On Wednesday, October 16, 2019 at 7:51:15 PM UTC-5, kinsell wrote:

Unfortunately, not all LFP batteries have a BMS, and of those that do,
not all have low-voltage cutoff. Of all the misinformation that gets
spead about on LFP's, that right at the top of the list.

Given how easy it is to add a low-side power switch, I wonder why you
would build an automated, computer controlled tester that lacks this.
Adding it would make it useful for a wide range of batteries.

Kinsell - You have me thinking now.

While both my Stark and Bioenno batteries has a BMS that cuts off at 10Vdc, it wouldn't be too difficult to add an Arduino relay shield to the mix. It could remove the load for non-BMS lithium batteries and for SLA's.

These shields contain four 3A 24Vac relays and cost about $4.50 (cheap! see https://www.ebay.com/itm/323801575423). The neat thing about these shields is that they stack and make a nice tidy package. I would have a stack of;

LCD Display
-----------
Relay Shield
-----------
Arduino

Once the battery charge drops to the low volt trigger point, I would remove the load (turn off the relay) from the battery via coding. One relay rated at 3A should be ok but I might use two relays in parallel to be sure.

I just ordered a couple of the relay shields and will report back.

On 10/16/19 7:40 PM, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
On Wednesday, October 16, 2019 at 7:51:15 PM UTC-5, kinsell wrote:

Unfortunately, not all LFP batteries have a BMS, and of those that do,
not all have low-voltage cutoff. Of all the misinformation that gets
spead about on LFP's, that right at the top of the list.

Given how easy it is to add a low-side power switch, I wonder why you
would build an automated, computer controlled tester that lacks this.
Adding it would make it useful for a wide range of batteries.

Kinsell - You have me thinking now.

While both my Stark and Bioenno batteries has a BMS that cuts off at 10Vdc, it wouldn't be too difficult to add an Arduino relay shield to the mix. It could remove the load for non-BMS lithium batteries and for SLA's.

These shields contain four 3A 24Vac relays and cost about $4.50 (cheap! see https://www.ebay.com/itm/323801575423). The neat thing about these shields is that they stack and make a nice tidy package. I would have a stack of;

LCD Display
-----------
Relay Shield
-----------
Arduino

Once the battery charge drops to the low volt trigger point, I would remove the load (turn off the relay) from the battery via coding. One relay rated at 3A should be ok but I might use two relays in parallel to be sure.

I just ordered a couple of the relay shields and will report back.


Good, that would be a nice addition to your project. You can also
Google "low-side power mosfets" for a different option that takes less
power to drive. Probably available in a stackable module also.