RIP motor bike

I have built my fair share of battery packs. Most of the cost is in the labor. If you know what you are doing and already have the appropriate tools you can usually build a pack yourself for at least half the cost of a commercially available one.
I prefer pouch cells over 18650’s because I have more experience with them- that said charging them is more complicated, but if I'm building something for me, then it won't be an issue.
 
I was thinking of making one but the cost has kept me from doing it. A decent brand name mid drive kit with a middle of the road battery is close to 1000 CDN.

There are motors for much less but by time you add the rest of the parts and hope the thing works. Plus some sort of battery and hope to not burn the garage down. Maybe one day I hope to give it a try.

I was on Market place looking for a bike, there are lots of e-bikes for sale and all they need is, you guessed it, a battery.

 
I was thinking of making one but the cost has kept me from doing it. A decent brand name mid drive kit with a middle of the road battery is close to 1000 CDN.

There are motors for much less but by time you add the rest of the parts and hope the thing works. Plus some sort of battery and hope to not burn the garage down. Maybe one day I hope to give it a try.

I was on Market place looking for a bike, there are lots of e-bikes for sale and all they need is, you guessed it, a battery.

All of the mid-drive and hub motor kits got very expensive during the covid lockdowns, and they never really came back down in price.
 
All of the mid-drive and hub motor kits got very expensive during the covid lockdowns, and they never really came back down in price.
Same with the 18650 batteries. They were a couple bucks each, not anymore, now they are 5 each. I wanted to make a simple pack for lights on my bikes, not so cheap any more.
 
Same with the 18650 batteries. They were a couple bucks each, not anymore, now they are 5 each. I wanted to make a simple pack for lights on my bikes, not so cheap any more.
I don't even look at 18650 cells for packs anymore. 26650(26700) cells are the smallest I will go, and I am looking at even bigger cells now due to their higher capacity and discharge rates. Great for lower voltage with a higher capacity or enormous discharge capability.

Lately my eyes have been fixed on specific LiPO and LiFePO4 cells, both metal cased and pouch style as they tend to offer the highest amperage for their size and weight and/or more stable chemistry. I just haven't had a recent project to build a battery for in a while, so I haven't bought anything yet. Now that I have an interest in an inflatable fishing raft that can mount a trolling motor I am looking at options for building a 12V pack with a 160ah rating using SPIM08HP cells (3.7V 8ah per cell, about 3/4lb per cell weight) that each has a maximum continuous discharge of about 400A. They are bag cells used in large commercial bus/truck packs. Said pack should weigh maybe 40lbs or so when completed, with 30 lbs of that being the actual cells, and will have zero risk of overheating while running a trolling motor that has a max draw of 40 amps lol.
 
Yeah, I have run lithium iron phosphate in some gear- receiver/servos and in the remote specifically because they were very stable in impacts and didn't fall off a ledge once voltage was low (losing control with the throttle open is nightmare fuel)

At the time I was in the hobby, they were always sold high capacity, low discharge.

I do have a nasty 4S lithium cell I pulled from a faulty 10,000A jump pack I need to fo something with. That badboy will crank over a dead 10L Detroit diesel like nothing.
 
Lipo’s are great just gotta be sure to maintain them well
Yes, and manage the heat generated. That is why I want to use the cells I named in my trolling motor battery pack. Heat from charging and discharging is what tends to do the most harm to LiPo packs and ends up causing swelling. Using cells that individually have a 400A peak continuous discharge per pack, in 10 parallel packs of 4 in series, on a motor that pulls max amps of 36-40 at full throttle means it is pulling 1/10th of the rating of each series pack. The pack should run very cool under such a light load so swelling shouldn't be a big problem.
 
Fun fact, some guys who raced used to intentionally heat up the lipo's for more snap out of the gate, it got so popular they actually make heated sleeves for it. But consider they would rather kill a $100 cell faster if it meant winning races.

The two things I've seen wreck lipos faster than anything is- pulling enough amps to cause voltage sag for extended amount of time and improper cycling I.E, storing them fully charged, fully discharged and doing deep cycles.

I have killed many a lipo, especially drone racing.
 
Fun fact, some guys who raced used to intentionally heat up the lipo's for more snap out of the gate, it got so popular they actually make heated sleeves for it. But consider they would rather kill a $100 cell faster if it meant winning races.

The two things I've seen wreck lipos faster than anything is- pulling enough amps to cause voltage sag for extended amount of time and improper cycling I.E, storing them fully charged, fully discharged and doing deep cycles.

I have killed many a lipo, especially drone racing.
Something universal for most Lithium battery types is that they are their most efficient, and get the longest life span when charged only to about 90-95% of their max rated voltage, and discharged down to about 5-10% charge of their minimum voltage. Bottoming out lithium cells is the worst thing you can do to them, although over charging them can also do harm... and be dangerous as heck. That's why the one component I never cheap out on is the BMS, and especially a BMS that has programmable min and max charge voltage so you can set "100%" and "0" as lower/higher figures than their actual numbers to help prolong cell life.

I don't race RC stuff. My battery packs are often bigger, quite a bit bigger in fact. My last project was a battery bank setup for a small 1970's Winnebago Brave 19ft RV renovation that a friend was doing. He had very specific amperage requirements, both amp hours and peak amp capability so he could run a 12V electric rooftop heater/air conditioner, fridge, and lights in an off-grid scenario for several hours at a time (with solar panels and main hookup charging options. Most people would just spend the money on big honking deep cycle 12V battery (or 3 in his case), but he wanted to store the battery in a place that standard batteries just wouldn't work.

Building a 12V 1000 Amp hour battery setup that is at most 5 inches tall was quite a fun challenge,
 
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