Registered: 1485224294 Posts: 2
Reply with quote #1
I've seen comments that the watts you run battery analyzer at does not affect the outcome... For the most part I agree if you are testing 3S LiPo packs. The analyzer will still keep counting Wh even if the batteries can't reach the watt set point. This affects LiPo packs slightly (<10%).. But it affects dual 18650's a lot depending on the battery.
I just ran dual LG HB4's at 100W on 4 x 1ohm resistors mounted on a large heat sink. They could only reach 100W - 18 times - cumulative Wh = 5.73. Program kept running and counting Wh even though at the end it was only reaching <5W while firing. Analyzer calculated Wh @ 9.49. This is not unexpected when you look at test data from Mooch.
Question is, do we really want to count capacity when device is only reaching 10% of setpoint? I want to upload these results into the community spreadsheet, but I think there has to be a real world filter, for example - don't count any Wh after the unit cannot reach 75% of setpoint. I've gotten similar results with multiple matched, new 18650's
In this case it means a capacity of 7.95 vs 9.49 = big difference.
Registered: 1437592337 Posts: 1,516
Reply with quote #2
this is pretty much how i handled dialing in my 133's and 167's. i'd put the the calculated Wh value in then vape down to weak battery and take note of the Wh remaining. this is with the preheat power maxed out. if i can't get the full power from the device, even for 1 second, i consider the cells dead (needs recharge). this is why 2 sony vtc5a cells only give me a little over 14.43 Wh's at max wattage of 133, calculated is 19.24. this Wh number would be higher if my preheat power was lower. so yes, i understand what you're saying. evolv's batt analyzer squeezes out every last drop of capacity. it doesn't take into account "OK, stop analyzer after test wattage can no longer be maintained." evolv is open to suggestions, there is a thread here where you can do that.
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Registered: 1435398945 Posts: 2,449
Reply with quote #3
You are right, the increased sag with cylindrical batteries will have a significant effect on the result. But the main purpose of the test is to make a charge vs voltage curve for you batteries and you don't have to run them that low while vaping. But because these devices throttle back when they hit the low cut off limit you would not be running them too low or damaging them. The capacity figure is correct and I agree you are unlikely to use it all, but that is personal choice really and you can just lower the figure.
__________________ • I am not employed by nor do I represent Evolv Inc. All opinions are my own, they are just opinion not fact and can be wrong • Latest versions of EScribe: DNA 200/250 • DNA 75 Common problems