Disclaimer: Batteries in the image are dead and bad and I’m just using them to do some test fitting. Also the final product will contain a PCM which isn’t pictured.
Just looking for some help from the community. I’m trying to make a battery pack that will fit into a 3/4 inch PVC pipe, and I’m looking for some spools of thin sheet metal that I can use to replace the wires below, you know something similar to what you would find inside a production Li-Ion battery pack. It’s possible for my LED setup to pull ~10A (2 x 72WS2812) and I currently have it wired with 18AWG. I should be able to get away with 22AWG for the 10A correct? In it’s current form it fits but it’s really tight. The final product will eventually be wrapped in head shrink if space allows.
Info: These are 18650 Li-Ions hooked up in parallel and then in a series. The Green wire, marked C on the white board, is the wire for the PCM to monitor each 3.4v cell.
I’ve regular copper tape, 1/4" wide, and my setup was pulling 12A from one piece that’s about the length of the battery. Definitely thinner than wires running along side the batteries.
I was thinking about that, if I use that I need to find some thin shrink wrap since I have several connections. Does the tape require soldering? I was thinking about spot welding the strips if I found something that would work.
I’ve used copper tape, it was self adhesive. My LiPo cells were scavenged from “dead” laptop batteries, so some had missing insulation. I couldn’t use heat shrink because of the wall thickness, and so my first attempt used regular brown parcel tape. Its very thin, and held very well. My second attempt I used kapton tape, but I actually think I got better results with the layering of parcel tape and copper “tracks”. The parcel tape pack is certainly more rigid.
I use an RC LiPo battery monitor, that monitors each individual cell, and it alarms if one cell drops too low, or indeed if the whole pack does.
I use a balanced charger, and for “dead” batteries, they have lasted exceeding well.
I have another 30 cells waiting to go into a bigger pack, but I’ve just bought some pre manufactured RC LiPo batteries in differing form factors, to compare with my franken cells.
I run 4 strings of 50 x WS2811s off of the packs.
Almost forgot, the tape is soldered on to the battery, use lots of good quality flux, a nice hot iron, with plenty of thermal mass, and its a quick touch.
If you cut on a spiral, you can get a pretty long strip of aluminum from a can. I haven’t used it for this purpose, but I’ve salvaged it by cutting the strips wider than I need, and then use a straight edge and sharp blade to trim them down to the final width. CAUTION: VERY SHARP EDGES!
So I should clarify what I did. I order my 18650 power cells with solder tabs on them. Makes it easier/safer to solder wires on to them. I took one strip of insulating electrical tape and ran it lengthwise along the battery where the negative tab is. On top of that I stuck copper tape and soldered the tab to it. Now I have, on the other end of the battery, a tab (+) and a copper tape end (-). After soldering wires to both of those (one red, one black), I insulate each one with heatshrink before wrapping both together in heatshrink.
Ohh great ideas. I’m going to use copper tape for the connections. I found out that my local batteries plus will weld tabs on my batteries, so I can get them done in a custom pattern to match my traces/tape runs. Final question, for the serial connection between the + and - does that need to be in the center of the run as pictured in my diagram? Seems like it should so the resistance between the individual batteries would be the same, or is it so minor that it doesn’t matter? Asking because it would be way easier to make the connection at the end instead of the middle.
I’m gonna make a new post when I build this in the next month so with plenty of pictures.
My device uses a single 18650 power cell (which is not the same as a standard 18650 battery by the way.) I use a MAX8903-A to charge and monitor it (during charging only). It’s a 2A, 1-cell charger which allows me to charge it either via USB or an external supply (up to 16V). It automatically monitors the power cell and cuts off when it’s fully charged. I can also charge it under load although that takes longer. Monitoring discharge is done in-software. When it reaches a certain threshold, the software automatically cuts out and won’t do anything other than blinking a red LED to tell me it needs recharging.
