Scavenging one nearly new battery to make another?

Batteries, Chargers, and Battery Management Systems.
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mammonista   10 W

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Scavenging one nearly new battery to make another?

Post by mammonista » Mar 15 2019 9:37am

Okay so this is probably a dumb idea and anyone who tells me that?... well, thanks in advance for the warning! :-) :thumb: :thumb: :thumb:
A couple of years ago when I started down the e-bike path for some dumb reason I bought a couple of 'monster' 20ah 48v LiFe battery packs from China. I had a couple of fat tire bikes I was building for my gf and myself. Her bike is a front hub motor Mongoose and mine is a Cyclone 3k mid-drive powered Gravity Monster. After a few, infrequent trips on the coastal dunes here in Oregon I've pretty much got most of the bugs worked out of my mid-drive Gravity. With a 3-speed IGH Shimano Nexus this thing has tremendous torque and is able to leap tall buildings in 'low' and cruise all day long at 25mph in 'high'. If there's a weak point in the bike though it's that ginormous battery pack that is strapped to a cheap rack suspended from the seat post. That battery adds 25lbs. to the Gravity's 60lbs. for a total of 85lbs. ! Not a big deal with cruising up and down the beach, but a very big deal when trying to climb a dune on an angle. So I would dearly love to take the battery apart, buy a few extra cells, and custom build a 72-volt battery pack with say 12ah of capacity that would fit above the motor inside the frame...or I could just buy another from China.
But if I do that, then I have a 'spare' battery pack that I can't imagine I have a need for.
So just how difficult would it be to take that big pack apart? 'Unsolder' all the connections? And reconfigure my existing cells into a 72-volt pack? I've only used this pack a half dozen times so it's essentially new...
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Chalo   100 GW

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Re: Scavenging one nearly new battery to make another?

Post by Chalo » Mar 15 2019 12:01pm

Hypothetically, you can take your old packs apart and reconfigure the cells with a new BMS into a different configuration. But in practice, it might be really difficult to disassemble your packs without damaging the cells. Do you even know what kind of cells are in there?

I commend the choice to get the battery off of a seatpost rack. That setup is just begging for trouble.
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Re: Scavenging one nearly new battery to make another?

Post by john61ct » Mar 15 2019 12:05pm

See what you can get for it and buy what you want

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Re: Scavenging one nearly new battery to make another?

Post by mammonista » Mar 15 2019 2:36pm

Thanks Chalo, John,
No, I don't know much about the battery packs other than I bought them from a Chinese supplier and paid $350 each for them. (?) Have no idea what kind of cells are in them. They weigh about 24lbs. each and dimensionally are huge. And according to the CA have 58.3 volts on them coming off the charger. So I'm guessing they're 52 volts and maybe 20 or 25 amp hours? For some reason I can't find the original invoice...
Is is possible to unsolder the connections on each of the cells? How is that accomplished? And once I settled on a configuration for a replacement (72volts and 10-12AH) how hard can that be. Pretty hard? Moderately hard? Easy peasy?
There's a seller on amazon who's selling 10-packs of Panasonic '18650b' for $80. How many would I need to put together a 72-volt system. Another seller is selling a 72-volt 80amp BMS for $65. That's if I go the 'build it myself' route. How much more would I need besides a lot of wire and some sheet metal (I like to build stuff!)?
Any input appreciated.
And of course I can buy a 72-volt battery pack from China for 343 british pounds (anybody know what the exchange rate is these days?
thanks again for any input,
Mark

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Re: Scavenging one nearly new battery to make another?

Post by mammonista » Mar 15 2019 2:51pm

So I found the original invoice from a Alliexpress seller 'Risun Motor'. The invoice says they're 48volt 20 ah batteries. So why is the CA saying they're holding a 58.3 volt charge at 100%. I'm such a dweeb!

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Re: Scavenging one nearly new battery to make another?

Post by john61ct » Mar 15 2019 5:52pm

No way to tell from here what's in there.

Every type has its own challenges, and some are basically impossible for non-specialists.

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Re: Scavenging one nearly new battery to make another?

Post by krlenjuska » Mar 15 2019 6:06pm

mammonista wrote:
Mar 15 2019 2:36pm
Is is possible to unsolder the connections on each of the cells? How is that accomplished? And once I settled on a configuration for a replacement (72volts and 10-12AH) how hard can that be. Pretty hard? Moderately hard? Easy peasy?
I bought used Flyer battery and decided to use cells for some project. I broke my fingers until i managed to get all cells from it. Also i changed heat shrink for all 60 cells and i cleaned + - surface with dremel so i can spot weld cells again.
Cells are great so far and im satisfied with this.
Its much easier to get new cells but this can be done. Especially if you have low budget like i did. 60€ for 60 cells + 3€ for heat shrink.

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Re: Scavenging one nearly new battery to make another?

Post by Hillhater » Mar 15 2019 6:33pm

Sounds like you do not actually know what voltage or capacity your pack is, let alone what cells are inside.
The cells may not be soldered...many packs are now welded connections.
Do you even know what voltage your bike needs ?...will it work with 72v ?
I suggest you start by doing a few checks with a multimeter to confirm what you have .
Battery building/modification is not something to be undertaken by everyone.
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Re: Scavenging one nearly new battery to make another?

Post by 999zip999 » Mar 15 2019 7:10pm

Sorry sounds like cheap no-name battery China use as is. Just use it in within its rated discharge. Long time ago ping medical battery you also rated it. Kill a 48v 20ah old Ping on a 40amp controller. 2,100 watts for a 1,200 watt pack. Ping has better packs now. You don't. You buy shoes at Payless you get Payless Shoes.

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Chalo   100 GW

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Re: Scavenging one nearly new battery to make another?

Post by Chalo » Mar 15 2019 9:33pm

It's not clear whether you intend to use a 72V pack on your current bike or on another project.

If it's another bike, it would be cheaper to match the motor you use and the performance you want to either 48V or 96V. Then you can use your big packs either in series or in parallel accordingly.

If it's the same bike, you need to open up one of you batteries and see what's going on in there. You have either a 14S lithium ion pack or a 16S lithium ferrophosphate pack. The BMS board required to configure one kind of cell versus the other to 72V is entirely different.

You don't know whether you have 18650 cells that are welded together, or pouch cells that are stuck together with adhesive, or something else yet. If it's the former, it will be a hassle to break up and rearrange the pack. If it's the latter, it might be physically impossible to separate the cells without destroying them.

Either way, you shouldn't carry a pack that size on a seatpost rack. Sooner or later you'll wind up with a seatless and battery-less bike at an inopportune moment.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Scavenging one nearly new battery to make another?

Post by mammonista » Mar 15 2019 11:07pm

Chalo,
Good points all! About all I know about this battery pack is I paid for a 48volt -20ah 'brick' from Risun Motor in China about a year ago. Because of a lot of other projects and some time getting the Gravity/Cyclone 3k mid-drive all sorted out I've only used the battery seven or eight times since new. Never had an issue with it although I did get stranded once when I ran it dry with that big cyclone motor and no good way to measure how much juice was left. Now the bike has a bluetooth programmable controller and the cycle analyst so I'm not overly worried about getting stranded again. But you're absolutely right about that big, heavy battery on the end of the bike. Not overly concerned about the seat post rack as I'm not doing any jarring riding out there on the dunes trails and the rack seems solid enough. But balance is frickin' horrible and trying to keep the bike going straight while traversing dunes is nearly impossible because the rear end wants to slide out from under me all the time. And since the Cyclone is capable of 3,000 watts with 72 volts why not go there? With the current 48 volt battery the Cycle Analyst says it's pulling 2,000 watts at full load/throttle. And that's enough for 99% percent of riding situations...
So I'd like to go 72 volts and figured I could save a few bucks cannibalizing the current battery.
But you're absolutely right in that I have absolutely no idea what cells they used. I also have absolutely no idea how they're joined together. So maybe it just makes more sense in putting that battery on the shelf and custom building my own 72-volt Panasonic or Samsung brick. As I may have stated earlier, some guy on Amazon is selling a 10 pack of Pansaonic 3400 m ah 18650s for $80. But how many of those would I actually need to get to a usable 72 volts? They also sell an 80 watt, 72 volt bms for $65. Is that the route I wanna go? You guys are the experts here...
thanks in advance,
mark

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Re: Scavenging one nearly new battery to make another?

Post by kcuf » Mar 16 2019 1:43am

dumb idea
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Re: Scavenging one nearly new battery to make another?

Post by amberwolf » Mar 16 2019 4:16am

mammonista wrote:
Mar 15 2019 11:07pm
some guy on Amazon is selling a 10 pack of Pansaonic 3400 m ah 18650s for $80. But how many of those would I actually need to get to a usable 72 volts?
At what current?

You need to determine the max current your controller will ever draw.

Then you need to determine the max current the cells themselves can handle without heating up or sagging too far in voltage.

THen determine how many of those cells you'll have to have in parallel to supply more than the max currrent the controller will draw.

Then divide 72v by 3.7v, which gives you the nominal number of cells in series you'll need.

Multiply the series number by the parallel number, and that's how many cells you need, at a minimum, to build a pack to do what you want.

Add more parallel cells if you want better longevity, or if you need more total capacity than the minimum above gives you.


Then do a bit of cardboard aided design, or do it with math, or however you prefer, and make sure that many cells wlll actually fit in the space you have available, and that their weight won't break anything in the moutnings/etc youv'e got.

They also sell an 80 watt, 72 volt bms for $65.


An 80watt bms probably would run lights on a bike. It wouldn't run the motor, probably not even offground, certainly not on ground with a rider.

You need a BMS that can supply more current / watts than the bike will ever actually use, so the BMS won't shut down under any normal usage of teh system.

Then you need cells that can supply more than the BMS will ever allow, so the BMS can protect the cells from ever seeing a load greater than they can handle.

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Re: Scavenging one nearly new battery to make another?

Post by dogman dan » Mar 16 2019 7:02am

One of the problems you will find, is that you damage the pouches as you peel them apart. Each section of cells in parallel will be stuck with double side tape to each other. So as you break up the pack, you will have to peel that tape, and it typically damages the pouch some. Very slow and careful with that. Usually easy though, to break up lifepo4 packs into 12v sections, of the same amp hours. Not stuck between each 12v block. Desoldering not hard, but unsticking those cells is a bitch.

And, a 72v lifepo4 pack will still be pretty heavy, just because its lifepo4. And its not likely to fit in the frame either, unless you make it so small the motor kills it quickly.

Your best approach for some hooligan riding would be a 5-10 ah lipo pack, and careful charging and storage outside. After all these years, and having a bike battery burn my garage, I'm still using the "dangerous" lipo batteries. I just don't bring them inside. But a 44v 10 ah pack ( 12 cell pack) is light enough for the rear rack of my off road bike, and small enough to fit any triangle. my bike is a y frame btw, or I would carry in the triangle.


48v lifepo4, is typically 16 cells in series, which when full, is 58-60v. 48v in other chemistries charges to different voltage, but is always at least 54v. FWIW, 12v lead charges to 13.5-14v. When your battery is about half discharged, it will be near 48v.


Lastly, put some home made struts under that rack, for your longer, more mellow rides with the battery you have.

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Re: Scavenging one nearly new battery to make another?

Post by mammonista » Mar 16 2019 11:09am

okay, so scavenging one battery is a bad idea. and my original plan was to have two of these big bastards to run an electric outboard motor I planned on building for leisurely cruising local lakes and rivers in a small boat. so that still seams to make sense.
and while the monster battery on the rear rack of my cyclone is stable enough back there (I added a couple of steel stabilizing straps) all that weight over the back wheel makes riding our coastal dunes here in Oregon a little scary at all the wrong times. As stated earlier the rear of the bike wants to slide out from under me at low speeds on anything but the flat and level.
that's no big deal when we're out here:
Image


but not cool when we're out here!:
Image
Image

So my choices seem to be
1) Rolling the dice and buying a Chinese 10-12ah 48, 52, or 72-volt battery that will fit inside the frame above the cyclone motor. That will mean relocating the bluetooth controller but not a big deal, and building a custom mount for the battery pack, also not a big deal.
Image

2) Spending a whole lot more money and buying a battery pack from Luna. not really an option for me as I have some issues with the company.
3) Designing and building my own pack. Cyclone sold me the controller to go with their 3k motor and they say it's good for anything the motor can handle (72volts). So how much science is involved in designing and building a custom pack? Apparently quite a bit according to some folks here, and not so much according to others. My dad was an electrical research engineer for a large defense contractor for his entire life and was irritated to no end that I wasn't born with electrodes shooting out of my ass (as he apparently was). So asking for his help on anything electrical was far more painful than it was worth. And after all who likes helping a nooby? Seriously! So I'm leaning toward option #1 as I had good luck with the two monster packs I already bought from the 'Chinese'. But if there was an easy way to learn the science behind building a 'one off' battery I'd be interested. Sounds a lot cheaper than even the Chinese route and you know exactly what's going into it.

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Re: Scavenging one nearly new battery to make another?

Post by 999zip999 » Mar 16 2019 12:36pm

20s 18650 called 72volts 24s lifepo4 is called
72volts. You would need between 6 to 10 in parallel or as needed.

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Re: Scavenging one nearly new battery to make another?

Post by mammonista » Mar 16 2019 2:09pm

Huh?, What?
This guy is selling: "Authentic 10-Pack NCR 18650B 3400mAh Panasonic 3.7V 18650 Rechargeable Lithium Ion Battery Flat Top For Led Flashlight Torches And DIY Power Bank" on Amazon.
1-These are good/great cells right?
2-How many would I need to achieve say 12ah, and in what kind of configuration?
The motor/controller combination is 'standard' 3k Cyclone and the bluetooth programmable controller they suggested.
This controller is also available from Bezos and company:
"20S 72V(84V) 80A 18650 Li-ion Lithium Battery Protection Board BMS MOS + Balance Module"
3-That would do the trick right?

I realize I'm going to need to study up on battery architecture, construction, wiring techniques, etc. but I'm willing to learn and I think I saw a primer on those things somewhere here on endless-sphere.

answers?

thanks in advance,
mark

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Re: Scavenging one nearly new battery to make another?

Post by krlenjuska » Mar 16 2019 2:14pm

mammonista wrote:
Mar 16 2019 2:09pm
Huh?, What?
This guy is selling: "Authentic 10-Pack NCR 18650B 3400mAh Panasonic 3.7V 18650 Rechargeable Lithium Ion Battery Flat Top For Led Flashlight Torches And DIY Power Bank" on Amazon.
1-These are good/great cells right?
2-How many would I need to achieve say 12ah, and in what kind of configuration?
The motor/controller combination is 'standard' 3k Cyclone and the bluetooth programmable controller they suggested.
This controller is also available from Bezos and company:
"20S 72V(84V) 80A 18650 Li-ion Lithium Battery Protection Board BMS MOS + Balance Module"
3-That would do the trick right?

I realize I'm going to need to study up on battery architecture, construction, wiring techniques, etc. but I'm willing to learn and I think I saw a primer on those things somewhere here on endless-sphere.

answers?

thanks in advance,
mark
20S 4P should give you 12-13ah

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Re: Scavenging one nearly new battery to make another?

Post by mammonista » Mar 16 2019 10:03pm

So I know I'm showing my ignorance here but that's 20 total 18650 Panasonic 18650 3400 mAh 3.7v batteries in four parallel groups. Is that kinda right? :-) Laugh all you want at my expense by the way. I don't mind. ;-)
But are those Panasonic batteries the good stuff? Is $8 a piece about right?
And the 84 volt/ 80amp BMS for $65 sound about right?
Finally where's the "noob guide" to building one of these things?
thanks in advance!
Mark

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Re: Scavenging one nearly new battery to make another?

Post by amberwolf » Mar 16 2019 11:30pm

mammonista wrote:
Mar 16 2019 10:03pm
So I know I'm showing my ignorance here but that's 20 total 18650 Panasonic 18650 3400 mAh 3.7v batteries in four parallel groups.
20s means twenty cells in series.

4p means four sets of series cells placed in parallel.

So you would need 20 * 4 = 80 cells to make a 20s 4p pack.

As to whether that will run your system, I already posted the steps you must take to determine what you need. If you don't do that, and just guess, you may or may not end up with a useful battery.

Finally where's the "noob guide" to building one of these things?
There is no one guide, because there are many ways to do it.

But you can read up on the longer 18650 pack building threads, and the discussions about various 18650 cell types, to learn about the things *not* to do as well as the things you must do, and the things you should do.

The best "guide" thread if you only read one is probably the one with a title something like "things not to do building an 18650 pack"; can't recall the actual title. but really, you should look at how various people ahve built theirs, and hwo they turned out, so you know what worked and what didn't, and what others with experience thought of the build.

There are some links in Spinningmagnets' Sitcky INdex threads in the various sections; the ones int he batery section probably have some good info for you.

There are also numerous spotwelder threads, which while they focus on the spotwelder itself, they also discuss cells and packs.

Then there are the threads about various weldless and solderless interconnect systems, some in the batteyr seciton and some in the for sale section.

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Re: Scavenging one nearly new battery to make another?

Post by dogman dan » Mar 17 2019 7:29am

A small enough 72 battery to fit in that triangle will be quickly killed by 3000w. 3000w capable 10ah lipo can fit there, or, just be light enough to carry on the rear. Part of your problem is a motor in the triangle already.


Dump that controller, or limit it somehow, and 1000w worth of 72v can fit. Best possible cells of course, the cheap stuff won't cut it.


Your existing lifepo4 can still have some uses, cutting it up into 12v sections should be easy, typically they don't tape together all of it, but rather have 12v blocks of it stuck together. This opens up some options for you, continue to carry 24v of it on the rear is one way to go, then stash the rest where ever it can fit, including on the handlebars. It won't handle perfect that way, but it will work better if you lose half that rear rack weight. Or, if you have use for 12v, convert it into a huge 12v battery, to run a trolling motor or camper stuff.


Split that pack just in half, and carry each half in lower panniers on the rear will help quite a bit as well. anything but 20 pounds up high will improve your ride.

But eventually, investing in a light, small in AH, but very powerful lipo pack will be your best bet. You can carry a 10 cell 10 ah pack in back, 36v, and easily fit another in the triangle. About 6 pounds on the rack, you'll barely feel it. but you will have a 700 watt hour, 72v battery that is small enough to carry anywhere on the bike, in sections.

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Re: Scavenging one nearly new battery to make another?

Post by mammonista » Mar 17 2019 11:17am

Amberman, Dogman,
Many, many, many thanks!!!!
Okay after doing a ton of reading last night my thinking has changed on this, and is continuing to evolve. (?)
1) I need to be able to make a battery (or if I buy a premade Chinese battery) with some kind of detachable mount so I can take that sucker off for charging. Since new I've been charging the huge 48-volt, 20ah batteries on the back of the bikes in my basement! wtf?
No more! From now on I'm detaching them and charging in the backyard in a cinderblock enclosure far from any structures.
2) Building a custom 72-volt battery box with an enclosed bms shouldn't be too difficult and figuring out how to link all the cells will take time but there is plenty of info here on es to guide me through the process. Of the dozens of Chinese suppliers on Ali there are a couple who are selling "Protected Panasonic 18650 NCR18650B 3.7V 3400mAh Rechargeable Li-ion Battery" for 4.65 british pounds (?) each. What the heck does 'protected' refer to? But at that price I'd pay about $500 for the 80 batteries needed to make a 72-volt pack. Are there better batteries out there? I'm assuming the Panasonic batteries are LiFePo. Should I be looking at different battery density though for less cells (and less size) but the same power? I know I've read the answer to that somewhere.
Time to read more.
Thanks again!
mark

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Re: Scavenging one nearly new battery to make another?

Post by mammonista » Mar 17 2019 11:20am

By the way, I definitely want the custom enclosure above the cyclone motor and inside the frame. I can move the controller anywhere. I just want the battery box inside the frame so I can get rid of that rear rack. for the kind of riding we do, specifically down the face of some steep sand dunes, I want to be able to shift my weight all the way to the back of the bike over the rear tire. So I don't want anything like a rack back there in the way.

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Re: Scavenging one nearly new battery to make another?

Post by spinningmagnets » Mar 17 2019 11:49am

Just to let you know, IF the true "fully charged" voltage of your existing battery packs is 58V, then they can be used as a back-up power source, since many inverters that convert DC batteries to 120V AC have a 60V input max.

Typically the 48V labelled packs have 13 cells in series, and the 52V packs have 14 cells in series count. The ebike world still has a lot of new enthusiasts every month, so I recently wrote "my version" of ebike battery building basics:

https://www.electricbike.com/introducti ... -design-1/

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Re: Scavenging one nearly new battery to make another?

Post by Hillhater » Mar 17 2019 5:39pm

mammonista wrote:
Mar 17 2019 11:17am
.... What the heck does 'protected' refer to? But at that price I'd pay about $500 for the 80 batteries needed to make a 72-volt pack. Are there better batteries out there? I'm assuming the Panasonic batteries are LiFePo. Should I be looking at different battery density though for less cells......
mark
Just so you know,...
Panasonic 18650 3400B are LiCo cells, not LiFePo.
A 20 s,4 p , pack of those Pana 3400B " protected" cells, will give yo approx 1.7 kW Max.
"Protected" means they have a built in current limiter (set to 6.7A) , so 4p can only supply 26/27 amps max.
And at that discharge you can expect 6+ volts of sag from the 20s pack.
Learn how to use data like this..
https://lygte-info.dk/review/batteries2 ... %20UK.html
Those Pana 3400B cells are very good....in the right application...but they do not suit yours !
There are better (and cheaper) cells available.
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