Need Advise on battery pack configuration

[hillma]

I'm at an early part of my ebike project, I've been reading 100's if not 1000's of related posts on this forum and have settled (for the time being) on a design using a mid mounted RC motor - Astro 3210 ish - driving something along the lines of a Don Rocha inspired reduction system and retaining the bikes rear gearing.

Before I start looking at frame designs I need to get my head around the battery pack as what ever I come up with will need to enclose the batteries, controller and wiring etc within the frame and be totally hidden.

I've settled on about a 0.5KWh pack ( I live on a small island 15 miles by 10 miles but with a few big hills), any extra can be "plugged" into the bike and carried in a ruck-sac or something similar as I'm aiming for something which is as light as possible for 80% of the time where extra battery capacity is not needed.

My question is, what are the benefits or downsides (ie cell management, charging, voltage sag, cabling etc) of connecting 6 of these (http://www.hobbyking.com/hobbyking/store/__21944__Turnigy_nano_tech_12800mah_2S_40_80C_Lipo_Pack_TRA2875_Summit_E_Revo_E_Maxx_compatible_.html )packs together in series to get my 44.2v 12.8 Ah pack vs going the route of connecting two packs in parallel comprising 3 x 6s 4Ah cells such as these (http://www.hobbyking.com/hobbyking/store/__14316__Turnigy_4000mAh_6S_30C_Lipo_Pack_DE_Warehouse_.html)? From a packaging and total KWh my preference is to go with the 12.8Ah cells is series unless I've missed something?

Thanks for your understanding of my first post on here and the muddled question!

Mark

[kudos]

Totally un-related but what Island do you live on? I live on an Island and I feel Island ebiking has it's own peculiarites.

Edit: I've been using 4 x 4500mah 6S nano-tech lipo in a 12S configuration. I've just ordered another harness from Ice so I can run one of your proposed configs of 2S3P.

I think either would work, but most people would go for the 6S batts instead of the 2S.

Kudos

[hillma]

Hi Kudos, I'm on the "other" Island, if the weather was any better we could probably see each other ! Gotta update my profile with accurate information now I'm good to post.

Mark

[kudos]

Hehe, when I read the Island dimensions I thought it might the 'J' word.

We're all friends here in the ebike world though. I presume you've seen NeilP on here? He's on your Island too.

Kudos

[hillma]

I've not yet come across any other local members but would be keen to meet up with any who could share thoughts, ideas and experiences of their builds/conversions. How have you found getting hold of components?, you mentioned ICE, are they a UK provider as I've not heard of them?

[kudos]

Ice is short for Icecube57, he's a member of these forums that will make you a custom LiPo harness to suit what ever battery configuration you would like to use.

As for component suppliers, you'll be shopping globally at this time. No one does everything you need as far as I've found.

You've gone for a mid-mount straight out of the gate instead of a hub motor, so my experience won't be of much use to you I'm afraid. Plenty of other on here though to ask.

I'd like to have a mid-mount bike at some point though, I'm eagerly awaiting what Tench comes up with, he's also on the forums and has built a beauty of bike and is now planning to design and build some frames that can accept a variety of motors.

Good luck..

Kudos

[dogman]

Look up Niel for sure, at least online if not in person. He's very sharp!

For me, less wires is always good, but others value the lowest possible cost per watthour. Depends on what floats your boat.

4, 6s, 5000 mha packs plus Icecube 57's charging harnesses, plus a 350w meanwell power supply, plus a 300w RC charger makes a great way to get started with hobby king RC lipo.

44-50v 10ah, easy to swap between charging and running, and fits nice on any bike. Call it 12 mile range at full speed. Easy to add 5 ah more and have 18 mile range.

Monitoring the pack is another story. I do fine with a Cyclanalyst monitoring just the pack voltage, because I don't try to get the full 100% discharge.


That is, however, a verrrry interesting 2s 12ah pack. I've been saying they should make something like that, for those who are piling up more than 1 kwh of capacity, and bulk charging at all kinds of odd voltages above 72v.

About 15 of those would be fun.