Supercapacitors instead of the battery in the car

A supercapacitor or ionistor is something between a battery and a conventional capacitor. It has many advantages that the battery does not have. Therefore, I will introduce you to a fully working prototype of a battery for an ionistor machine. With it, you can not just start the engine a couple of times, but quite fully operate the car for unlimited time.

Will need

  • Supercapacitors (ionistors) 2.7 V 500 F.

  • Balance protection fee.

This is enough for the first prototype.

First engine start test

I bought 6 supercapacitors and a balance protection board, they are sold individually for each ionistor, and sometimes there is a solid line for six pieces.

Put it all together.

The protection board eliminates the overcharging of supercapacitors with voltages higher than 2.7V, so it is almost necessary to use it if the elements are switched on in series.

Next, I soldered the terminals and installed this battery on the car. But first it must be charged with a small current of 5-7 A to the operating voltage. It took 10-15 minutes of time.

After connecting, the car started up without unnecessary difficulties, the engine worked stably, the voltage in the on-board network was kept at the proper level.

In the course of this experiment, the following advantages and minutes became clear: the battery from the ionistors quickly discharged when the ignition was turned off, namely, somewhere after 5-6 hours the voltage dropped to 10 V. It was a minus, and the plus was that even with this voltage the car was still starting, since for the ionistor any voltage is working, unlike the battery.

As a result, it was no longer possible to start the engine after one day. And I decided to fix this shortcoming in the following design.


Here is a diagram of a second battery prototype.

I will make a reservation right away: there is no solar panel and a second battery in it. It also uses a line of supercapacitors with a balanced board. Also added is a battery charge controller, a couple of switches, a voltmeter and a small 7.5AH battery itself.

The operation of the device is as follows: before starting the car, open the hood and click the top switch according to the scheme. Through a powerful 50-watt resistor with a resistance of 1 ohm, the ionistor begins to charge from the battery. It is impossible to charge directly without this resistor, since for a battery this will be equivalent to a short circuit.

Everything about everything takes 15 minutes of time. This is not critical for me. After that, you can start a car and drive. A Schottky diode is also inserted in parallel with the resistor. It serves to charge the battery after the engine is started.

And the battery is charging through the charging controller.

It is needed so that each time you do not click the power switch, but turn it on and go once: get up at the store and leave for a couple of hours. And if the ionistor starts to draw current from the battery, and discharge it below 11.4 V, then the charging controller will immediately turn it off. This will protect the battery from full discharge, which can destroy it prematurely.

The lower switch is used to connect a voltmeter to either ionistors or a battery.

Fully operational supercapacitor battery

Assembled the whole circuit in a plastic box. Temporarily natural, clean ride and try innovation.

Top view of the device.

Protective controller.

Powerful current limiting resistor.

A digital voltmeter is visible through plastic.

Install on a car instead of a standard battery.

We turn on the ignition and try to start the engine.

The motor started quickly, without any problems.

The ionistors and the battery are being charged, as indicated by the voltmeter.


Now, more about the advantages and disadvantages:


  • Unlike a battery, supercapacitors more reliably cope with peak inrush current. Start-up is more reliable.

  • Low voltage is fully operational.

  • It has a low weight, from which the whole box can easily be carried home just in case.

  • For start-up, you can charge even with batteries and calmly go on the road.


  • Big self-discharge. Of course, you can move around, but if you need to turn on the dimensions or the alarm for a short period of time, there is not enough energy for that, naturally, with the engine turned off.

Well this is what came to mind. Now about the cost. On Ali Express, super capacitors are not so expensive. And if you count them 6 and balanced protection, it will come out cheaper than an acid battery.

That’s all for me. I hope my experiment was informative and interesting for you. Good luck everyone!