ebike batteries.... sorry

#1
this has likely been hashed before, but is it insane that i have priced out the equipment and the cells to make a 10cell 36v battery for only a hundred bucks more than buying a ready to go new one? this is inlcuding everything i can find that i might need to build the battery, i had some of the tools, like a soldering iron, but i am including a battery spot welder into the cost (actually a spot welder and a hot air soldering station, not for soldering, i just don't have a heat gun for dealing with a big chunk of shrink tube, a hot air soldiering station would do it and it has more uses for 20 bucks more). i've been playing with electronics since i was 15 and before that i was into building lowrider bikes, is it really as much of a no-brainer option as it seems to be to me? looks like it would cost me about 3-400 bucks to rebuild the battery in my bike with 3 more cells (the pack will fit them, but i will probably have to destroy them and hope i don't destroy the aluminum case, they glued the cells in) including buying a fresh 10 samsung cells along with the tools i don't have to make it. to buy a 36v battery that i can't put inside my frame would cost about 300 bucks. is it unusual that getting the tools to make batteries appears to be ultimately more economical than buying a battery? eventually i'm going to need another one, and the parts to make the battery itself are only about a hundred bucks.
 
#2
oh, and to make sure i know what parts i need in a battery i'll list what i have figured out blindly reasearching with no feedback. bms, cells, pure nickel strips, hot glue, lead wires, soldier. for a 36v 10s1p pack that would be about a hundred bucks, there is more take than give. (using samsung cells from amazon btw)
 

JoePah

Well-Known Member
#3
Good luck with your new hobby! There are a lot of new skills to learn, but worthwhile, esp when it comes to the spot welder..

Someone else on this site built his first pack with used laptop batteries as a learning tool.. that seems like a great idea.

you may want to get some ideas from the Endless Sphere website which caters to DIY builders.
 
#4
Good luck with your new hobby! There are a lot of new skills to learn, but worthwhile, esp when it comes to the spot welder..

Someone else on this site built his first pack with used laptop batteries as a learning tool.. that seems like a great idea.

you may want to get some ideas from the Endless Sphere website which caters to DIY builders.
you are more than likely correct, but i have a further question. are the shimano m355 factory modified for ebikes that is floating around a good (according to my local bike shop illegal to sell) idea or is there something better at a similar price? or is it really easy to modify a brake for an ebike? while the kos brakes on my current bike once properly adjusted scared the crap out of me enough to release the brakes and catch the handlebar in my ribs as i flew through the air and the bike stopped, that was just because i crunched the brakes entirely at full speed, scared the crap out of me, locked up more than i would expect from cheap brakes against a 51lb bike with 10lbs of bags and crap on it.

here are the brakes i am looking at: https://www.ebay.com/i/331976394152?chn=ps
 
#5
and if i'm going to build my first battery pack, i will use the proper tools. i could save a huge ammount of money by using one of my 24v ups batteries and a solenoid switch with an amperage cutoff (momentary breaker) switch and a couple copper probes. i will build my first battery the right way with the right equipment, because it really isn't that expensive compared to the cost of the battery if you buy it by itself, not to mention i need a custom battery because i intend to either put it in the battery case that came with this bike or i am going to build one into the area where that battery was, inside the bike. and having the equipment i can reuse the parts that i am pulling off of this bike and build another battery for my backup bike that can use the old hub motor from this bike and the old controller, or just build a battery for any ebike kit, bms units are cheap, batteries don't cost much either, the assembly is where batteries get expensive, and i'm not just willing but able to do that leg work.
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#6
by the way, the bags on the back are just bags. there are no batteries there. not even any holes for wires to pass through. its just a pannier bag.
this was an insurance picture, until i upgrade and get my backup bike setup with electric i cannot replace this bike, thus insurance.
 
#8
I did a double take when you said 10 cell 36V pack. With 18650 cells, that's a 10S-1P 2.5AH battery. It won't run much of a motor will it?

If I had a dead microwave for the transformer, I might buy the control circuit and make a spot welder, but I don't really want to. I've seen the youtube videos where guys zap nickel directly with a battery and a relay. I suppose it works, but I'm dubious about it being reproducible.

Still, why not. If you know how a BMS works plus the voltage limits on lithium, and make it safe, it should be a fun hobby. You might save money in the long run, but it's the setup and buying stuff that will get you.

It's like building kit bikes. I pay more postage for a motor than the importer pays for the whole ebike. Plus I still need the other parts.

My battery forays were hacking a 10S-2P into a 13S-2P to get 48V. Soldered the extra cells. Changed the BMS. DIdn't work well. Bad voltage sag. I also made a 3S-3P 12V battery. That worked better.
 
#9
I did a double take when you said 10 cell 36V pack. With 18650 cells, that's a 10S-1P 2.5AH battery. It won't run much of a motor will it?

If I had a dead microwave for the transformer, I might buy the control circuit and make a spot welder, but I don't really want to. I've seen the youtube videos where guys zap nickel directly with a battery and a relay. I suppose it works, but I'm dubious about it being reproducible.

Still, why not. If you know how a BMS works plus the voltage limits on lithium, and make it safe, it should be a fun hobby. You might save money in the long run, but it's the setup and buying stuff that will get you.

It's like building kit bikes. I pay more postage for a motor than the importer pays for the whole ebike. Plus I still need the other parts.

My battery forays were hacking a 10S-2P into a 13S-2P to get 48V. Soldered the extra cells. Changed the BMS. DIdn't work well. Bad voltage sag. I also made a 3S-3P 12V battery. That worked better.
you definitely got me thinking and your more than kinda right. i'm only throwing a 500w hub motor at it, and i don't need more than 45 mins to an hour on throttle alone out of it, i normally pedal. should be pretty close with 10s1p, but thinking about it i am going to abandon the battery casing that came with this bike, get rid of that and the mount point inside the frame for the battery to connect and i could fit a 10s2p battery no problem. i think i'd get enough out of a 10s1p for what i need, particularly considering that a further upgrade i intend to do eventually is adding an option to hook up an aux battery, but a 10s2p battery would be a little more comfortable, won't warm up as much i think. and i can even route the cable from battery to controller inside the frame without compromising the fold, one less cable running outside the bike.

EDIT oh, and the cells i'm looking at are samsung 30q cells, so it would be according to their spec sheet 3ah. they seem like the best bang for the buck quality cells i can get new. maybe some day i'll salvage cells, but for doing this the first time as i have said i intend to get the right equipment and do it close to the "right" way. so new cells for me.

oh, and i wish i could just modify my battery, adding 3 cells would technically do the trick for what i want to try, but they gunked the cells into the battery casing way too much for me to think i would be removing them without destroying the cells. its one of those aluminum tube batteries with plastic caps on the ends.
 
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#10
I was looking at the Xtreme scooter e-bikes in 2015. They didn't have your model then. The specs say it's 24V and uses a 7S LiFePO4. These are not the same cells as the 18650. Different voltage. Different size. You should get a nice boost in performance at 36V if it doesn't blow up.

Can your controller components can handle 36V? Probably. Best to check the capacitor ratings.

I have bikes with motors of similar power to yours. A 36V-4AH 10S-2P will get me 12-16 miles at 12-14 mph pedal assist, and there's not much assist left in the last 4 miles. I would estimate 8-12 miles with your proposed build, and it's going to shorten the life of the 30Q cells. I would suggest a 10S-2P with those 30Q's and put it in the saddlebags. Switch from the frame battery to the bag battery with connectors/cable.
 
#11
my controller likely can't handle 36v, i intend to replace it and the rear hub motor. it is a standard sized controller that is in the frame right under the seat, can fit pretty much any controller i want in there. on pedal assist alone i get about 14-15mph although my bike computer could be a hair off on speed, they are never the most accurate things in the world. i can do that for over an hour, i can get about around 40 minutes on throttle alone, and with throttle and pedaling 20mph doesn't take much effort. and doing some measuring i can fit 10s-2p inside the frame where the current battery is, just wont have a nice battery pack anymore =P. the only really nice thing about the bike is the frame, the rest of the parts are either budget bicycle parts (think 250-350 dollar walmart bike) and a cheap ebike kit just like you can find on amazon. the battery pack i consider part of the frame though because it is made specifically for the frame.

(not likely to do the upgrade till next year, but when i do i intend to take the old controller and hub motor and battery if it is still working and throw it on my old columba 26 folding bike)
 
#12
I was looking at the Xtreme scooter e-bikes in 2015. They didn't have your model then. The specs say it's 24V and uses a 7S LiFePO4. These are not the same cells as the 18650. Different voltage. Different size. You should get a nice boost in performance at 36V if it doesn't blow up.

Can your controller components can handle 36V? Probably. Best to check the capacitor ratings.

I have bikes with motors of similar power to yours. A 36V-4AH 10S-2P will get me 12-16 miles at 12-14 mph pedal assist, and there's not much assist left in the last 4 miles. I would estimate 8-12 miles with your proposed build, and it's going to shorten the life of the 30Q cells. I would suggest a 10S-2P with those 30Q's and put it in the saddlebags. Switch from the frame battery to the bag battery with connectors/cable.
oh, and regardless of what the webite might say i've had the battery pack open, there be 18650 cells in there.
 
#13
Soldering is a bad idea. Hopefully you found one of the two welders on endless-sphere. Next I wouldn’t bother with anything less than 10s 3p. Less than ep cells will be a saggy battery with any decent output controller. The Sunnko welders can be a coin toss, and the wrong source of cells could saddle you with fake rewrap cells. I have several welders, and they work well. Although one is about to be shipped back to Germany for an important update/fix. Get Micah Toll’s battery building book on Amazon. It’ll save the day. It appears from reading posts you still have some ground to cover. Good luck, and enjoy the adventure!
 
#14
Soldering is a bad idea. Hopefully you found one of the two welders on endless-sphere. Next I wouldn’t bother with anything less than 10s 3p. Less than ep cells will be a saggy battery with any decent output controller. The Sunnko welders can be a coin toss, and the wrong source of cells could saddle you with fake rewrap cells. I have several welders, and they work well. Although one is about to be shipped back to Germany for an important update/fix. Get Micah Toll’s battery building book on Amazon. It’ll save the day. It appears from reading posts you still have some ground to cover. Good luck, and enjoy the adventure!
i'm not getting a decent controller, just like what came with the bike i'm gonna throw a cheap ebike kit at it. keep in mind that i'm not expecting to make some sort of high performance thing, and my commute even on this bike is about ten minutes both ways. this is just the start of a hobby and getting the basics set up.
i also don't intend to soldier the batteries, a sunkko spot welder with decent opinions from youtube users is only about 150 bucks on amazon, and it is a tool that i intend to use more, thus why i am planning to get set up to make batteries instead of just buying a battery pack. just pricing from amazon with all the parts i can think of to make a 10s2p battery is about 430 bucks, i'm adding 200 on top of that in my mind just for unknowns, and the battery itself is only around 150-190 of that. to buy the battery i am making new it is about 350 to 400, and i'm going to want more of them over time because: hobby. so it is allot cheaper for me to just get set up to make batteries the proper way.

EDIT: on the soldiering i was just talking about if i could get the cells out of my battery without destroying them i would be willing to risk soldiering three more on instead of having all the equipment to actually make a battery. either way i still intend to get the equipment, because i am still going to need MORE battery packs, and buying them instead of making them is dumb unless you need the convenience from everything i have managed to figure out. and once again: hobby. computers have been my hobby for decades, but prices on graphics cards are completely untenable right now so i gotta diversify. i don't make much but i don't spend much either, leaves me with a bit of disposable income that tends to go into whatever hobby i'm messing with at the time.

also, on the sunkko welders, i've seen the inside, i could rebuild the whole thing if i needed to, it isn't complicated. once again: hobby. every problem i run into is just more fun for me to figure out. oh, and the biggest complaint on the sunkko welders no matter where you go are people blowing their breakers because they think they can run them on a 15 amp breaker. long story short: they can't.

also i'm gonna be buying every part i can source on amazon, while you can end up with bogus crap on amazon for sure, you can also ruin a seller who sells that bogus crap on amazon pretty easily. means the bogus crap isn't that common unless you intentionally look for it. i'm not gonna thermally test the 30qs i get, i'm just gonna check their voltages, put the battery together with the bms, and let the bms do it's job. next set of tools will allow for real cell testing.

battery building is just a skill i've never needed to put in my back pocket, so while i know how to do it, i haven't done it. so i don't have the "skill" just the knowledge of how.
the question in this thread was if i was the only person who noticed that it is WAY cheaper in the long run to set up to properly build batteries than to just buy them, like exponentially cheaper, like so cheap that the batteries have to be called overpriced.
and my pricing is a hair different than the original post because i went ahead and added 10 more 18650s, this is all preliminary research so nothing is set in stone, just like i started researching ebikes about this time last year, and ultimately decided to go with what looked like a reasonable but cheap fully built ebike to start, i am now thinking over things on how i am going to turn that frame (forget about the bike) into what i actually want, i don't expect that to be a thing for a couple years, because while i have a little disposable income, it is still just a little, but my computer has a direct lineage to the year 2000 and a used 486 and is now pretty beast other than the gpu, that is called a hobby.
 
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#15
I’ve had Sunnko welders and sold them as parts to fellas that couldn’t get parts to repair theirs. Consider the Arduino welders. Sounds like you could build your own and have a welder you CAN repair and get parts for.
I started with unused recycled batteries and graduated to higher grade cells. The two welder kits on endless_sphere are the nicest Ive used.

Where will you get batteries? Also a reliable fella on ES with some 29e cells for $2.49. A great reliable cell!

Why 30q for low power? I’d go the 29e or even 26f on ebay.

There’s another resource thread, all my parts came from reliable well known sources on aliexpress. The also a great seller on ebay. Supower.
 
#16
I’ve had Sunnko welders and sold them as parts to fellas that couldn’t get parts to repair theirs. Consider the Arduino welders. Sounds like you could build your own and have a welder you CAN repair and get parts for.
I started with unused recycled batteries and graduated to higher grade cells. The two welder kits on endless_sphere are the nicest Ive used.

Where will you get batteries? Also a reliable fella on ES with some 29e cells for $2.49. A great reliable cell!

Why 30q for low power? I’d go the 29e or even 26f on ebay.

There’s another resource thread, all my parts came from reliable well known sources on aliexpress. The also a great seller on ebay. Supower.
battery choice is just a function of amazon availability, i'm not going too far to source parts and by the time i act most everything i have in mind right now will probably change. i'm using amazon to get estimates on how much this is gonna cost so that my ideas don't scale me over my head. i'll definitely have to check out those kits, been wanting to play with arduino for years anyway just never had a good excuse. as for recycled batteries, if i could go to the samsung website and just order them direct i'd do that (EDIT: you kinda can, ridiculous price). i'll worry about recycled batteries after i am comfortable and can do proper thermal testing. there are some more powerful batteries available on amazon, but at premium prices, and i don't really need much power in the first place. a 500w hub motor isn't THAT greedy, especially a cheap one from a cheap ebike kit with a cheap controller.
 

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