Please give this newbie battery examples and Pictures

[CONSIDERABLE SHOUTING]

Hey dudes, I'm about to try building my first pack but, I'm spooked and it's holding me up.

I'm pretty set on some kind of 48 volt (13s) pack- or a 52 (14s) that I charge with a switched-mode 48-volt battery charger to increase it's lifespan (I think that'll work?). I have all my measurements, but I don't know what I should make my pack out of, what I should protect it with other than heat shrink wrap, or if I'm freaking out simply because I'm spooked and this is a big new thing for me. I'm building it all out of salvaged 18650s from laptop and dyson batteries so I'm not worried at all about making it a little janky or cheap looking.

Could you dudes do me a solid, and post pics of any and all battery packs you like that you think I should try to ape? Like what I should Kapton tape the hell out of, or heat shrink, or battery boxes made from what material? Hell, even if you think I should go 36 volts first just to not be so freaked out? I'd really appreciate it.

 

[999zip999]

Grasshopper you'll make a battery pack for the controller and motor you want to use how fast you want to go and how far. Do you have any hills what type of terrain how fast do you want to go ? use laptop cells can be a little sketchy. You want build a battery pack out of used laptop cells as they're meant for a laptop that sitting on your kitchen table and not something to push 250 lbs. Some battery packs can only product 15- 20amps. So 50 volts at 20amps is 1,000 watt. 50volts at 40amps ( The controller ) is 2,000 watts. How many watts you need ?

 

[Jordan325ic]

You can't just throw a bunch of used 18650 cells together to make a safe battery, they need to be carefully grouped by capacity and internal resistance. If you're nervous about battery building you should also be very nervous about using used cells.

I would watch some tutorials. Ebikeschool.com has many good battery-building videos on youtube.

 

[CONSIDERABLE SHOUTING]

Grasshopper you'll make a battery pack for the controller and motor you want to use how fast you want to go and how far. Do you have any hills what type of terrain how fast do you want to go ? use laptop cells can be a little sketchy. You want build a battery pack out of used laptop cells as they're meant for a laptop that sitting on your kitchen table and not something to push 250 lbs. Some battery packs can only product 15- 20amps. So 50 volts at 20amps is 1,000 watt. 50volts at 40amps ( The controller ) is 2,000 watts. How many watts you need ?

It'll be built to lean around those problems of discharge; it'll all be ATL and samsung cells tested through a Opus BT charger, with the worst difference so far being ~50 milliohms (assuming their discharge profiles are similar, I haven't yet found one for the ATL cells even though I have so many). I think I have enough that I could go as far as a 13s5p in size. I only realistically need 20 miles of range, but more is more. Paths to school and one supermarket is flat, rest is hills. Motor is a 350w bafang that at 48v can pull a max of ~621 watts per my math last time. It'll be a front wheel drive.

You can't just throw a bunch of used 18650 cells together to make a safe battery, they need to be carefully grouped by capacity and internal resistance. If you're nervous about battery building you should also be very nervous about using used cells.

I would watch some tutorials. Ebikeschool.com has many good battery-building videos on youtube.

I have, have tested, and I'm still spooked 8)
Still need pictures and examples of what people do, and what has worked for them and why!

 

[999zip999]

I'm assuming that you're building a mountain bike type thing or a cruiser because that matters as you need space for a battery a lot of full suspension frames don't have any space for a battery. Got to plan it out.

 

[999zip999]

Dr. Angel has a lot of battery building like you doing
.https://endless-sphere.com/forums/viewtopic.php?f=14&t=26383#p381104
Read this. It's has a year of reading.

 

[CONSIDERABLE SHOUTING]

Dr. Angel has a lot of battery building like you doing
.https://endless-sphere.com/forums/viewtopic.php?f=14&t=26383#p381104
Read this. It's has a year of reading.

I have been, actually! It's a lot to digest. My only complaint is that he doesn't have a segment on what he used for enclosures.

 

[DogDipstick]

I will post pics of EV cell builds I have done. I do get alot of feedback from friends as to what is out there and what to buy ( one guy putting down 600A on Battery Clearing house Mercedes cells same way I built these). Built six or seven full ebike packs. Happy customers. Of course i use all recycled EV cells and rip em down, datalog, and build. Great pricing and longevity. I do recommend.

I will post some pics then when I get the garage warmed back up.

 

[Hillhater]

Dr. Angel has a lot of battery building like you doing
.https://endless-sphere.com/forums/viewtopic.php?f=14&t=26383#p381104
Read this. It's has a year of reading.

I have been, actually! It's a lot to digest. My only complaint is that he doesn't have a segment on what he used for enclosures.

I recall him using a variety of enclosures...the original ezip pack cases, Rihno cases, etc..
But i thought you were hooked on Barncats “dry assembly”. pack system ?
Thet would be advisable for use with “recycled” cells, which may need frequent attention.
PS .. that 50 mohm variation in cell IR is not good !

 

[999zip999]

Ok you want pictures I built this 20s 1p 8ah $140 battery.
Just Bulk charge never out of balance.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=106666#p1562110
It's a big somewhat heavy weird shaped box for a bicycle I thinking 14s1p might be more manageable. So that's a learning experience. Size yes I made a cardboard box as you should to.

 

[docw009]

For an ebike battery. I would say 50 milli-ohms max for series resistance.

Looks like the new regime in DIY battery building these days is cell holders. No more gluing the cells together. There's only the glue and tow films of shrink wrap separating the cases, and if they are at different potentials, you don't want them in contact. Builders are also using insulator rings around the positive end, even with cell holders. If you're not using a cell holder, put that green paper between the cans at different potentials.

After building a couple of shrink wrapped blocks. I re-celled some old batteries that I had. I thought that was the better approach, to have a battery in a hard case that fit in a cradle.

Accordingly, I bought a Hailong 1 case from China, 40 bucks. Stuffed it.

 

[999zip999]

doc so 14s4p what cells and ampage do you use it at ? Yea real world use.

 

[DogDipstick]

For an ebike battery. I would say 50 milli-ohms max for series resistance.

Lol. I kinda disagree. Last one I built was 20milliohms. 1mOh/group.
The one before that was 10 milliohms. Measured, 72v, 20s, nominal battery. 0.0005 Ohm per group. 2p, 20s, 30Ah, of 1mOh cells.

50 is ok... I have seen worse... but you can feel the difference from a 50mOh to a 25mOh. Definitely dont go over 60moh. Pack will sag bad under typical heavy load.

Highest IR cell I use is 1.5mOh on a bad day, Lowest is 0.8mOh-1mOh. A 18650 is.. 20-40mOh for a good one? Yes, the resistance drops when you parralel them.. but 4p of 30mOh cells is... still 7.5mOh, per group..
First one I built hovered around 24-40mOh. Depending on the temp that day. I still ride it. but yea the pack should be measured if you want to know what the health of the pack is.

doc so 14s4p what cells and ampage do you use it at ? Yea real world use.

Yeah if the total load is in the range of under 50A.. Sure Ok. That would still make an ok low speed ebike pack.

I wanna hit 400A pluss though. Lol. I have reached 280A out, maxed out that controller. Mmmm cheap recycled power.

 

[spinningmagnets]

I assume that the Dyson cells are for a cordless vacuum? If so they "might be" high-amp cells.

As to the laptop computer cells, they are most certainly low-amp cells that are designed for long run-time, and lowest production price.

https://www.electricbike.com/introduction-battery-design-1/

 

[docw009]

For an ebike battery. I would say 50 milli-ohms max for series resistance.

Lol. I kinda disagree. Last one I built was 20milliohms. 1mOh/group.
The one before that was 10 milliohms. Measured, 72v, 20s, nominal battery. 0.0005 Ohm per group. 2p, 20s, 30Ah, of 1mOh cells.

I was thinking per cell. So .050 ohm per cell is .025 per cell in a 2P. The corresponding 10S-2P will show .25 ohms and drop 2,5V at 10 A. I've got several old 10S-2P's now dropping 10V at 10A. Fully charged packs are shutting off with throttle. That means about .200 ohm IR per cell. I guess I will retire those packs or put them in parallel with something.

 

[DogDipstick]

I was thinking per cell.

Oh yeah... Ok. I thought that was the whole pack measured...
To get the same power, out, and sag, voltage drop, as one of my Chevy cells... from 50mOh 18650 cells.... you would need 50p to get the the IR of one of the Chevy cell @ 1Moh. 50 cells in parallel.
Or a 25p of 25mOh = 1mOh
50p of ( 50mOh ea. 18650) = 1 Chevy cell ( 1mOh each) ( power density, the 18650 would hold alot more energy density for the volume though probably). I love EV cells. They go hard. You wouldnt even notice a 10A discharge sag. But the volume is so much. Even Zips SPIM08HP cell pack is like 3-4mOh per group max probably.

The advantage to be had i cylindrical cells is volume management, ( any shape) and energy density IMO. Dont get me wrong, I own a K-Welder and do use it. They have a place. It is handy to have the building system. If I had the money I would be building custom 20p 18650 packs for sure with copper / nickel sammywich.

 

[docw009]

doc so 14s4p what cells and ampage do you use it at ? Yea real world use.

The purple cells are old Samsung 30Q, 3AH, 10A, So it should be a nice 48V12AH battery if the cells are still good after 4 years. I bought 100 at $1 each from Battery Clearing House.Advertised as never used, but old. Who knows how old. I will be testing this battery in the Spring.

The orange cells are new Lishen 2170SF, rated at 4.5AH and 13.5A, This makes for a 48V13.5AH. I'm getting 10-11AH, and I'm OK with that, They were around $4/cell.

I have two other batteries built over the winter that also have not been used yet. One is a 10S-2P pack using new Lishen 21700 5AH 9.6AH cells, I put them inside an old UPP 10S-3P 18650 bottle battery case. I hope to see 7-8AH out of it,Tje old pack was running down at 4.5AH. The last battery is a 36V 9.6AH 10S-3P using inexpensive EVE 33V cells, which are 3.2Ah 10A. Those cells were $2.50 each.

I've got a bunch of used 18650's still, including Molicell INR18650A, 2500mah and 20A never cycled. LG MH1, 10A and testing out around 3.2AH, probably with a summer's worth of use in a rental fleet, more used Panasonic NCR18650BD' 10A cells also testing out at 3100mah. I won't mix them, but there's enough of each to build a 10-12AH battery,

 

[Hillhater]

For an ebike battery. I would say 50 milli-ohms max for series resistance.

Lol. I kinda disagree. Last one I built was 20milliohms. 1mOh/group.
The one before that was 10 milliohms. Measured, 72v, 20s, nominal battery. 0.0005 Ohm per group. 2p, 20s, 30Ah, of 1mOh cells.

50 is ok... I have seen worse... but you can feel the difference from a 50mOh to a 25mOh. Definitely dont go over 60moh. Pack will sag bad under typical heavy load................

DD.. no disrespect, but you have miss interpreted the OP who is refering to the difference of 50mohm in IR BETWEEN 2 tested 18650 cells.....

ATL and samsung cells tested through a Opus BT charger, with the worst difference so far being ~50 milliohms

.....and by comparing your packs using high capacity cells, just adds to the confusion of what to expect from the OPs build.

 

[DogDipstick]

DD..

Oh I understand the statement now. I really dont trust those opus. I am here cause he did ask in a different thread about the big cells and how I built them, and I wanted to post pics of copper plates and rivet style... ... but I think I follow... I am pretty sure Mr. SHOUTING knows the difference from the two very different types of built batteries.

Thanks for clarifying for me. Still, I think 50 mOh is ridiculous difference in cell IR? I aim for less than 10% difference in IR max, cell to cell in any group, or string. That little dis charger.. the 18650 Opus. Three Rs. Reliability, reproducibility, and repeatability are the three foundations to battery testing. If you get a fluke measurement, test it 2x again.

 

[CONSIDERABLE SHOUTING]

Yep, which is why I use the Opus's internal resistance tester 3-5 times per cell and take the average. Even in some of these battery packs I'll get brand-new cells testing 60-80 Milliohms and one that's ~150.

Did a count today and in-total, I have around ~111 of these blue cells and ~36 of the Samsungs. The Samsungs are not worth it- many have internal resistances of over 150Mohm, so their best-case use is likely going to be something low power from what I understand. I think I have enough of the blues to overcome their low-power use, however the bike it'll go on has no space for a standard pack in between the frame rails- which is part of the reason I started the thread. I COULD do something like this aluminum enclosure from ebay underneath or on top, but I suppose it all comes down to options and best-use case.

https://tinyurl.com/4t2u24y4
(Ebay link)

I'm still not sure on the manufacturer for the blue cells. Secondlife Storage says they MIGHT be ATLs, but that's just teh closest I can find.

I assume that the Dyson cells are for a cordless vacuum? If so they "might be" high-amp cells.

As to the laptop computer cells, they are most certainly low-amp cells that are designed for long run-time, and lowest production price.

I can tear a few open, but they have all been random cells so far.

 

[gobi]

Think heat and conduction/radiation to cool the pack, don't wrap it like a newborn baby,
Watch youtube videos of major brand packs being opened.

 

[CONSIDERABLE SHOUTING]

Discovered the producer of my pack is the "A&S power" company and got more details on the cell; they rate the cells for 1C of discharge at 2 amps, so even a small 3P or 4P pack should have no sag powering the small motor and controller I have. The controllers only go to 13 amps; practically worthless to most, but I got them for literal pennies :lol: Assuming they work, of course.

Think heat and conduction/radiation to cool the pack, don't wrap it like a newborn baby,
Watch youtube videos of major brand packs being opened.

HAHA, MY LITHIUM CHILD
Most seem to just do plastic cell holders and shrinkwrap.

 

[Hillhater]

Discovered the producer of my pack is the "A&S power" company and got more details on the cell; they rate the cells for 1C of discharge at 2 amps, so even a small 3P or 4P pack should have no sag powering the small motor and controller I have.

Prepare yourself for dissapointment !
A typical “laptop” 2ah cell will sag 0.1-0.15v at 1C ( 2.0 amp discharge)
So a 13s ,4p, 48v pack will sag 1.3v -2.0v ..@1C ( 8amps discharge)
And at 50% SOC it will be operating 9+v down from its initial full charge voltage !