Modular battery packs

T

Tim Jing

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Feb 22, 2017
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Curious if anyone has build their 18650 packs for modular use. The goal is to have a 48V powerwall charged via solar, and modular battery packs that can power my ebike and other portable power needs. mike's DIY Tesla powerwall has a cool modular pack setup, but I'm not sure it can supply enough power for an ebike individually.

has anyone else thought about doing something like this?

Thanks.
 
I'm kinda thinking something similar. But more for plug and play. I want to be able to pull a pack out and work on it if necessary. I suppose I could make it so that I could use the same pack in various other devices. That would be pretty neat, actually. Thanks for the ideas. ;)
 

One way to do it. ~1kwh on this pack (Low cap cells used that was left over)
 
I'm building a 24V system using a mix of different designs to help me work out which works best. System overview:

Part of my system isa1kWh pack/module built inside an old metal Dell computer case which I use for my sons go-kart. (This vid shows it with the old GEL batteries:
)

After using the go cart for a bit I just plug that module back into the system.
 
daromer said:

One way to do it. ~1kwh on this pack (Low cap cells used that was left over)
Click to expand...

Dear Darometer, good to chat with you when the Aussie went live sat morning(Or evening in your time). Your pack is so complicated I would prob blow something up.

:)
 
I don't see ebike packs as lending themselves well to modular use, generally finding a place to fit a pack on a bike is an exercise in creativity in the first place unless the bike and the pack are specifically engineered to go together.

A lot of the popular combinations of bike and pack give a poor handling and off balance machine, a good ebike pack is the bulkiest thing on the bike and needs to be near the center of gravity or will foul up the handling.

Edit: One place it might work on the right type of bike is mounted on the forks, I've seen several bikes set up a bit like a cargo bike but with the pack being the "cargo". If you keep it close to the center line of the steering head the weight doesn't bother the steering as much as you might think, people rarely yank the handlebars around on a bike, gentle nudges are the rule. A fork mount is a good option for a wheelie prone machine too.
 
Tim Jing:

Nah its not that complicated :)

The whole pack consists of 14 mini-packs in series. Every mini pack contains of 11cells in paralell.
All cells do have their own fuse.
The whole pack it self is fused also and then i used a XT60 connector in the end.
 
Elmo, I'm going to carry the pack above the read wheel. like old school bikes when people carried stuff with them :)

Daromer, why do people use fuses rather than a small bms like most bike battery packs. BTW I like your wiring ideas, but I am debating 13s6p with individual bms's on each pack.
 
Fuse and a BMS is not the same thing and they dont make the other one not needed :) Yes a BMS could have a fuse built in but most dont.
BMS can do several different tasks and below are some of them:
* Monitor voltages
* Monitor temps
* Balance cells in a string
* measure capacity
* Protect from over/under voltage
* Protect from over current
* And much more...

So for me the fuse is just extra safety that doesnt cost me much to add.

Only go 13s if your equipment cant handle the higher voltage 14s give. The BMS im working on will be handling several packs at once. But its made for indoor use and not e-bike if thats your goal (Bit unsure may have missed something)

I like to have modular design with several packs with their own system. Its a bit more expensive though...
 
Darometer

I would like to have the modular packs for when I'm at the land and ofcourse the ebike when I'm not near an electrical plug. Ofcourse I could just go with a solarwall and use those to charge a dedicated ebike pack and a generator. And after watching your explosion video, I'm thinking these battery packs are not too volatile as long asthere is some sort of monitoring system for charge and temps.

There are a few youtubers that are flat out nuts on how much shortcuts they are taking in their projects. Which I hope most people do not follow. The ebikeschool channel is very good.

 
Note that there are different type of 18650 cells. Those taken out of laptop cells are not always known for high current output. So before you do anything i recommend to actually look into how much current you will need for your bike. Because if you want to be on the safe side thats important.

Its quite a difference on a ebike with 250w motor compared to one with 2kw... Also the voltage :)

The one you linked are the same as me except he added a China-BMS to it that will keep track of under and over voltage and current protection. And thats good to have.

Also beware of that some nickel strips are not that good.. And in those cases soldering is alot better. Since i havent done any e-bikes myself i dont have any experience in that field more than ideas on how i would do it.... :)

Note that its not easy to get 18650 to explode... I heated mine with a heating gun that produced 600+ degree of air :)
 
[ATTACH said:
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TimJing pid='2716' dateline='1487771895']Curious if anyone has build their 18650 packs for modular use. The goal is to have a 48V powerwall charged via solar, and modular battery packs that can power my ebike and other portable power needs. mike's DIY Tesla powerwall has a cool modular pack setup, but I'm not sure it can supply enough power for an ebike individually.

has anyone else thought about doing something like this?

Thanks.
Click to expand...

If you build up the battery packs, the balancer is necessary.
 

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I wouldnt say "necessary", but its definitely good to have unless you have 100% or close to 100% equal packs or you manually go in and balance every other day.
 
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