The bistander thread

[altrez]

Just for fun, you might put a kilowatt meter between your battery charger and the wall when you charge your battery. It will give you an idea of how much energy it actually takes to charge that battery back to where you started compared to what you got out of it.

That's a great idea! I have a few different ones.



-Altrez

[Turion]

Just for fun, you might put a kilowatt meter between your battery charger and the wall when you charge your battery. It will give you an idea of how much energy it actually takes to charge that battery back to where you started compared to what you got out of it.

[altrez]

Here are the results of the 3rd test with the Split-The-Positive configuration.

Test setup was LIFEP04 12.8v 16Ah 204.8Wh / Razor motor MY 1016-B / PWM to control speed and amp draw configured in Split-The-Positive / boost module set to 26v. RPM on motor was 991 and the amp draw on the battery was .785mA I checked the amp draw and RPM's during the test and adjusted to keep them steady if I needed to.

BK601 at Start:
100%
VO 13.33v
VL 12.81v
037 mohm

Fluke Voltage test:
13.34v

BK601 at end after 30 minute rest:
100%
VO 13.29v
VL 12.85v
031 mohm

Fluke Voltage test:
13.31v

I have decided to do one more test in the morning. This test I will just use the PWM and motor to see what results I get.

-Altrez

[altrez]

Hi Altrez,
I assume you mean 787mA, not .787. I don't think the motor will run on less than 1 milliamp.
bi

It was early and I was sleepy lol.

-Altrez

[bistander]

Hi Altrez,
I assume you mean 787mA, not .787. I don't think the motor will run on less than 1 milliamp.
bi

[altrez]

Here are the results of today's test.

Test setup was LIFEP04 12.8v 16Ah 204.8Wh / Razor motor MY 1016-B / PWM to control speed and amp draw configured in Split-The-Positive / boost module set to 26v. RPM on motor was 982 and the amp draw on the battery was .787mA I checked the amp draw and RPM's during the test and adjusted to keep them steady if I needed to.

BK601 at Start:
100%
VO 13.33v
VL 12.81v
037 mohm

Fluke Voltage test:
13.35v

BK601 at end after 30 minute rest:
100%
VO 13.30v
VL 12.78v
037 mohm

Fluke Voltage test:
13.31v

The 3rd and last test is planned for tomorrow morning.

-Altrez

[altrez]

This morning I ran the 2nd part of the test that Turion posted. My results are listed below along with some notes:

This is what Turion posted for part 2.

"..Set the output of the boost module to around 26 volts. Connect the positive out of the boost module to one side of the motor, and the other side of the motor to the positive of the battery. You may need to increase the output of the boost module to get it to run the motor at the same RPM as it ran directly off the boost module rather than between the positives as it is running NOW. If necessary, make the voltage adjustment to get the same RPM.."

Turion is correct about needing to adjust the setup to match RPM's, for test 2 in order to get the motor to run at around 1500 rpm's I had to adjust the PWM up to the point the amp draw on the battery went over 1.2 amp's, I am trying to keep the amps around the C20 mark for the battery so I adjusted the PWM to pull the correct amount of current from the battery in testing as the previous test. This put the RPMs on the motor around 970.The PWM is setup in the Split-The-Positive setup and the motor is connected to the PWM like normal.

Test setup was LIFEP04 12.8v 16Ah 204.8Wh / Razor motor MY 1016-B / PWM to control speed and amp draw configured in Split-The-Positive / boost module set to 26v. RPM on motor was 970 and the amp draw on the battery was .780ma I checked the amp draw and RPM's during the test and adjusted to keep them steady if I needed to.

BK601 at Start:
100%
VO 13.33v
VL 12.81v
037 mohm

Fluke Voltage test:
13.34v

BK601 at end after 30 minute rest:
100%
VO 13.29
VL 12.77
037 mohm

Fluke Voltage test:
13.31v

I will do the 2nd test in the morning and post results.

-Altrez

[altrez]

Here are this mornings test results.This is test number 3.

Test setup was LIFEP04 12.8v 16Ah 204.8Wh / Razor motor MY 1016-B / PWM to control speed and amp draw / boost module set to 14v. RPM on motor was 1585 and the amp draw on the battery was .775ma I checked the amp draw and RPM's during the test and adjusted to keep them steady if I needed to.

BK601 at Start:
100%
VO 13.35v
VL 12.83v
037 mohm

Fluke Voltage test:
13.36v

BK601 at end after 30 minute rest:
100%
VO 13.30
VL 12.78
037 mohm

Fluke Voltage test:
13.32v

The next 3 tests will be with the load in the split-the-positive configuration. As posted by Turion. The next 3 test will be done with an amp draw of ~.775ma

-Altrez

[altrez]

Hi Altrez,
For 30 minutes at 1/2 Amp, you use 1/4 Ah. On the 16 Ah battery, that amounts to 1/64 (1.6%) of the capacity. It is nearly impossible to see a change in OC Voltage with that small of a delta SOC with LiFePO4 due to its flat characteristic curve. Small difference in internal resistance could be caused by temperature.

I'm not sure what the objective of this test is and Turion is no help. But comparisons involving SOC of batteries is always difficult, even more so with LiFePO4. I suggest using a wattmeter or two capable of recording watt hours. Look at energy out of battery and into the load for equal time periods for case 1 vs case 2.

Regards,
bi

Hello bistander,

I am doing the tests the way that Dave posted because that is what I said I would do. I plan to try and do them as close to perfect as I can and then we can all review the results. I have some watt meters that I could add but want to do this first round as basic as possible. And I agree with you on the SOC, lets see what tomorrow brings on day 3 test 3.

-Altrez

[bistander]

Hi Altrez,
For 30 minutes at 1/2 Amp, you use 1/4 Ah. On the 16 Ah battery, that amounts to 1/64 (1.6%) of the capacity. It is nearly impossible to see a change in OC Voltage with that small of a delta SOC with LiFePO4 due to its flat characteristic curve. Small difference in internal resistance could be caused by temperature.

I'm not sure what the objective of this test is and Turion is no help. But comparisons involving SOC of batteries is always difficult, even more so with LiFePO4. I suggest using a wattmeter or two capable of recording watt hours. Look at energy out of battery and into the load for equal time periods for case 1 vs case 2.

Regards,
bi

[altrez]

Here are this mornings test results. I am going to try again tomorrow morning with an increased load.

Test setup was LIFEP04 12.8v 16Ah 204.8Wh / Razor motor MY 1016-B / PWM to control speed and amp draw / boost module set to 14v. RPM on motor was 894 and the amp draw on the battery was .498ma I checked the amp draw and RPM's during the test and adjusted to keep them steady if I needed to.

BK601 at Start:
100%
VO 13.35v
VL 12.74v
044 mohm

Fluke Voltage test:
13.36v

BK601 at end after 30 minute rest:
100%
VO 13.32
VL 12.80
037 mohm

Flue Voltage test:
13.33v

I am charging the battery in the evening to full this seems to be around 13.56v when the changer says its done. All tests are done in the morning after an overnight rest period for the battery in testing.

-Altrez

[altrez]

My test results are not what I expected. The main issue is that I did not use a big enough load on the battery. For those who are interested this was the result. Each test was preformed 3 times on the battery before and after testing.

Test setup was LIFEP04 12.8v 16Ah 204.8Wh / Razor motor MY 1016-B / PWM to control speed and amp draw / boost module set to 14v. RPM on motor was 390 and the amp draw on the battery was .178ma

BK601 at Start:
98%
VO 13.21v
VL 12.60v
044 mohm

Fluke Voltage test:
13.22v

BK601 at end after 30 minute rest:
100%
VO 13.18
VL 12.66
037 mohm

Flue Voltage test:
13.19v

I am going to crank up the load and try it again in the morning.

-Altrez

[altrez]

Hello Everyone,

I am getting everything together for the first part of the test. I am using a spare battery to get it setup so I will not have to adjust anything while I am running the main test. Also I am going to control the RPM's of the motor with a PWM to keep everything as close to perfect and fair as possible.





Test part 1:

Test battery with BK 601 Run the motor from the boost converter hooked up like normal for 30 minutes, let rest for 30 minutes take notes and then charge the battery and let rest for 12 hours.

-Altrez

[BroMikey]

bro,
Want to find old threads I started. Click on my name. The page I took a photo of will come up.
Turion.png

Near the top click on "About" and then down at the bottom of the page (scroll down) you will see a link that says "Find all Started Topics" You can scroll through those until you get to whatever "old" thread you want to look at.

Oh I didn't know that thx. Aaron didn't tell me that. He must be building. I'll let you know. BRB

[Turion]

bro,
Want to find old threads I started. Click on my name. The page I took a photo of will come up.
Turion.png

Near the top click on "About" and then down at the bottom of the page (scroll down) you will see a link that says "Find all Started Topics" You can scroll through those until you get to whatever "old" thread you want to look at.