The bistander thread

[altrez]

This morning I ran a 30 minute test of charging the battery. My charger charges at a rate of around .250mA AC per hour. I think this is = to around 2.8A DC going into the battery? On the next test I will put an amp meter on the charger's DC side to be sure.



At the start of the 30 minute charge cycle these where the readings from the battery:

BK601
100%
VO13.32v
VL12.80v
037 mohm
Fluke Voltage Test: 13.33v

After a 30 minute rest:

BK601
100%
VO13.66v
VL12.87v
056 mohm
Fluke Voltage Test: 13.63v

-Altrez

[bistander]

I got three of these from eBay. I have not had a chance to take them apart or test them.
<snip>
I lost my rc watt meters so I just ordered two more. I also ordered one of these.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

-Altrez

Cool. Nice looking battery.
I noticed those newer wattmeters that use the pass-thru current sensor. Must be a Hall sensor for the DC units. They also have AC units using current transformers. Nice alternative to the shunt (current viewing resistor).
bi

[altrez]

I got three of these from eBay. I have not had a chance to take them apart or test them.




I lost my rc watt meters so I just ordered two more. I also ordered one of these.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

-Altrez

[altrez]

Hi Altrez,
I'm happy to have you post on this thread. Interesting instrument you show. Let us know how it works. I thought you had one or two of these type.
https://www.amazon.com/dp/B07QNKF79J..._3kzhFbWKDDSD0
They seem to work well to give the accumulated Wh or Ah for a test.
Did you ever get the bigger Lithium battery?
Regards,
bi

Hi bistander, I do have a few of the watt meters you posted. I can rig one up on the next test. I did get the bigger Lithium battery's and at the price I paid they are a good value, let me get a few pics.

-Altrez

[bistander]

I picked up this to log the watt hours.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Looks like it will give me the option to export to excel as well.

-Altrez

Hi Altrez,
I'm happy to have you post on this thread. Interesting instrument you show. Let us know how it works. I thought you had one or two of these type.
https://www.amazon.com/dp/B07QNKF79J..._3kzhFbWKDDSD0
They seem to work well to give the accumulated Wh or Ah for a test.
Did you ever get the bigger Lithium battery?
Regards,
bi

[altrez]

I picked up this to log the watt hours.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Looks like it will give me the option to export to excel as well.

-Altrez

[altrez]

Altrez,
it looks like you only use ~5 watt-hours for the test. I suggest using a DC wattmeter which displays watt-hours between the charger and battery as well as the killawatt meter on the AC outlet. This will give you an efficiency of your charger as well as energies required to recharge the battery.

Lithium cells are noted for being virtually 100% "charge" efficient, meaning Ampere-hours in equal Ampere-hours out. The battery's charge-discharge energy efficiency then is equal to (V-I'*R)/(V+I"*R)*100%, where V= open circuit battery voltage, I'= discharge current, and I"= charge current. This assumes constant current discharge (I') and constant current charge (I").
Nice tests. Thanks for sharing.
bi

Hello bistander,

Thank you for calculating the watt hours. I am going to order a logging watt meter and run the test again. Sorry for hijacking your thread!

-Altrez

[bistander]

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,
it looks like you only use ~5 watt-hours for the test. I suggest using a DC wattmeter which displays watt-hours between the charger and battery as well as the killawatt meter on the AC outlet. This will give you an efficiency of your charger as well as energies required to recharge the battery.

Lithium cells are noted for being virtually 100% "charge" efficient, meaning Ampere-hours in equal Ampere-hours out. The battery's charge-discharge energy efficiency then is equal to (V-I'*R)/(V+I"*R)*100%, where V= open circuit battery voltage, I'= discharge current, and I"= charge current. This assumes constant current discharge (I') and constant current charge (I").
Nice tests. Thanks for sharing.
bi

[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