Page 64 of 68

Re: Homemade Battery Packs

Posted: Sep 05 2018 12:59pm
by jcool3
DrkAngel wrote:
Sep 02 2018 8:53pm
Battery repair success.
3 of 4 defective batteries now metered at 4Ah+.
Got 3 more replacements, likely defective too, scheduled for delivery next week.
Could be as many as 6 good batteries for $100 ... and some work. 36V 26.4Ah .733kWh

Hoverboard batteries, typically, do not have the balance function with their BMS.
Opening the pack and manually balancing recommended, if usable capacity drops, or fails to fully charge to 4.20V.
Saw that listing originally. Glad I didn't bite on it. Thanks for posting.

Re: Homemade Battery Packs

Posted: Sep 08 2018 8:29am
by DrkAngel
3 replacement packs arrived ... Just as bad as the 1st batch, except ... no pretense of being Samsung - no branding on cells!
Labeled 2015, one with a leaking cell pair.
Opened up and balancing to same voltages before 1st capacity test.
Replacing leaking pair with genuine Samsung.
No need for further reporting! ... ?

Re: Homemade Battery Packs

Posted: Oct 28 2018 10:31am
by DrkAngel
.
...
LiPo Resurrection?
DrkAngel wrote:
Jun 28 2017 6:06am
Thread Index


Now that the ...
Floureon 7S 5000mah 25.9V 40C Lipo Battery <$60 delivered from USA are all sold ...

"Recommended for rebuild of eZip 24V RMB battery packs.
Will fit up to 4 x 5Ah = 25.9V 20Ah vs oem 24V 10Ah (5-6Ah usable) SLA.
Every 24V controller I've ever tested works properly with 7s 25.9V battery, but a bit faster with some more torque ...

Image

eZip RMB pack internal dimensions:
150mm x 65mm x 230mm"
Dead Cell Rejuvenated after setting for several months

Last Spring, had a balancing accident with 1 cell of a 7s 5000mAh Floureon LiPo.
Fully discharged #3 cell. It apparently did not swell (in center of "brick" and discharge was extremely gentle through 12V 3A heating element) <1 Amp @4.2V discharge would lessen till < ¹/₁₀₀A as nearing empty.
All attempt at gentle recharging failed, Ni-Cd charge setting at .1A, would not hold charge!
Months later ...
Rechecking my batteries and on a whim tested the voltage on the Floureon LiPo with the dead cell ... got a .43V, hmm.
Decided to try charging again and surprise, it was taking a charge, started with a "Ni-Cd .1A" setting till above 3.2V then charged LiPo .1A till 3.6V then bumped to .5A till 4.20V.
Ran a test discharge-recharge at 1A for a metered 5128mAh ! Yippee ...
Will monitor for self-discharge before labeling "resurrected".

So ... possibly, there might be hope for some "bad" LiPo! ... ?

Unknown-puzzled as to why it started taking charge again and seems to have full undiminished capacity! ... ?

Re: Homemade Battery Packs

Posted: Oct 28 2018 4:35pm
by DrkAngel
More fun
Customer brought in some interesting batteries the other day.
Geteed.jpg
Geteed.jpg (29.25 KiB) Viewed 4334 times
Main Features:
● Quick charge current is 1100mA, quick discharge current 22000mA (22A), max discharge current 30000mA (30A)

Original owner tried soldering to cells but couldn't get a good stick. So sold new in boxes to me at great price.
Only 10, so not enough for any decent build, but I got cheap enough I can find some good use for.
I do have a few 26650 LED flashlights.
Could solder a few, 3s2p - 3s3p as 60-90A 12V car jumper.
Should solder at least a couple cells to demonstrate proper soldering methodology.

Re: Homemade Battery Packs

Posted: Oct 28 2018 4:53pm
by 999zip999
DrkAngle you are trying to hold a lighting bolt in a small box and just use a trickle or the whole bolt.And there a mystery. ???

Re: Homemade Battery Packs

Posted: Oct 28 2018 4:53pm
by 999zip999
#####

Re: Homemade Battery Packs

Posted: Oct 28 2018 9:30pm
by DrkAngel
Will test Resurrected 7s 5000mAh Floureon LiPo tomorrow.
36V 600w front hub motor runs just fine at 25.9V.
I have 7s cell monitor meter and will be able to monitor all cells for any excessive sag.
1. Cell passes capacity test
2. Preliminary, looks OK on self Discharge
3. Tomorrow will determine if C-Rate meets oem, compared to the "good" cells

Re: Homemade Battery Packs

Posted: Oct 30 2018 4:52am
by DrkAngel
DrkAngel wrote:
Oct 28 2018 9:30pm
Will test Resurrected 7s 5000mAh Floureon LiPo tomorrow.
36V 600w front hub motor runs just fine at 25.9V.
I have 7s cell monitor meter and will be able to monitor all cells for any excessive sag.
1. Cell passes capacity test
2. Preliminary, looks OK on self Discharge
3. Tomorrow will determine if C-Rate meets oem, compared to the "good" cells
Accidentally fully discharged cell seems to be fully rejuvenated!
Voltage sag and resultant voltage match the "good" undamaged cells nicely during and after a 60% discharge, used 3000mAh of 5000mAh. Final test will be self-discharge over a several-many day resting period.
I am metering with a Fluke meter with 1/1000V accuracy.
1st test at present 40% charge, if good will follow up with test at 100% (4.20V).

These 7s 5000mAh Floureon LiPo seem to have been a bargain purchase. 5 for $240 = $48 each. (370 per kWh) Price was $60 each, but due to mis-listing I got a free one.
Could build 2x 25.9V 10Ah eZip battery upgrades for $98 each, compare to oem 24V 9.6Ah LiFe offerings @ $540.
Alternatively, would make a nice 14s2p 51.8 10Ah battery for my 48V 1000w rear hub build, 48V rated at 28mph, 51.8 should push to 30mph. (1 spare)

Although they seem excellent quality, no self-discharge and equal capacity, I will add 7s BMSs for safety and longevity.

Re: Homemade Battery Packs

Posted: Nov 02 2018 5:07am
by DrkAngel
DrkAngel wrote:
May 09 2018 3:52am
.
...
Electric Wheelbarrel Battery Upgrade - Update

Moved about 4 cubic yards of topsoil, about 30 x 150' round trips, half with ~200lb, half empty.
12.3V full to 11.6V, about 50% of 25.92Ah pack.
25.92Ah is oem new rated, actual probably still greater than 20Ah, even with moderated charge voltage.
Wheel barrel with "new" lipo battery, certainly, a very usable tool!
Getting Garden ready for Winter ...
Have 6 cubic yards of good topsoil and some cubic yards of seasoned Horse manure to rejuvenate beds with.
Just have to remind volunteers to recharge up at night.
Pantry Garden produced 1500lb+ of fresh vegetables for giveaway this year, up about 50% from last year.
Electric wheelbarrel made moving things so much easier.
Just got a good chipper-shredder--mulcher to recycle plant waste and coarse wood chips into better mulch - will cover beds for the Winter and turn into soil in the Spring.

Will pull Lithium battery and store in my basement for the Winter.

See - Raised Bed Gardening - Cement Blocks!

Re: Homemade Battery Packs

Posted: Nov 04 2018 5:23am
by DrkAngel
DrkAngel wrote:
Oct 28 2018 4:35pm
More fun
Customer brought in some interesting batteries the other day.

Image

Main Features:
● Quick charge current is 1100mA, quick discharge current 22000mA (22A), max discharge current 30000mA (30A)

Original owner tried soldering to cells but couldn't get a good stick. So sold new in boxes to me at great price.
Only 10, so not enough for any decent build, but I got cheap enough I can find some good use for.
I do have a few 26650 LED flashlights.
Could solder a few, 3s2p - 3s3p as 60-90A 12V car jumper.
Should solder at least a couple cells to demonstrate proper soldering methodology.
Discharged-charged a sample cell.
After brief trial in flashlight, iMax B6 1A discharge to 3.0V metered 4278mAh
iMax 1A charge to 4.22V metered 4323mAh
It's so nice, and rare, to find a non-major manufacturer that produces honest capacity!
Have not tested heavy C-rate discharge but would still rate as excellent.
Pricier than I normally buy but got good enough deal that I am buying compatible chargers and flashlights.

Re: Homemade Battery Packs

Posted: Nov 04 2018 11:40am
by DrkAngel
Noticed my April 2014 25.9V 25.94Ah build had lost power with increased voltage sag. At 1st, thought it might be the cold weather but took it apart to be sure.

Image

The side bank (bottom in picture) is in 2 segments and the tinned copper braid connecting them had a deteriorated solder connection. re-soldered and did a manual balance and all looks fine now. Will do a monitored full cycle and report on present capacity.

At 5 years of reasonably constant use, this is one of my most successful reliable builds.

Re: Homemade Battery Packs

Posted: Nov 04 2018 3:59pm
by 999zip999
Great to have success. Carry on.

Re: Homemade Battery Packs

Posted: Nov 10 2018 9:55am
by DrkAngel
.
...
Time for Winterizing batteries!

Electric wheelbarrel battery (11.1V 25.92Ah) to be removed, tested drained to 50% for storage (~3.85V per cell).
25A BMS added in Spring.
Will also replace charging port, weathered and sketchy at present.

EBike 25.9V 25.92Ah LiPo discharged to ~50% for Winter Storage.

Max Cell 33.3V 25.92Ah battery tested and discharged to 50% for storage

Cool Cell 33.3V 43.2V tested and tuned, will discharge to 50% for storage

24V lawn mower 25.9V 34.56Ah battery suffered failure on the 7th "s" I added when upgraded from 22.2V to 25.9V. Will test remaining banks discharge to 50% for storage. Will rebuild in Spring. May invest in 7s 45A BMS in Spring?

25.9V 26.4Ah Samsung 22p eBike battery tested and tuned for fair weather Winter use on my fendered Comfort Cruiser

2 - 36V 13.2Ah triple hoverboard battery builds tested for use on Snow Beast, 1 in insulated camera bag, 1 in eZip oem rack mount case.

Will adapt some 3s pocketable battery to power visor heater on snowmobile helmet, possibly red flasher on helmet rear also?

Also considering additional marker lighting, was using LED headlight (flashlight) and flashing taillight, almost got hit twice last night riding home after dark (~6pm)
Getting dark early with Winter coming and time change.

Re: Homemade Battery Packs

Posted: Nov 18 2018 11:53am
by jcool3
liitokala36.jpg
Has anyone tried making a case out of fiberglass cloth and epoxy resin? I would wrap over the PVC case with
fiberglass cloth and then saturate the cloth with epoxy resin. I want to add some attachment points like they
use in surfboards also. This is for my ebike. UV cure solarez would probably work much faster, but I already have the
epoxy.

Re: Homemade Battery Packs

Posted: Nov 25 2018 5:44am
by docware
DrkAngel,

Is 3,85 V storage voltage meant for LiPo only or also for Li-ion cells ?
If yes, do you have any reason to use such high voltage for winter storage ?

Re: Homemade Battery Packs

Posted: Nov 25 2018 8:22am
by DrkAngel
docware wrote:
Nov 25 2018 5:44am
DrkAngel,

Is 3,85 V storage voltage meant for LiPo only or also for Li-ion cells ?
If yes, do you have any reason to use such high voltage for winter storage ?
Oft recommended is storing at ≤ 50%
With some of my mapped cells 3.85V is closer to 20-25%
Newer cells this is near 50-60%
With the majority of my builds 3.85V is noticeable less than 50% but safely above 0%
Will have to moderate storage voltage for my Samsung 22p cell builds to ≤ 3.65V.

Image

Image

Image

Image

Image

Image

Capacity Mapping (Optimal Charge-Discharge Voltages)
.

Re: Homemade Battery Packs

Posted: Nov 25 2018 9:00am
by docware
Just a few facts.
3,85 V is about 60 % SOC for most of Li-ion cells. But probably, this is not so important. Here is something more interesting :

All Li-ion cells (LG, Panasonic, Sanyo,Samsung, Sony) are sent and stored for many months at 3,5 V .

Here, at well known video
https://www.youtube.com/watch?v=9qi03QawZEk#t=1h7m56s
at 1:07:55 is Jeff Dahn speaking about store of cells at cca 3,5 V for years.

In the Lithium Ion Rechargeable Batteries Technical Handbook (SONY) there are some graphs for long term storage tests. Storage at 3,2 V have smaller capacity loss than storage at 3,8 or 3,9 V.

https://cdn.sparkfun.com/datasheets/Pro ... 20MSDS.pdf

Storage characteristic 20 C.jpg

All these facts invoke qestions :
Do all of you really still use archaic 3,8 (3,85) V for winter storage ?
Is there any reason why not to use 3,5 V for Li-ion cell long term storage ?
….or less for those brave enough … :-)

Of course, I am assuming BMS current in the standard range 10 – 30 microamps. And normal Li-ion cells with low self discharge. Definitely not any old recycled cells from laptop.
Also assuming that any device like battery gauge is really switched off. Just Li-ion cells and BMS.
And if you are not sure, you should check battery voltage each 3 - 4 weeks, let´s say.

Re: Homemade Battery Packs

Posted: Nov 25 2018 9:21am
by DrkAngel
Al cells vary at optimal usable voltage!
Some cells are effectively empty at, as high as, 3.75V.

Image

Storing at below "empty" is liable to be damaging (and dangerous)!
I like to ensure a "safe" storage voltage, which is dependent on cell formulation.

It is important to investigate your battery's "usable voltage" before deciding on a storage voltage!!!

Re: Homemade Battery Packs

Posted: Nov 25 2018 9:31am
by docware
Can please shortly describe methodology of your measurement ?

Re: Homemade Battery Packs

Posted: Nov 25 2018 9:51am
by DrkAngel
Describes multiple methods, including:
Actual mapping from measured-metered charge;
Derived from manufacturers discharge graphs;
more.

Re: Homemade Battery Packs

Posted: Nov 25 2018 10:23am
by docware
Well,
back to the merits of my question. In the light of the facts I mentioned, do you still consider 3,85 V suitable voltage for winter storage of non recycled Li-ion cells ?

Re: Homemade Battery Packs

Posted: Nov 25 2018 11:31am
by DrkAngel
docware wrote:
Nov 25 2018 10:23am
Well,
back to the merits of my question. In the light of the facts I mentioned, do you still consider 3,85 V suitable voltage for winter storage of non recycled Li-ion cells ?
DrkAngel wrote:
Nov 25 2018 9:21am
Al cells vary at optimal usable voltage!
Image

#1 Too deep discharge destroys batteries!
IMO optimal storage would be @ 20-50% capacity (voltage varies by formulation!!!)
I would never store at "0%"!
The danger of 2-5% capacity loss per year palls at the risk of destroying your battery due to further self-discharge, discharge through BMS, etc.

Possibly at the same, or even greater, consideration is storage temperature.
Optimal storage temperature is usually listed as near 40ºF.
.

Re: Homemade Battery Packs

Posted: Nov 25 2018 12:24pm
by docware
I hope we are speaking about cells from trustful manufacturers like LG, Panasonic, Sanyo, Samsung, Sony, with low self-discharge rate. Definitely not fake cells.

From my measurement of 18650 cells from all above mentioned manufacturers, there is at least 20 % of capacity bellow 3,5 V even at 3 A discharge.

Lygte measurements display more than 20 %.


Samsung 30Q.jpg
Sanyo GA.jpg



Let´s take a new battery with really small capacity 11 Ah. After few years of usage the capacity is only 70 % thus 7,7 Ah. If I put this battery to sleep at 3,5 V, it has at least 20 % of capacity, thus 1,54 Ah. 20 microamps BMS takes off 0,072 Ah during 5 months of storage. Two orders bellow the capacity for winter storage.

I have never mentioned storage at 0 % capacity.

Of course, optimal storage temperature is presumption also.

Re: Homemade Battery Packs

Posted: Nov 25 2018 1:30pm
by DrkAngel
You must 1st realize the difference between static voltage (after discharge) and sag voltage (during discharge)!
If you notice ... when used, I draw data from minimal discharge rates (0.2A < 0.1C)

Image

Note difference between red line and yellow line!
Discharging "Voltage" sags drastically from actual cell voltage.
When discharge removed red (voltage) line will rise slightly ...
When discharge removed yellow (voltage) line will rise greatly, to above red line.

Re: Homemade Battery Packs

Posted: Nov 25 2018 2:56pm
by docware
Well, it´s my mistake that I take into account only cells like Samsung 30Q, Sanyo GA, SONY VTC6, LG MJ, ….. Cells that are on the market few years and that have suitable capacity and power for ebikes.

I completely missed (for me) exotic cells like Samsung ICR18650-28A which are not adequate for ebikes. Max discharge current for Samsung ICR18650-28A is 5,6 A. Simply I consider only suitable, modern cells.

Samsung ICR18650-28A.jpg
Samsung 30Q 0,2A 3A.jpg
Sanyo GA 0,2A  3A.jpg


So you are right, owners of such exotic cells should use winter storage voltage 3,7 V.

I agree, we have to measure voltage at least few hours, better 24 hours after discharging or charging, after the voltage change is stabilized enough.