build your own battery box, do they exsist?

jimmyhackers

jimmyhackers

10 kW
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May 11, 2015
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im going to finally be stepping upto to lithium tech, albeit on a budget.

and therin lies the reason for this questioning.

i cant afford a new lithium battery so im going to be using old laptop batteries to make one. some of which may fail and require replacing.
ive made my spot welder now. but im wondering if i should use it. with a battery all welded together it would make replacing single a dead cell a lot more hassle. and also make noticing one that has gone the dodo ways pretty hard.

so do they make a box for a load of 18650 cells that turns into a 48v or possinbly a 60v battery when you close the lid?
failing that i think im gonna make one.

link me up if they do exsist.

thanks in advance
jim
 
looks like im going custom then :S
 
There are also thread like that from Leamcorp and at least a couple others about packs built without soldering or welding the cells together.

There's posts about the newer Zero Motorcycle packs that are also made that way.
 
nice to hear zero have finally cottoned on...either that or they're nice to their customers. (dont spose they sell just the boxes?)

unlike some forklift companies who have been doing sneaky things for ages. many forklift rental companies will charge your for a full battery replacement when really they only need to replace a cell or two.

and the irony/cheek about it is in their yard they more than likely have numerous spare cells already lying about from other customers theyve ripped off.

basically if you had a fleet of the same forklifts up for rent and one spare battery. every time a rented forklift battery goes youd find the cell thats gone wrong, replace it, clean the rest of the battery so it looks new, charge the customer for a whole new battery.

very underhand but ive had numerous forklift technicians admit it to me. even to the point where they will ask customers about their maintainace to test the "water" and see if the customers clueless enough about it all to be duped.

lets hope electric car companies dont go down the route of apples... "is it broke? do you need an upgrade...yes?....well why not just buy a new one?"

i dread to think how many "dead" batteries have been binned due to a single "unreplacable" cell.

once i get my cells i can work to their dimension to make my box....then in the future when i can afford or they start making cheaper better cells its a 5minute job to upgrade my battery instead of a days work of building a battery pack back up.
 
ive been ebaying.....

and ive come to the conclusion......i can buy some parts for my design from there.

so far i think id need about 50x 4x18650 (in parallel) holders which would cost about 50quid.

mount two in parallel per cell on a board to make 1s8p "cells". which could slide into a box. depending on size i may go fo 1s12p.

and i think im gonna go for 60v so id need a 16s so itd end up being a 16s8p.

however it ends up....16s8p (128 individual cells) or 16s12p(192!!individual cells). im probably going to go for as big as i can fit (with scope for future in mind). the lovely thing about this all is.... if i dont have enough cells to fill it fully i can still use the same box just at a reduce Ah capacity.

going further i figure i could build and test each cell individually. meaning theres far more scope for mixing and matching (mismatched) cells.
i.e. i could run one cell (full) with 8 "not great ah" singular cells with the other full of only 5 "good ah" singular cells aslong as thier overall capacities were similar.

ive bought 20x 10.8v lio-ion 4200mah 44wh laptop batteries (for under 80 quid!!) and they should be all the same make/model. i figure they're in a 3s2p configuration meaning 6x 3.6v 2100mah li-ion cells per battery so i should have 120 cells to play with.
thinking about that... 2100mah a cell might mean they are 14450 size and not 18650. i wont know untill i dissasemble

hopefully they will all be of a similar state (im expecting/hoping for around 2000mah per cell)
anything above 1500 should be usable, that number might drop when i see how good of a purchase ive made : )

http://www.ebay.co.uk/itm/291455509918?_trksid=p2060353.m1438.l2649&var=590546076510&ssPageName=STRK%3AMEBIDX%3AIT heres the kinda things im gonna buy, 14450 size cells would mean i could use aa size battery boxes and i have seen a few 10 in parrallel ones that would simplify the build even more so
 
batteries arrived. 20 laptops making for 120x 18650 cells :D

all of 3 hours to strip em down and do some preliminary tests, here's a pic of em all out.


here they are sorted into "groups"


50x cells at 3.5v or above (should be good), 32x at 1v-2.5v (possibly recoverable), an 38x at 0v (most likely unrecoverable)
you can see in the second picture i removed the "low" and "no" volatge cells from each group of six so you kindof get an idea asto how each laptop battery "died".

was interesting to see how/why a laptop battery had "failed" irronically it didnt seem a cell problem but the small BMS chips on each battery that had failed/malfunctioned and it was that that had destroyed/random particular cells.
i.e. in some batteries i found both 0v and 3.9v cells and a bms board with that distinctively "burnt pcb" smell.

all i need now it to make a box for it all :S
still finding it hard to find a 8-10x 18650 parrallel battery box/holder. can only find 4x 18650 which isnt the end of the world. just means twice as much work.
 
I've been chasing my tail looking for the same thing for almost a year. I am convinced a kit that would allow a home build without welding or soldering would be a HUGE hit. Sadly the one Chinese maker never responds and the battery boxes introduced by manufacturers have never come to fruition, at least not for sale.

That said, I've experimented with laptop batts too. Only to find they just don't hold up. But it sure is fun and a great learning curve. Have fun. I look forward to reading about what you come up with.

Best,

Tom
 
thanks for the interest. if you have simple woodworking skills and a router the box should be fairly simple to construct.

i guess as you said youve been experimenting you'd get the "wiring up" side of the box.

bit worrying hearing that about laptop batts not holding up. ive got 78 of a possible 120 : S
how did yours not "Hold up"??

which leads me on nicely to this evening adventures, at my friends who runs/owns an e-cig shop.

short of it is my cells are 2.2ah capacity at a 1 - 1.5ishC dischare rate. meaning if i put 8 in parallel i get 17-26amps continuous. which is what i need.

he rubbed in the fact the cells he sells are rated at 25c and 2.9 to 3.5 ah and cost around 2 - 3pounds each (depending). i got 120 for 76 quid making for 63p a cell. i told him to give me a call when he can match that kinda price.

and 120!!! i hear you say, but i said loads were at 0v....... ive sucesfully revived all cells using "sneaky" methods.
im yet to fully amphour test them all but i thought id get started at the worse end with a cell that i found at 0v.
even ones that were completely zero volts have been revived and AH tested on my imax with 2000ish mah put in..... and around 2000mah coming out.

i did feel a bit gutted when i tested all 120 and some were "dead" meaning i thought i had only 50ish cells.
but i looks like i can use em all.

just waiting on china/ebay now for the cell holders than i can get to some woodworking.
 
You're on the path of endless-cubed, the nether regions where spherical enjoyment distorts to an unrecognisable shape. Mind you, I'm all for self-punishment - its the reason I put on my camel-hair shirt in the morning. Leave a box of chocolate out in the open long-enough and even Mr. Gump will admit it becomes nothing but a festering mass of maggots and melt.
 
and i thought i said some wierd things after smoking cannabis. :D

not quite sure if that was a comment, compliment or an insult? text always leaves out the subtleties of sarcasm.

endless cubed and spherical made me think its a compliment like "your one of the endless spherites now" and i got all excited/happy
like hey "your one of us"

but the comparing my work as self punishing then the like a box of melted choclate quote.....is where the "compliment feeling" went a bit south.
maybe it cuz im british, maybe im wierd, maybe quoting awesome films is your mantra.
many people take my mantra as "offensive" when it not it just mean be "individual"

not suprising when its. "everyone pisses on the floor, be a hero! shit on the ceiling"

either way....please elborate what your message meant. im confused : S
 
ah i seee.... yep definately wandering the desert currently.
 
thought id do a little update on my battery box.

its built but not wired or "lidded"

heres a few pics



waiting on some "approproate amperage" leads and connectors.
once they arrive i can see what size they take up on the side of the battery.

then i can get round to the lid. which should hold all the packs inplace then also cover the external plugs and terminals.

ended up on a 6cell8pack 24ish volts battery design. means my imax chargers are still usable. i have to build another box to get the minimum 48v for my ebike. but im going to end up building 2 more becasue i really want 60 volts plus.

an estimated weight of the single box full should be under 4kg. considering i have 5x 12v 20ah SLA's (7kgs each) on my bike atm, i should be shedding close to 23kgs with 3 of my boxes.
 
I'm really impressed your thing is rising pretty fast! :eek:

Sincerely one of the best neat / cost saver / easy to build unwelded pack box I've ever seen.

The energy density still looking good, for the chance to super-fast changing a cell it is really priceless. I think I would do a similar approach if I had to build a pack with laptop / used / different branded cells.

I think you finally tested the inner metal (steel / nickel) conductors and worked right under 4A. So what wiring gauge you will finally install in each 1s4p box?

Did you think about install a voltmeter on each 21.6V box, or do you want to install where the 3 21.6V box are serialed?

And, what ideas do you have when it will come time for charging? how is the best reliable way do you think it would work?

I think I made too much questions but this project really thrills me up! super-suscribed :lol:
 
thanks for the interest.

im going for 14awg silicone wire. its rated to 55amps. well above what i need

i think ill use deans connectors, nice and compact with high amp capability, hopefully i can find an appropriately sized terminal block so the deans connectors will simply screw in rather than needing soldering.

then i just get an "extended" balence lead extender cable thingy to wire up its own balence connector.
with a standard balence lead i can use my rc battery checkers as a tiny portable meter.

as for amp hours its not bad but its not great. a single bank provides around 12,000 to 16,000mah. some cells are at a reduced capacity. so roughly 1500mah to 2000mah per 18650 cell. im wading through a sea of 240 individual 18650 cells trying to cobble enough really good cells to make my pack "even".

unsure of max discharge rate...but i did temporarily wire up one "good cell" in series to my bike to add an extra "3.7v"
cells all stayed cool.bike was nice and punchy as always, same ride time. when i got home the cell was at 3.72v so it could of gone for longer. took in about 10amp hours on the charge. so looks good for bike saftey/compatibility.
my bike is essentially a 20=24amp max to 10amp continuous power drain.

my suposedly "20ah" SLA give up the ghost at 13ish amphours depletion. so even if i do end up with a 12ah battery itll still equal my old lead acids performance wise.

cant wait till i get my bits then. once i have one battery finished. i can exchange two lead acid batterys at 14kgs for one lithium battery pack at 4kgs and start seeing the miracle of weight loss :)
 
heres another pic of all three boxes.



every cell is interchangeable between every box.

all fit snuggly with no wobble. so far so good.
 
I love the concept so far, but I wanted to bring up an important question: Are you splitting the total required current between enough parallel strings so that you're not going to exceed the current capacity of those battery holders? I bought some of the holders too, recently, and found that there really isn't much of a rating for the current you can put through them. I know from experience the AA, AAA, etc battery holders do not do well under high current loads... meaning that they melt. Just something I thought you should consider if you haven't already. I haven't read all the details in your thread so forgive me if you've already addressed this.

It is a very interesting arrangement!
 
thanks for the interest. during soldering the wires to the cells the tabs in the holders themselves got rather hot. strangely enough the plastic held up suprisingly well....

i figure the soldering joints ive done will melt before the plastic does. but at 20amps max draw...i doubt i will do either

ive also soldered/strung a peice of thickish coper wire across each side of each cell. soldered to each tab. just incase the tabs themselves wernt ampy enough.



been soldering all day. 48joints of 14awg to deans conectors......im high on solderflux, i have asbestos hands, i "wasted" 2hours of my life :( ...

but i have one battery ready, currently being tested. so far so good. :)
wiring could of been a little neater but ill just claim i was going for the "handcrafted" look

only gotta do it twice more and them put a lid/cover on each one. : S

my friend also mentioned a beehiveesque look.....my surnames hackwood...."Hackwoods Hive Battery" sound good?
 
disaster strikes....

i put all 3 batteries on my bike for a test... went round my block. and the tabs got hot enough to melt the plastic holders.

but all is not lost....

it was only the intersecting part of the tab closest to the edge where the output wires were attached on each cell that got hot. where the current was at it highest.

so ive begun adding copper wire to each of the tabs to beef up their traces.

i tried using my soldering iron and it didnt cut the mustard. so i tried my hho torch and the solders turned out lovely but i melted the hell out of the plastics even more so in doing it, so....

my friend has a proper solder flow station and a proper soldering iron so ill be seeing if that will do what i need it to.

on my short trip around the block....the bike performed ok but worryingly not as well as 5x12v 20ah lead acids.
on full throttle my 3 stage meter dropped to one light. top speed was reduced also by 5ish mph.
bike was pleasantly a lot lighter though.

my hope is this limited performance was due to the restriction in the battery holders. i.e the current was limited/wasted by heating up the tabs interconnectors. so when the tab interconnectors are beefed up (288 solders later :s ).....this restriction wont be there and i should get full power from my batteries to my controller/motor.
 
HUZZAH!!!

2 minor burns and 288 solders later she works. no hot things or melty stuff.

lights stayed at a full three bar and torque/acceleration is through the roof compared to my lead acids and this new batteries prior "melty" performance.
top speed seems the same however.

managed a full 2 and a half laps around my block.....and got a flat tyre. sods law.

so extended testing is off untill i get a new inner tube.

probably best i did get the flat.....its 2am and i hadnt wired up my lights to the new battery system yet
 
finally it was dry so i was able to take my bike out this evening with my new batteries for an extended run.

thing went flawlessly. an hour and a half of riding on my usual route and every cell when i got back home was at 3.78 to 3.80 v's. that means theres more in them. so ive extened my range over lead acids.

torque is definately up. felt a lot more wooshy under acceleration. it pulled a lot stronger with higher speeds up hills (even very steep ones). you can feel the punch of the motor when you twist the throttle, its like i have more throttle controlability with this new torque.
i figure this isnt just the weight loss alone, the lithiums can really give more amps.

at a few points under acceleration the front end felt very "light" almost like it wanted to wheelie :)

i was worried the bumps in the road etc might wobble out a cell or two from the holders.....and this worry was double on the one battery that is mounted upside down (my bad). however those holders have a real firm grip and nothing budged an inch.

with the weight loss, my suspension has definately improoved. feels a lot smoother to ride. i little bonus i didnt expect.

all in all as you may of guessed....im very happy.

if someone ripps my idea off and mass produces a neater, smaller, plastic waterproof varient on my design and makes loads of money from it.....
please send me some boxes for free.
 
Im thinking of jamming my lipo RC packs in one of these

http://www.jaycar.com.au/Enclosures-%26-Panel-Hardware/Metal-Boxes/Diecast/Sealed-Diecast-Aluminum-Enclosure---222-x-146-x-55mm/p/HB5050

Good protection for a crash, good protection if they catch fire, Ill pop vent holes so its not a bomb :) Long as i have the holes big enough it should vent worst case. Thoughts ? Id rather have the holes pointing against another bit of metal, that way when it vents it hits a plate first not my nuts or leg.

Possibly Id like to slip 4 temp monitors in between the four packs and have these feed back to an alarm of sorts or a relay, or pack voltage display up on the bars.

I have a heap of flat temp monitors from old laptop battery packs, these would be perfect. Actually the old laptop packs have a thermo switchs in them :) i tested it with a lighter :) works a treat, this linked to a relay could work as a nice safety switch, however they had to get fairly hot before they ticked, maybe 60c . mmm ill test further
 
Wouldn't these be the easiest and safest solution?
https://endless-sphere.com/forums/viewtopic.php?f=31&t=71951
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