vehicle battery supercapacitor kit ideas

[Jamie M]

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:

https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878

(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

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

3. 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.

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

cheers,
Jamie

 

[Whoey Louie]

On Tuesday, January 21, 2020 at 3:35:05 PM UTC-5, Jamie M wrote:

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:

https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878

(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

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

3. 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.

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

cheers,
Jamie

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?

 

[Dave Platt]

In article <r07vhb$uqg$1@gioia.aioe.org>, Jamie M <jmorken@shaw.ca> wrote:

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?

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.

 

[Jamie M]

On 2020-01-21 1:41 p.m., Whoey Louie wrote:

On Tuesday, January 21, 2020 at 3:35:05 PM UTC-5, Jamie M wrote:
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:

https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878

(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

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

3. 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.

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

cheers,
Jamie

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?

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:

https://imgur.com/a/a8DPG5u

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

 

[Sjouke Burry]

On 21.01.20 23:55, Jamie M wrote:

On 2020-01-21 1:41 p.m., Whoey Louie wrote:
On Tuesday, January 21, 2020 at 3:35:05 PM UTC-5, Jamie M wrote:
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:

https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878

(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

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

3. 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.

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

cheers,
Jamie

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?



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:

https://imgur.com/a/a8DPG5u

Short link turns up an error.

 

[Rick C]

On Tuesday, January 21, 2020 at 5:55:49 PM UTC-5, Jamie M wrote:

On 2020-01-21 1:41 p.m., Whoey Louie wrote:
On Tuesday, January 21, 2020 at 3:35:05 PM UTC-5, Jamie M wrote:
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:

https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878

(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

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

3. 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.

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

cheers,
Jamie

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?



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:

https://imgur.com/a/a8DPG5u

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

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.

https://www.walmart.com/browse/batteries-and-accessories/car-batteries/91083_1074765_1104292_5926828?fitmentParams=partTypeId%3A2476%23baseVehicleId%3A18440%23SubModel%3AALL%23EngineBase%3A1113

The Walmart brand was $50.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[Jamie M]

On 2020-01-21 3:02 p.m., Sjouke Burry wrote:

On 21.01.20 23:55, Jamie M wrote:
On 2020-01-21 1:41 p.m., Whoey Louie wrote:
On Tuesday, January 21, 2020 at 3:35:05 PM UTC-5, Jamie M wrote:
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:

https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878


(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

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

3. 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.

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

cheers,
Jamie

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?



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:

https://imgur.com/a/a8DPG5u

Short link turns up an error.

Hi,

Here it is in the truck:

https://imgur.com/a/4xWCpSt

cheers,
Jamie

 

[Jamie M]

On 2020-01-21 3:27 p.m., Dave Platt wrote:

In article <r07vhb$uqg$1@gioia.aioe.org>, Jamie M <jmorken@shaw.ca> wrote:

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?

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.

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

 

[Michael Terrell]

On Tuesday, January 21, 2020 at 6:28:22 PM UTC-5, Dave Platt wrote:

In article <r07vhb$uqg$1@gioia.aioe.org>, Jamie M <jmorken@shaw.ca> wrote:

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?

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.

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

 

[Michael Terrell]

On Tuesday, January 21, 2020 at 4:41:39 PM UTC-5, Whoey Louie wrote:

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?

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

 

[Jamie M]

On 2020-01-21 5:48 p.m., Michael Terrell wrote:

On Tuesday, January 21, 2020 at 6:28:22 PM UTC-5, Dave Platt wrote:
In article <r07vhb$uqg$1@gioia.aioe.org>, Jamie M <jmorken@shaw.ca> wrote:

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?

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.

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

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

 

[Jasen Betts]

On 2020-01-21, Jamie M <jmorken@shaw.ca> wrote:

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:

https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878

(16V-83F)

http://www.samwha.com/electric/product/list_pdf1/DB.pdf

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

--
Jasen.

 

[Jasen Betts]

On 2020-01-22, Michael Terrell <terrell.michael.a@gmail.com> wrote:

On Tuesday, January 21, 2020 at 6:28:22 PM UTC-5, Dave Platt wrote:
In article <r07vhb$uqg$1@gioia.aioe.org>, Jamie M <jmorken@shaw.ca> wrote:

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?

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.

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

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.

 

[Michael Terrell]

On Wednesday, January 22, 2020 at 1:02:40 AM UTC-5, Jasen Betts wrote:

On 2020-01-22, Michael Terrell <terrell.michael.a@gmail.com> wrote:
On Tuesday, January 21, 2020 at 6:28:22 PM UTC-5, Dave Platt wrote:
In article <r07vhb$uqg$1@gioia.aioe.org>, Jamie M <jmorken@shaw.ca> wrote:

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?

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.

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

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.

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 Volts. Delco was aware of the problem in the early '60s. The first item after the power lead was a 'Spark Plate' which was a very thin piece of double sided 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 capacitance values in automotive systems, but only after a large filter choke.

 

[bilou]

On 21/01/2020 21:35, Jamie M wrote:

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:

https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878


(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

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

3. 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.

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

cheers,
Jamie

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.
Capacitor is a 1000 ÂľF x 16 V in my case.
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.

 

[Jamie M]

On 2020-01-23 3:08 a.m., bilou wrote:

On 21/01/2020 21:35, Jamie M wrote:
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:

https://www.ebay.com/itm/16V-83F-Farad-Capacitor-Super-Capacitor-2-7V-500F-With-Protection-Board-Module/223685920878


(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

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

3. 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.

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

cheers,
Jamie

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.
Capacitor is a 1000 ÂľF x 16 V in my case.
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.

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