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Current Capacity Tester Meta (which to buy?)
#11
(11-14-2019, 05:18 PM)OffGridInTheCity Wrote: I found early on that they won't discharge at 1000ma reliably...    They run for a while but then 'stop' mid-way thru the capacity of the cell. 

They do that when they're getting too hot. Make sure the fans are actually working and/or try adding some better cooling Smile
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#12
I was actually writing a message last night, re-considering and going with the Li-500s, since they're so cheap. I think I'm leaning that way now.

Considering these are tool packs, and not laptop packs, they're rated for at least 20A, if not 60A discharge. I'm skeptical that I'll see any difference between 1A vs. 0.5A discharge rates on these cells.

In car use, well, I'm hoping for 120 mile range, which is 2 hours at highway speeds, on 2000mAh-ish cells, so, ~1A or 0.5C is about the normal steady draw. Of course, if I want more acceleration, they're capable of 60x that (for 2 minutes, until empty). Differential, axles. tires, frame, and motor are the limits long before that, roughly in that order. 4000 cells * 4.2v * 60A = 1,008,000 watts. Or 1344 horsepower. 13x what the original engine maxed at.

Realistically I don't think they'll ever draw more than 10A, and that'd be the occasional time I'm goofing off after a red light. For these cells, that's child's play.
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#13
There is a Huge difference between 0.5 and 1a for cells in bad shape.
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#14
So if you wanna stress your cells at 1A or higher - you can build ZB2L3 diy discharger.
Lii-500 is good for capacity test - also it seems its more accurate than Opus but its without cooling.
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#15
(11-14-2019, 04:20 AM)MattsAwesomeStuff Wrote:
Quote:Also, consider that the Opus will test cells twice as fast because of 1000mA vs 500mA, so double the throughput

*nod*... I'd forgotten that detail.

Side effect is that I'm not only changing brands, I'm also changing discharge rates, which will change capacities. So I'll have to be sure to keep old stock separate from new stock, and try to come up with some mathematical translation between the two systems and apply it in Excel before I feed that to the rePackr.

I think you've pretty much made up my mind.

I do not think incorporating "old test process" and "new test process" cells is actually that hard.
Treat the sets of cells from the different test processes as if they were making thier own strings and then combine the cells into the final packs together.
E.g. if you have 1400 cells going into 14s100p configuration. If 280 cells were tested with "Tester A" and the remaining 1120 cells were tested with "Tester B". Use repacker to configure 280 cells into 14 equal groups of 20 cells. Then use repacker to configure the 1120 cells into 14 equal groups of 80 cells.
Then combine each group of 20 cells with a group of 80 cells.
The final 100p packs should then all be the same as each other.
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#16
Quote:There is a Huge difference between 0.5 and 1a for cells in bad shape.

For laptop cells where 1A is close to their maximum discharge rate, sure.

But on tool cells, even the crappiest, worst ones have 20A spec. So the difference between 500mA and 1A discharge is only going to show up on a cell that is extraordinarily wrecked. At that point, 0.5A vs. 1A would only show a difference if you're looking at a cell that's 95% damaged but not 97.5% damaged. But if the cell is that thrashed, it's going to be represented in bad capacity performance and rejected on those grounds.

That is... I can't imagine a cell that has ballpark correct capacity, but would show any difference between 500mA and 1A discharge. I don't think it's possible.

On 2500 cells, I think maybe 15 or so were heaters, and they were all heaters or charging, not discharging. And those were all 0V cells I was trying to rescue.

I think literally zero cells at 500mA, out of the entire bundle, got warm on discharge.
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#17
(11-14-2019, 05:25 PM)daromer Wrote: I run Opus and 1a. It stressen the cells more. The Opus oauses because it gets hot.
1a discharge is for sure preffered since it weeds out more cells

Beware that if you test at 0.5a then max current later is 0.5 a.....

I uses Opuses with 80mm PSU fan. Prevents them from pausing.
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#18
If you are interested, i have some zb's for selling, with a lot of resistors, here on marketplace.
All zb's are matched, btw
They did a great job for me
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#19
(11-14-2019, 04:20 PM)mike Wrote:
(11-14-2019, 04:14 PM)DiggsUt Wrote:
(11-14-2019, 03:10 PM)mike Wrote:
(11-14-2019, 01:42 PM)DiggsUt Wrote: I'm surprised the Lii-500 wasn't mentioned.  Besides being well rated they have dropped in price to about $10 on Ebay these days as long as you have time to wait for shipment from China.

Those do not test at 1000mA either, which is why I didn't recommend that one.

I haven't verified the test but they do show on the display they are discharging at 1,000mA although I've heard they may be charging at 500mA.

They don't actually discharge at 1000mA. The 1000mA is the charge rate. With that setting, they will charge at 1000mA then discharge at 500mA. It's silly how they have it set up and a lot of people buy them thinking they will discharge at 1000mA. Maybe it's that way on purpose...

And this practically adds at least 25% to the test time, assuming the tester also charges with the same charger ... and 50% if you only use the charger for the discharge cap test.

I've researched into this when deciding to get charge testers and this is the reason I went for Opuses instead.
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#20
So here I am again doing the graph and chart thing.

I like facts and there is no better way to provide facts than with actual visual graphs.

Over the next couple of days I will provide the charge/discharge/charge charts for the OPUS, LiitoKala, Foxnovo, Zanflare, and SKYRC.

The charts will include Buss Voltage (BV1) Load Voltage (LV1) mA, and ambient temp and cell temp.
All chargers/dischargers/testers will be set to run at 1A (1000mA) charge discharge cycle.
I have built a special "proxy battery" that allows me to use my "analyser" to track and chart the Voltage , Amperage and Temperature of the cell in its own environment removed from the charger and any heat it may produce.


More explanatory pictures to follow.

Initial trial of the Foxnovo.
The battery was at full charge when inserted so discharge started right away I will try to get a better chart for this test.
So as you can see even when set at 1A capacity check mode it only discharges the battery at 500mA when done it does charge the battery at ~1A


The Opus set to 1A.

This is a very odd charger/tester and I now understand why cells get hot during its use.
Even though the "tester" shows 1000mA on the display, in the background it cycles the discharge between 500mA to some spikes as close to ~2.5A.
Opus ~10 minutes closeup of mA discharge.

It seems to keep a mean of ~1A and the charge side behaves similar but somewhat muted.
That explains to me at least why cells being charged/discharged on this tester tend to run hot. It shows this in the ambient v/s cell temp chart.



More to come 

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