Split ebike battery

Batteries, Chargers, and Battery Management Systems.
eMark   100 W

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Re: Split ebike battery

Post by eMark » Oct 15 2020 2:09pm

"download/file.php?id=281045" ... IDEAL triangle area
ASSUME THIS IS THE SMALLER TRIANGLE AREA (excluding pivot suspension area) within the larger inside bike frame triangle. Following is based on smaller triangle area that doesn't include space taken up by pivot suspension. Did you already assume any protective buffer area outsie that pack triangle area as top dimension is only 300mm (11.81") and 240mm only 9.45".

14S4P with 56 LG Chem M29 2850mAh 10A (11.4Ah) ... advantage is its cycle life longevity more than power ...
https://eu.nkon.nl/lg-inr18650-m29-2850mah-10a.html ... €2.11 ($2.47) = $138.32
https://e4bike.ru/page/battery-shape-co ... 0276174225
https://e4bike.ru/page/battery-shape-co ... 9243174225


14S5P with 70 LG Chem M29 2850mAh 10A (14.25Ah) ... just may be the best solution if you've time to acquire the skill
https://eu.nkon.nl/lg-inr18650-m29-2850mah-10a.html ... €2.11 ($2.93) = $172.90
https://e4bike.ru/page/battery-shape-co ... 7330148221

14S3P with 42 Samsung 40T 4000mAh 35A (12Ah) ... more for its power performance than its cycle life ...
https://eu.nkon.nl/samsung-inr21700-40t ... h-30a.html ... €4.95 ($5.79) under quantity of 50 = $243.18
https://e4bike.ru/page/battery-shape-co ... 7282199220
https://e4bike.ru/page/battery-shape-co ... 7330148221

14S4P with 56 Samsung 40T 4000mAh 35A (16Ah) ... capacity and power performance more than cycle life ...
https://eu.nkon.nl/samsung-inr21700-40t ... h-30a.html ... €4.75 ($5.56) minimum quantity of 50 = $311.36
https://e4bike.ru/page/battery-shape-co ... 7330202220
https://e4bike.ru/page/battery-shape-co ... 6313173225

Shouldn't there be room enough to fit a 14S5P 18650 triangle DIY pack in that inner triangle area of your lIDEAL bike (controller located where you planned to locate the lower split 7S4P pack. NOTE: for cycle life longevity charge to 4.1V/cell and discharge to only 3.35V. Thus, the actual Ah capacity is less then shown above (maybe a 14S5P 18650 M29, if you're up to the task ...
https://eu.nkon.nl/lg-inr18650-m29-2850mah-10a.html ... €2.50 each ($2.93) = $205.10
https://e4bike.ru/page/battery-shape-co ... 7330148221

Here's a 14S6P with 84 Samsung M29E ... https://eu.nkon.nl/catalogsearch/result/?q=M29E 2750mAh 8.25A (16.5Ah) ... €2.50 x 84 = €210 ($246.12)
https://eu.nkon.nl/samsung-inr18650-29e.html ...
https://e4bike.ru/page/battery-shape-co ... 3350147237
no idea which one to recommend LG M29 or Samsung M29E ... https://eu.nkon.nl/catalogsearch/result/?q=M29E

LegacyCode   1 mW

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Re: Split ebike battery

Post by LegacyCode » Oct 16 2020 4:25am

eMark wrote:
Oct 15 2020 2:09pm
"download/file.php?id=281045" ... IDEAL triangle area
ASSUME THIS IS THE SMALLER TRIANGLE AREA (excluding pivot suspension area) within the larger inside bike frame triangle. Following is based on smaller triangle area that doesn't include space taken up by pivot suspension. Did you already assume any protective buffer area outsie that pack triangle area as top dimension is only 300mm (11.81") and 240mm only 9.45".
Problem still remains, there's probably no option for me to fabricate some enclosure within a reasonable time and cost wise considering how many tools I'd have to buy and things to learn, i wouldn't be surprised if it took me up to a year. Some pre-made extruded aluminum enclosures that require some holes drilled seems like a better solution to me, unless there's some triangle shaped enclosure i can buy somewhere that allows me to drill some holes and attach to the frame the same way. (I've looked around haven't seen any)
eMark wrote:
Oct 15 2020 2:09pm
no idea which one to recommend LG M29 or Samsung M29E ...
That LG cell might be good option, do they differ a lot for the 30q or 40t? I've seen the Samsung cells recommended in a lot of places because they are supposed to last long

Image
bladeweld.png
bladeweld.png (158.2 KiB) Viewed 352 times
Got the car battery and tested the welder on some blades

john61ct   100 GW

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Re: Split ebike battery

Post by john61ct » Oct 16 2020 10:58am



For longevity 50E is much better than 40T, but latter withstands higher burst C-rates.

Do not build from 30Q, output inconsistency leads to unreliability in big packs

goatman   10 MW

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Re: Split ebike battery

Post by goatman » Oct 16 2020 1:05pm

if youre only running a 20 amp controller thats 4/5amps/cell then youre better off running a LG battery, even upto 7amps/cell
i wouldnt run a 50e if you look at its lifecycle at 5amps, theres better batteries

https://www.imrbatteries.com/content/samsung_50E.pdf

a 30q or 40T id run at 5 to 15amps/cell where you could get the pack upto a good operating temperature or if you want high regen amps

eMark   100 W

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Re: Split ebike battery

Post by eMark » Oct 16 2020 3:54pm

Being that your primary need is capacity (Ah) for ground covered (km) and cycle life longevity consider 35E (8A). Besides NKON still has inventory of the older 30Q 136 cell with reports of sporadic high self-discharge. Wouldn't consider 30Q until NKON gets the newer 30Q 141 cell. Instead of a 15-20A rated power performance cell or 21700 cell consider the Samsung 35E ... https://eu.nkon.nl/samsung-inr18650-35e.html

Here's a 100 cell DIY pack (20S/5P) in a bike having same restricted area as your IDEAL bike ...
https://www.electricbike.com/wp-content ... 186504.png

Being you've got a spotwelder you really should consider either a 14S6P or 14S7P (35E) triangle DIY with 20.7Ah or 24Ah rating (with room for the BMS at bottom of either one) ...

https://e4bike.ru/page/battery-shape-co ... 0200601520 (14S6P)
https://e4bike.ru/page/battery-shape-co ... 0200598520 (14S7P)
https://e4bike.ru/page/battery-shape-co ... 0200600520 (13S7P)

Checkout these excellent design/build articles by spinningmagnets ...
https://www.electricbike.com/introducti ... -design-1/
https://www.electricbike.com/introducti ... -design-2/
https://www.electricbike.com/introducti ... ng-part-3/

999zip999   100 GW

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Re: Split ebike battery

Post by 999zip999 » Oct 17 2020 5:40am

Enclosure get some lids or a container cut it up and get a roll of duct tape how hard is that ??? Look in your neighbor's trash can.
Or one of those corrugated plastic yard signs on the outside done deal free just wait till the elections over. How hard is life really.
Free !

LegacyCode   1 mW

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Re: Split ebike battery

Post by LegacyCode » Oct 17 2020 7:47am

Been trying to figure out how many cells i can fit into things using inventor this one from aliexpress can hold about 50~60 18650 cells at 180mm length or so with space for a bms
https://www.aliexpress.com/item/32931329946.html
casecell.png
casecell.png (316.11 KiB) Viewed 293 times
also looked at a pvp pipe wtih a 100mm diameter and a 1.8mm thick wall, that didn't seem to be an option compared to aluminum enclosure

john61ct   100 GW

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Re: Split ebike battery

Post by john61ct » Oct 17 2020 8:20am

Look at the PVC fenceposts, square profile, pretty strong, ready-made caps can be sealed waterproof but still removable

LegacyCode   1 mW

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Re: Split ebike battery

Post by LegacyCode » Oct 17 2020 4:56pm

eMark wrote:
Oct 16 2020 3:54pm
Being you've got a spotwelder you really should consider either a 14S6P or 14S7P (35E) triangle DIY with 20.7Ah or 24Ah rating (with room for the BMS at bottom of either one) ...
I'll keep them in mind! 112 cells cost 300 euro or so at nkon
I'll read through these at some point, seems useful!

john61ct wrote:
Oct 17 2020 8:20am
Look at the PVC fenceposts, square profile, pretty strong, ready-made caps can be sealed waterproof but still removable
Took a look at the hardware stores, they dind't seem to have any of this

john61ct   100 GW

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Re: Split ebike battery

Post by john61ct » Oct 17 2020 6:47pm

Yes plastic fenceposts might be illegal in the more civilized countries
Screenshot_20201017-194724.jpg
Screenshot_20201017-194724.jpg (36.85 KiB) Viewed 269 times

goatman   10 MW

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Re: Split ebike battery

Post by goatman » Oct 17 2020 11:43pm

steel studs are easy and cheap and you could cut them with a good pair of scissors if you dont have snips.just look at a construction site dumpster and get them for free. you can reinforce with fiberglass and paint with plasti dip spray to waterproof

viewtopic.php?f=6&t=103833&p=1522913&hi ... o#p1522913

if you get the triangle shape you want with the stud. put wax paper or a garbage bag on tabletop lay down fiberglass mat on bag add resin and roll out, put stud on it and wrap the mat up and around the stud, let dry and you have a boxed in triangle box that fits your frame. you get the idea.

999zip999   100 GW

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Re: Split ebike battery

Post by 999zip999 » Oct 18 2020 5:29am

Can be done with plastic corrugated campaign signs with a layer a plastic storage container tub cut up with a layer of duct tape.

eMark   100 W

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Re: Split ebike battery

Post by eMark » Oct 18 2020 12:15pm

LegacyCode wrote:
Oct 13 2020 2:25pm
i will mostly just use it as round bike to get where i need to be, we don't really have any hills here. will limit it to 25km/h (legal limit) and no throttle because you need a license for that, my normal trips are going from my town to a nearby city which is about 15~20km to and back
If this mini cube 52V 30Q battery (possibly has the newer 141 30Q's) is illegal for your current use what makes you think your split 52V 30Q or 70T builds are legal? With this mini-mighty 52V you could've already been whistling on your IDEAL to nearby town :wink:

https://lunacycle.com/52v-mighty-mini-c ... -3-pounds/
https://www.youtube.com/watch?v=CLngOq7jWnM

How long before you're able to get a license, and use a throttle to control your power plant's speed so not to exceed your current 25km/h (15.5mph) restriction with the use of what now could be an illegal 52V (or even 48V) power plant ?
LegacyCode wrote:
Oct 11 2020 6:45am
I'm also not 100% sure what BMS i should get, I've been looking at daly BMS 100a
You're asking for trouble when you said you don't even have a license so illegal to have a throttle on your IDEAL e-bike.

Have you now decided to build two 6S5P packs instead of your original two 7S4P design ...

download/file.php?id=281215
download/file.php?id=280959

LegacyCode   1 mW

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Re: Split ebike battery

Post by LegacyCode » Oct 18 2020 2:02pm

eMark wrote:
Oct 18 2020 12:15pm
If this mini cube 52V 30Q battery (possibly has the newer 141 30Q's) is illegal for your current use what makes you think your split 52V 30Q or 70T builds are legal? With this mini-mighty 52V you could've already been whistling on your IDEAL to nearby town :wink:

https://lunacycle.com/52v-mighty-mini-c ... -3-pounds/
https://www.youtube.com/watch?v=CLngOq7jWnM
I don't think there's any restrictions on battery's I'm not 100% sure though i couldn't find any info on it.
Thats from the US and seems like quite a lot for 6ah, Shipping and import costs would add to the price quite a bit.
eMark wrote:
Oct 18 2020 12:15pm
How long before you're able to get a license, and use a throttle to control your power plant's speed so not to exceed your current 25km/h (15.5mph) restriction with the use of what now could be an illegal 52V (or even 48V) power plant ?
I've got a DCP-18 display it allows you to set a speed limit, I'm not planning to add a throttle to the bike now or anytime in the future. Would need a license, insurance, license plate and some stuff I'm not aware of to be allowed to legal used that on the road
I'm fine with 25km/h it needs to stay safe too instead of being a danger on the road.
eMark wrote:
Oct 18 2020 12:15pm
You're asking for trouble when you said you don't even have a license so illegal to have a throttle on your IDEAL e-bike.
100a bms was based on suggestions from a few sources claiming it's safer to go for a bms that can handle more.
eMark wrote:
Oct 18 2020 12:15pm
Have you now decided to build two 6S5P packs instead of your original two 7S4P design ...
I haven't decided on anything yet, I'm taking my time figuring things out, reading here and there (some of the links have been very helpful) The image was just something to get a visual on how many cells could go in a specific enclosure.

Gonna work on some list of tools/parts I'd need I'm getting a bit overwhelmed with all the information at once and should take it one step at the time, I'm leaning towards the Samsung 35e cells right now.
999zip999 wrote:
Oct 18 2020 5:29am
Can be done with plastic corrugated campaign signs with a layer a plastic storage container tub cut up with a layer of duct tape.

I'm not in America!, haven't seen any of those signs here anywhere!
goatman wrote:
Oct 17 2020 11:43pm
steel studs are easy and cheap and you could cut them with a good pair of scissors if you dont have snips.just look at a construction site dumpster and get them for free. you can reinforce with fiberglass and paint with plasti dip spray to waterproof

viewtopic.php?f=6&t=103833&p=1522913&hi ... o#p1522913

if you get the triangle shape you want with the stud. put wax paper or a garbage bag on tabletop lay down fiberglass mat on bag add resin and roll out, put stud on it and wrap the mat up and around the stud, let dry and you have a boxed in triangle box that fits your frame. you get the idea.
Gonna look into that, sadly not much construction going on here the government has put most of it on hold and won't grant licenses to build much due to some recent environmental laws

john61ct   100 GW

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Re: Split ebike battery

Post by john61ct » Oct 18 2020 3:09pm

Be happy you live somewhere that cares for the environment.

There is no need to build using roadside scraps, all these materials mentioned are cheaply available brand new.

The sign material is called Coroplast here, generic term is "corrugated plastic cardboard sheeting", waterproof and lightweight.

LegacyCode   1 mW

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Re: Split ebike battery

Post by LegacyCode » Oct 19 2020 2:57am

I think 84 Samsung 35e would be a good option (s14p6) for 20.7ah and 48a max if i'm correct? that should be enough the controller in the motor has a 25a max rating from what i found.

Cells : Samsung 35e x84
Step Down : https://www.aliexpress.com/item/4000816351721.html (plastic one)
Switch : https://www.aliexpress.com/item/33002820947.html
Relay : Looking for one with proper ratings
Fuse : Still looking
BMS : More reading to do
bschem.png
bschem.png (48.64 KiB) Viewed 196 times
Haven't looked into all the other things yet, got some kapton tape on order, soldering supplies I've got for the most part, I've looked for nickel strips on aliexpress but read that there's a lot of low quality/bad stuff there will have to look for a place where i can get something good (nkon had but a bit pricy)

For the BMS I'm mostly clueless at this point, a lot of conflicting information to be found if a pack would be 48a max I'd assume a 50a would be enough but at the same time I've seen many claims that getting a higher rated one is better to be safe, No idea if a smart one would be much better to have or not, it seems handy but at the same time is it worth going for one.

Havent decided on any enclosures yet, been contacting some sellers on aliexpress asking what they have available and if they can customize sizes, still need to look into some of the suggestions here.

Some of this tape might be useful I've seen it being used, will have to take a look if anyone sells that locally
https://www.aliexpress.com/item/33025667789.html

eMark   100 W

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Re: Split ebike battery

Post by eMark » Oct 19 2020 11:10am

LegacyCode wrote:
Oct 18 2020 2:02pm
I've got a DCP-18 display it allows you to set a speed limit, I'm not planning to add a throttle to the bike now or anytime in the future. Would need a license, insurance, license plate and some stuff I'm not aware of to be allowed to legal used that on the road. I'm fine with 25km/h it needs to stay safe too instead of being a danger on the road.
So do you basically have 5 speed settings to punch for speed/power as your throttle control? So in 4th with a 12S7P with 80amp controller and the Bfun BBS02 could LC go at least 12km/h (15.5mph) in 4th (and even faster in 5th) ?
LegacyCode wrote:
Oct 18 2020 2:02pm
100a bms was based on suggestions from a few sources claiming it's safer to go for a bms that can handle more.
That's AOK! Samsung 35E 12S7P pack (12x8A=96 amp power) with an 80 amp controller and your 100A BMS. That way you're never drawing more than 6.66 amps from your each of your 8A p-groups (12 x 6.66 = 80 amps). Will still give you plenty of power (and speed) in 5th. The primary reason for 12S7P (84 cells) instead of 14S6P (84 cells) is the extra Ah capacity which is more important to you than sacrificing extra capacity for more power and speed. Besides your 750W mid-drive will last longer with 12S than 14S. The other advantage of 7P (23.45Ah)) over 6P (20.10Ah) is even rated at 23 usable Ah's your controller LVC should be adjusted to 38.5V (3.2V/p-group) for cycle life longevity of your battery pack. So, realistically your actual 12S 35E capacity will be closer to 19Ah (and there may be times where you only charge your pack to 49V (4.1V/p-group) which will further reduce your pack's capacity. All for the sake of getting as many charge/discharge cycles out of the life of your upcoming LaborOfLove (LOL). Whether a 12S7P or 14S6P both have 84 18650 cells.
LegacyCode wrote:
Oct 18 2020 2:02pm
I haven't decided on anything yet, I'm taking my time figuring things out, reading here and there (some of the links have been very helpful) The image was just something to get a visual on how many cells could go in a specific enclosure.
I've been playing around with a layout that should fit in that space ... https://e4bike.ru/page/battery-shape-co ... 8407203253 ... let me know if those dimensions will be a good fit and still allow extra padding space for a slightly larger enclosure. I'm in the process of figuring out the series and parallel connections. Will take photo of diagram and post later today or tomorrow to get further suggestions from others on best electrical routing of the 12 series and 7 p-groups. Wouldn't your BBS02 (750W) last longer with a 12S pack instead of 14S pack.
LegacyCode wrote:
Oct 18 2020 2:02pm
Gonna work on some list of tools/parts I'd need I'm getting a bit overwhelmed with all the information at once and should take it one step at the time, I'm leaning towards the Samsung 35e cells right now.
Practice, practice, practice spot-welding on some old alkaline cells you can get ahold of. So when it comes time to spot-welding the appropriate size nickel/copper for your series and parallel connections you'll have perfected your technique so as not to start a fire, damage your cells and hopefully have all 84 healthy cells the first time you charge your pack.
999zip999 wrote:
Oct 18 2020 5:29am
Can be done with plastic corrugated campaign signs with a layer a plastic storage container tub cut up with a layer of duct tape.
I'm interested enough to fabricate an enclosure and airmail it to LC if we can agree on the exact (mm) dimensions. LC needs to become proficient at spot-welding. That's his biggest challenge.

Waynemarlow   1 kW

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Re: Split ebike battery

Post by Waynemarlow » Oct 19 2020 12:31pm

You're making life much too difficult for yourself. We've been doing much like you propose for a number of years on converted bikes, first with a BBS02 and latterly a modified TSDZ2 in rough mtb conditions. We are getting about 700m of climb over about 40km off road using the 13S2P packs. On road you could double that distance no problem and more if you have less climbing to do.

We first used 30Q's in 13S3P config then 13S2P then 35E's in 13S2P which was a sort of failure as they lose voltage in the last part of the discharge under load, enough to trip the BMS low voltage + they tend to get out of balance too easily. We moved over to 13S2P using the 40T 21700 cells which have been a great success.

Simple rear saddle bag is enough or in your case look for a Wildman toptube case.

999zip999   100 GW

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Re: Split ebike battery

Post by 999zip999 » Oct 19 2020 1:37pm

Best place to buy bafang HD maybe 1,500 watt ?

markz   100 GW

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Re: Split ebike battery

Post by markz » Oct 19 2020 1:56pm

999zip999 wrote:
Oct 19 2020 1:37pm
Best place to buy bafang HD maybe 1,500 watt ?
Why not in your own state, California?

LegacyCode   1 mW

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Re: Split ebike battery

Post by LegacyCode » Oct 19 2020 3:19pm

eMark wrote:
Oct 19 2020 11:10am
So do you basically have 5 speed settings to punch for speed/power as your throttle control? So in 4th with a 12S7P with 80amp controller and the Bfun BBS02 could LC go at least 12km/h (15.5mph) in 4th (and even faster in 5th) ?
5 Levels of peddle assist, it should just cut off peddle assist above 25km/h, T think it was possible to add more, should still have one of those same programmers they use floating around in a bin somewhere,
eMark wrote:
Oct 19 2020 11:10am
https://e4bike.ru/page/battery-shape-co ... 8407203253 ... let me know if those dimensions will be a good fit and still allow extra padding space for a slightly larger enclosure. I'm in the process of figuring out the series and parallel connections. Will take photo of diagram and post later today or tomorrow to get further suggestions from others on best electrical routing of the 12 series and 7 p-groups. Wouldn't your BBS02 (750W) last longer with a 12S pack instead of 14S pack.
Think it might be tricky to make that fit, I'm waiting for a Chinese seller to get back to me on some enclosures.
eMark wrote:
Oct 19 2020 11:10am
Practice, practice, practice spot-welding on some old alkaline cells you can get ahold of. So when it comes time to spot-welding the appropriate size nickel/copper for your series and parallel connections you'll have perfected your technique so as not to start a fire, damage your cells and hopefully have all 84 healthy cells the first time you charge your pack.
I have a few old cells i pulled from something laying around that i was gonna practice with at first, before moving on to the real thing
eMark wrote:
Oct 19 2020 11:10am
I'm interested enough to fabricate an enclosure and airmail it to LC if we can agree on the exact (mm) dimensions. LC needs to become proficient at spot-welding. That's his biggest challenge.
Thank you for the offer, i think it will be okay though, i might go to the hardware store on wensday maybe they have something i can use as enclosure and some of that fiberglass tape. just hate going out right now we're on some half lock down again because the corona is getting out of hand.
999zip999 wrote:
Oct 19 2020 1:37pm
Best place to buy bafang HD maybe 1,500 watt ?
The 750w bbs02b i have i got from aliexpress, sorted by most orders and had it shipped from a Germany warehouse

Michael B   10 mW

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Re: Split ebike battery

Post by Michael B » Oct 19 2020 7:42pm

In my 13s3p triangle example earlier I planned it out beforehand as best I could.
I wanted to use the pre-formed nickel (with slits) to make the spot welding process less fiddly.
In my low amp application I still wanted to have at least two serial connections between each trio of parallel cells.
I wanted to know where the BMS balancing wires were going to be and wanted them located near the outer edge.
I wanted the main BMS to battery connections to be conveniently near each other.
I draw the battery as I imagine it fitting in the bike triangle
13s3p triangle a.png
13s3p triangle a.png (184.11 KiB) Viewed 140 times
13s3p triangle b.png
13s3p triangle b.png (185.26 KiB) Viewed 140 times
Nickel.PNG
Nickel.PNG (224.44 KiB) Viewed 140 times

999zip999   100 GW

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Re: Split ebike battery

Post by 999zip999 » Oct 20 2020 7:10am

Here's a guy in new for sale section
viewtopic.php?f=31&t=92223

eMark   100 W

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Re: Split ebike battery

Post by eMark » Oct 20 2020 9:28am

eMark wrote:
Oct 19 2020 11:10am
So do you basically have 5 speed settings to punch for speed/power as your throttle control? So in 4th with a 12S7P with 80amp controller and the Bfun BBS02 could LC go at least 12km/h (15.5mph) in 4th (and even faster in 5th) ?
LegacyCode wrote:
Oct 19 2020 3:19pm
5 Levels of peddle assist, it should just cut off peddle assist above 25km/h
Won't that depend on the size of your pack and then choosing a controller with appropriate amp rating? You don't need to be pulled over for exceeding the legal speed limit (with not plans to get a license) :wink:
LegacyCode wrote:
Oct 19 2020 3:19pm
Think it might be tricky to make that fit, I'm waiting for a Chinese seller to get back to me on some enclosures.
Here's another insightful article by spinningmagnets on frame triangle pack enclosures. Fabricating your own protective padded enclosure would be a worthwhile winter project ... https://www.electricbike.com/triangle-bags/
LegacyCode wrote:
Oct 19 2020 3:19pm
The 750w bbs02b i have i got from aliexpress, sorted by most orders and had it shipped from a Germany warehouse
999zip999 wrote:
Oct 19 2020 1:37pm
Best place to buy bafang HD maybe 1,500 watt ?
If as LC originally planned to use either 30Q (15A) or 40T (20A) cells with an 80amp controller wouldn't he have shortened the life of both his 14S5P (30Q or 40T) pack as well as his BBS02B 750W mid-drive motor? He forgot to account for a safety margin (at least 1.3) for cycle life longevity. Don't abuse the cells with a controller that allows max cont discharge rating of cells.

I like Michael B's 13S3P triangle pack for a beginner spot-weld project with either 30Q 141 or 40T cells. It would satisfy 90% of your e-bike outings. Wouldn't there be room enuf and some to spare for a 13S4P(or5P) triangle pack in that 300mm x 240mm space? If NKON stocked MJ1 (10A) cells I would have suggested them instead of 35E (8A). With either a 12S7P or 14S6P pack of 35E cells you only need a 40 amp controller and should have no problem going 25km/h, if not more.

My grandson is in the process of deciding whether or not he wants to invest the time and money in a similar build as yours so it was by no means wasting my time planning out the following triangle configurations. In fact I enjoyed the mental exercise :)

Here's my effort assuming that your 300mm x 240mm inside triangle area doesn't include the space in the larger triangle that's taken up by the pivot arm and spring suspension (10 1/16" length = 255.6mm and 5 9/16" = 141.3mm, then 10 7/8" = 276.3mm and 6 7/16" = 163.5mm). As you can see there is more space vertically between the cells in the diagram so i took that into account when figuring the actual minimum height dimension. The diagram i used was the actual 18mm cell size. There should be enough room for sufficient padding in the enclosure to absorb any bumps along the way. Keep us posted on your winter project. It took me two months doing alot of figuring and refiguring before beginning my first build and that was after i had most of the materials, kit, cells, etc. I've learned more times than i'd like to admit that haste makes waste. You may even want to buy a few more cells than you'll actually need for your finished pack.
Attachments
12S7P or 14S6P Minimum Pack Length & Height Dimensions.jpg
12S7P or 14S6P Minimum Pack Length & Height Dimensions.jpg (340.95 KiB) Viewed 119 times
Minimum Dimensions of Enclosure - IDEAL Bike with Bfun BBS02 48V 750W Mid-Drive Motor.jpg
Minimum Dimensions of Enclosure - IDEAL Bike with Bfun BBS02 48V 750W Mid-Drive Motor.jpg (474.88 KiB) Viewed 119 times
12S7P 48V-2 LegacyCode copy.jpg
12S7P 48V-2 LegacyCode copy.jpg (444.94 KiB) Viewed 119 times
14S6P 52V-2 LegacyCode.jpg
14S6P 52V-2 LegacyCode.jpg (444.54 KiB) Viewed 119 times

999zip999   100 GW

100 GW
Posts: 9745
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: Split ebike battery

Post by 999zip999 » Oct 20 2020 12:36pm

40amp controller is about the safe limit.

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