Some of you might know by now that I'm a little off center. That's obvious from reading some of my posts.
Well, I'm at it again by making my own battery holder for 8 (4S/2P) AA NiMH batteries.
I will say up front that this is a hack job. It's done with hand tools and it's not the kind of quality you would find from some of the members here, who make battery holders using their equipment and machining skills. If you want a battery holder and don't want to go through the huge hassle I have, then just fork over the bucks and buy a good one here on CPF.
I try to make everything I can by myself. It's basically because I want to know if I can and if it will work. It's just my own personal preference.
In case anyone else might want to foolishly try this, I will list the parts I used and where I got them.
First off, I will tell you that if you do not have a drill press, you do not want to try this at home! The holes that have to be drilled, have to be as exact as possible, or it will not work. It's not worth the time trying, without at least a drill press. Of course, my drill press is a little unusual and nowhere near close to being exact. For anyone not already knowing it, I made a wooden drill press that I can slide my DeWalt hand drill into.
Here's a photo:
This is the latest version of the press. I widened it to fit better over a bench vise. I am using heavy duty drawer slides from the local HD, for the up & down. The rest is plywood and poplar that I already had.
Here's a shot of the basic components, (some of them).
The plastic rod is 1-3/8" Nylon, the copper is 0.010" sheet from Etsy, the brass and copper tube is 5/32" tubing from a local hobby shop, the springs came from CNQG. The template I made from Aluminum sheet from the local hobby shop (which just closed the doors the other day due to hobby king).
I bought a CMT brand 15mm Forstner bit and that is what I used to bore the holes for the batteries. It worked just about perfect.
But..... My template was off as you can see in this photo. One of the holes is farther outboard than the rest. The plastic is 6/6 Nylon rod stock (1-3/8"), from Drillspot. I buy a lot of materials from Drillspot whenever I find them with free shipping. Most of it comes from Granger, don't know how all that works out, but I think it might be old stock at a reduced price. I used the Nylon because it is made to closer tolerances than some of the other plastic rod stock.
The second photo shows the holes drilled for the brass rods around the outside and the copper rod in the center.
So I made two of these plastic end caps. I cut them off with a hacksaw and drilled the holes using my drill press.
Then it's a matter of making the contact plates out of copper sheet.
This will be a 4S/2P setup when it's done. 4 in series done twice for more amperage (parallel).
Since it's serial/parallel, I ended up with the 2 negatives and the two positives on the negative end, so I am using the copper tube in the center, to take the positive back up to the top. In order to make it easier for me and my shaky hands, I just tinned the whole contact plate for the negatives and set the springs in place. Much easier to just heat the whole plate and let them settle in.
Here's the contact plates for the top end.
Nothing fancy here. I do not try to make perfect circles. Instead, I just cut out the hexagon shapes and sand the points off, to make them almost round.
The next shots are of the holder put together.
Here's the negative end. The terminal wraps around the edge and out to form a contact for the spring. Not very centered, but it will work.
Again, the negative end, from the inside.
The positive end form the inside.
The positive end from the top.
I have not decided on how to finish the top terminal yet, but you can see how it might go. The brass rods fit snug in the plastic, but I decided to use 1/8"x7/8" Pop rivets to expand the brass rods, so they would not pull out. Well, they could pull out, but it would take a lot more force now. The pop rivets came from Amazon, as I could not find 1/8"x7/8" Aluminum with a steel pin, in any local store. What I forgot to do, before I put the ends together, was to put the shrink tube on the copper rod. As long as the battereis have shrink on them, it should not be a problem.
Here's what it looks like with the batteries in it.
It Works! 5.23vdc off my cheap meter, from eneloops charged a week ago.
That's about it. I can say it took FOREVER to get this done and it was not pleasant. It was not exact enough either. These need to be made with a lathe and an end mill, in order to get precise. I will not be making any more of these than I absolutely have to, for builds that I will do this winter (when it cools off).
OH, TJ this thing will be on it's way out to you. You can figure out what type of positive nub you want on it and finish it off as you want. Have fun with it!
Last edited by Old-Lumens; 07-07-2012 at 04:54 PM.
Reason: getting the photos in the proper places.
Thanks for all the support.
Fortunately or unfortunately, I spent most of my life in manufacturing. I have been in many shops and seen what kind of work can be done with modern tooling. That's why I say it's a hack. For hand tools, it came out pretty good, but I drool whenever I think of being able to touch a lathe or end mill again. That's not in the picture, so handmade is better than not made, LOL.
Duct tape, Ha, I've got plenty, but I didn't want to go too far!