Seeking recommendations for battery pack

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ElectricBikeBuilding
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Seeking recommendations for battery pack

I'm looking for battery pack recommendations for a ~36V with max dimensions of 5"x 5"x 15".

I'm building a custom battery box/holder behind the seat post. The seat stays are installed but I can't go any further until I know the exact dimensions of the batteries.

Here is a link to more details of the project:
http://electricbikebuilding.com/replaced-the-seat-stays-to-make-room-for-electric-bike-battery-box

I would consider building my own to get the dimensions I need but it would be nice to start with a complete pack. Some issues would be the location of the charge port and switch.

Thanks for the recommendations.

reikiman
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Re: Seeking recommendations for battery pack

Oh my, that's some fairly serious chopping on the bike - when we met at InterBike I didn't realize you went that far with it.

Anyway - there are several vendors in our Vendor Directory (http://visforvoltage.org/vendors) that sell completed battery packs. I've used a pingbattery.com 36v15ah pack for about 2 years that's still going fine and is perfectly adequate for a bicycle. Max discharge rate of 30A or so is fine when the bicycle has a 25A controller, eh? Just have to be willing to have duct tape on the battery pack ;-)

Some other vendors (such as e-BikeKit.com) sell packs packaged into aluminum cases. I'm sure you saw plenty of aluminum cases at InterBike and know the type.

I'd tend to do one of those before building a pack out of cells. I've had bad experience with that, but it could just be me since there are plenty of people who do build packs out of cells. I've made several posts about the journey with getting my Headway-based pack to work, bad BMS's and a recent unfortunate encounter with a spiral bound notebook ... well ... is the hassle of that worth whatever joy you get out of building your own? Well, okay, you're building a custom frame so maybe you have a different motivation than I do.

Current EV Tech supplies headway cells, the orange cell holders, bus bars, and several BMS options. It's complete overkill for a bicycle since it supports a 10C discharge rate - a 10A pack would support a 100A discharge. I have no idea whether the BMS's they carry are any good. Make sure to put it in a box, and don't set it down on a spiral bound notebook, eh? I promise you one thing, that's a bad idea. Assembling headway packs is pretty straightforward, the orange blocks are kind of like lego bricks. The BMS might be good and BMS is recommended because it allows you to plug in the charger and walk away with few worries. My headway pack right now does not have a BMS and a) charging is done with a 48v SLA charger rather than LiFePO4 charger (so that there's less worry about overcharging cells), and b) I can't ride it to exhaustion to avoid too-deep a discharge.

- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
- Electrified Electra To

ElectricBikeBuilding
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Re: Seeking recommendations for battery pack

Yes, I'm not afraid of the cuttoff wheel and torch :-) My next project will be a frame from scratch using everything I've learned on these prototypes. I took a bike frame building class at UBI to learn how to do it. I want to build eBikes exactly the way I like them.

Thanks for the tips. I like the pre-packaged packs but am having trouble finding one that I like with the dimensions that I need. The more I read about building my own pack, the more I'm liking it. I can make my own box like I did in my previous project and control exact placement of the switch and charge port. I'll leave out the spiral bound notebook of course.

EV Tech? I didn't see them in the vendor list. Where to buy headway cells and parts? Is there a more appropriate cell to use for an ebike?

Thanks again.

marylandbob
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Re: Seeking recommendations for battery pack

I purchased some 4 AH @20C lithium polymer cells from "All-battery.com" that could be used to build a lightweight, 24 AH, 36 volt battery, within your size limitations, for your bike, utilizing 60 of these cells, connected in series/parallel arrangement, with groups of 6 parrallel cells connected into a series string of 10 such 6 cell groups. A battery management circuit and suitable charger would be required, and maximum discharge capability would be 480 amperes! (around 20 Horsepower!)-IF you had a motor to take it! This would give great cruising range on the average bicycle, probably around 30 miles or more, without pedaling!-Bob

Robert M. Curry

ElectricBikeBuilding
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Re: Seeking recommendations for battery pack

Thanks Bob. I looked at those lipo cells and am intrigued. I'm going to keep researching this because I'd like to learn more about it and build my own. There are too many choices for my tiny brain at the moment. I'll need to find a bms and charger too, more choices. I really like the way some of them are packaged as flat rectangles with the tabs. Are the tabs just soldered together in the different configurations? How does the bms get wired into it all? More questions.

For now I'll see if Ping will make his 36v 10ah in the size and shape I need. I heard that he will do this. That will be the quickest solution for me at the moment. I have many frame projects I want to get done. I'll continue with the lipo battery experiment in the background because it is interesting.

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