BULIDING MY FIRST EBIKE, NEED SOME POINTERS.

[PARADOXICLES]

Hello, im in the process of building an ebike, this will be my second electric vehicle ( the first was a power wheels when i was a kid). i have been doing lots of research, which led me here, and i think you might just be able to help, i have lots of questions, some im finding as i search the forums. some i have yet to discover... i guess i will start form the beginning cuz there is alot

I have a 21 speed mountain bike i am converting to an E bike. after many weeks of research, i found a kit seamed pretty much perfect for reaching my goal. i bought a 48v 900w duel motor mid mounted kit from gngebike.com out of hong kong. here is a link the the specific product page for the item i bought.

http://www.gngebike.com/900wbrushed.htm

http://www.ebay.com/itm/48V-900W-2-MOTORS-brushed-MID-DRIVE-ELECTRIC-MOTORIZED-E-BIKE-CONVERSION-KIT-/200722109114?pt=LH_DefaultDomain_0&hash=item2ebbf852ba

it seams their site has more pics, and the ebay page has more info.

i have high hopes for this kit, it appears to be of good quality, but there was a problem no one could foresee of my bike having an overhang in front of the bottom bracket, which causes the motor mount to not line up properly with the bottom bracket, i plan on cutting the over hang section of oval tubeing off to create a nice flat edge that lines up with the bottom bracket are, this shouldnt significantly effect the structural integraty of the bike as it is over hang, but if it dose i have a few ideas to reenforce it including having reinforcement professionally welded on. ( just thought i should mention this part of the project so others can know of these problems as to avoid them or prepare for them)

and of course as with everything these days, it dosnt come with batteries.... which is where my first question comes in. how do i know which batteries are best to buy? the manufacturer's info is very confusing, and seams to be missing the info about my model ( all pages seam to have a general description that covers most their models) this is the info they provide.

"2.What battery is recommended for this kit?
If the kit is 24V, you need two 12V batteries, (lead acid or lithium), or one 24V battery.After they are linked together,
the minimum capacity should >12AH and recommended>20AH
If the kit is 36V, you need three 12V batteries, (lead acid or lithium), or one 36V battery.After they are linked together,
the minimum capacity should >12AH and recommended>25AH

this dose not mention my 48 volt kit, or its needs, and communicating with the manufacturer is not getting me answers due to the language barrier. i want to make sure i get the maximum power possible, with out over powering the motors, as well as the largest charge possible ( for maximum riding range). i am also looking at wiring the batteries up with a selector switch to switch between a parallel and series wiring to witch between riding and charging ( oh yeah, a charge will be wired permanently in to the set up as well so i can charge anywhere i need)... if my idea works, this should allow me to charge the 4 batteries as if they were one big 12v battery, but still use them for riding in the requered 48v set up, all with out removing the batteries. i am considering using batteries similar to these... depends on what i find

http://www.batterystuff.com/powersports-batteries/LFX09A2-BS12.html

will these batteries work for my needs? also, if you have any recommendations for better, or more affordable batteries, i will gladly look into them.



the next stage of my build is i would like add in solar pannels, probably on the battery box which will be mounted on a rear seat rack. if possible, i would like to even create some custom made solar hubcaps ( not using that space is such a waste, and would provide a big area for collecting sunlight)....how do i figure out what specs are required to properly change the batteries?


the last stage of my project is to arrange an array of batteries and panels in a trailer for even more range, and maybe to even haul a bit of camping gear or something.

i know there is alot to take in here, but any help would be GREATLY appreciated. thank you!

 

[spinningmagnets]

Ping is a respected and trusted supplier of LiFePO4 batteries, here is his 48V page. I would recommend his $533 15-Ah size at a minimum (more is better). http://www.pingbattery.com/servlet/the-48V-LiFePO4-Battery-Packs/Categories

There are other options, but Ping is the only one I'm familiar with. If you get this pack, you will need to put it inside some type of box with padding to protect it.

Since the GNG kit is driving the Bottom-Bracket (BB), the motor will have some gears to ease their acceleration loads, this lowers the system amp-draw (as opposed to a direct-drive "one speed" hub motor).

 

[geeeyejo1]

I could be wrong but guessing that the stated weight of that battery (1 lb) is probably a typo - my guess would be closer to 10lbs - multiplied by three for 36 volts would make for a heavy battery setup. As per previous poster, better off with a ping or similar pack at a higher AH capacity.

 

[Brentis]

Welcome aboard. You have found the home for all your ?'s.

My first pointer would be to read all the gng build threads on the sphere.
There are lots. Then read all the build threads you can handle.
Then read some battery tech threads.
Read read read.

Second pointer, get a camera of some sort. We need to see a pic of your bike to get a better idea of the changes you want to make.
I don't like the idea of frame modification unless you are in the know.
It my be cheaper and safer to start with a different frame.
Like they say a pics worth a thousand words.

Third pointer forget the battery linked, On marketing disgust alone.
It is marketed/made to look like a 12v9ah battery.
But it is not. It is equivalent. Pbeq. I call bs marketing.
That is likely a 4s2p life battery. Maybe even a123 26650.
Not a 12v9ah battery for that price though.

Like spinning magnets suggested buy a battery from an established reputable dealer and you will be glad you did. Ping, cellman, etc.

Ok i have other pointers but I'm on an iPhone and have no more patience for pointing.
Good luck to ya. Lets see some pics :wink:

 

[geeeyejo1]

Got my 48v15ah Lifepo4 pack for $426 shipped from sunthing28 on eBay. Have read a few good things about his batteries so took the plunge- waiting on delivery and will advise on performance when it arrives. Seems to be several good Lifepo4 vendors out there...

 

[PARADOXICLES]

Thanks for the replies, im just gonna make this one for all of them.

spinningmagnets and geeeyejo1 , thanks for the suggestions,..... the gng site dosnt have the info for my 48v kit i got from them but according to according to gng the recommended is 20 Ah for their 12v, and 25 for their 36v kits...... so the shouldnt the Ah be more like 30Ah or so for my 48v kit, not 15 Ah ??? ( just a guess)??? .. it seams to me that your suggested batteries dont meet the specs right?.. this is one reason i went with the 4x 12v 9 Ah battery... should give me 48v 36Ah, correct? if possible i would like even more Ah so i can have the furthest range possible.... but sofar it seams most places thats about the most ill get for my budget, which should be more then enough sense it exceeds the (estimated) minimum specs........ i also chose 4 12v batteries rather then one 48v battery because if one goes bad i can easily replace just the one with another of the same thing, reducing cost, plus it is my understanding it is easier to charge 4 little batteries with a lower voltage then one big one with higher voltage, meaning the 4 smaller batteries should charge faster right?... also greeyejo1, you mentioned the weight, i am only looking at lithium ion batteries, which according to numerous pages ive checked out, for a battery that size are about 1 pound, and yes, the led acid ones are abotu 10 pounds according tot he same sites, they are only like 6in x 4in x 4in or so (depending on specific battery)


Brentis ....thanks..i had no idea that any one would know who gng are, let alone have forum pages for them, i just found them on ebay, liked their kit and bought it, and assumed that would be the last i hear of them, i tried to find the info you mentioned, but a search for gng pulled up nothing, and searching manually did too.... im still not familiar with this site...

Pbeq.??? 4s2p life battery. Maybe even a123 26650.??? what? i have no idea what any of this means..... you will have to explaine............. and as far as the battery site i linked to, that was just for an example of the general type of battery im aiming for and price range, not necessarily the site i will use...... i guess the above stuff i mentioned can be a response to you as well. as i said im trying to get the absolute longest range possible....... im hoping ,i dunno, 10 miles minimum....15 i would consider good....20 excellent........... im sure the only way i could ever get more then that is with my battery trailer idea... but that is a far off phase of the project, need to get the basics in place first.

once again thanks for the suggestion and answering my questions

 

[dogman dan]

I will second the suggestion of a 48v 15 ah pingbattery, or similar equivilant such as the one sold by sunthing. Why that size? Because less size IS often not enough for a 500-1000w motor setup. A 10 ah lifepo4 may work fine at first, but as it ages and loses capacity, it then becomes too small, and dies quickly compared to a larger pack. Pingbattery is a lifepo4 battery made from foil pouches that are capable of about 2 c discharge rates. Pingbattery.com is the place to look at them. I am personally biased towards Ping as the seller because I have been using them nearly 5 years, and have found them convenient and reliable. If problems occur, ping's CS is as good as it can be without actually shipping a battery back to china.

What's 2C? C rate measures a batteries abiltiy to deliver power. A 10 ah battery discharged at 1c is 10 amps of current. Amps is the flow rate, amp hours is a capacity measurement. Bottom line, you need enough capacity, so your flow rate is adequate. A 15 ah battery capable of 2c will provide 30 amps when you need it to climb a hill, and be very comfortable providing about 15 amps for cruising full speed.

In addition, a 48v 15 ah battery is just about as large a lifepo4 pack as can be conveniently carried on bicycles. Any larger, and it will be heavy, large, and tend too unbalance the bike unless split into two pieces to carry in a pannier setup. If your setup ran on 36v, you could get 20 ah of it in the same size and weight package. But in 48v, 15 ah is about as big as can be carried easy.

48v 15 ah will weigh about 15-16 pounds, be about the size of a smaller shoebox, and give you 18-30 miles of range depending on your speed.

As for solar charging. I tend to not recomend it, other than a way to gain attention to your bike as a green vehicle. To charge a 48v 15 ah battery reliably in one day, you will need a large panel. About 150w minimum, and that's if you live in a sunny place as I do, with 6 hours of insolation daily average. Most places, you'd need 200w of panel. It's large enough to actually need a trailer to carry it, so your trailer idea is sound.

Solar charging by putting up a 200w stationary panel, with a second lead acid storage battery is a definite option. But with charging a 48v 15 ah battrery running about 15 cents a charge from the grid or less, it's hard to justify the large expense. Say you build the solar charging station for about $1500, then youd have to charge 10,000 times to break even. Call it 30 years to pay for itself?

Again, nothing wrong with a small panel on the bike as a PR device, but use it to charge something small. Perhaps your lighting system? Port for your phone to keep charged, or suchlike.

 

[geeeyejo1]

4 each 12v 9ah batteries run in series will produce 48v 9ah - run in parallel they will produce 12v 36ah. You can only add the voltage or the ah (depending on how configured) not both. As Dogman said, 9ah is rather low capacity and 15ah seems to be the best trade off in capacity and size/weight. Not familiar with the gng kit requirements but two 24v 15ah batteries would likely work as well in series. I give you props - the mid motor seems ambitious for a first build - I opted for a basic rear hub setup but like the idea of running the motor through the drive train and using the bikes gears - good luck! Alot of good information on this forum...

 

[Brentis]

Brentis ....thanks..i had no idea that any one would know who gng are, let alone have forum pages for them, i just found them on ebay, liked their kit and bought it, and assumed that would be the last i hear of them, i tried to find the info you mentioned, but a search for gng pulled up nothing, and searching manually did too.... im still not familiar with this site...

Pbeq.??? 4s2p life battery. Maybe even a123 26650.??? what? i have no idea what any of this means..... you will have to explaine............. and as far as the battery site i linked to, that was just for an example of the general type of battery im aiming for and price range, not necessarily the site i will use...... i guess the above stuff i mentioned can be a response to you as well. as i said im trying to get the absolute longest range possible....... im hoping ,i dunno, 10 miles minimum....15 i would consider good....20 excellent........... im sure the only way i could ever get more then that is with my battery trailer idea... but that is a far off phase of the project, need to get the basics in place first.

once again thanks for the suggestion and answering my questions

No problems. When using the search function of this site make sure to check the use google option.
It helps. Here are a few.
The intro to gng ebike.
http://endless-sphere.com/forums/viewtopic.php?f=28&t=42785

An update.
http://endless-sphere.com/forums/viewtopic.php?f=28&t=45740

Some builds.
http://endless-sphere.com/forums/viewtopic.php?f=6&t=44623

http://endless-sphere.com/forums/viewtopic.php?f=28&t=46113

PbEq represents lead acid equivalent.
So that lifePo4 battery can supply the same cold cranking amps as a12v9ah lead acid.
Which describes the amount of current the the battery can safely supply.
Not a measure of its capacity(how long it lasts).

A123 is a company that produces some of the best lifePo4 cells available.
26650 is a type of cylindrical cell. 26mm diameter x 65mm length.
I suspect that the battery linked is 4 cells in series for 12v approx.
and 2 cells in parallel for 4.6 ah approx.
again I am guessing because the seller is practicing deceptive marketing practices.

Your 900w 48v kit likely has a 20 amp controller.
So you need to find a battery that can supply that at minimum.
A 48v 20ah battery should give you 20 mile range easy.
Much depends on your terrain, weight,speed,aero.
48v15ah might do it with some pedaling.

iPhone patience just ran out.
More later

 

[PARADOXICLES]

ok thanks for all the info guys, once again making a general reply, and ill make it short

why do you keeps suggesting a 15 ah batter when it appears that i probably need 20ah? i do not under stand ...im no rocket scientist but to the best of my math abilities 15 is less then 20.... so im very confused by this suggestion..


also what is the average price, im looking on ebay as a price check... not sure, seams to vary widely... my budget is probably about $450 ( including shipping)


and yes, it appears that that the "use google" feature is off by default, which may explain why no results ever came back for my searches.... thats a weird feature ive never seen on a page before... ill do some browsing and see what info i come across, looking at the links you shared right now.

once again thanks guys ( and maybe girls, i have no idea hahah)

 

[geeeyejo1]

My understanding is that the max discharge rate could be the same for both the 15ah or the 20ah batteries - the 20ah would just have a greater range. That is you would likely have the same speed with both batteries. At your budget of about $450 shipped you can get a 48v 15 ah battery ( I paid $426 for mine shipped). A 20ah battery will most likely exceed your budget. As previously stated a 20ah battery is also quite a bit bigger and heavier making placement and weight distribution more challenging as well.

 

[dogman dan]

Actually, no.

A larger battery, of a given c rate will tolerate a larger amps rate of discharge. Take a really cheezy 1c lifepo4 for example. 10 ah can do 10 amps, 15ah can do 15amp, 20 ah can do 20 amps, and so on.

Fortunately, the 1c lifepo4 packs have mostly gone off the market, and nearly all sold now have a 2c or even 3c rate. A123 is much more, and headways somewhere in between. So a 48v 15 ah pingbattery ( 2c at least) is able to easily discharge 30 amps for short periods, and the typical draw of an ebike of 15-20 amps is fine for that 15 ah size.

Again, if you buy a big honking 20 pound 48v 20 ah brick of lifepo4, and carry it on a rear rack, your bike will ride like shit. So I often recomend the 48v 15 ah, because it is adequate for a 20 amps controller, and it weighs less. It may be small enough to carry in the ideal location, inside the frame triangle.

As for range, that depends on your speed, hills, flapping coat or not, etc. Typically an ebike gets somewhere between 25-35 watthours per mile when going about 20-25 mph. A 48v 15 ah pingbattery has about 750 wh in it. I got about 22 miles out of one traveling 22 mph, many many many many many times. But riding slow, pedaling a lot, I got 35 miles out of one quite a few times.

 

[geeeyejo1]

Actually, no.

A larger battery, of a given c rate will tolerate a larger amps rate of discharge. Take a really cheezy 1c lifepo4 for example. 10 ah can do 10 amps, 15ah can do 15amp, 20 ah can do 20 amps, and so on.

Fortunately, the 1c lifepo4 packs have mostly gone off the market, and nearly all sold now have a 2c or even 3c rate. A123 is much more, and headways somewhere in between. So a 48v 15 ah pingbattery ( 2c at least) is able to easily discharge 30 amps for short periods, and the typical draw of an ebike of 15-20 amps is fine for that 15 ah size.

Again, if you buy a big honking 20 pound 48v 20 ah brick of lifepo4, and carry it on a rear rack, your bike will ride like shit. So I often recomend the 48v 15 ah, because it is adequate for a 20 amps controller, and it weighs less. It may be small enough to carry in the ideal location, inside the frame triangle.

As for range, that depends on your speed, hills, flapping coat or not, etc. Typically an ebike gets somewhere between 25-35 watthours per mile when going about 20-25 mph. A 48v 15 ah pingbattery has about 750 wh in it. I got about 22 miles out of one traveling 22 mph, many many many many many times. But riding slow, pedaling a lot, I got 35 miles out of one quite a few times.

Got it - so the C rate makes up for what would appear to be not enough amps in a 15ah battery. So given the OP's kit and budget a 48v 15ah battery would be the ticket...

 

[wesnewell]

C rate is the max discharge rate of the battery multiplied by the AH capacity of the battery. For a 10ah battery. These are the max *rated* discharge rates.
C/2=5A
1C=10A
2C=20A
20C=200A
etc.
Note that many manufactures may over rate their batteries. And that using them at max C rates will likely end in a much shortened life span. Case in point is that almost all lifespans of lifepo4 battery packs are calculated using less than a 1C rate. You can find this in the fine print for some as stated as <1C. So if they state a 2000 cycle lifespan, that's likely calculated on a C/2 discharge rate. RC lipo lifespans are usually rated at 500 cycles, but that's pulling a C/2 rate also. Most ebike controllers pull somewhere between 20-40A max. Pulling 40A on a 10ah 20C pack is well under a C/2 rate. Actually a C/5 discharge rate. IOW's, it's my opinion that you'll get more cycles out of a 20C RC lipo pack than a 1C or even 2C rated lifepo4 pack. That and the fact that it cost a lot less, weighs a lot less, and takes up a lot less space is the main, but not all reasons, why I use RC lipo.

 

[docnjoj]

Hey Wes! Maybe my math is offf but pulling 40 amps on a 10 amp battery would be 4C. Please correct me if I am wrong~
otherDoc
Edit: Oh I get it! You were using 20 C lipos as your example. I'm also used to Hi C rate with A123. Sorry!

 

[geeeyejo1]

C rate is the max discharge rate of the battery multiplied by the AH capacity of the battery. For a 10ah battery. These are the max *rated* discharge rates.
C/2=5A
1C=10A
2C=20A
20C=200A
etc.
Note that many manufactures may over rate their batteries. And that using them at max C rates will likely end in a much shortened life span. Case in point is that almost all lifespans of lifepo4 battery packs are calculated using less than a 1C rate. You can find this in the fine print for some as stated as <1C. So if they state a 2000 cycle lifespan, that's likely calculated on a C/2 discharge rate. RC lipo lifespans are usually rated at 500 cycles, but that's pulling a C/2 rate also. Most ebike controllers pull somewhere between 20-40A max. Pulling 40A on a 10ah 20C pack is well under a C/2 rate. Actually a C/5 discharge rate. IOW's, it's my opinion that you'll get more cycles out of a 20C RC lipo pack than a 1C or even 2C rated lifepo4 pack. That and the fact that it cost a lot less, weighs a lot less, and takes up a lot less space is the main, but not all reasons, why I use RC lipo.

Wes - what would be the Lipo equivalent to use for a 48v 1000w Yescom kit with the stock controller? Seems 15s (3-5s 20c in series) plus another 3-5s in parallel would provide 55.5 volts and 10ah but would the higher C rate of these batteries blow the stock controller?

 

[PARADOXICLES]

ok,i got alot to say, so the last few days ive been doing some research, while it is far more money then i hoped to spend, i think i am going to go with 2 of pings 48v 10A , for a total of 48v 20A. i feel that as of my current knowledge, that seams to be the best option in the long run. i want to place one of each of the batteries in a saddle bag configuration, this should significantly lower my center of gravity, as well as place more weight on the rear ( powered) wheel,maybe creating more traction, if not, no bigg deal, its mostly the lowering of my center of gravity im going for. also, because its the 20A, i should get good range, and max power, with out putting extra stress on the battery, keeping it in the 1c rating during regular use, only pushing it into the 2c area when its relay needed ( or if ever), this gives me another benefit as well, if one of the batteries dies, both as in regular discharging, as well as like permanently dies and needs replacing, i will still have the one battery to operate on at that 2c rating( 48v 20A) until i replace the other, which would be the only one id need to replace, savign me money. and it frees up the back rack i was planning on getting, to be used for other things.


As i mentioned in my first post, ive had some problems with the kit i got from GNG, one being that the motor mount frame did not light up properly because my bike has an over hang of frame in front of the bottom bracket...i had originaly considered havign a welder cutoff the over hang and weld on some reinforcement inside the frame, but thats yet another cost tot the project, so i was thinking of alternatives, and i remembered that back in high school i "found" various street signs, so i decided to create a motor frame out of one, i used card board mock ups untill i found one that seamed to work, drew the pattern on the back, cut it out with a dremel, drilled some holes, and bent it in a vice with a rubber mallet..... i thought it would be cool to use the reflective properties of the sign as part of my color scheme of my bike sense it would mesh well ( blue and silver bike, yellow sign,). it was workign well for the most part untill the bending step, at this point the like .5mm glass sticker that gives the signe its reflection, cracked, id guess around 70-80 degrees was where it broke. i think if i had sliced the stiver along the bends, it would of fractured on the lines, and looked ALOT neater, but oh well...another thing is, this new bracket is made of aluminum, the old one is steel... i weighed them..... steel was 20.5 ounce...the aluminum one( despite being bigger) was 12.5 ounce.... a40.1% reduction in weight... thats always a good thing...over all it seams like it will work, but i have some straightening to do on it, and another problem to fix before i do much more

 

[PARADOXICLES]

so i have another obstical to over come. when i received the kit, i local bike shop helped remove the peddles ( free of charge) cuz i did not have a crank arm extractor, apon trying to put the bottom bracket it in( a step to early i might point out) the shop owner ( who claims to have been in business for 39 years) could not get it to fit, the lable says left and right, and we fallowed that, but it would not screw in, he came to the conclusion, as did i, that it dosnt fit, that the treads were wrong... later on i played with it again ( haahha) and realized that that if i put it in backwards, so left marked side was on the right, and so on, that the threads would screw in just fine, but this created the problem of now, the cenral axel is backwards aswell, meaning my peddles could only be attached to it on the left side ( the 2 ends are not the same length), which clearly dosnt match up with every other part on my bike.... after looking at it all and playing around,i have come to the conclusion, that the threaded end cap that is permenatly attached to the one end, and the other open end, are mixed up.... the threded cap was placed over the wrong end of the bottom bracket.......i wrote gng asking them about this, all they had to say was " it is not wrong" but my many hours of playing around with it, as well as the bike shop guy, say it is... there is simply no other way to install this part other then to put my peddles on the left...it physically wont fit together any other way, which dosnt work

i have a solution, do you think this will work? i will post a pic, and as you can see, my bottom bracket is one solid peice, nothing can be taking off because it is pressed together..it apears that the silver metal part in the middle, is holding the 2 sets of bearings at each end so they do not slide off, holding each other in place... im thinking if i cut them iddle of this silver part, WITHOUT cutting the axel inside, the 2 sets of bearings should slide off the ends, and then i can revers them so the bearing attached to the threaded cap and be placed on the right side, allowing the peddles to be on the right as well, like they should be..and once assembled that small cut shouldnt effect the function.. pretty much it just seams like the threads got put on the wrong end and pressed into place and need to be reversed....

 

[geeeyejo1]

so i have another obstical to over come. when i received the kit, i local bike shop helped remove the peddles ( free of charge) cuz i did not have a crank arm extractor, apon trying to put the bottom bracket it in( a step to early i might point out) the shop owner ( who claims to have been in business for 39 years) could not get it to fit, the lable says left and right, and we fallowed that, but it would not screw in, he came to the conclusion, as did i, that it dosnt fit, that the treads were wrong... later on i played with it again ( haahha) and realized that that if i put it in backwards, so left marked side was on the right, and so on, that the threads would screw in just fine, but this created the problem of now, the cenral axel is backwards aswell, meaning my peddles could only be attached to it on the left side ( the 2 ends are not the same length), which clearly dosnt match up with every other part on my bike.... after looking at it all and playing around,i have come to the conclusion, that the threaded end cap that is permenatly attached to the one end, and the other open end, are mixed up.... the threded cap was placed over the wrong end of the bottom bracket.......i wrote gng asking them about this, all they had to say was " it is not wrong" but my many hours of playing around with it, as well as the bike shop guy, say it is... there is simply no other way to install this part other then to put my peddles on the left...it physically wont fit together any other way, which dosnt work

i have a solution, do you think this will work? i will post a pic, and as you can see, my bottom bracket is one solid peice, nothing can be taking off because it is pressed together..it apears that the silver metal part in the middle, is holding the 2 sets of bearings at each end so they do not slide off, holding each other in place... im thinking if i cut them iddle of this silver part, WITHOUT cutting the axel inside, the 2 sets of bearings should slide off the ends, and then i can revers them so the bearing attached to the threaded cap and be placed on the right side, allowing the peddles to be on the right as well, like they should be..and once assembled that small cut shouldnt effect the function.. pretty much it just seams like the threads got put on the wrong end and pressed into place and need to be reversed....

Why can't you use the original bottom bracket from your bike with the kit? Could be wrong but do not think you can cut that sealed bottom bracket without adversely affecting the bearings...

 

[wesnewell]

Wes - what would be the Lipo equivalent to use for a 48v 1000w Yescom kit with the stock controller? Seems 15s (3-5s 20c in series) plus another 3-5s in parallel would provide 55.5 volts and 10ah but would the higher C rate of these batteries blow the stock controller?

With the stock controller, you can use anything from 12s to 15s. 12s is really perfect for the controllers LVC, which is ~42V. LVC will cut off the motor before you can reach a dangerously low battery voltage. You should get about 28mph top speed with 12s. Using 6 cheap 4s hardcase packs you can make a 10ah 44.4V pack that will charge to 50.4V for ~$140, or make a simpler 10ah 12s pack using 4 6s lipos for a little more. Beyond 12s imo, only 14s and 15s are plausible. If you have a 14s charger, 14s might be just right for you, but you'll have a harder time configuring a 14s pack that the 14s chargers can charge. 15s otoh is easy to charge 5s packs in parallel using any 6s charger. It will also get you the most power and top speed, maybe 35mph. Crates don't blow anything. It doesn't matter if you use 10C or 80C batteries, the controller is not going to pull more than 30A, which on a 10ah pack is 3C. Higher voltages are what will blow the controller. 15s charges to 63V. right at the upper rate limit of the caps in the controller. The fets are rated for 70-75V, so won't be an issue. In really, the caps shouldn't be either as long as you don't go over 15s. The controller I use has 100V caps and I go over that all the time up to 100.8V without a problem.

 

[NeilP]

If you go to a max of 14s, then you can balance charge if needed with a Hyperion 1420 charger without re config of the pack..so 14s is good, though the plugs on 7s packs can be a pain..a 3s and a 4s..so adapters need to be made up