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Re: Homemade Battery Packs

Posted: Dec 01 2017 7:59am
by DrkAngel
Updating 12/17
DrkAngel wrote:
Nov 05 2017 7:55pm
25.9V 26.4Ah #1 finished

7s12p Samsung cells are capable of 120A continuous 240A surge but controllers are <30A and installed 40A fuse (trying new 58V fuses & holder)
Just finished 1, had to test drive it ... rain stopped for awhile.
No BMS installed! Turned out were only 20A continuous.
Mostly worried about parasitic draw when customers let set for the Winter.


10s2p Bricks disassembled into 8s2p + 2s2p and I was oh so tempted to build as 8s12p ... but needed for 24V bikes and I already have the 7s chargers.

25.9V 26.4Ah #2 nearly complete
Just need to run the parallels and power rails and install fuse.
High C-rate cells improve cold weather performance!

Samsung ICR18650-22p build is doing remarkably well in the colder weather!
There seems to be no noticeable deterioration in performance between the 70ºF weather of a couple weeks ago and the present 30-40ºF. Top speed stays in the 21mph range and acceleration seems the same.

The ICR prefix indicates Lithium Cobalt, same basic formulation as my previous laptop 18650 and LiPo builds (that suffered horribly from the cold) so I would have to attribute the cold weather performance "preservation" to the enhanced C rate of these Samsung cells.


Although the same basic formulation, additives, or some other alteration does shift the capacity map substantially!
LiCo laptop cells had capacity till about 3.70V while the Samsung cells map good capacity till 3.40V.
Sadly, this nixes my idea of combining cells, to hybrid the higher capacity laptop cells with the higher output Samsung cells.
While the Samsung would help output capability, a large percentage of it's capacity would be wasted, unless endangering or damaging the Laptop cells by excessive discharge.

Re: Homemade Battery Packs

Posted: Dec 15 2017 10:23pm
by DrkAngel
While might not ethically be a homemade battery pack ...
... so simple, easy and useful, I had to post it up.

Got a large batch of 36V 4.4Ah (genuine Samsung cells!) hoverboard batteries.
Previously paralleled together 4 for a 36V 17.6Ah battery for testing old brush hub motor.

Anyhow, 3 hoverboard batteries fit nicely in the eZip RMB battery case.


For my Snow Beast, eZip (24V 450w) volted up and geared down for 20mph@36V (675w). The Samsung cells seem very cold tolerant! 13.2Ah might not seem like much but great for my short Winter trips, nice for short spurts near 30mph if used on my cruiser eZips (Dual battery rack and switch allowing 25.9V on one side and 36V on the other). Just flip the switch for TURBO

Re: Homemade Battery Packs

Posted: Dec 18 2017 8:19am
by DrkAngel
36V hoverboard compilations making 33.3V builds ... obsolete?
Retasking, or retiring 33.3V 43.2Ah LiPo "Cool Cell".


Rewire into "12V" inverter pack? (12V 129.6Ah!)
Rebuild into 36V SLA electric lawnmower housing?

Re: Homemade Battery Packs

Posted: Dec 19 2017 12:22pm
by Hummina Shadeeba
how you think these will do? think it's .5mm copper strip but will do them with some very thin foil at the connections to contour better.

can be stacked lengthwise or on top of each other with different copper strip that recesses better so nothing comes close when lengthwise or stacked. just 3d prints and copper pressed with another print and flexible tape. Will have to see how the tape holds it's compression.

its a super minimalist design for under a skateboard with minimal room

Re: Homemade Battery Packs

Posted: Dec 22 2017 4:00am

Re: Homemade Battery Packs

Posted: Dec 22 2017 6:33am
by DrkAngel
DVDRW wrote:
Dec 22 2017 4:00am
Safe connection?
safe connection.jpg
safe connection.jpg (103.54 KiB) Viewed 4164 times
Tape protecting Positive\Negative interface on top of cell is a good idea.
Bonded solidly ... but to tape-cell's shrink wrap.
Advise wrap entire battery horizontally with duct tape to additionally stabilize Pos wire.
Fold Pos wire to exit at top, then duct tape? (provides "shock absorber" type protection for wire-connection)

- The term "battery" refers to a combined collection of items working together in cooperation..
EG An artillery battery is an assembly of guns.
Thus an electrical "battery" is a assembly of "cells".
A single cell is not appropriately considered a "battery"!

Re: Homemade Battery Packs

Posted: Dec 23 2017 10:51pm
by markz
If I were you, I would add something to the corner of the 18650 can, plastic points card from any store, glue it onto the can in an L shape (upside down to protect the top and side), re glue wire, zip tie around, gorilla tape around just like the zip tie. Then proceed.

Yeah relooking, if you can shove a piece inbetween the wire, solder and can, you might not be able to.

Re: Homemade Battery Packs

Posted: Jan 03 2018 9:52am
by DrkAngel
Samsung ICR18650-22p 10s2p hoverboard batteries are going too fast!
29 originally
-2 for 1st power tool packs
-12 for 2 x 25.9V 26.4Ah eZip builds
-4 for WE 36V 17.6Ah pack
-3 for eZip 36V 13.2Ah
-3 for alternate "bag" 36V 13.2Ah
5 left (100 cells) + a few dozen leftovers from 7s12p eZip builds

Must reserve enough for my 750/1000w rear hub build, has switch for 750w "legal" and 1000w "TURBO".
Will build as 14s, as these Samsung cells have capacity till a static 3.40V.
(14s will hit 30mph+ in TURBO mode and will use streamlined posture and possible fairing to enhance speed-range)
So a 14s10p is doable with unassigned cells and I can "steal" another 60cells from 36V "alternate bag" if want larger ... or 2 smaller batteries.

Still have several power tool upgrades to consider:
Ridgid 18V Lithiums x3 = 15 cells
Ryobi 18V Lithiums x2 = 20 cells
B&D 24V >> 25.9V x2 = 28 cells
Oh boy ... gonna need more cells!

9s12p 33.3V 31.2Ah 1kWh+ - 2018

Posted: Jan 16 2018 7:39am
by DrkAngel
9s12p 33.3V 31.2Ah 1kWh+

Previous 9s12p eZip battery was constructed of re-recycled Sanyo laptop cells, with an actual ~20Ah capacity..
Used over the Winter on my 36V Snow Beast, it performed nicely, as long as I kept it warm ...

Ran it on my Comfort Cruiser over the Summer and pretty much finished it's useful life.
Cells were scavenged from previous builds >> from recycled laptop batteries = re-recycled.

33.3V 31.2Ah - 9s12p - Winter 2013-2014
2013 9s12p was constructed of 9 12 cell "bars"
2018 9s12p is constructed of NOS 12 cell laptop batteries in 4p segments, that stack nicely.
2p segments in top row were originally planned to be used as #9p, but realized will function much better by building 7-8-9p as 4x3 segments. I will swap 2 red (Sanyo) pairs to far right segment.

33.3V 31.2Ah - 9s12p - 2018
9s12p 2018.jpg
9s12p 2018.jpg (182.84 KiB) Viewed 3590 times
This build was planned as a replacement for my geared down volted up Snow Beast and for trips on my multivolt capable PA (Pedal Assist) and CC (Comfort Cruiser). Since original plan I've acquired a quantity of Samsung 36V hoverboard packs that perform much better than laptop cells in the cold. (Re-geared Snow Beast lower for 36V optimal performance!)

33V 31.2Ah @ 1038mAh will be dedicated for cruising with WOT restraint or traveling with 25mph+ PA capability.
With restraint, motor only could provide ~50 miles @18mph ... also have 33.3V 43Ah Cool Cell build I could carry for additional 70 miles.
But ... that is nearly 7 hours in the saddle ... :cry: ... might better push towards 23mph with recharging break.

Notable is that prolonged riding requires pedal assist to keep butt alive. On my Century run (100 eBike miles in 1 day) I had to re-position seat multiple times and take several walkabout breaks to make ride barely tolerable.

Future projects will include a convertible motorcycle type seat for comfort and more aerodynamic seating profile.

Re: 9s12p 33.3V 31.2Ah 1kWh+ - 2018

Posted: Jan 20 2018 3:08pm
by DrkAngel
33.3V 31.2Ah - 9s12p - 2018

Wedged cells tightly into pack for soldering.
wedged.jpg (139.08 KiB) Viewed 3415 times
Might be simplist build ever!
Note each 4 cell segment has a tab ... which can be folded over and soldered to my heavy tinned copper braid.
Also, I slid cardstock between cells and banding strips as additional safety measure.
solder tabs.jpg
solder tabs.jpg (147.49 KiB) Viewed 3415 times
I will build a small shelf to support masonite shelf over screw point.
Hot melt supporting formica.
shelf.jpg (35.34 KiB) Viewed 3415 times

Re: 9s12p 33.3V 31.2Ah 1kWh+ - 2018

Posted: Jan 21 2018 1:27pm
by DrkAngel
All cells were balanced charged, 1s72p for the Sony (green) and 1s36p on the Sanyo (red), more than a year ago.
All Sony @ 4.05 still within 1/100V of each other.
All Sanyo @ 4.04 still within 1/100V of each other.

Cells were all capacity tested (2016) and proved near 95% of rated, and with the proven minuscule, and equal, self discharge this looks to have the potential to be my best build yet.

At 32Ah, it will never exceed 1C discharge rate and will cruise at <.4C.
With moderated charged\discharged voltages, should be usable for many-many years!

Re: 9s12p 33.3V 31.2Ah 1kWh+ - 2018

Posted: Jan 24 2018 5:33pm
by DrkAngel
... :lol: ...

Finally finished 33.3V 31.2Ah eZip battery!
Naming MaxCell due to the 9s12p being the maximum number of cells that will physically fit in eZip RMB battery shell.
(And to differentiate from my 33.3V 43.2Ah insulated "Cool Cell")

Simple but very snug fit. To secure cells tightly and to protect solder points, top and bottom are covered with 1/8" closed cell foam sheets. Had to put a little weight on case to close properly ... center bows out a bit, center screw removed to allow 9s12p fit.

Side A was nice and straight forward, nice straight runs with heavy tinned copper braid.
Any connection over positive ends of cells were protected with additional HD duct tape!

Side A.jpg
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Side B required a few curves, which was easy if braid curved before flattening.

Side B.jpg
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Installed the new 58V rated fuse holder with 40A fuse. Upgraded charging wire to 18ga, unlikely to charge over 5A, will upgrade to 14ga if I ever want to charge at max recommended 15A.
Entire battery wrapped in clear boxing tape to stabilize and protect. Meter leads poke through easily, for testing.
Sides wedged firmly with sturdy cardboard.

I did add 1/2 cell height wood blocks to support rows 2-4-6-8
Fused.jpg (171.75 KiB) Viewed 3277 times
MaxCell Specs:
33.3V 31.2Ah = 1038.96mAh - 1kWh+
9s12p = 108 cells
NOS from HP laptop batteries.
72 Sony 2600mAh + 36 Sanyo 2600mAh
Arraigned as 9s8p(Sony)+4p(Sanyo)
Both types effectively "empty" at a static 3.70V
20-21mph (will go 25mph in my upgeared eZips)
Including shell, battery build weighs 12lb 0oz

Compare to eZip OEM SLA battery:
24V 10Ah = 240mAh < 120mAh usable
15lb 9oz

Box of 80 Fullriver LiFePO4 26650 3.2V 3300mAh

Posted: Feb 03 2018 9:08pm
by DrkAngel
Running short on the Samsung cells, deal is long gone, decided to save remaining intact 37V 4.4Ah BMSed for 36V projects, that leaves several eZip battery cases with SLA or worn out Lithium.
Might have found an extremely cheap, acceptable solution.

LiFePO4 26650 3.2V 3.3Ah cells (9.9Ah continuous discharge).
The eZip RMB battery case will hold 8s5p

25.6V 16.5Ah for $50 !!!
Compare to
oem SLA
24V 10Ah (5Ah usable) for $129 !

No where near the 26Ah-32Ah I've been building recently but such a great price from such, supposedly, safe technology cells ... gotta give them a try.

More than 300% usable capacity of SLA.
268% capacity of 6.14Ah eZip LiFePO4 option at $350.

Reputedly, from at least one source, 8s (25.6V) LiFe can use the same Lithium charger as my standard 7s (25.9V) LiCo! ... ???

Re: Box of 80 Fullriver LiFePO4 26650 3.2V 3300mAh

Posted: Feb 04 2018 3:23pm
by DrkAngel
DrkAngel wrote:
Feb 03 2018 9:08pm
Reputedly, from at least one source, 8s (25.6V) LiFe can use the same Lithium charger as my standard 7s (25.9V) LiCo! ... ???
7s (LiCo) x 4.20V = 29.4V
29.4V ÷ 8s (LiFe) = 3.675V

LiFePO4 charge.jpg
LiFePO4 charge.jpg (126.73 KiB) Viewed 3030 times
3.675V charge voltage looks within acceptable range ... ?
Unlike LiCo, LiFe seems to need higher voltage, prolonged charge cycle..

LiFe charge discharge.jpg
LiFe charge discharge.jpg (54.32 KiB) Viewed 3030 times
Thus, it seems important to use a charger, rather than a power supply.
The higher voltage, prolonged charge cycle must disconnect at some low current (charging amperage - mA) point.
Similar, somewhat, to SLA charging methodology ...
In fact, at least one manufacturer of LiFe batteries, Dakota, advises that their 4s (12V) battery can be charged with a typical 12V SLA charger.

Good article on LiFe charging - PowerStream

Re: Box of 80 Fullriver LiFePO4 26650 3.2V 3300mAh

Posted: Feb 05 2018 9:49am
by DrkAngel
Corrected (sorry) typographical errors, wrong volts etc

Minimum LiFePO4 charge voltage looks to be ≥ 3.40V, recommended is variously listed as 3.60V - 3.65V and maximum is listed at ≤ 4.20V.
I might test bulk (power supply) charging as high as 3.50V.
(I need a low mA charge current disconnect! - to turn power supplies into "proper" chargers.)

Test and preliminary, at least, charges will be performed with one of my iMax B8's, which does include a LiFe dedicated setting.

FullRiver cells will be individually tested:
1. Delivered Cell voltages will be tested and marked
2. All cells fully charged (with iMax)
3. Cells left setting for several days (test for self discharge) and marked with resultant SD voltage
4. Cells put under identical load and marked with voltage sag (comparative IR (Internal Resistance))
5. Each cell "cycled" with same iMax (metered Discharge\Charge) and labeled with "Capacity"
6. 5p banks will be built with equal, "cumulative" capacity banks (each bank of equal capacity)
(by actual capacity total or arranged by capacity and sorted into banks as 1 2 3 4 5 6 7 8 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 8 etc)

Re: Box of 80 Fullriver LiFePO4 26650 3.2V 3300mAh

Posted: Feb 05 2018 10:39am
by DrkAngel
LiFePO4 Capacity "Map" Test


Re: Box of 80 Fullriver LiFePO4 26650 3.2V 3300mAh

Posted: Feb 16 2018 3:09am
by DrkAngel
Received 80 26650 LiFe cells.

Beginning tests:

1. delivered voltage
62% within 3.327V >> 3.330V
2 high near 3.34V
10 low near 3.30V

2. Preliminary capacity test
Will test representative samples 1st.
Need reliable connections for charge\discharge\charge test.
Problem - method of connecting to test leads.
As temporary solid contact, I do not wish to permanently attach.
Using Neodymium magnets attaching leads is somewhat sketchy.
a. Built 6 "attachments" by placing 2x8mm Neodymium discs inside 1" lengths of 1/4" TCB (Tinned Copper Braid) and squeezing copper braid flat.
Connection reliability and consistency seem very good!
b. Have 2" copper foil tape.
Foil around Neodymium magnets should provide even better contact.
Small squares would connect cells in series
Rectangles could attach to cells with lead attachment point

Running 1st trials with magnets inside TCB

Re: Homemade Battery Packs

Posted: Feb 16 2018 4:53am
by Buk___
DrkAngel wrote:
Feb 16 2018 3:09am
Need reliable connections for charge\discharge\charge test.
Problem - method of connecting to test leads.
As temporary solid contact, I do not wish to permanently attach.
Using Neodymium magnets attaching leads is somewhat sketchy.
There's a photo in one of the (IIRC) 3-way cell tests of the tester using trigger clamps to hold the connections onto the cell.

Re: Box of 80 Fullriver LiFePO4 26650 3.2V 3300mAh

Posted: Feb 16 2018 1:58pm
by DrkAngel
Cu wrapped magnets perform nicely!

Magnets in:
Tinned Copper Braid - Left
Copper adhesive foil - Right

CuWrap.jpg (66.09 KiB) Viewed 2766 times
Magnet in Copper foil supports 3+ LiFePO4 cells
CuWrap hang.jpg
CuWrap hang.jpg (40.33 KiB) Viewed 2766 times
Built 5s parallel connectors
1s5pCumag.jpg (66.77 KiB) Viewed 2766 times

Re: Homemade Battery Packs

Posted: Feb 17 2018 8:26pm
by EbikeAus
Just found this thread so thought I'd add my current build for the 48v rear hub build I'm putting together.
Cells are pulled from recycled power tool packs.

This first pack is 14s 4p of Samsung 30Q.

Just need to connect BMS.

Will be heat shrinked and housed in tool box with on/ off switch.
Mounted on rear rack.

Re: Homemade Battery Packs

Posted: Feb 17 2018 10:14pm
by zro-1
Pics in my build thread of the 13s2p backpack battery I built. ... 5#p1355250

Re: Homemade Battery Packs

Posted: Feb 18 2018 5:05am
by EbikeAus
Completed battery, well almost, just need connectors. I'm thinking XT60 or XT90

Re: Box of 80 Fullriver LiFePO4 26650 3.2V 3300mAh

Posted: Feb 25 2018 12:23pm
by DrkAngel
Still working on LiFePO4 testing method.
LiFe has a very "tight" voltage capacity map.
seems to require some overpressure to "fill".

Re: Homemade Battery Packs

Posted: Feb 25 2018 5:55pm
by steveo
Hi Everyone,

I was wondering if there is a cell matching software available online. I would like to use it to build a high discharge battery for one of my projects using the VTC4 cells.

Thanks in Advance


Re: Box of 80 Fullriver LiFePO4 26650 3.2V 3300mAh

Posted: Feb 25 2018 8:48pm
by DrkAngel
DrkAngel wrote:
Feb 25 2018 12:23pm
Still working on LiFePO4 testing method.
LiFe has a very "tight" voltage capacity map.
seems to require some overpressure to "fill".
Charge-discharge testing the LiFePO4 ...
But I don't really like, or see the point in, discharging to the iMax LiFe "discharge" 2.00V!
So, with multiple iMax, I am charging to the 3.60V LiFe,
then discharging ti the LiIo 3.00V.


While LiFePO4 are rated as 3.65V - 2.00V, I feel:
Gentle cycling is better for breaking in and should still provide accurate comparative capacity.
5p @ 3 Amp = <.2C and I would rate as cells effectively "empty" @ 3.00V