$3.41 Battery Capacity Tester

ercoerco Posts: 19,515
edited 2017-04-04 - 20:57:18 in General Discussion
I just got mine today, now I can test my 10 AH Li-Ion cells' real capacity. :) http://www.ebay.com/itm/112336467549

What's the safe cutoff voltage under load for Li-Ions, 3.7V?

This guy gives this tester a thumbs-up: https://syonyk.blogspot.com/2015/10/zb2l3-v20-zhiyu-battery-tester.html

"When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

- Pablo Picasso

Comments

  • I was skimming though what the seller is offering, and faintly heard the sobbing of my wallet....
    Then realized that I've opened 40-some tabs of things to take a closer look at!
    o.o

    Keep 'em coming, erco!
  • ercoerco Posts: 19,515
    GIMME YER LUNCH MONEY! :)
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • erco==jessie james with a cash register!
  • Did anyone else order one of these?

    I ordered one on April 5 and never received it. Sent the seller a message on May 26 but got no response yet.

    Buyer beware!
  • ercoerco Posts: 19,515
    Yes, I received mine and use it a lot. Works great.

    Don't stop believing'!
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • I got one. One thing, though, I connected it to a LiPo starting at 4.05V using the power resistor marked 7.5 ohms 5W that came with the gadget. The measured current started out at over 1 amp. I thought, that's funny, 4.05V/7.5Ω should be only a bit above 0.5A. It turned out that the resistor was close to 3.5Ω, not 7.5Ω. What the?! I think previously I hooked it to a 6V SLA using the same resistor. Not a good idea. My bad. The fully charged SLA at 6.8V would push more than 5W into the resistor and probably degraded it seriously. Oops. A word to the wise, match the resistor to the battery.

    I now have a 20Ω 10W resistor now on there to draw close to 0.2A from the smaller 2.5Ah LiPo, a closer match to its capacity and the use case. The gadget works well and I'll probably order a couple more. It would be easy enough to build something like it, but hey! not for that price. I set the cutoff at 3.1V, up just a bit from the 3.0V cutoff that the gadget uses as the default for what it determines is a LiPo. This if for instruments, not a motor. I want it see the usable capacity for a 3.0V low dropout regulator.
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2017-05-31 - 13:51:22
    I opened a case with eBay and supposedly the seller issued a refund.

    I ordered one from a different seller for $2.98...

    Tracy - thanks for info about using the correct resistors
  • Hey Erco. My wife still hates you. Keep it up bud. We ran out of shelves.
    Founder of Kinvert
    https://www.kinvert.com/
  • ercoerco Posts: 19,515
    So Tracy, you think your SLA damaged the power resistor previously? Had to believe even China has 50% tolerance parts!

    BTW mine measures right at 7.5 ohms.
    Hey Erco. My wife still hates you. Keep it up bud. We ran out of shelves.

    I ran out of shelves many moons ago!

    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • Erco, my first inclination is, of course, blame the *&@% supplier, however, the rational mind soon kicks in. It's possible but rare to have a resistor mis-marked. Highly more likely I do something stupid like connect without thinking. SLA: 6.9V/7.5Ω = 0.92A. 6.9V*0.92A=6.35W. In a 5W resistor. Hot! But not scorched or even discolored. I am kind of surprised that the resistance went down. I'd think it would go up. I'll never know for sure. It is reassuring that the one you have does in fact check out at 7.5Ω! I have to remember NOT to put the bad one back on the shelf!

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