[david85]

My testing has started, and as promised, I will post the results as they come in.

I started by conducting the same test 3 times.

The tests consisted of running a Minn Kota 50 electric trolling motor at setting 3/5 (drawing 25 amps) in a barrel of water for 1 hour.

Heres how it stacked up for test 1:

Voltage measured with no load at full charge: 13.43V

Voltage under load after

15 min: 13.16V

30 min: 13.14V

45 min: 13.13V

60 min 13.12V

Voltage after test:

5 min: 13.26V

10 min: 13.26V

15 min: 13.28V

Ambient temperature: 10 celsius

--------------Test 2:

15 min: 13.12V

30 min: 13.09V

45 min: 13.08V

60 min: 13.08V

Voltage after test:

5 min: 13.25V

10 min: 13.26V

15 min: 13.26V

Ambient temperature: 7-10 celsius (test started and 7 and ended at 10)

--------------Test 3:

15 min: 13.16V

30 min: 13.14V

45 min: 13.13V

60 min: 13.13V

Voltage after test:

5 min: 13.27V

10 min: 13.28V

15 min: 13.29V

Ambient temperature: 15 celsius (in direct sunlight, so battery was closter to 19)

I also turned the motor on and measured the voltage sag at each of the 5 settings:

no load: 13.43V

Setting 1 (10A): 13.38V

Setting 2 (15A): 13.36V

Setting 3 (25A): 13.3V

Setting 4 (30A): 13.27V

Setting 5 (62A): 13.07V (this setting is fun)

OK, pictures:

Shown are: Amp meter, Motor running at 25 Amps, Complete setup (battery, barrel, motor), Volt Meter, and charger.

The 4 lights on one end of the panel are showing voltage equilizing of the indivitual cells. The other two lights are RUN and CHARGE.
Run is green when ever the charger is working,
Charge starts off as red, then changes to yellow at 80% charge and finally to green when charge is complete (run light turns off when charge shows green).

I want to mention that these were VERY mild tests and don't really prove anything. Next tests will be with longer and longer run times until I can observe the rated energy storage of the battery. High draw tests will have to wait until I have a HD amp meter (in theory the battery can pump out 2000 amps.

Stay tuned........

[rfengineers]

David,

Thanks for keeping us informed. I will be monitoring your progress.

Joe

[david85]

Originally Posted by rfengineers

David,

Thanks for keeping us informed. I will be monitoring your progress.

Joe

No problem. I just hope they live up to the claims because I want to be able to rip it up for longer drives with my EV I just don't see that as being reasonable in a lead sled.

OK, some unofficial updates.

Took our 18' boat to the lake today and for the first time ever, never started the engine. After having to repeatedly tighten down the clamps on the trolling motor (like I said, it is peppy), we were off for a lazy run around the lake. Ran the motor at full power for about 50 min till we got bored and decided to pack it in. Speed was actually pretty good considering the small size of the motor. (guessing 5 MPH)

I had the voltmeter and amp meter hooked up for the run.
Amps were right at 60 the whole time. Volts dropped to 12.78V initially when I first turned the motor on, but only fell to 12.77 by the end of the run. No noticeable loss in power at all, but relatively speaking, the test was very mild.

I consider this unofficial because I didn't take any notes during the test (going from memory), so take it with a grain of salt.

By the way, In case anyone is wondering how well the min kota motors work, I will give them a passing grade. They do make some noise at full power (more in reverse), but its still whisper quiet and is perfect for trolling. Can't beat the reliability or simplicity. Just hook up the two wires and turn it on.

[david85]

More official results.

Conditions before start of test:

outside temperature: 11.5 Celsius
Battery open circuit voltage: 13.82 volts

Test begins.........

Amp draw reads 28 Amps on setting 4, but could be 30, I need to verify the specs of the motor and see what others are seeing with this motor.

Closed circuit voltage:

1:00 = 13.33 volts <<< I measured a voltage after 1 min to show initial voltage drop
15.00 = 13.04 V
30:00 = 13.03 V
45:00 = 13.02 V
60:00 = 13.02 V <<< I took measurements every 15 minutes only for the first hour to act as a control for previous tests, then every 30 minutes for the remaining 4 hours because I've got other things to do!
1:30:00 = 13.01 V
2:00:00 = 12.99 V
2:30:00 = 12.97 V
3:00:00 = 12.93 V
3:45:00 = 12.92 V <<< sorry, I was late checking the voltage.....(other things....)
4:00:00 = 12.91 V <<< ambient temperature 12.2
4:30:00 = 12.90 V
5:00:00 = 12.88 V

SHUTDOWN.......

Open circuit voltage after load:
5:05:00 = 13.08 V
5:10:00 = 13.10 V
5:15:00 = 13.10 V <<< ambient temperature 11.3

End of test.....

The battery did well and is on charge right now for the next test. Next step will be to repeat the test to verify the results.

If my amp readings are in fact 30 amps, then it means I have reached 75% of the battery capacity with this test. 30 amps x 5 hours = 150 AH.

The battery is rated at 200 AH. So far so good, but I'm just getting started........................................... .stay tuned

[mark1030]

Originally Posted by david85

More official results.

Conditions before start of test:

outside temperature: 11.5 Celsius
Battery open circuit voltage: 12.82 volts

The open circuit voltage before the test is less than it is at 1 minute operating. Is that right?

[david85]

Originally Posted by mark1030

The open circuit voltage before the test is less than it is at 1 minute operating. Is that right?

No its not, thanks for catching that. I looked at my notes again and it was in fact 13.82 not 12.82.

I've made the correction to the post.

[TX_Dj]

David,

What is the "resting voltage" of the battery 24 hours after shut down, with no charging? How much does it recover? This may be a better measure of the SOC for the cells after the tests are concluded.

[david85]

Originally Posted by TX_Dj

David,

What is the "resting voltage" of the battery 24 hours after shut down, with no charging? How much does it recover? This may be a better measure of the SOC for the cells after the tests are concluded.

Not a bad idea. I'll do that after I repeat the last recent test.

[dimitri]

Dave,

do you have any plans to test this batt at 1c to 3c load? That would be most beneficial for EV application. I would love to know how many Ah it can deliver at 1c continuous and bursts of 2c or 3c. Its nice to know that it holds up well at 0.3c, but it doesn't tell us how it will hold up in real EV load conditions due to Puekert's law. Are these rated for 1c continuous or more?

Also, I apologize if I missed it somewhere, but can you publish weight and dimensions of the individual battery? My understanding is that prismatic LiFePo batteries have relatively low energy density, which makes complete pack quite bulky and heavy, although still better than lead-acid.

Thanks for publishing your test results, looks great! I keep a close eye on these since it will be my next pack once my current pack dies...

[david85]

I'll be working up to that, dimitri. For now I am equipped to test long low C discharge to verify the (claimed) rated energy storage of the battery, so thats what I'm working on. The energy density is on average around 100wh/kg for most Lifepo batteries that are made in china like the one I am testing. Having said that, I do not know the exact weight of these ones yet. But they feel comparable to a 600 CCA starting battery.

Keep the comments comming guys! If you have any suggestions to make the tests better, I'll do what I can to incorporate your ideas. I'm not exactly a 'man of science', after all.