CONSIDERABLE SHOUTING
10 kW
- Joined
- Jun 15, 2019
- Messages
- 809
So I've got a """fun""" idea for the braintrust.
I go to a warehouse reseller like a hoarder for electronic parts and returns. From this location I've obtained literally thousands of dollars of parts for hundreds, and some of those things are ~20V power tools typically missing their batteries. What started as a simple hand chainsaw with a brushed DC motor has grown to a hedge trimmer, my home cordless drill, a leaf blower, and now an impact gun. Most of these tools were bought for a handful of dollars, with the chainsaw bought for literally 50 cents. Most only have 2-wires for their packs, with some even marking the positive and negative terminals.
On top of bags and BAGS of XT60s, I've also nabbed nearly every lithium battery I could find and I've now salvaged tons of cells- Notably, I have ~111 A&S power cells and over 36 Samsung 18650-28A 2H52 cells. With the average price for a 6-cell laptop battery being 50 cents that means on average, I've spent a total of ~$0.08 cents per cell 8) Give or take a few. Problem however, is most of these cells are arguably pretty terrible with the A&S power ones having only a 1 Amp discharge. The Samsungs aren't much better with internal resistances averaging around 150 milliohm each. They all test as having capacities between 2300 to 2400mah. The Samsung cells seem to have discharge rates 2.5 times the A&S power cells.
Typically these cells would likely be useless- except for those tools, which gave me an idea for my first battery pack. Typical tool packs output 20-30 amps which a MASS of batteries can do, and I have enough (combined of both groups 147 cells) for a big 6S24P battery including a plastic enclosure with a weather seal I nabbed for 50 cents (are you seeing a theme lmao). Such a battery would only pump 22-24 amps depending on the number of parallel strings I have, could use a cheap BMS like One of these, and I have a large repository of 24v wall chargers for real slow, consistent recharging. I also plan to add quality of life and "Good sense" things, like a cell balancer or making it easy for me to test banks of cells. I'd even like to be able to plug it into a 24v inverter for whatever I need, as it would be over a kilowatt. I could put XT60s on my tool packs for connectors, and strap the big pack to a backpack for general use.
My question is- with ALL that nonsense, does that build seem to make sense? I imagine with such low drain the Samsung's high internal resistance wouldn't matter much, and the battery would be more for learning followed by consistent light use. I'd also try the copper-nickel sandwich for the cells as well. What do you all think? Pictured is one layout possible in the case that maxes at 22P, because there's another side about 3cm x 26cm where I should be able to sneak 2 more 6S strings.
I go to a warehouse reseller like a hoarder for electronic parts and returns. From this location I've obtained literally thousands of dollars of parts for hundreds, and some of those things are ~20V power tools typically missing their batteries. What started as a simple hand chainsaw with a brushed DC motor has grown to a hedge trimmer, my home cordless drill, a leaf blower, and now an impact gun. Most of these tools were bought for a handful of dollars, with the chainsaw bought for literally 50 cents. Most only have 2-wires for their packs, with some even marking the positive and negative terminals.
On top of bags and BAGS of XT60s, I've also nabbed nearly every lithium battery I could find and I've now salvaged tons of cells- Notably, I have ~111 A&S power cells and over 36 Samsung 18650-28A 2H52 cells. With the average price for a 6-cell laptop battery being 50 cents that means on average, I've spent a total of ~$0.08 cents per cell 8) Give or take a few. Problem however, is most of these cells are arguably pretty terrible with the A&S power ones having only a 1 Amp discharge. The Samsungs aren't much better with internal resistances averaging around 150 milliohm each. They all test as having capacities between 2300 to 2400mah. The Samsung cells seem to have discharge rates 2.5 times the A&S power cells.
Typically these cells would likely be useless- except for those tools, which gave me an idea for my first battery pack. Typical tool packs output 20-30 amps which a MASS of batteries can do, and I have enough (combined of both groups 147 cells) for a big 6S24P battery including a plastic enclosure with a weather seal I nabbed for 50 cents (are you seeing a theme lmao). Such a battery would only pump 22-24 amps depending on the number of parallel strings I have, could use a cheap BMS like One of these, and I have a large repository of 24v wall chargers for real slow, consistent recharging. I also plan to add quality of life and "Good sense" things, like a cell balancer or making it easy for me to test banks of cells. I'd even like to be able to plug it into a 24v inverter for whatever I need, as it would be over a kilowatt. I could put XT60s on my tool packs for connectors, and strap the big pack to a backpack for general use.
My question is- with ALL that nonsense, does that build seem to make sense? I imagine with such low drain the Samsung's high internal resistance wouldn't matter much, and the battery would be more for learning followed by consistent light use. I'd also try the copper-nickel sandwich for the cells as well. What do you all think? Pictured is one layout possible in the case that maxes at 22P, because there's another side about 3cm x 26cm where I should be able to sneak 2 more 6S strings.