A123 32113 Ultra-B cell, cycling so far

[zeropointbug]

photo 9

[mistercrash]

Since you have the cells and you started this thread then you are now obligated to find out what voltage these hold with a load of 150Ah. How hot they get also. Get to work

[zeropointbug]

Hmm, I don't have a way to actively measure current above 10 amps besides my eagletree which I could try and find and rig it up for PC use. I would have to come up with a discharge source, maybe a steel rod comes to mind? I could use the hand clamp I am using now, compressing some copper mesh wire onto the cell ends, while using booster cables to make a lead to the discharge source, whatever it may be.

I will have to do some searching, I will try and make this happen though.

[zeropointbug]

I can't find my Eagletree for actual amperage rates, but...

I have been rigging up some discharge wire coils,first made out of 16 ga. wire, then I used to 12ga. wire to spread the heat out more. For the last test I did was 8 ft of 12ga. wire (0.013 Ohms load) wrapped around a 2" 1/16 aluminum tube for heat dissipation. I was using booster cables before for connection, but took them out of the equation, and instead soldered some bare 4ga. FLAT ribbon cable onto the wire and sandwiched two of them onto the cell terminals using the clamp you saw in the previous picture. I then made connection by clamping the two ribbon cables together using clamps.

Now, I only tested it for 32 seconds as the electrical tape on the wire coil was melting and burning pretty quick and things were heating up all around very fast, the cell, on the other hand, was warm, hitting 102 F after 32 seconds of discharge.

Discharge voltage was 2.75 volts instantly after I made connection, but quickly climbed to ~2.83+ volts for the entire discharge.

In those 32 secs. I discharged 1298mah (charger put thtat amount back in).

If you calculate the amperage rate using the discharge load in Ohms (0.013 Ohms), you get 215amps:

2.8volts / 0.013Ohm = 215 amps

But, if you go by the actual mah put back into the cell and multiply by 32 second discharge, you only get 146 amps:

32 sec / 60 = .53 mins x 60 min/hr. = 112.5 x 1.3Ah = 146 amps
Obviously, you have to go by the rough calculation of 146 amps.

To me, 146 amps @ 2.8 volts plus looks to be very nice for an A123, and I would hope to see a good number as the cell weighs 180grams for 4.4Ah.

I also did a quick calc, when charging the voltage increase ~0.06volts at 20amps, so going by that, 150A / 20A = 7.5 x 0.06 = .468 3.3volt cell subtract 0.468 = 2.83 volts, exactly what I saw when discharging.

2.8v x 4 cells = 11.2 volts..... at 150 amps, that would be able to start a small car engine I would think, damn near anyways.

I will look for the eagletree so we can get some real discharge tests going. I will also make a more robust discharge coil, one that won't melt and fall apart...

[mistercrash]

Thank you very much for this, and like you said, the cell performed rather excellent. 146amps that's something like 33C for that cell which kept a pretty low temp. Where can we get those cells if you don't mind saying? Or maybe I should stop being such a lazy bastard and find it myself