I’ve been researching Salt Water Batteries for the past week or so. Im rained in now, so might as well learn how to build a prototype today.
I have a one month plan to:
Light an LED
Run a small motor
Charge a mobile.
Charge a laptop.
Run a medium sized fan.
Run a 10 watt Marshall amplifier.
Using a salt water battery setup.
I made a scrappy research document here:
I will make the first electrodes out of aluminium and copper, but hope to graduate to graphite and magnesium.
If anyone has any ideas, please let me know.
NOTE: 1) I understand that Salt Water batteries are not as efficient as lithium, and may end up ten times the size of a regular battery. However, there are many, many benefits. They’re being produced by many companies now.
Tons of good videos on youtube, from DIY set ups, to commercial rigs.
Regarding charging; From what I’ve seen, salt water batteries seem to get a small voltage from the materials themselves.
You can get 0.5 volts from most materials. Graphite plus magnesium (the best combination) gets you nearly 2 volts. Easily enough to run a light or (closer to 5 volts) charge a mobile phone. There are many videos on youtube.
Charging a phone is just a cool gimmick. I’d like to make something bigger.
Once you link a few cells together in series, you can get higher voltages, and charge a laptop, or a small fan. Yes, the batteries are 10x bigger, but they are environmentally friendly, and liberating on many practical levels.
People are powering their farms from huge, commercial units. There are many vids in the doc I linked.
Your Shovel Guitar is the talk of the town, BTW. People are almost queuing up to see it. I have many stories. Looking forward to making an upgrade next time I have some spare cash.
If you talk me through the practicalities of making a salt water battery display, the HHC roadshow will get even better. I hope to power lights and a fan within a month.
Do you know where I could buy magnesium or graphite rods/electrodes?
I know I can get graphite from pencils.
This guy has a fairly solid design. He’s using dirt, not salt. And just nails and copper as Cathode/Anode pairs. You couldn’t charge more than an LCD device with a battery his size… but what he built can be scaled. Multiple racks of ice-trays hooked in series could be good.
There are people getting well over 100 volts in some videos.
Having thought about it, his design is one of the best out there. It also dispenses with the issues of sloshing water, and other salt water issues.
Imagine powering a small marshall amp from something like this.
Electricity is induced when two dissimilar alloys are in the presence of an electrolyte. You would improve upon this model by having a copper rod, your zinc coated bolts (galvanized) in each of the cells (cubes) then connecting them in series until the desired voltage is reached (may have to increase the number of cells under a load) then connect the same about in parallel to increase the amp hour rating of each earth battery so that is can power useful things (chargers ect.) You might also introduce a bit of salt water (an electrolyte) to improve conductivity and the electrolysis process.
So metal blends touching something that has electrolytes (or heat)?
You may consider looking up “the Seebeck effect”. Fascinating stuff
Yes you create electricity when you stick electrodes into some solution. The solution can be lemon, potatoes, or whatever.
The key though is the reaction wont last forever. You gotta put electricity into it to charge it. Otherwise it gets extremely expensive replacing chemicals.
Ha, yes. Graphite seems to be best. Is that on Taobao or something? I’d prefer to source everything from a local suidian, or Guanghua, in Zhongxiao Xinsheng.
You’re right that the reaction eventually ends, and that is a minor hassle. People have come up with various hacks.
Im patient enough to change the dirt every couple of days, if I managed to run a small amp. That would be damn useful, cos it’d mean I could play on a proper amp outside.
From the ice-cube tray video, he says this in the description:
TO RECHARGE THE BATTERY; just add 1 or 2 teaspoons of water to each “cell” and the battery will be “recharged”. for increased voltage make more than one battery and hook them together.
The salt water out door are simply there to conduct, allow in exchange. Adding water is not “recharging”.
It’s an interesting challenge as a project but economically pointless unless you’re sourcing the metal bits from scrap
Water is hydrogen ash. It has no energy content, in fact it takes a LOT of power to turn water into hydrogen, and to get energy back you’re wasting a lot of it from making it, compressing it, transport and all that.
If you want power for running stuff, solar panel is going to work much better. Then a battery pack, perhaps LiFe pack that’s cheaper than traditional lithium for nighttime use is going to be better.
Lemon/citric acid with zinc and copper electrode can work, however it won’t give much power.
Even if saltwater battery works, it would still require you to put energy into it to hold a charge, but believe me, I’ve done it before. What you will end up with is a mixture of sodium chlorate, sodium hydroxide, sodium hypochlorite. The solution is going to be incredibly caustic, and the cathode needs to be made from grade 2 titanium, while the anode needs to be made from saltwater chlorination anode (we call this mixed metal oxide, it’s a titanium mesh covered in platinum group metal oxides). You get energy out of this by mixing the resultant sodium chlorate with a fuel, and light it and it goes BOOM!
Stick with known good design if you want DIY rechargable battery, such as sulfuric acid and lead electrode. But lead acid battery absolutely SUCK for constant drain, and self discharges fairly quickly (which is why your car battery dies if you left a head light on, rendering you a car that won’t start).
Seriously, 18650 cells are not that expensive, and they’re really great at what it does. Hook it up to solar cells to charge them.
