I bought one of those from a different manufacturer and returned it. I couldn't hear the click on anything I tried it on. So then I bought a beam torque wrench. I believe it's fairly accurate but it can be a bit difficult to handle. I like the bicycle torque wrenches I have seen but they are only good for torqueing the nuts to the cells.I think it's about time I bought one of those.
My reading of the latest spec sheet indicates they rate capacity at 0.33C (a little over 92 amps) and de-rates by a small percentage for 0.5C and 1C.Low-C test (at 30A) yielded 287AH so all-in-all we're pleased with the cells and would recommend them and Amy.
I didn't give you any details on the transaction itself - suffice to say that nothing unusual to report. Our biggest frustration was the lack of shipping info, but this is not Amy's fault (it's the way it is). It would be really great to be able to do all the tracking ourselves.
I found out too late that if I had used the DIYSolar code she would've included double busbars. Pity .... seeing as we've already ordered and paid for another 100 cells.
I have asked Amy for more info regarding these welded terminals. She mentioned that the new contact surface area is stainless steel. She's getting more info. I guess we'd all like to know a bit more ....
I'm actually waiting on delivery of a thermal camera to better evaluate if the temperature rise is due to the cell chemical reactions or the resistance of the connections. Even with a thermal camera, it will be difficult to get definitive results.
I can use my 4 wire Yaorea meter (I also have a Fluke 87 V). It can measure quite low resistance, the biggest problem is being able to get at the terminal surface with a busbar in place. I do know some of my temperature rise is due to my testing with 40 amps with 10 gauge wire, just started switching to 8 gauge. Using Ancor wire and crimp connectors (Ancor again). Being anal retentive, I had to order the Ancor crimp tool to go above 10 gauge, probably my 10 gauge crimp tool would work, but it would bug me if not perfect. Of course you can also use battery lugs and even heavier gauge wire (or even lugs with 8 gauge wire). Ancor makes some very high quality products, and everything is already tinned.If you can probe cell terminals themselves, voltage drop from cell to cell through contacts and busbar will tell you watts dissipated in the metal. More difficult to decide if heat is flowing into cell or transferring to air (unless convection, emissivity etc. are part of your vocabulary) but it should give a qualitative understanding.
Down to whatever millivolts your DMM reads, unless you have a fancy bench DMM with microvolt sensitivity. We're using op-amps or instrumentation amps to resolve microvolts - in our case to determine ripple. That lets us use scopes with sensitivity a bit better than millivolt. You might be able to use an eval board or breadboard as preamp to get to microvolts.
I would like to store cold in an ice chest and duct air for cooling during peak rate times. Freezer with jugs of water and blower is one idea. Possibly ducted air heat exchanger to deal with condensing/icing issue. But freezer compressor running 16 to 18 hours isn't anything like the wattage/BTU of a central A/C running 6 to 8 hours; seems sufficient to replace a window air conditioner but need heavier equipment for whole house. Haven't evaluated whether a 20 cubic foot freezer is enough ice. Could be, as my freezer ran continuous several days to re-freeze contents.
These cells work best (and last longer) below 0.5C so if you need more current consider adding another bank in parallel.