Search found 361 matches

by eMark
Mar 03 2021 5:32pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

no to storing at 2.5v What thread are you using to post your findings on the number of cells in your 1s70p 7-day voltage leveling experiment that suffer from high self-discharge having disassembled the 1s70p to check individual cell voltages after resting for another 7 days? Are you planning to dis...
by eMark
Mar 03 2021 5:05pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

30Q and 40T are the only cells ive found that like to continuously cycle, other cells will lose half their lifecycle... https://endless-sphere.com/forums/viewtopic.php?f=14&t=109601 Isn't that generally true with all high drain energy density cells? Has any DIY builder ever reported high self-d...
by eMark
Mar 01 2021 2:21pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

so the 3.43v cell is still self discharging how much per day? That 3.43v cell was the one cell out of ten with the highest self-discharge that we used for experimenting with deep discharges in February as a possible "fix" or at least minimize s-d. charge to 4.20v, deep discharge so only 2...
by eMark
Feb 26 2021 2:58pm
Forum: Battery Technology
Topic: BMSs
Replies: 11
Views: 299

Re: BMSs

I forgot to mention, I believe, that after the pack shut down, my cell examination had cells with voltages that differed by as much as a volt from cell to cell, which sort of told me why BMS shut all down...imbalance...and wondered why. You told me you never received the barrel bolts with either yo...
by eMark
Feb 25 2021 2:12pm
Forum: Battery Technology
Topic: "desulfate" 40T and 30Q and VTC6 and P42a
Replies: 28
Views: 1082

Re: "desulfate" 40T and 30Q and VTC6

going to desulfate some salvaged 30Q from bad packs 5 cells at 1.97v 1s5p charged to 4.2v at 3amps then discharged to 2.5v at 3amps (0.6amps) curve looks fine charged to 4.2v at 3 amps then i discharged them a little bit and theyre sitting at 4.02v . now just put them on the shelf and see what happ...
by eMark
Feb 24 2021 2:44pm
Forum: Battery Technology
Topic: 40T, neodymium magnets, plasti dip cycle test
Replies: 129
Views: 7261

Re: 40T, neodymium magnets, plasti dip cycle test

got some salvaged 30Q-136 where the spotwelds were really bad/weak, should be able to clean them with a sanding drum and use magnets made a 1s70p and slug taped them together to equalize the voltages for a week then take it apart ....... and build 17s4p What kind of test did you do before ( ..........
by eMark
Feb 23 2021 5:02pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

Will be interesting if your procedure also provides a "fix" even if just temporary. Are you going to disassemble the packs so you can determine which are the good 30Q (136) cells and which ones suffer from high self-discharge? If two-thirds of the cells in your packs are good i'd just salv...
by eMark
Feb 22 2021 5:09pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

my battery guy has 300- 30Q from faulty packs, i agreed to buy 80 from him to try the "desulfate" thing on them. ill be able to share the results, if it works ill buy all of them Do you have any idea how labor intensive and time consuming is my "de-selfdischarging" routine? Hope...
by eMark
Feb 20 2021 3:01pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

That infamous cell 2S3P, 3.43/.44V (5S3P Sub-Pack 1) that I thought was history still has life. Apparently those two DOD experiments (after first charging to 4.2V) have apparently reversed its high rate of self-discharge. One DOD was to discharge below 2.5V until the bounce back voltage was only 2.5...
by eMark
Feb 20 2021 1:17pm
Forum: Battery Technology
Topic: Any advice about my pack design
Replies: 8
Views: 331

Re: Any advice about my pack design

This arrangement allows for three series connections between P10-P16. What about just three series connections (1S,3S,5S) between P1-P9 instead of all five. Made good use of that one empty cell space in bottom right corner https://scontent-cdt1-1.xx.fbcdn.net/v/t1.15752-9/151937771_127728829232837_4...
by eMark
Feb 19 2021 4:10pm
Forum: Battery Technology
Topic: Any advice about my pack design
Replies: 8
Views: 331

Re: Any advice about my pack design

Thank you for your accurate answer, that will help for sure. How accurate is questionable?? Any doubling of resistance when doubling the connection distance can be mitigated by increasing size of bus bar strip to equalize overall pack demand (e.g the connections between p-15 to p-16). What do you t...
by eMark
Feb 19 2021 2:38pm
Forum: Battery Technology
Topic: Battery design advice required
Replies: 19
Views: 525

Re: Battery design advice required

one nickel-plated copper bus bar measured 2.4mΩ ... doubling length only 2.6mΩ im confused by what youre saying...i assume doubling the length of anything is going to double the resistance produced by it. the connections maybe are a bigger loss than the distance but none the less doubling your wire...
by eMark
Feb 18 2021 4:42pm
Forum: Battery Technology
Topic: LG HG2 ?
Replies: 2
Views: 308

Re: LG HG2 ?

In the mid-90s Macalester College, St. Paul, MN sponsored the publication of a new magazine entitled "Business Ethics" in cooperation with their MBA programs. Its small circulation never caught on with the business world. It only lasted a couple years. Do you think it's possible that "...
by eMark
Feb 18 2021 4:11pm
Forum: Battery Technology
Topic: Battery design advice required
Replies: 19
Views: 525

Re: Battery design advice required

Yes, it is 30% more nickel and 30% more resistance. My calculations showed a 39% increase in losses (1.28 Watt vs 0.92 Watt). Are you sure? My AideTek SM8124A (4-wire) tests with nickel-plated copper confirmed that there would be nowhere near a 30% increase in resistance with a 30% increase in leng...
by eMark
Feb 18 2021 2:52pm
Forum: Battery Technology
Topic: Any advice about my pack design
Replies: 8
Views: 331

Re: Any advice about my pack design

Yes sorry, about to spot weld. Isn't there almost as much [orange arrowhead bottleneck] concern with p-14 (gray) connecting to p-15 (white) in comparison to the interconnections between the first twelve p-groups ? Spot-weld another longer bus bar strip between the p-15 white cell (closest to the or...
by eMark
Feb 17 2021 4:05pm
Forum: Battery Technology
Topic: Battery design advice required
Replies: 19
Views: 525

Re: Battery design advice required

IF you orient all the cells staggered instead of in rectangular pattern as in your pic. dont know why you write .07% which is a tiny amount. doing the x on the rectangularly arranged cells would be 30% more strip needed and 30% more resistance. If it were a triangular pack and bus bar length was a ...
by eMark
Feb 17 2021 3:27pm
Forum: Battery Technology
Topic: Manual balance discharge device?
Replies: 24
Views: 580

Re: Manual balance discharge device?

I'm still testing my no-weld 20s5p design. Intentionally going without BMS. Going great so far and pack is pretty well balanced but need to quickly knock .15V off a couple groups to get whole pack to full charge. Why do you need FULL charge especially when using two different name brand salvaged ce...
by eMark
Feb 16 2021 4:04pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

if it was me, you already have the batteries ...10s3p, you have 10 "K" cells, id put 1 "K" cell in with 2 "141" cells per cell group Will put the ten new "K" cells in 2P position with ten of the other good cells in 1P & other ten good cells in 3P position...
by eMark
Feb 15 2021 8:13pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

so the 3.43v cell is still self discharging how much per day? Yes, i believe so and will know if still the same or different in two weeks when compared with 1/15 chart on p. 1. As usual i was still editing my previous post another time shortly after your post. Maybe, want to go back and reread as t...
by eMark
Feb 15 2021 7:04pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

Experimental tests indicate that the storage mAh capacity of the 30Q "141" cell with the highest self-discharge (3.75V to 3.43V from 1/2 to 1/15) does not diminish its ability to store the same capacity as the other twenty good "141" cells (10S3P) showing NO self-discharge from 2...
by eMark
Feb 13 2021 7:39pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

yes i typed wrong, wasnt clear me too so am reposting a couple paragraphs that need further clear-if-cation :wink: I spent nearly 30 minutes making several edits after posting the above lengthy post. So, for those that may have opened it soon after my post and likely confused ... my apology. Even a...
by eMark
Feb 13 2021 3:14pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

no to 30Q fixing itself One question (with respect to 30Q) is: What is acceptable mild discharge? Maybe, he meant was self-discharge higher than normal, but not as high as a certain percentage of cells in a 30Q battery pack. Do you generally agree with BlueSeas previous post pasted below (i do) ......
by eMark
Feb 12 2021 4:27pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

I got a Samsung pack 40t 20s6p still testing and a little worried as these thread has changed my mind. I brought a 8p 14s nese kit and was going to buy the Samsung 30q. But will not know. My be second choice is Samsung 25r. But be is Samsung any good. Maybe a should do a new thread ? Confused. You'...
by eMark
Feb 12 2021 2:43pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

so the 3.44 cell is the only cell thats been discharged all the way to 2.5v and recharged to 4.2v while the other 9 were discharged to 2.5v and then partially charged Yes, it was the only cell of the ten discharged to 2.5v and even below 2.5v. using my manual discharging device (1.25A) and then &qu...
by eMark
Feb 11 2021 4:21pm
Forum: Battery Technology
Topic: Self-Discharge UPDATE On 30Q 141 Cells
Replies: 68
Views: 2249

Re: Self-Discharge UPDATE On 30Q 141 Cells

lets do some math, you stated from above 0.6amps x 12hrs=7200mah What is apparent is that when balance charging (resistance discharging) is incorporated with this 2S5P pack of cells (suffering with varying degrees of self-discharge) that the capacity shown when balance charging (resistance discharg...