Homemade Battery Packs

I have a B8, the discharge function only worked for one partial pack, I'd be careful with those if you plan on using the discharger.

I use two 12V headlight bulbs wired in parallel to discharge cells in parallel and an old dual 120V hotplate to discharge series cells more than three or the full pack.

DrkAngel said:

Ordered 2 iMax B8's from HobbyKing.com, 2, to save shipping.

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Jonathan in Hiram said:

I have a B8, the discharge function only worked for one partial pack, I'd be careful with those if you plan on using the discharger.

I use two 12V headlight bulbs wired in parallel to discharge cells in parallel and an old dual 120V hotplate to discharge series cells more than three or the full pack.

DrkAngel said:

Ordered 2 iMax B8+'s from HobbyKing.com, 2, to save shipping. (2 for $111 shipped)

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There is a large percentage of fake B6's & B8's.
I purchased the "Genuine" from reputable source, they list genuine and fake (B6), both for sale.
Got the new model, B8+ ... black with colored buttons.

Yes, I have 2 older style (blue) that I have been disappointed in, blew a MOSFET trying to charge at 5A (replaced), lost voltage regulation on #1 bank, failed again, trying to charge at 5A, etc.
Got a box of shiny junk ...

But I will give the "Genuine", new style, a try.

DrkAngel said:

Jonathan in Hiram said:

I have a B8, the discharge function only worked for one partial pack, I'd be careful with those if you plan on using the discharger.

I use two 12V headlight bulbs wired in parallel to discharge cells in parallel and an old dual 120V hotplate to discharge series cells more than three or the full pack.

DrkAngel said:

Ordered 2 iMax B8's from HobbyKing.com, 2, to save shipping. (2 for $111 shipped)

Click to expand...

Click to expand...

There is a large percentage fake B6's & B8's.
I purchased the "Genuine" from reputable source, they list genuine and fake (B6), both for sale.
Got the new model, black with colored buttons.

Yes, I have 2 older style (blue) that I have been disappointed in, blew a MOSFET trying to charge at 5A (replaced), lost voltage regulation on #1 bank, failed again, trying to charge at 5A, etc.
Got a box of shiny junk ...

But I will give the "Genuine", new style, a try.

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Evidently the maximum allowable discharge power is about 20 watts. http://www.skyrc.com/index.php?route=product/product&product_id=12

I didn't find that out until after mine would no longer discharge since the power limitation on discharge isn't listed in manual as far as I can tell.

FWIW, my blue one still charges fine, I've been running it nearly continuously for a couple of weeks now with no problems on the charging.

Received my large quantity of recycled laptop Li-Po and am experimenting with a testing methodology.

Packs are in a 3s2p configuration - 11.1V 4320mah.

Stage 1
Charge all cells to a preliminary voltage .
These cells are oem charged to 4.05 - 4.10V per cell.
For testing purposes I am charging to 4.15V.
(This will allow a more noticeable bleed down, for less than perfect cells.)

Stage 2
Monitor bleed down of cell voltage.
Preliminary check at 1 day, will recheck for a minimum of 1 week.
Packs with the most consistent voltage retention, combined with consistency of all cells in 6-pack will be chosen for pack construction.

Stage 3
Discharge test
I run the 3s2p pack through a V-A-Ah-w meter into a 12V to 120V AC inverter to 2 muti-speed fans, producing a 2200mah drain (~.5C).
Initial voltage drop of pack and cells are noted and recorded, this is a fine comparative IR measure and a confirmation that both cell of each pair are good.
Drain is maintained for 15 minutes (timer w/alarm), voltage of pack and banks are recorded, then drain removed.
Next 3s2p pack is attached and initial voltages noted and recorded.
Previous packs, final pack and cell, voltages noted and recorded. (About a 1 minute delay from drain removal)
These are larger flat cells, so all voltages are marked directly on the cells.

Object of testing is
#1 eliminate bad packs
#2 determine packs with best consistency among all cells
#3 rate packs by comparative capacity (final voltage after a closely timed regulated drain should provide an excellent comparative capacity)

Stage 4
re-re-cycling
Less than perfect packs will be separated for other projects
OEM pack will output an initial 4C surge but blows a built in fuse after a continued 2C drain, each cell individually fused.
1st test will be to determine output characteristics with fuses bypassed.
(cordless power tool fodder)

"Bulk", packs of lesser capacity will be built into utility packs for 12V power tools, 110V AC inverters, 12V camp lanterns
25.92Ah is smaller than and half the weight of 7Ah SLA

PS 1st test batch consists of 18 6-packs of of previous 36V 26Ah build (tested only, never used) and about 35 packs from recent purchase that failed charger test, the rejects, freebees, (received free replacements!)
Testing with the expendables and perfecting testing methods before moving on to the good packs.

PSS About 6 packs had some puffed cells ... these might be relegated to ... safety evaluation testing ...
Remote camera and expendable test leads preferred.

Sorry to interrupt, but I have a much simpler question. I have the XT60 connectors to link my new Ping pack with the EZIP, so what wire should I use. I'm tempted to use a heavy cord from a microwave oven but I assum it's rated for no more thhan 15 amps - I just like the idea of having a flexible, sheathed cable. What should I really use? Stranded 12 or 10AWG?

LeftieBiker said:

Sorry to interrupt, but I have a much simpler question. I have the XT60 connectors to link my new Ping pack with the EZIP, so what wire should I use. I'm tempted to use a heavy cord from a microwave oven but I assum it's rated for no more thhan 15 amps - I just like the idea of having a flexible, sheathed cable. What should I really use? Stranded 12 or 10AWG?

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You were previously involved in this discussion - What wire Ga? - and were offered multiple reasonings on various wire gauges.
While I am enthusiastic about "Inspiring and Enlightening", when people insist that I tell them what to do ... it tends to leave me feeling sad and frustrated ...

So ...
Heavier wire gauge is better.

Rather than re-hashing the same discussion ...
And since I refuse to tell someone what to do ...
I add some more possibilities!


If you like the microwave heavy cord, and have enough, run 2 lengths?
Each length has 3 - 15A capable strands?
Use all 3 wires of one as positive, 3 wires of other as negative?
This should give you 45A continuous at the UL rating ... ?

or

Run a single length?
Run all 3 wires as positive?
Run negative through the bike frame? (Excellent with aluminum frame! Good with steel frame. )

Sorry if I seem a bit rude ... I strive to add some information (fuel) and start a spark of inspiration ... that spark, turning into a flame ... warms my spirit.
When that spark fails to catch, I feel it might be some failure on my part ...

Just as an aside...the XT60 fits Turnigy 12-Ga silicone-insulated wire perfectly, and you can use 5mm-3/16-inch heat shrink with it. The XT90 fits the Turnigy 10-Ga perfectly, and that combo uses 6mm-1/4-inch heat-shrink. I like to take needle-nose pliers and turn the pins so that the solder socket-cups point up when the connector is laying flat...doing that makes soldering to these very fast and easy.

What I'm having trouble grasping is why I should use 10 or 12 AWG wire to attach a pack to a 14 AWG wiring harness. I was looking at using the apparently 12 AWG wires on the pack for the battery's XT60 female connector, and either new 14 AWG stranded or the presumably 14 AWG microwave cord for the cable to connect to the XT60 I will install on the right side battery power cable. I thought maybe I should go with heavier wire, but then what happens at the connection to the bike's harness? Whatever I do, according to the conflicting answers I got earlier, there will be too much heat under maximum load. or there won't be. I don't plan on using maximum load for more than a few seconds (I don't believe I've done it at all, yet), so I was trying to get some advice on what is safe vs what is optimum. Not everyone wants to become an expert in every aspect of every activity, like adding a new battery pack to an EZIP. Clearly I'm in the wrong topic, though, so carry on.

LeftieBiker said:

What I'm having trouble grasping is why I should use 10 or 12 AWG wire to attach a pack to a 14 AWG wiring harness. I was looking at using the apparently 12 AWG wires on the pack for the battery's XT60 female connector, and either new 14 AWG stranded or the presumably 14 AWG microwave cord for the cable to connect to the XT60 I will install on the right side battery power cable. I thought maybe I should go with heavier wire, but then what happens at the connection to the bike's harness? Whatever I do, according to the conflicting answers I got earlier, there will be too much heat under maximum load. or there won't be. I don't plan on using maximum load for more than a few seconds (I don't believe I've done it at all, yet), so I was trying to get some advice on what is safe vs what is optimum. Not everyone wants to become an expert in every aspect of every activity, like adding a new battery pack to an EZIP. Clearly I'm in the wrong topic, though, so carry on.

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You have been offered various knowledgeable opinions ...
If you need more opinions do a search for "amps awg" "wire gauge amps" or similar.
Eventually, you will have to "man up" and make your own decisions!

Otherwise, unluckily ... in my opinion, you will find someone perfectly willing to tell you exactly what to do.

Just chucked this together to get the bike going. I will frame mount them at a later date.

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Frog box from BMSbattery. Three 4s 5Ah hardpacks, spaced apart with a couple of wood blocks and some camping mat foam to take up the slack. Trimmed down take-away container held with double sided tape. Smart bms with led's installed and the temperature bead inside the middle hardpack. With the lid on it is all pinned securely. However, that take-away tray will not stand a good drop up-side-down. The batteries will smash it I'm sure.

No idea why they omit the leds at factory. They left the accompanying resistors on board, doing nothing. I would of happily paid more for the led version if it were possible. Took me hours to find and fit the right ones.

I have a few questions pertaining to this thread in regards to Li-ion laptop cells and the Imax B8 charger drkangle uses.

I checked all the voltages immediately after removing from the pack, organized into groups based on their voltage, etc... I left batteries in groups of 1s2p or 1s3p depending on how they were connected in the pack. When you have a 2 or 3 that are tabbed together and they are dead or nearly dead, is it worth my time to separate and try to charge individually?

I noticed some batteries that were in the 1.x voltage range completely died after a charging attempt, could I be doing something to kill them such as charging at too high of a rate, or do some batteries just do that?

My Imax B8 will not charge to 4.2 on the lipo setting, it will only take the battery to 4.16, but my "wall warts" go to 4.20 and 4.22. I'm wondering if I should charge to 4.16 with my Imax then finish them with my "wall warts" or does it even make a difference? Also, anyone here know anything about the calibration menu on the Imax? It's not documented anywhere but when you power on the unit while holding enter and < it gives you a menu with -20 thru +20.

So far, just from observation, any batteries that were 3.x volts when pulled from the packs are maintaining their charged voltage within .1. Many of the 2.x are maintaining within .2, anything that was 1.x when pulled is a toss up... and anything that was dead has not come back to life.

First point. Anything with 1.x V should be thrown away.
Second point. I also throw away anything with 2.x V as well.

Then I charge the 3V and up batteries, checking to see that they aren't getting hot. Some will get hot as they charge, I junked them too.

For end charge voltage, why not stick with 4.16? Going higher just shortens your battery life considerably.

Got a dead or low cell or two? Cut them out and chuck them.

When I first recommission my laptop cells, I individually charge as much as possible so that they all start at the same voltage. Some simply won't charge up to 4.15V so they get chucked in the recycle bin as well.

Good luck. If you're feeling really fancy you could get an IR meter off ebay and start sorting them by IR as well.... a lot of work though for a big pack like mine- 15S24P!

I was following a recommendation a few pages back from drkangel about charging to 4.2 for testing purposes. After testing, my plan is to only charge to 4.1v and not discharging past 3.5v. Admittedly, I'm hesitant to use any of the batteries that came from a pack with 2.x voltage without some extensive testing. I will be building a 7sXp pack depending on how many good batteries I have, and how many I can cram into an ezip case. I will follow your recommendation to discard anything dead, but possibly keep my 2.x and 1.x batteries for lights, power tools, and other "not-so-important" projects if they hold some charge.

BTW, I was already thinking about some IR testing and ordered a watt meter from ebay based off a video I saw here http://www.youtube.com/watch?feature=endscreen&v=usRE3gLFnOc&NR=1

As long as you charge beyond your working voltage, the purpose is the same.
Tho ... Higher voltage does demonstrate voltage "bleed down" ... sooner.

EZip pack will fit 7s12p.
Initially I cut the center screw section, the use of segmented spacers should allow center screw retained.
3/16 - 1/4" paneling spacers should support the cells nicely.
I like Masonite, a high density pressed board of great durability. (Used as floor underlayment and as bathroom paneling)
Most importantly I use it as a support-barrier between cells and the contact screw heads!



Oh!
Pack is wrapped with clear boxing tape, easy to see through.
Pink high density (~1/8" closed cell) foam below batteries, and above, to firmly retain cells.
Movement (rattling), leads to cracked solder connections!

I do intend on building an 8s12p 18650 build in an eZip pack, just have a couple problems.
Except for the pre-2009 ezip controllers it's tough to find controllers with 29.6-33.6V compatibility, 70mm width - to fit in eZip compartment.
I've already regeared all my eZips for 20mph capability at 25.9V, I'd hate to re-re-gear one then, possibly, re-re-re-gear back, if not happy with the results?

Thanks for the tips on the ezip case, I will definitely follow those.

In some of your earlier posts I noticed you were leaving cells in pairs, but a few posts up from this you mention you're testing at 3s2p. Are you re-soldering them in this configuration after testing pairs, or testing straight out of the pack? Also, my Imax B8 has a discharge function that will time how long it takes before the battery reaches it's preset discharged voltage. I was playing with it a couple nights ago and set it to discharge at at approximately 1c and it took about 43 minutes to discharge my battery pair (this pair had a significant voltage drop during initial tests so I wasn't concerned about damaging it). Can the Imax be used in this manner to gauge battery health / capacity vs your 12v inverter test?

Love this thread, but it's information overload for me after reading the whole thing...

friendly1uk said:

No idea why they omit the leds at factory. They left the accompanying resistors on board, doing nothing. I would of happily paid more for the led version if it were possible. Took me hours to find and fit the right ones.

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When you ordered the BMS what settings did they program? Did you order the higher current option?

Judoka said:

Thanks for the tips on the ezip case, I will definitely follow those.

In some of your earlier posts I noticed you were leaving cells in pairs, but a few posts up from this you mention you're testing at 3s2p. Are you re-soldering them in this configuration after testing pairs, or testing straight out of the pack? Also, my Imax B8 has a discharge function that will time how long it takes before the battery reaches it's preset discharged voltage. I was playing with it a couple nights ago and set it to discharge at at approximately 1c and it took about 43 minutes to discharge my battery pair (this pair had a significant voltage drop during initial tests so I wasn't concerned about damaging it). Can the Imax be used in this manner to gauge battery health / capacity vs your 12v inverter test?

Love this thread, but it's information overload for me after reading the whole thing...

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iMax should work just as well.
Could rate by timed discharge also.
But "rating" by mAh is more accurate - takes longer.

I, for 18650 Li-ion cells ...
Initial bulk charge,
separate ... into pairs,
self-bleed down observation,
then rebuild as 3s2p for inverter drain test.
Each pair rated by residual voltage.
Then resorted ...


Recycled LiPo
The above "few posts up" was referencing testing a batch of Flat Lithium polymer that I'm recycling from laptop CD bay secondary batteries, 3s2p configuration.
Just got done testing and sorting the "rejects" - ones that oem laptop charger would not charge properly.
Chose 15 best for 25.9V 7s12p eZip pack rebuild.
1. Least self-discharge
2. equal cells in pack
3. Best remaining voltage after measured drain

Have another 15 for 2nd pack and lots more for "playing with" ...
large 12V pack for 110AC inverter use,
remove fuses, discharge capability tests, cordless power tool pack upgrades,
"safety testing" with over-volting, excessive drains etc.

After evaluation of testing procedure, pack performance etc. I will begin building Primo packs.
All cells matched by year of manufacture, IR, and capacity (matching retained voltage after 1 hour drain at .5c).

"Quick Test"
I did not perform any precise capacity testing, merely a reasonable comparative test.
1. Same beginning voltage
2. Timed-measured drain
3. Compared remaining voltage
Measured comparative IR, for future reference-evaluation?

Comparative IR (Internal Resistance)
I rate a comparative IR by measuring cell voltage before removing .5C drain, waiting till voltage recovers ...10min, retesting voltage then comparing.
Comparative IR varied more by year of manufacture than remaining capacity.
12.08V with a continuous .5C drain exhibited between .5V and 1V "sag"(6.4% to 12.5%).

Oh! I did build an INDEX.
Located in #1 post, with a shortcut in my signature ... below.

Here's an update on my battery testing, would like some feedback to make sure I'm doing everything correctly.

My Imax B8 has a discharge function I'm using to test capacity, I have it set to discharge at 4 amps for a 1s2p setup. This works best for me because I can put a battery on discharge in the garage, then check on it an hour later (I never leave the house while charging or discharging). The Imax will keep track of the time it took to discharge the battery. This is just a comparative test because I do not feel the Imax has accurate voltage readings. It's very common near the end of the discharge cycle for the Imax to report 3.17 volts while my multi-meter reports 3.51. I feel the important thing is to use the exact same testing procedure each time.

Starting Voltage - It was going to be a little time consuming to discharge, then charge all the batteries back to the exact same voltage. I believe if they are close, this will work since I'm looking for large differences in capacity. Unfortunately when I did my charging for the initial bleed down testing, I had wall chargers charging to 4.20, 4.20, 4.22, and the Imax to 4.16.

Testing - The Imax does not instantly go to a 4 amp draw, it takes 20 - 30 seconds to build up to it. Once it reaches 4 amps, I wait approximately 10 seconds to get my "Load Volt" reading. I use the beginning and load readings to calculate my sag and resistance. After the discharge is complete, I wait 10 minutes or more to get my end voltage.

Results - I was surprised to see a poor discharge time on a couple batteries that performed well on the bleed down test, thus making me believe this discharge test is essential in gathering a good lot of batteries to build my pack with.

So my question to those who have done this several times is, do my numbers appear normal and do my test procedures seem solid? Battery G1 has high resistance and sag, poor discharge time, but look at it's end volts... seems weird, might try retesting. Similar results on battery B1.

Judoka said:

Here's an update on my battery testing, would like some feedback to make sure I'm doing everything correctly. ...

Results - I was surprised to see a poor discharge time on a couple batteries that performed well on the bleed down test, thus making me believe this discharge test is essential in gathering a good lot of batteries to build my pack with.

So my question to those who have done this several times is, do my numbers appear normal and do my test procedures seem solid? Battery G1 has high resistance and sag, poor discharge time, but look at it's end volts... seems weird, might try retesting. Similar results on battery B1.

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Method seems sound.
Likely, as indicated by initial "sag" and final "recovered" voltage, G1 has one cell bad. Separate, test and keep good one for flashlight etc?
B1 ... possibly 1 bad, more likely 2 "poor" cells, as indicated by moderate initial sag.

Also ... Regard "bleed down test" as only step 1 in a series of elimination trials.

These are my diy batteries so far, left to right:
Panasonic NCR16850B 17.5AH 10S5P; A123 20AH 12S; A123 20AH 24S

Got a bit more done to the frog box.
I wanted this

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So I chopped it up

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Held it back with a lip, and from slipping with a pin.

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This worked remarkably well, but I thought a few more fixings never hurt.

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Then I thought about if the fixings fall in though. I hadn't realised it was totally exposed to the rain either. So I stress tested my extra fastenings to destruction, and actually they were very good.
So, some work with the fabric tape and bathroom sealant, and it's all ready for painting. Silicone sealant used this way is all the fastening I needed, the rest was pointless once the sealant come out the cupboard. It is also removable not permanent. Water proof and an insulating layer. I know it will be very reliable. It just looks ****

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So I painted it

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Now It looks like **** that's been painted. At least it is dark in there.


Has it been done before? My controller is going in the same enclosure.

agniusm said:

These are my diy batteries so far, left to right:
Panasonic NCR16850B 17.5AH 10S5P; A123 20AH 12S; A123 20AH 24S

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You guys make me jealous with those awesome 20ah packs! And from what I read you get them for $20 each from victpower right?

Agnius makes the best A123 kits in the world. I think you can get 20ah cells from OSN but they will be more expensive. Apparently Victpower is scraping the bottom of the recycle barrel.
otherDoc

I recently built a 12p14s pack for my wifes e-bike. I had the good fortune to obtain a box (~60) of brand new laptop batteries, so I cut up 28 of them and built a pack. I took pictures of the project and the results. Is this the place to post or is there a better thread?



Just a picture of the jig I made to help solder the cells into a string.

That's pretty sweet, I would love to see more pics of your project. They are even pink for your wife, I bet she loves that.... LOL