Search found 41 matches

by ltosolini
Nov 04 2018 5:13pm
Forum: Battery Technology
Topic: overdischarged wina LiFePO4 50ah cell
Replies: 5
Views: 251

Re: overdischarged wina LiFePO4 50ah cell

Anyway even after this bad experience I am still convinced that it is better without BMS. Lets say that I destryed this cell, this is 60 Euro but I managed to get home safe and fast with my scooter even with this single cell at 0 Volt. If I had the BMS, the scooter would had stopped in the middle of...
by ltosolini
Nov 04 2018 5:04pm
Forum: Battery Technology
Topic: overdischarged wina LiFePO4 50ah cell
Replies: 5
Views: 251

Re: overdischarged wina LiFePO4 50ah cell

So I removed immediately the cell that went down to 0 Volt; it is a wina lifepo4 50ah. It is also swelling. I managed to resuscitate it and so I charged it 10ah which is 20% of capacity and it held the charge for 1 week then it went down to 2.7Volt. Then I tried a full charge and I could push 28ah w...
by ltosolini
Oct 21 2018 3:45pm
Forum: Battery Technology
Topic: overdischarged wina LiFePO4 50ah cell
Replies: 5
Views: 251

overdischarged wina LiFePO4 50ah cell

Today I badly screwed up.... No BMS and overestimated my pack charge! On the way home I was noticing lack of thrust in my scooter powered by 20s LiFePO4. As soon as I reached home, I measured that one cell was 0 Volt, this is a cell I knew it was the weakest link. Immediately I put the pack on charg...
by ltosolini
Feb 25 2018 4:32pm
Forum: Battery Technology
Topic: SuperCapacitor
Replies: 2
Views: 294

Re: SuperCapacitor

Today I put my idea to a test connecting the super-capacitor in parallel to the battery main leads: it didn't make any difference. So the problem is that when I ride, especially during acceleration or deceleration, the individual voltmeters that I have on every cell randomly show abnormally low volt...
by ltosolini
Feb 24 2018 1:15pm
Forum: Battery Technology
Topic: greasy orange dirt
Replies: 7
Views: 396

Re: greasy orange dirt

This substance doesnt smell and in some places it is christallized looking like cane sugar. So consensus is for a leak. The cell is still performing well. Do you think there is any security concern? I dont have BMS but rule out any overcharge because I have developed a system that cut off charger as...
by ltosolini
Feb 24 2018 9:36am
Forum: Battery Technology
Topic: SuperCapacitor
Replies: 2
Views: 294

SuperCapacitor

Experts, on my e-scooter I have connected a cell-checker on every battery which give me real-time voltage reading. At times during acceleration, but also deceleration, they give very low reading, kind of unrealistic such as 2.6V, but only for one sample and then go back to normal. I suspect this to ...
by ltosolini
Feb 23 2018 4:58pm
Forum: Battery Technology
Topic: greasy orange dirt
Replies: 7
Views: 396

greasy orange dirt

Experts, it has been one year since I put version 2 of my Elettra2500 e-scooter on the road and now I have decided to open it for a thorough check-up. All looks good apart from a greasy orange dirt on the top of one of the Winston 40ah cell. Do you have any idea of what it can be? And above all, do ...
by ltosolini
Sep 08 2017 12:54am
Forum: Battery Technology
Topic: voltage surge after vacation
Replies: 3
Views: 346

Re: voltage surge after vacation

My mad! I made a typo in my first post: where I typed 2.28 I meant 3.28, 2.30 -> 3.30 The voltage reading is accurate, I measured with a second meter cell #14 and measurements are ok: 3.30 Volt idle and 3.6+ Volt under charge. This morning I gave it another try: - started with idle cell #14 @ 3.30 V...
by ltosolini
Sep 07 2017 2:56pm
Forum: Battery Technology
Topic: voltage surge after vacation
Replies: 3
Views: 346

voltage surge after vacation

I had a nasty surprise coming back from holiday..... My scooter is based on 20x winston 40ah LIFeYPO4 prismatic cells in series; before leaving for holiday I left the battery at roughly half charge, in pretty much balanced state and disconnected the main leads. After roughly 5 weeks I reconnected th...
by ltosolini
Apr 02 2017 4:00pm
Forum: Battery Technology
Topic: cell checker draw
Replies: 5
Views: 345

cell checker draw

Experts, I am using three of these cell-meters to keep my 20S 50Ah LiFePO4 always under control. It has a ground pin and 7 cables to connect to a series of 7 cells to provide individual voltage reading: It works pretty well indeed. Considering a current draw of 35ma on the ground pin, I initially th...
by ltosolini
Mar 18 2017 2:14pm
Forum: Battery Technology
Topic: hellp with high-voltage-cut-off
Replies: 0
Views: 129

hellp with high-voltage-cut-off

need help 'cause I am stuck with something I really cannot understand!! Last year I built a balancing system based on TL431 low voltage regulator for my 20S lifepo4 pack, so I bought 25x TL431 from mouser and all went well. Now I am building a high-voltage-cut-off also based on TL431 and very simila...
by ltosolini
Mar 12 2017 2:43am
Forum: Battery Technology
Topic: Disposing of LiPo
Replies: 73
Views: 5682

Re: Disposing of LiPo

want to revive this thread where latest post is two years old....hoping to hear there is a way to make good use of my fat old cells. So, now that my second build is on the road with a mix of winston, sinopoly and Wina LiFePO4 cells, I have twelve Wina 50ah cells from my previous build which are badl...
by ltosolini
Mar 02 2017 5:05pm
Forum: Battery Technology
Topic: advise for opto-coupler
Replies: 3
Views: 312

advise for opto-coupler

I want to build an over-voltage-cut-off for my bulk charger for my 20S LiFePo4 pack. I am thinking of using TLV431 voltage reference for every cell: the TLV will drive the optocoupler. The first optocoupler to fire will switch a flip-flop which will disconnect the charger. I need advise on optocoupl...
by ltosolini
Feb 22 2017 3:29am
Forum: Battery Technology
Topic: Did i fry my battery?
Replies: 40
Views: 1705

Re: Did i fry my battery?

Before the winter I put every cell of my 20s LiFePO4 pack in storage mode by pulling power down to 3.2V. A couple of days ago I wanted to revive the pack and started a bulk charge monitoring every single cell voltage every roughly half an hour. It all went well for 2 hours with all cells pretty much...
by ltosolini
Feb 19 2017 4:35pm
Forum: Battery Technology
Topic: under-rated charger: is this a scam?
Replies: 2
Views: 220

under-rated charger: is this a scam?

Experts, I recently bought this charger which is rated of output current of 1 Amp, but today I connected it to a LiFePo4 Wina 50ah cell and all that I can see is a miserable 0.6Amp :-( http://www.ebay.it/itm/221876225877 As you can see from the attached photo I just connected the charger to the firs...
by ltosolini
Jan 29 2017 3:59pm
Forum: Battery Technology
Topic: concurrent/independent charging
Replies: 1
Views: 199

concurrent/independent charging

Experts, I don't know if concurrent or independent charging is the right term for what I am going to described, the fact is that neither serial nor parallel applies.... My new electric scooter will be based on a 20S LiFePo4 battery pack with following cells: - 8 winston 40ah brand new cells - 4 sino...
by ltosolini
Jan 19 2017 5:05pm
Forum: Battery Technology
Topic: pressure or not?
Replies: 7
Views: 447

Re: pressure or not?

How can it be explained why the LiFePo4 cell excersise pressure at high current?
Is this related to charge, discharge or both?
Thanks,
Luca
by ltosolini
Jan 18 2017 1:25pm
Forum: Battery Technology
Topic: pressure or not?
Replies: 7
Views: 447

pressure or not?

Experts, after ending up with 12 badly swollen cells out of my 20 pack of Wina 50Ah LiFePo4 I have learned the hard way that this type of cell must be mechanically contained in order to put a uniform pressure to avoid swelling. I wonder if I should do the same for winston 40 AH or Sinopoly 40AH LiFe...
by ltosolini
Jan 14 2017 4:38pm
Forum: Battery Technology
Topic: Bad BMS
Replies: 0
Views: 135

Bad BMS

Happy to be back on the community! I have been very busy till recently with work and study, so I had to park my Electra project for a while...... Today I tested the BMS that I bought a couple of years ago because I was in fear that the overcharge function is not working: http://www.batterysupports.c...
by ltosolini
Nov 10 2016 4:38pm
Forum: E-Vehicles General Discussion
Topic: Silicon or hot glue or what to fix connectors
Replies: 6
Views: 745

Silicon or hot glue or what to fix connectors

In the previous build of my electric scooter I used hot-glue to insulate and firmly hold together cables welded to cells and connectors. But thinking over it, now that I want to rebuild the scooter from scratch, I realize that it was a bad idea, because if a cables warm up they can melt the glue, th...
by ltosolini
Nov 06 2016 8:50am
Forum: Battery Technology
Topic: melsen 72v40ah battery pack
Replies: 0
Views: 209

melsen 72v40ah battery pack

I just recently found this product from Melsen: http://melsen.en.made-in-china.com/product/SBvJMzXEaxUR/China-Melsen-LiFePO4-Battery-72V-40Ah-Rechargeable-with-BMS.html In essence it is a 20s 40ah LiFePO4 battery pack 200x200x253 mm size, 16 kg weight inclusive of BMS. Considering that I am about to...
by ltosolini
Nov 01 2016 4:16pm
Forum: Battery Technology
Topic: No BMS, just balancing?
Replies: 4
Views: 457

Re: No BMS, just balancing?

I am also considering removal of the BMS from my Elettra 2500 scooter. To safeguard against low voltage I will install this cell checker tuned at 2.9V; I will put 3 of them to cover all 20 cells and fit them in the dashboard so that I have constant control of the battery pack; plus they blink and ma...
by ltosolini
Oct 30 2016 7:09am
Forum: Battery Technology
Topic: What is this current?
Replies: 3
Views: 309

What is this current?

This is a Wina 50Ah cell. I noticed that the aluminium cage is at ~+3.2 Volt with respect to the anode. So I wanted to measure how much current can flow from the case to the anode getting to figures between 0.2 to 4 mA. What is this current? Can be somehow be related to self discharge? If there is a...
by ltosolini
Oct 30 2016 6:26am
Forum: Battery Technology
Topic: wina exit strategy
Replies: 3
Views: 346

Re: wina exit strategy

I must make late justice to Wina cell and take my share of responsibility. I have opened the scooter and removed the cells; i found out the following enlightening result. Out of 20 wina 50Ah cells: - 8 cells that were housed in low compartment, reaching to half the size of the cell, are swollen in t...
by ltosolini
Oct 29 2016 4:29pm
Forum: Battery Technology
Topic: cell containment
Replies: 4
Views: 430

cell containment

I learned the hard way that if there is no pressure on the side of the battery this can easily swell; it is even worse if the pressure is not uniform: https://endless-sphere.com/forums/viewtopic.php?f=14&t=84399 In my case the battery are held is a metal box we reach to lower half of the battery; so...