Post by Burkeomatic on Oct 23, 2022 23:02:49 GMT
Alright, I am going to walk yall through how I build these LiIon packs as I build this one. I am currently building a 4S2P LiIon pack out of 21700 cells for my dragon. This should give me 8400mah and plenty o current. This applies to all batteries.
I have come to realize that these batteries could actually be used in most DTFB builds because we don't put on these gnarly motors that pull all kinds of current. A 3s1p battery made out of eve 25p cells would be 2500mah and 20amps sustained and 30 amp burst. Weighing slightly more than a 3s1000mah, it would easily give you pretty close to a 30 min flight time. My 4s 50c 2200mah lipos are pretty much overkill on everything except for my jet.
First, start by figuring out what layout you want, what current you will draw, etc. I only draw 40-50 amps of current, so there are some 18650s that would work, and do. I also want a ''stick battery'' layout. If you don't know what parallel and series mean, it would behoove you to look it up.
There are pros and cons to these batteries, the have more capacity at the trade off of c rating or current they can provide. IE, a 2500mah 18650 may be able to provide 25a current, but a 3000mah 18650 will only be able to provide 15a.
I am using Molicel p42a 21700 that provide 3.6v, 4200mah, and 45a per cell.
Batteries get their name from their size. So a 18650 battery is 18mm diameter and 65mm long. A 21700 battery is 21mm diameter and 70mm long.
In parallel, current and capacity adds, in series, voltage adds.
ALWAYS MAKE SURE YOU ORDER YOUR BATTERIES/NICKEL STRIPS FROM A REPUTABLE SOURCE.
I like 18650 battery store. They are reputable, have pretty much the best prices on the web, and are a US based distributor and offer quick shipping. I haven't waited anymore than a week. www.18650batterystore.com/
The batteries can be counterfeit and underperform which could be a fire hazard, or super lame if you think the 5000mah pack you just built has a capacity of 3000mah, and nickel can be nickel plated steel which has far less current capacity than pure nickel.
UPDATE - I RECENTLY BOUGHT REASONABLY PRICED NICKEL STRIP FROM AMAZON AND IT WAS NICKEL PLATED STEEL. I WAS ABLE TO RETURN IT, BUT ONLY GET YOUR NICKEL FROM A REPUTABLE SOURCE LIKE 18650 BATTERIES.
DO NOT BUY YOUR NICKEL FROM AMAZON.
You however can still buy your JST balance leads, xt60s, wire, and pvc wrap from there.
You test nickel by scraping it well with sandpaper, and letting it sit in saltwater for a day. If there is rust, it is nickel plated steel, if there is no rust, it is pure nickel.
You can also solder these packs together, but I have seen enough convincing evidence that it is suboptimal to do so. Therefore, even in my cheapness, I decided spot welding was the best solution.
Order your materials:
You will need nickel strips, probably as thick as your spot welder can handle.
Your batteries, whatever and how many you ordered.
Some form of tape.
Solder/soldering iron.
Spot welder.
Fish tape.
JST balance plug.
XT60 or whatever battery lead you are using pigtail
PVC shrink wrap.
Safety - You all know I am not the biggest safety ninny, but safety is important here. Most things are the same as standard LIPO safety procedures. If you don't know how to safely handle, store, and use lipo batteries, you have no business building a LiIon pack. The main difference is LiIon cells can be discharged further than your standard LIPO batteries, which means you can always run them to your ESCs battery cut, they can be safely discharged down to 3v per cell.
Additional safety info.
-Know safe operating procedures with the soldering iron.
-Clear your work station of all conductive things and work on a non conductive surface. It is real fun to accidentally short your battery on a stray nickel strip and have it weld itself to the battery, and having to pry it off while it is arcing at you. Ask me how I know.
- Wear eye protection with spot welding. If for whatever reason you don't have the nickel pressed down and firm on the surface below it, the spot welder can fling a molten hunk of nickel in a random direction.
Ok, I like to start by doing prep work on my batteries. I put tape around the outsides to provide some extra ''rubbing insulation'' and I also use the PVC insulators at the top of the battery. That wrap where it wraps all the way around to the top of the positive terminal is all that is insulating the negative part of the battery. The whole outside of the case is negative.
Then you need to get your nickel strips cut, I will be stacking them based on current. I have seen some people only stack them one high. I am not sure how much this matters. Here is a chart that tells you what you should be stacking.
Get your cells taped together and cut your nickel strips. There are some 3d printed cell holders, but tape worked better so I just used that.
Spot weld strips on to battery.
This is my spot welder, can't say I would recommend it for a couple of reasons. First, I thought the ''pen'' set up would be easier, but it actually isn't, and it is hard to tell if you have both electrodes evenly on the surface, and as you can see, they kind of move a little, so it requires readjustment. That was the main reason I went with this one, and it ended up being wrong. Secondly, it seems to be deteriorating rapidly. I am not sure how many more packs I'll be able to make with this. I will be buying another one.
Test your spotwelds with something non conductive. Don't put the force of God on it, but you want to make sure they won't tear off.
Repeat process until all your parallel cells are done. I am calling each of these a ''cell'' because that is how they will be acting. If I were doing a 4s3p, I would have 3 batteries here.
This is how we will line them up. We are going to be putting strips between the outside ones then flipping it over and putting it in the middle.
Tape them together then spot weld some more nickel strips.
Ok, now you should have this, essentially 2 2S2P packs.
Ok, get them taped together and flip em over.
Now we are connecting the middle ones. I put tape on the outside ones because if you connect those outer ones you will short the circuit and have some sparks.
Just for perspective, we are welding the bottom of the battery, and the outer parts are going to fold up to be the positive and and negative leads.
This is how the balance plug goes in.
Basically, you start with the one on the left looking at it as it plugs into the charger. That goes to the positive lead, or I call it 1. Then the cord after that goes between cell 1 and two, so that is two. Then 3 goes between cells 2 and 3, and 4 goes between 3 and 4, and 5 goes to the ground terminal.
This is another pic of what I am doing, 3 goes at the bottom, or the middle where the series connects, and 2 and 4 go the places it is going to fold. Obviously, you could just leave the battery in the brick shape too.
I have come to realize that these batteries could actually be used in most DTFB builds because we don't put on these gnarly motors that pull all kinds of current. A 3s1p battery made out of eve 25p cells would be 2500mah and 20amps sustained and 30 amp burst. Weighing slightly more than a 3s1000mah, it would easily give you pretty close to a 30 min flight time. My 4s 50c 2200mah lipos are pretty much overkill on everything except for my jet.
First, start by figuring out what layout you want, what current you will draw, etc. I only draw 40-50 amps of current, so there are some 18650s that would work, and do. I also want a ''stick battery'' layout. If you don't know what parallel and series mean, it would behoove you to look it up.
There are pros and cons to these batteries, the have more capacity at the trade off of c rating or current they can provide. IE, a 2500mah 18650 may be able to provide 25a current, but a 3000mah 18650 will only be able to provide 15a.
I am using Molicel p42a 21700 that provide 3.6v, 4200mah, and 45a per cell.
Batteries get their name from their size. So a 18650 battery is 18mm diameter and 65mm long. A 21700 battery is 21mm diameter and 70mm long.
In parallel, current and capacity adds, in series, voltage adds.
ALWAYS MAKE SURE YOU ORDER YOUR BATTERIES/NICKEL STRIPS FROM A REPUTABLE SOURCE.
I like 18650 battery store. They are reputable, have pretty much the best prices on the web, and are a US based distributor and offer quick shipping. I haven't waited anymore than a week. www.18650batterystore.com/
The batteries can be counterfeit and underperform which could be a fire hazard, or super lame if you think the 5000mah pack you just built has a capacity of 3000mah, and nickel can be nickel plated steel which has far less current capacity than pure nickel.
UPDATE - I RECENTLY BOUGHT REASONABLY PRICED NICKEL STRIP FROM AMAZON AND IT WAS NICKEL PLATED STEEL. I WAS ABLE TO RETURN IT, BUT ONLY GET YOUR NICKEL FROM A REPUTABLE SOURCE LIKE 18650 BATTERIES.
DO NOT BUY YOUR NICKEL FROM AMAZON.
You however can still buy your JST balance leads, xt60s, wire, and pvc wrap from there.
You test nickel by scraping it well with sandpaper, and letting it sit in saltwater for a day. If there is rust, it is nickel plated steel, if there is no rust, it is pure nickel.
You can also solder these packs together, but I have seen enough convincing evidence that it is suboptimal to do so. Therefore, even in my cheapness, I decided spot welding was the best solution.
Order your materials:
You will need nickel strips, probably as thick as your spot welder can handle.
Your batteries, whatever and how many you ordered.
Some form of tape.
Solder/soldering iron.
Spot welder.
Fish tape.
JST balance plug.
XT60 or whatever battery lead you are using pigtail
PVC shrink wrap.
Safety - You all know I am not the biggest safety ninny, but safety is important here. Most things are the same as standard LIPO safety procedures. If you don't know how to safely handle, store, and use lipo batteries, you have no business building a LiIon pack. The main difference is LiIon cells can be discharged further than your standard LIPO batteries, which means you can always run them to your ESCs battery cut, they can be safely discharged down to 3v per cell.
Additional safety info.
-Know safe operating procedures with the soldering iron.
-Clear your work station of all conductive things and work on a non conductive surface. It is real fun to accidentally short your battery on a stray nickel strip and have it weld itself to the battery, and having to pry it off while it is arcing at you. Ask me how I know.
- Wear eye protection with spot welding. If for whatever reason you don't have the nickel pressed down and firm on the surface below it, the spot welder can fling a molten hunk of nickel in a random direction.
Ok, I like to start by doing prep work on my batteries. I put tape around the outsides to provide some extra ''rubbing insulation'' and I also use the PVC insulators at the top of the battery. That wrap where it wraps all the way around to the top of the positive terminal is all that is insulating the negative part of the battery. The whole outside of the case is negative.
Then you need to get your nickel strips cut, I will be stacking them based on current. I have seen some people only stack them one high. I am not sure how much this matters. Here is a chart that tells you what you should be stacking.
Get your cells taped together and cut your nickel strips. There are some 3d printed cell holders, but tape worked better so I just used that.
Spot weld strips on to battery.
This is my spot welder, can't say I would recommend it for a couple of reasons. First, I thought the ''pen'' set up would be easier, but it actually isn't, and it is hard to tell if you have both electrodes evenly on the surface, and as you can see, they kind of move a little, so it requires readjustment. That was the main reason I went with this one, and it ended up being wrong. Secondly, it seems to be deteriorating rapidly. I am not sure how many more packs I'll be able to make with this. I will be buying another one.
Test your spotwelds with something non conductive. Don't put the force of God on it, but you want to make sure they won't tear off.
Repeat process until all your parallel cells are done. I am calling each of these a ''cell'' because that is how they will be acting. If I were doing a 4s3p, I would have 3 batteries here.
This is how we will line them up. We are going to be putting strips between the outside ones then flipping it over and putting it in the middle.
Tape them together then spot weld some more nickel strips.
Ok, now you should have this, essentially 2 2S2P packs.
Ok, get them taped together and flip em over.
Now we are connecting the middle ones. I put tape on the outside ones because if you connect those outer ones you will short the circuit and have some sparks.
Just for perspective, we are welding the bottom of the battery, and the outer parts are going to fold up to be the positive and and negative leads.
This is how the balance plug goes in.
Basically, you start with the one on the left looking at it as it plugs into the charger. That goes to the positive lead, or I call it 1. Then the cord after that goes between cell 1 and two, so that is two. Then 3 goes between cells 2 and 3, and 4 goes between 3 and 4, and 5 goes to the ground terminal.
This is another pic of what I am doing, 3 goes at the bottom, or the middle where the series connects, and 2 and 4 go the places it is going to fold. Obviously, you could just leave the battery in the brick shape too.
Just as an FYI, he rummages through the recycled battery bins at Lowes and Home Depot, strips the lion batteries out, tests them, and keeps the good ones for a yet-to-be-determined project....
) I think all of my small planes are XT30s now.