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vehicle battery supercapacitor kit ideas

Hi,

I have installed and tested a supercap on a V8 engine as an experiment to avoid buying a new lead acid battery:

Here is the supercap I used:

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(16V-83F)

I soldered ring terminals to it and bolted it directly to the 12V battery (in parallel with the battery).

Before installing the supercap the battery was weak and turning the key would not even turn the starter motor, I am guessing there is some form of undervoltage lockout in the starter motor circuit, as the battery voltage didn't dip that far below 12V, maybe down to 10V.

Once the supercap was installed the weak battery+supercap was floating around 12.3VDC, and the supercap had more than enough power to start the V8, after starting a few second later the alternator kicked in and quickly (maybe 1 second) charged the supercap to over 14VDC. I noticed a slight squeal in the alternator belt during the supercap charging once, but not in later testing.

The parasitic draw of the supercap on the battery is quite low if I measured correctly I think it is quite a bit below 1mA to hold the supercap at ~12.3V.

Since this seems to work and probably won't wreck the alternator, I won't try these improvements, but maybe for an "off the shelf" kit that people could buy instead of replacing their dead battery they would be a good idea:

  1. add a 50A+ fuse in series with the supercap

  1. add a high power resistor to charge the supercap from the battery/alternator.

  2. alternatively to #2, add a high power (12V at 10A+) switcher to charge the supercap from the battery/alternator. This switcher should have low quiescent current and essentially no current draw when the supercap is charged above a certain voltage, to avoid draining the battery.

  1. Add a high power (50A+) diode between the supercap and battery/alternator to discharge the supercap when starting the vehicle.

cheers, Jamie

Reply to
Jamie M
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Great idea. $35 for a cap to bandaid a failing battery, plus whatever else it took to put it together. How much was a new battery?

Reply to
Whoey Louie

Hi,

I used 2 rolls of electricians tape, some packing foam, heatshrink tubing and a bit of solder. Taped over the foam to make a shock absorbing enclosure. Here is a picture before putting it in the vehicle:

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The supercap has some advantages over a new battery I think. ie the cold weather cranking amps are reduced with a battery but not really with a supercap. Also it is lower maintenance, since a weak battery is fine, no need to recharge it or add electrolyte? :)

Also the voltage stability is improved when a supercap is used, except for the initial draw after starting to recharge the supercap.

New batteries are maybe 4x the price.

cheers, Jamie

Reply to
Jamie M

Short link turns up an error.

Reply to
Sjouke Burry

Hardly. I paid something like $70 for a battery for a pickup a year ago. If the supercap was a practical solution they would be sold as such or included in cars.

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The Walmart brand was $50.

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  Rick C. 

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Reply to
Rick C

Hi,

Here it is in the truck:

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cheers, Jamie

Reply to
Jamie M

That's fine, up until the point at which the lack of maintenance results in the battery developing shorted cells. At that point, you end up with a permanent drop in the battery voltage, and thus a loss of cranking power that the supercap can't compensate for.

Reply to
Dave Platt

At that time, I think it is good to toss the battery, and charge the supercap from the cigarette lighter socket. If the battery ever gets shorted cells I will post results of that experiment.

cheers, Jamie

Reply to
Jamie M

I bought a new battery for my pickup truck for $49.95 a few weeks ago at a Rural King store.

Reply to
Michael Terrell

Or the battery develops and open cell, and the voltage across the capacitor goes high.

Reply to
Michael Terrell

The supercap is rated for 16V, I tested it to over 15.5V, the over voltage protection dissipates into SMT resistors for each of the 6series

2.7V supercaps. This weak battery drops to 12.3V quickly with a small load, so I'm not too worried about it going above 15.5V.

cheers, Jamie

Reply to
Jamie M

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With the blue wrap they might be counterfeits. also 65 degrees centigrade is a worry in an automitive application.

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  Jasen.
Reply to
Jasen Betts

I think the regulator will be fast enough to prevent damage to the capacitor. assuming a 100A alternator it'll take most of a second to put a volt onto that capacitor.

--
  Jasen.
Reply to
Jasen Betts

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itor goes high.

Have you ever looked at the battery of a running vehicle? The battery was a very low ESR, compared to a capacitor, yet you can see spikes over 24 Volt s. Delco was aware of the problem in the early '60s. The first item after t he power lead was a 'Spark Plate' which was a very thin piece of double sid ed PC board that would arc over at 50 Volts. The electrical system is nasty , especially the inductive loads and their back EMF. I have used high capac itance values in automotive systems, but only after a large filter choke.

Reply to
Michael Terrell

Hi I applied successfully your idea on a much smaller scale to a remote door bell 433MHz transmitter. It should work for TV remote too.

It allows still using the 12 years old and dead original battery . Slow charging the capacitor with a small solar panel is the next step.

Reply to
bilou

That sounds interesting, would be good to have a solar panel in a car to charge the supercap too maybe. There are lots of youtube videos about putting supercaps in cars, some don't even use a battery, but the supercap I have drops in voltage too quickly for that to work.

cheers, Jamie

Reply to
Jamie M

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