Fun with batteries, cells, and chemistry!

I've got all sorts of things I want to try, and rather than starting a new thread for each one, I'll put it all here. It's all battery related somehow!

First thing, I want to 18650 my old fluorescent camping lantern. It's 12V, and normally takes two of those big 6V lantern batteries. They don't seem to last very long, and I hate to keep throwing dead ones out, so I bought some D-cell adapters so I could use NiMH cells and recharge them. New problem: That's 8 cells that have to be charged up each time. I figured one of the dead 6V batteries would make a great container for the 18650s since the lantern is made to fit those already. Just have to open one up and get rid of the dead F-cells.




Of course, the zinc cell containers have long since decomposed, making the cells a bit of a pain to extract. But as a bonus, I got 4 intact carbon rods.




I'm going to have to do something with those later...

For now though, I'm looking at the interior of the battery case, and it looks like I can fit nine 18650s in there.




If anyone has a recommendation for a compact 3s protection board with a decent low voltage cutoff, I'd appreciate it. The lamp will keep operating until below 3V (although dim), and the boards I've seen have a very low cutoff Voltage. I'll keep looking though.

So... what should I do with the other battery case? Another 3s in parallel? Dummy cell for contraband?

It would be better to use a 3.7V protection circuit along with a 12V boost converter. Would make for a much easier build.

That's a good idea!
Do boost converters draw phantom power though? I know the buck converters do. Sure would make charging easier though.

I could add one of those TP4056 boards with the current and low voltage protection. Although, everything I've seen that offers low voltage protection cuts off at 2.5V. Seems awfully low to me. But they do offer 3A current protection. That's plenty for what I want to do.

Just put the switch between the battery and the boost converter. That way the converter isn't powered at all until you turn it on

Yeah. As Korishan said, just add a switch to prevent parasitic discharge.

If you want a lower charge and discharge threshold, you should use diodes with a 0.1V drop on the charging path, and a 0.6V diode on the discharging path.

Here's the schematic if you want:

Well, I've been thinking about it. I really like the idea of a booster so I can make the battery 6V just like it was originally. I'm also thinking I can add in a TP4056 board in such a way that I can charge it up without having to open the battery.

I've seen TP4056 boards with low voltage and current protection, and TP4056 boards with Voltage boosters. But I haven't seen a board yet with both. Not a big deal, but if anyone knows of one that isn't too bulky, I'd like to hear about it. I've also got loads of tiny switches that should work for turning off the boosters. I think the phantom draw would be small enough to ignore if the batteries are used on a regular basis, but being able to disconnect them during storage would be a nice feature.

Hahah, here's an idea for ya.

Take a wireless charger, such as this one and put it in the bottom of the holder (that used to be a cell). It is a micro usb out. So you can then plug the TP4056 directly into the wireless receiver. No need for any external wires!

The QI charger is rated at 5V@1000mA output. Now, it's probably gonna be closer to 800mA, but you just place the flashlight on the charger when not in use. Then you can use one of these chargersand build a custom base for it.

[img=300x300]https://i.ebayimg.com/images/g/sakA...m/images/g/bd4AAOSwd3dZZFRF/s-l1600.jpg[/img]

I'm actually currently waiting on these myself for another project. Gonna make my tablet wireless charging. But I need to put 4 of the receivers to give me the amps I need to charge it. Might need to use 6. Will see how it works out. I'll do a video of the project.

While I'm waiting for parts, I've decided to have some fun with the carbon rods I found in the 6V batteries.




I've seen a few examples of folks making their own batteries and I thought it looked like fun. So I'll attempt to make a carbon-something battery out of stuff I've got lying around. I've got some lead, empty pill bottles, and epsom salt. I made a simple mold for making lead rods. It held up to about 4 uses before it started really degrading from the heat.




Not sure if there is a specific concentration of epsom salt to water that works best as and electrolyte. So I just kept adding until it stopped dissolving. So here's my first result.




I got a little more Voltage after charging it up for a while. From what I've heard, the general consensus seems to be that these types of cells have a range of around 1.5V to 0.5V. I haven't gotten any measurable Amps yet, so I can't say for sure. I don't think these are going to be powering my house or car any time soon, LOL. But this has been very interesting to me so far, and I'd like to try other materials and see if I can get better results.

I hope to spend little or no money on this. I have too many other projects and hobbies that I can't afford. But I've got some other materials I can try.
- Aluminum
- Copper
- Tin/Antimony
- Steel
- Sodium Carbonate
- Sodium Bicarbonate
- Borax (Sodium Borate?)
- Sodium Sulfate
- Man, I've got lots of sodium products!
- Vineger
- Manganese Dioxide

Also, I was digging around the basement and came upon a stash of dead 6V batteries that I never got around to throwing out.




If I don't break any, I could get 40 carbon rods! And a small bucket full of Manganese Dioxide. Unfortunately, the zinc has long since degraded to zinc oxide and is unusable.

I've got lots of other chemicals around for baking, cleaning, automotive, etc... regular stuff. I don't know that they'd be any good for this sort of thing though. I might pick up some alum salt. That stuff supposedly makes good electrolyte.

Another thing you can use the carbon rods for are for making an electric forge. Get a large block of chimney insulation block and cut a large hole (about 5/8 to 2/3 the width of the block) about 5/8 - 2/3 the depth of the block. Then 1/3 of the way from the top drill two holes the size of the carbon rods at a slant towards the bottom of the hole you created. You'll want to aim about just under 1/2 way the depth of the hole. Then take some metal, place in the "now" crucible, apply high voltage to the carbon rods, and you have rabidly melting metal. Oh, you may also want to create a pour groove along the inside of the hole (but not on either side where the rods are in the block)
The nice thing about the chimney block is that it doesn't get super hot on the outside, maybe a couple hundred degrees F (or around 100C or so). A thick glove and you can handle it easily.

For the Carbon/Lead cell you created above, you need to connect several in parallel to get any noticeable amperage out of them. It's kinda like making a battery/cell from a potato or lemon.

Electric forge sounds interesting. I'm actually working on something similar but it will be more of a kiln than a forge. Perhaps I'll share it in the general section sometime.

I learned a little chemistry today. I saw a guy on YouTube mix a couple of his electrolytes together and he got better results. I tried with mine and got a precipitate. I did some research, and found out what I've made.

Started with epsom salt MgSO4 and sodium carbonate Na2CO3. Turns out they swap ions in water. So I ended up with Na2SO4 and MgCO3. Turns out magnesium carbonate is insoluble in water. That seems to be my precipitate. So what I added to my pill-bottle cell is water with sodium sulfate. I think the YouTube guy used sodium bicarbonate instead. Anyway, I think the proper chemical equation (except I can't seem to do subscripts) is: Na2CO3 (aq) + MgSO4(aq) => NaSO4 (aq) + MgCO3 (s).

These cells are supposedly chargeable, but I can't seem to get them to absorb anything. I even convinced my iMax charger that they were NiCd cells and it happily charged them at 0.1A for quite some time. Given their low capacity, I wouldn't want to charge them with any more current than that. I'm afraid I'd electrolysizeall the water. But they do seem to have steady Voltage when they sit idle. Here's my carbon/lead results so far:

Na2CO3 electrolyte: 0.4V
MgSO4 electrolyte: 0.8V
NaSO4 electrolyte: 0.9V

Haven't tried normal table salt yet. I've heard that's really corrosive to the electrodes. Though, that may be just zinc and copper, so I may try that anyway. I've also tried different concentrations of electrolyte in water. Doesn't seem to make a difference. I've also seen folks use paper or paper towels moistened with electrolyte water as a separator. Seems this should reduce internal resistance.

Anyone have suggestions of other electrolytes?

Still plan to play around with aluminum and copper for electrodes. Those along with the carbon and lead, give me plenty of combinations to try. Even though this will never actually lead anywhere, I can still see why people do it. It's been rather fun so far.

Still plan to play around with aluminum and copper for electrodes.

Click to expand...

If you haven't already, check out my posted video in the Video section. Copper/Aluminum with table salt-water, and sand.
Neat work playin with this chem stuff. It's all over my head, but I'm intrigued by the process and the results

Back to making an 18650 6V, I chose my cells and finally decided on how to wire them. I'm not sure I like this method exactly, but it works.







All bundled up with foam and it fits perfect! I've decided to wire up a TP4056 controller with Volt and Amp protection, as well as a Voltage booster and a switch. The switch will give me the option to disconnect the booster when the battery is not in use.




I originally set the booster to 6V, but I had some issue with the protection board. Turns out, running the incandescent lamp on the flashlight I was testing was triggering the Amp protection. The switch came in really handy for resetting the board.




I drilled a couple holes in the top to see the charging board's LEDs.




Test fit to make sure the switch won't interfere with the battery fitting in the lantern.




I did some math, and it turns out that boosting the Voltage was drawing too much current from the battery to run the light bulb in the flashlight I was using. Lowering it down to 4.8V (which happens to be the rating on the actual light bulb anyway) seems to make the current limiter happy. I'm less happy though, with the location of the adjustment screw inside the battery. I make an access hole for adjusting it now that the battery is all glued back together, but its pretty hard to find that tiny screw without seeing it. I'll try to address that in my next battery.




I'll have to make another before I can try them out on the lantern, but the flashlight works. It's a little washed out by the flash on the camera, but it is pretty bright. Just as bright as it has always been. I'm planning to swap out the bulb for an LED at some point. Should make Amps less of an issue.




With 9 cells in parallel, I could easily draw 5-6 Amps and not worry about them at all. I may have to reconsider using the protection board. I want the low Voltage cutoff, but 1A is a pretty severe limit for what I'm doing. I'll have to think about it for a while.

You could try potassium nitrate as an electrode, or if you like dangerous stuff, H2SO4, meaning sulfuric acid, with a molar concentration of 0.10mol/L.

For electrodes, you should try Al for the oxidizing agent,and Fe for the reductive agent. It would build quite a powerful battery.

However, to make it simpler, combining nickel and magnesium would build a 0.95V cell.

If you want to build the most dangerous one however, you could try using lithium on both electrodes, but the lithium would oxidize quite quickly.

As a separator, getting a ceramic separator would be quite good, as that would raise voltage by about 0.2V. It would quite difficult to get such a thin one however.

Well, I don't think I'll be getting that complicated very soon. Right now I'm just using whatever I can find around the house. I have enough to try 21 different combinations of electrodes, if I can find zinc. I thought I had some, but its just zinc plated stuff. I wonder if that will still work?
So far, I've done carbon/lead, carbon/aluminum, carbon/steel (I wanted carbon/iron, but I couldn't find anything that was just iron), and carbon/tin. The tin is actually lead-free solder which is 95% tin and 5% antimony. Its awful as solder, so I'm happy to use it up for this experiment.

I haven't worked on my 18650 6V batteries for a while. I'm not happy with the 1 Amp restriction of the circuit boards I bought, so I've been looking for alternatives. I think I found some but I'm a bit confused as to how they will behave. Here's the description:

The BMS is used for li-ion battery without balancing function

Features:
1) high-accuracy voltage detection circuit;
2) terminal of the charger using high voltage device;
3) Built-in three-stage over-current detection circuit (over-current 1, over-current 2, load short circuit);
4) MOS transistor can control the battery charge and discharge;

Parameter:
Over charge voltage: 4.250.05V
Over charge release voltage:4.230.05V
Over discharge voltage:2.540.1V
Maximal continuous charging current: 2A
Maximal continuous Discharging current: 2A
Over current protection: 3A
Size: L40*W4*T3mm
Weight: 10g

Click to expand...

So its advertised as 3A, but I think I'll only get 2A through it before it cuts off the current. 2A will be fine though. I only need 0.6A to run the lantern. But the flashlight uses just over 1A, so It would be nice to make batteries that are interchangeable.

I've been looking for something like this for ages. Finally found it!eBay, 5A CC/CV Adjustable

Starting out, I've always used a Volt bucker to try to revive stubborn cells.




Works ok, but you've got to sit there the whole time, bumping up the Volts to keep the Amps constant.

This fellow on the other hand, is much more automated. I had to fiddle with it at first, as there are no instructions, but I figured out the Voltage limit is set with the power in connected, then the current limit is set with the output device connected. Well anyway, this is what it looks like:




It has a couple LEDs on the lower board which indicate what it's doing, along with Volt and Amp displays. I've found the Volt display to be accurate to about 2/100s of a Volt.
Just to test it out, I'm very slowly charging a parallel set of 19650s using a 12V battery.




I also stumbled on a very comprehensive review of this device on You Tube:

This is gonna make my DIY cell charging so much easier!
(Carbon/Aluminum is the winner so far, but I've got lots more testing to do.)

I actually have 5 of these for mass charging big battery packs.

They are so awesome, mostly because I can set a max charging voltage of 4.1V, which is very useful, and what I'm using for 4 of them.

The last one is for charging up to 3.75V storage, and testing self discharge with measures over a week, for 12 weeks.