Micargi Seattle Hybrid

Tony01

Well-Known Member
Nov 28, 2012
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sf bay area
The two major problems with those cells are that they are huge for their capacity, and they are insanely expensive. The cheapest I saw was about $21 each, I don’t know what you’re paying but that is nuts. If you convert that to price per kwh, that’s around $820/kwh. By comparison the pouch cells I use, and the round cells other people use, come in at around $130-180/kwh and with the price of my packs my customers are paying around 4-500/kwh for a completed battery build. For the price, you’re paying for a pack that will never blow up and can dump high amps. But the fact is, that a cell with a regular chemistry will not only have 4x the capacity in the same space, it will also be able to dump those same high amps because discharge is a function of c-rating multiplied by capacity. So, instead of a 25c rating on an 8ah cell (25x8=200a) I’m using cells rated for ~6c peak on a, let’s say 50ah pack, or 300a peak. As a 36v50ah it would take approximately the same space as that ammo can. How do I know all this? I went with a different 8ah 25c cell for my first pack which was 4x the size it needed to be, and I was paying $200/kwh.

Generally for a well balanced ebike pack, you are looking for something with a 3c continuous discharge rating, scaled up in capacity to the discharge you need, which will end up giving you an actual useful range. Far as peak most cells will easily do double their continuous rating, in peak. Obviously you won’t be seeing more than a few seconds of peak discharge before you reach an uncomfortable top speed or something gets burned. Cells with a 25c rating are for other uses- like drag racing, starter batteries in cars, etc. In fact my car is going to be running a 12v pack built from those pouch style 8ah 25c cells. I built a little 12v24ah 600a rated pack as a jumper, and I’m probably going to build a version double the size. My car runs a ~850cca battery so something rated for 1200a peak would be perfect. These pouches also never blow up like your headways, which makes them perfect for use in a car. I’ve tried to blow them up! They just puff up/rupture and some smoke comes out but they never catch fire unlike regular EV cell chemistries.
 
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Forbidden Tuna

Active Member
Sep 3, 2019
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Kings Mountain, North Carolina
I had bought them a few years ago when batteryhookup had a big sale. I more or less just got these because they went together with busbars and I'm not skilled in putting together batts. I can't remember how much I paid but it wasn't as much as new ones are now.

I had commissioned a guy to build an 18650 cell pack but after months of him sending updates with pictures he completely ghosted me, claiming he got kicked out of his house so God knows what happened to that battery.

I'll probably look into building with the pouch cells and follow the build you did.

Do the pouch cells need breathing room for expansion or is it best to pack them down?
 

PeteMcP

Well-Known Member
Jun 27, 2017
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Went for an early morning spin on my BLUE BAMBOO eBike today. The smug look on my face as I cruised past the loooong queue of vehicles at the filling station here in Alnwick....
No joke....there are way more total f- - -wits out there than you can imagine. The government's memo that there will be NO shortage of fuel if we consumers just stick to our regular fill-up habits instead of panic buying fuel sure fell on deaf ears. Same numpties who emptied the supermarket shelves of toilet rolls at the start of Covid.
Good job my car use has dwindled to one trip to the supermarket a half mile away every two weeks these last couple of years, since we're virtually housebound due to Jen's health. My last fill-up was March 2020 when I topped-off the tank with 40 quid's worth of diesel and my Citroen's digital fuel gauge tells me I'm still good for another 108 miles.
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Forbidden Tuna

Active Member
Sep 3, 2019
108
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Kings Mountain, North Carolina
Still not ideal but for the time being I bought 4 of the hoverboard 10s2p packs, going to wire them in parallel to give me theoretically 17.6ah capacity. It's only a 750w controller so these batteries should be able to keep up just fine and with them in parallel my thinking is they won't be straining. I'm drawing up a fiberglass fake fuel tank to store the batteries, dad used to build Corvette body panels so he's going to show me his fiberglass skills. Might scratch that idea as soon as I see the 4 packs laid together and if so I'll just make a fiberglass case in front of the seat post.