WalkerYYJ
1 mW
Hi all, so for my first e-bike I decided to be an idiot and try my hand at building a custom pack from scratch, having never touched such things before.
Admittedly I’m not really all that sure how wise of an idea this was/is but if anyone has any input at this stage I would greatly like to hear it! I'd like to avoid burning my house down etc.
As of the time of this post I have the basic mechanicals done and am “close” to installing the cells.
I am using 20x 25Ah Fortune cells from ECPC: https://www.electriccarpartscompany.com/fortune-25ah-aluminum-encased-battery
They will be running in a 10s2p config with the goal being a 32V pack @ 50Ah I.E. ~1.6kWh.
For the BMS I’m planning on using a TinyBMS from Energus: https://www.energusps.com/shop/product/tiny-bms-s516-150a-750a-36
Its going to be powering a GMAC/phaserunner on a CETMA cargo bike https://cetmacargo.com/ plus lights, chargers & some sort of yet to be identified telemetrics suite.
I may add a second motor at some point if need be.
I wanted to try and get away from CNC stuff and get some practice with some manual tools/scribing/etc so this is really more of a project for the “learning” more than anything else.
The basic idea is this will be a quazi stealth build with the pack and all electronics living underneath cargo deck well out of site. The pack will be suspended from of the deck with shock isolation mounts and is NOT really intended to really be removed regularly. The bike will carry its own mounted charger aboard (Satiator). The intent is to operate it between 20%-80% capacity most of the time which will "hopefully" mean the pack and bike should last for a very long while (the primary goal of the build {other than learning} being longevity).
The box is made from 0.375"x2.5" 6061 barstock (cut down a bit) and 0.125" 6061 sheet. The batteries will be secured both mechanically and by double sided thermal tape. The idea is the batteries (should they generate heat) will dump it into the chassis. However with the single motor setup max draw should be <40 amps and in this config these cells should be good to ~150A sustained draw down soooooo in theory they should stay pretty cool (I'm in a cold climate). The cells will be held under compression once the box is sealed (not really sure if that's needed or not.)
Its sealed with silicone but does have some access ports and view ports (to check for things like condensation, status LEDs, etc). I'm intending to stuff some do-not-eat into it before final sealup. All fittings/switches/grommets/etc are IP67 rated.
Wanting to avoid making a bomb (if there's a thermal runaway) I've installed a 2" plug that's rated to pop at 5psi. There's also good pathing from the vents to the plug. I also have a few other places where pressure should be able to get out in the event of a failure. I'm debating stuffing rockwool into the remaining void spaces (for slowing a blow-off, should one happen), but not sure if that's a wise idea RE possible condensation and/or even necessary.
The BMS is mounted to a big chunk of aluminum which I am hoping will also help with longevity and higher current draw if I go to twin motors later. This specific BMS was selected because of its cold temp cut-off for charging. However again with this setup and a Satiator max charging current should be ~8A into config that should be good to 25A, so I suspect even if it were charged in cold WX (which it wont be) it should have a fair bit of safety margin.
If anyone sees any major issues that would be wise to address, please let me know!
More to come!
Admittedly I’m not really all that sure how wise of an idea this was/is but if anyone has any input at this stage I would greatly like to hear it! I'd like to avoid burning my house down etc.
As of the time of this post I have the basic mechanicals done and am “close” to installing the cells.
I am using 20x 25Ah Fortune cells from ECPC: https://www.electriccarpartscompany.com/fortune-25ah-aluminum-encased-battery
They will be running in a 10s2p config with the goal being a 32V pack @ 50Ah I.E. ~1.6kWh.
For the BMS I’m planning on using a TinyBMS from Energus: https://www.energusps.com/shop/product/tiny-bms-s516-150a-750a-36
Its going to be powering a GMAC/phaserunner on a CETMA cargo bike https://cetmacargo.com/ plus lights, chargers & some sort of yet to be identified telemetrics suite.
I may add a second motor at some point if need be.
I wanted to try and get away from CNC stuff and get some practice with some manual tools/scribing/etc so this is really more of a project for the “learning” more than anything else.
The basic idea is this will be a quazi stealth build with the pack and all electronics living underneath cargo deck well out of site. The pack will be suspended from of the deck with shock isolation mounts and is NOT really intended to really be removed regularly. The bike will carry its own mounted charger aboard (Satiator). The intent is to operate it between 20%-80% capacity most of the time which will "hopefully" mean the pack and bike should last for a very long while (the primary goal of the build {other than learning} being longevity).
The box is made from 0.375"x2.5" 6061 barstock (cut down a bit) and 0.125" 6061 sheet. The batteries will be secured both mechanically and by double sided thermal tape. The idea is the batteries (should they generate heat) will dump it into the chassis. However with the single motor setup max draw should be <40 amps and in this config these cells should be good to ~150A sustained draw down soooooo in theory they should stay pretty cool (I'm in a cold climate). The cells will be held under compression once the box is sealed (not really sure if that's needed or not.)
Its sealed with silicone but does have some access ports and view ports (to check for things like condensation, status LEDs, etc). I'm intending to stuff some do-not-eat into it before final sealup. All fittings/switches/grommets/etc are IP67 rated.
Wanting to avoid making a bomb (if there's a thermal runaway) I've installed a 2" plug that's rated to pop at 5psi. There's also good pathing from the vents to the plug. I also have a few other places where pressure should be able to get out in the event of a failure. I'm debating stuffing rockwool into the remaining void spaces (for slowing a blow-off, should one happen), but not sure if that's a wise idea RE possible condensation and/or even necessary.
The BMS is mounted to a big chunk of aluminum which I am hoping will also help with longevity and higher current draw if I go to twin motors later. This specific BMS was selected because of its cold temp cut-off for charging. However again with this setup and a Satiator max charging current should be ~8A into config that should be good to 25A, so I suspect even if it were charged in cold WX (which it wont be) it should have a fair bit of safety margin.
If anyone sees any major issues that would be wise to address, please let me know!
More to come!
