Capacity Mapping (Optimal Charge-Discharge Voltages)

[DrkAngel]

B&D 20V Max 1.5Ah - 30wh
Could not find model markings.
Sanyo assumed ... that is their signature color.

Very likely:
Sanyo UR18650WX 1600mAh 20A discharge rate (derated due to lifesaving reduce charged voltage)
20V 20A = 120V 3.3A
or
Sanyo UR18650SAX 1500mAh 30A discharge rate
20V 30A = 120V 5.0A

Sounds about right for decent drill or fair-decent 5½" circular saw.

Some Sanyo basic specs:



Likely actual use.

Black & Decker-Stanley purchased DeWalt and Porter Cable and Bosch

 

[DrkAngel]

Pulled apart more of the Black & Decker 20V Max packs:

2013 1.5Ah has Samsung INR18650-15L cells, rated 18A = 12C

2016 2.0Ah has Samsung INR18650-20Q cells, rated 15A = 7.5C

2 new packs with 4 tool kit has:
2016 1.5Ah has Samsung INR18650-15J cells, rated 25-30A = 17-20C

 

[Okami]

Could somebody to me (as newbie) explain how to ''graph'' the capacity points (''pockets'') for my battery?

I've got Sony VTC 4

Cells are: 6 in serial, 4 in parallel configuration (24cells total) [6S4P]..

Details:

So far - not fully - depleted battery I've charged till about 1900mah per cell, this is not taking the charge till 4.2v but only till 4.1v, so the ''left 100-200mah'' is in upper and lower region of capacity, if I can trust what my turnigy charger tells me on the screen.

I also suspect that cell can take in 2000-2100 mah as that is in the datasheets, where 2050mah is ''typical'', but for simplicity, I count 1900-2000mah as usable capacity per cell, part of reason - I never discharge too much nor charge till 4.2v)

I made a ''charge'' test of individual cell and it only showed 1973mah when brought up till 4.1, it was at something like 3.2v (no load) when I started charging.

I assume there easly might be these 150mah somewhere in there, If I did charge it till 4.2v..

Load for discharging was flashlight with cree ''XM-L'' Led-diode, so I assume about 1-2A discharge but it seems this is not as important here.

[Details about when in use and the ''low-end'' point of capacity - discharge]

What I've experienced so far is - Below 3.5v (3.45v) no load voltage there is very little ''practical'' capacity left.. IT is in 100-200mah range as my load typically consists of drawing 10-20A (2.5-5A per cell)..

So after these 3.4v.. the voltage drop becomes quite extreme.. Today when my no-load voltage bounced backed up to 3.2v.. during load, some of the time cells stayed in 2.7-2.8v range.. that was about 15.5-16v total, so when divided, I get to ~2.60v or even a bit lower.. I couldnt make it out what was the lovest value as my watt meter / power analyzer only showd up 17v+ as lowest voltage point it has recorded (not sure how it records it).. I assume this was a bit normal behavour, as the cells tend to sag more heavily when on their ''low side''..

--

[The ''Big Story'' short - ]

I would like to ''map'' the discharge capacity in the 3.5-4.1v Region.. how much Ah do I have left at, let''s say 3.7v - 3.8v - 3.9v points.. it looks like most energy is stored in this region but im not sure how much..

--

Throw in some ideas.. then I will tell how I imagine doing this but I still have a bit uncertainities in my head..

--

One of them - from what I saw @DrkAngel posted, it looks like discharge/charge capacity ''curves'' are inversed.. so I wont get ''the same picture'' for discharge and charge.. this suggests I might need an accurate way of measuring capacity/watthours when battery is discharged.. to do this, I probably need a fancy wattmeter / current sensor, as I dont own a Vesc (speed controller) which would be capable to 'store / measure' this data for me..

--
VTC 4 datasheet:

https://docs.google.com/file/d/0Bx9io5ZhKnhhRDFZSlFKd3dSZG8/edit

Discussion with a lot of charts about VTC 4:

https://endless-sphere.com/forums/viewtopic.php?f=14&t=53992

 

[DrkAngel]

If you have an adjustable power supply, and a mAh meter?

2.60V cell, set voltage to 2.70V and charge, note mAh till charged
2.70V, set voltage to 2.80V and charge, repeat

With iMax charger, or similar, set charge and time limit to 100mAh charge (or closer, 50mAh?).
Recommend closer at low and high end
Record Voltage after each "step" and chart.
Note: record voltage at static "settled" state. Several seconds after charge discontinued.

 

[Okami]

Cool, thanks @DrkAngel!

I already had this idea in my mind about 'filming'' the charge process, but with your ''methodology'' I should be able to ''stop'' at these set steps, in this way I wouldnt need to stop the video and perhaps get a bit more flexibility / accuracy!

So - does this mean - that Charging mah curve (graph) will be the same as discharged mah curve (graph)?


And yes I've got ''smart charger'' just did not think about ''creating little capacity steps'' to record the charged capacity..

I also got a wattmeter, so I could basically do a discharge test also with higher load, since these smart chargers usually have pretty low discharge load.. (side idea, should do a discharge test on a cell, then get the numbers )

----

[Edit]

Can someone comment on this, saw it in another thread:

Most. Chargers display cumulative mAhr during charging.....watch how much extra is charged above 4.0v to 4.2v !

So does this mean I will get a bit ''incorrect'' reading? I know that my charger starts balancing only at the end of charge.. as the voltages start to flash and it indicates the balancing process.. So I assume I could ''safely'' assume that capacity is somewhat correct till the balance charging phase, correct?

 

[DrkAngel]

SONY US18650VTC4

Did a graph at .4A discharge line
With these high discharge capable cells, should be close to static voltages.



3.40V static voltage looks to be effectively empty for these cells.
Simple line chart approximates capacity per .10V

3.4V - 3.5V = 195mAh
3.5V - 3.6V = 505mAh
3.6V - 3.7V = 405mAh
3.7V - 3.8V = 225mAh
3.8V - 3.9V = 200mAh
3.9V - 4.0V = 200mAh
4.0V - 4.1V = 175mAh
4.1V - 4.2V = 110mAh - lower than actual ... initial voltage sag!

3.50V - 3.70V "sweet spot"

 

[Okami]

@DrkAngel thanks for pointing this out! I already saw this graph but had problems inserting it into this thread! Im really happy that you ''confirm'' what I had observed..

It also seems to be correct.. from the numbers you gave me, I should be able to more precisely determine ''how much kilometers'' Ive got left.. I use this battery for my electric mountainboard

---

With ''static voltage'' I assume you refer to ''no-load'' / stabilized voltage, is this correct?

 

[DrkAngel]

Static as in not moving ...
Not charging or discharging, setting for some period.
Brief period necessary with high discharge rate cells. -
A few seconds pause should supply reasonable voltage reading.
or
Add voltage meter alarm.

New version $2



Alarm sounds when any cell voltage drops to your chosen voltage.

Set V to3.2V (leaving a resting 3.4V?)
Set V to 3.5V for enough low performance power to get back to base?

To set "empty" point during actual use:
With cells at 3.40V monitor cell Voltage and cruise at typical throttle, set alarm to noted voltage.

.

 

[Okami]

Yep, I already do have such alarm (without the nice case, though)..

Besides - I started ''mapping'' the voltage against AH / distance graph from what you gave me..

Today I had only something like 600mah(150mah per cell) usable below 21.07v (3.51v per cell)

I feel that coldness might also affect this a little bit.. since I saw that capacity can go about 100-200mah down per cell with lower temperature (graph from that high power cell thread)

It was quite cold today outside.. I would say about -5 degrees celsius (23F). Now at evening the termo meter showed even -8 degrees celsisus (18F)

--

So, as I said, 3.45v is probably the lowest effective voltage I can use.. My battery is now ''resting'' at 3.42v per cell (20.53v total) and I believe I sqeezed out another 200-400mah on top of the previous 600mah.

So it is quite accurate to say that there are additional 800mah below 3.5v (3.4-3.5)

The problem with them is that they are not ''easly obtainable''.. the board starts to cut out power.. and sag is awful.. I can drive a bit.. then it needs to rest.. then a little bit more driving is possible.. but this is nowhere useful..

--

It looks like I will need to include some headroom for 3.4-3.5v voltage range.. so it was ''accurate to say'' that there's about 800-900mah till ''totally empty'' in the 3.4-3.5v region..(195mah per cell - 0.1v)

 

[DrkAngel]

The LVC (Low Voltage Cutoff) ~20V on your controller is designed for 24V SLA? (or 22.2V LiCo with 3.6-3.7V "empty")
Running your 3.40V empty cells will cutout way early.
Recommend adding 4 more cells in series 7s4p = 25.9V
20V / 7 = 2.85V-cell hard cutoff allowing full use ...
But, you will have to rely on Low Voltage Alarm or meter to protect battery!

I have run a 24V eBike @ 25.9V 10,000 miles with no apparent ill effects!
Never had a 24V eBike, scooter, mini bike not run properly @ 25.9v.

Be aware, 14% more speed or range ... not at the same time though.

 

[Okami]

It is a simple ''car esc'' with a fan.. it is designed for 6s lipo, so im not so sure can it take more than that..

I also run sensorless, if that makes any sense and use a brushless motor.

-
I can set up the cut-off on the esc.. but it is set to something like 3.0v, have not really checked in a while as that involves hooking up the wires to the pc but these same wires which come from esc, are already glued in receiver, not to rattle loose.

---

Im good with the capacity the battery offers.. I just want to make a map/chart with how much ''estimated'' kilometers I can ride at each voltage level..

When it was warmer, I managed to charge about 7600mah into the battery (1900mah per cell).. I dont really care about these 600-700mah extra (150-180mah per cell).. as Im not going to constantly charge till 4.2v or below 3.4v..

Would be easier If i had a Vesc, with integrated data collection.. so unless I build my own arduino current sensor or find a way to ''capture'' values from wattmeter, I will have to rely on voltage to determine capacity/distance left.

---

For info, I usually calculate 800-850mah consumtion per kilometer. This comes at around 16-19wh/km depending on how you calculate.. I dont ride at max speed though.. more like at cyclicts speed (avg speed ~16kph / 12mph) and also my tires could be pumped up a bit more since that is what everyone recommends for these pneumatic tire boards.

 

[DrkAngel]

Samsung ICR18650-22p - LiCoO₂
(may have found good source - receiving 40 samples tomorrow)

2150mAh 10A continuous discharge (20A burst discharge)
.5C standard charge 1C quick charge = not recommended for regen ... unless large capacity pack!



4.20-4.15 = 15mAh - low, due to typical-initial voltage sag (300 - 500 cycles)
4.15-4.10 = 75mAh
-------------------------------------------------------------------------------------------------------------
4.10-4.05 = 135mAh (600 - 1000 cycles ... 2-3 years of daily cycling) 90%++ capacity of rated
4.05-4.00 = 165mAh
4.00-3.95 = 135mAh (1200 - 2000 cycles ... 4-6 years of daily cycling) ~80% capacity of rated with excellent lifespan
3.95-3.90 = 165mAh
3.90-3.85 = 150mAh (2400 - 4000 cycles ... 8-12 years of daily cycling)
3.85-3.80 = 115mAh
3.80-3.75 = 95mAh (4800 - 8000 cycles ... 16-24 years of daily cycling)
3.75-3.70 = 120mAh
3.70-3.65 = 155mAh (20 years++ of daily cycling! - age deterioration will kill before cycling deterioration!)
3.65-3.60 = 250mAh
3.60-3.55 = 250mAh
3.55-3.50 = 120mAh
3.50-3.45 = 115mAh
3.45-3.40 = 130mAh
---------------------------------------------------------------------------------------------------
3.40-3.35 = 35mAh
3.35-3.30 = 15mAh

3.40V - 4.10V static voltages look optimal nearly 50% capacity between 3.70 - 3.40V!

3.55V - 3.65V "sweet spot"



View attachment ICR18650-22p.pdf

.

 

[Okami]

Good info

Shows that compared to other 'zones' most capacity is in ~3.6v region.

 

[DrkAngel]

Samsung ICR18650-22p - LiCoO₂
(may have found good source - receiving 40 samples tomorrow)

2150mAh 10A continuous discharge (25A burst discharge - unconfirmed source)
.5C standard charge 1C quick charge = not recommended for regen ... unless large capacity pack!

Graphed up a capacity map from supplied minimal discharge plot.

.

36V 4400mAh "Hoverboard" battery
"SA11116601
Samsung Battery Cells, Super Long Working Time And Use Life for Your Electric Scooter.
Fit for 6.5" 7" 8" Self Balancing Smart Electronic Unicycle Scooter 2 Wheels

Due to the difference between the monitors, the picture may not reflect the actual color of the item. Thank you!

Description:

100% brand new and high quality

36V Li-Ion Battery pack is made of 20pcs 2200mAh Li-Ion 18650 Battery

Voltage : peak - 42V, working - 36V

Capacity: 4.4Ah

Power: 158W

Cut-off voltage: 26V

Max. discharging current: 30amp

Max Continuous Discharging Amperage: 20 Amps

Rated Discharging Amperage: 15 Amps

Charging Current: <5 Amps

Charging Voltage: 43.2 Volts

Dimension: 135*95*60mm

Net Weight: 970g

Lifecycle: > 85% capacity after 1000 cycles.

Lifecycle of single cell: >85% capacity after 1500 cycles, > 70% capacity after 3000 cycles. (<1C discharge rate and <1C charge rate)

Run time: 15-20km(Depends on weight and road condition)

Package include:

1 x 36V 4400mah Li-ion Battery For Smart Scooter Self Balancing 2 wheels Electric Unicyle"

 

[DrkAngel]

.
... 20 "new" Samsung ICR18650-22P cells for $34.99

In a 10s2p 36V 4.4Ah "brick", With BMS!
BMS type varies
XT60 connector

Intend on use as:
supplemental cells in laptop cell 7s 25.9V pack builds as buffer for surge demands
2, or more packs, in 36V cordless mower + 2600mAh laptop cells
For 36V front hub bike
As rebuild for 2 x 5s2p "18V" Ryobi, or similar, 4Ah packs - upgrade to 4.4Ah with 20A continuous 40A surge!

.

 

[parabellum]

Thanks for sharing.
Have you made a capacity test on some packs or cells?
Can you see what is written on cells metal shell, under the wrap?
Same guy sells identical packs with LG marked cells for same price. http://www.ebay.com/itm/BALANCING-SCOOTER-LG-36V-4-4AH-LITHIUM-ION-REPLACEMENT-BATTERY-PACK-6-5-8-10/172648854096?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D41376%26meid%3D26b8bf62df70487faa9f4331ae5680da%26pid%3D100005%26rk%3D3%26rkt%3D6%26mehot%3Dpp%26sd%3D172648851568
To be precise, LGEAMF11865 cells, and I found little to no mention and no data sheet on those cells. Alibaba and forums only, contradicting capacity info.

 

[DrkAngel]

Samsung oem pdf - up 5 posts

 

[parabellum]

Samsung oem pdf - up 5 posts

Yeah, oem specs are good. My concern is, are those cells genuine or just shrink wrapped Chinese no names. (equal Samsung and LG listing makes it even more suspicious)
Have you performed any tests on packs you got?

 

[cwah]

Nice thanks

 

[DrkAngel]

200 Cells - $249.99
Samsung 2200mAh 10A continuous - 20A surge
$167 \ kWh

.

 

[etard]

I just received 2 packs and have not checked them out yet, I am putting them in a Sondors with a DOA Pack that originally came with similar cells (at least same capacity).

First impression is good, just need to order some connectors to parallel the two packs

Same seller also has some LG packs, I'm wondering which is better?

 

[parabellum]

I just received 2 packs and have not checked them out yet, I am putting them in a Sondors with a DOA Pack that originally came with similar cells (at least same capacity).

First impression is good, just need to order some connectors to parallel the two packs

Same seller also has some LG packs, I'm wondering which is better?

There is at least some information in the net about samsung 22P, not much about LG cell. I bought 7 of this packs and 4 I have tested gave over 4.1Ah and under 4.3Ah, did 15 A discharge on 1 pack HVC to LVC as result 4.13Ah out and very hot pack somewhere under 60 Celsius.

HD on my laptop gave up and I lost all the detailed data on those packs, unfortunately. And about 6 month of my life, where the last backup was made. My brother told me more than once, use Mega and auto-sync.

Why would you use DOA pack? Did you fix it?

 

[DrkAngel]

200 Cells - $249.99
Samsung 2200mAh 10A continuous - 20A surge
$167 \ kWh
In a 10s2p 36V 4.4Ah "brick", With BMS!
BMS type varies
XT60 connector
.

Cells rated "empty" near 3.40V
Latest charge at 2.00A input
Still some charge ... 3.447V >> 4.22V = 4.252Ah (2p, 2.176Ah per 2.200Ah rated cell)
Seem to be reasonably-actually capable of rated 4.4Ah
(Testing latest batch of 10 x 10s2p (36V 4.4Ah))

 

[wineboyrider]

Look like tool packs.

 

[Hillhater]

Look like tool packs.

They are the packs for those "Hoverboards" that caused so much fuss when they started burning down peoples homes.
There were litterally millions of them made for kids world wide.
The battery packs are mostly fine with good quality cells, bms , etc..but some of the hoverboards were real shoddy crap with little protection for the battery or wiring, such that in the event of a crash shorts and pack damage is common.
https://www.cnet.com/au/news/why-are-hoverboards-exploding-and-catching-fire/