Tuesday, March 12, 2013

☈ Super Capacitor Vs Car Battery ☈

Unlike ordinary capacitors, batteries store energy in a chemical reaction. And because of this the ions are actually inserted into the atomic structure of an electrode. Unlike in an capacitor, the ions simply "cling". This is important because storing energy without chemical reactions allows super capacitors to charge up and discharge much, much faster than batteries.

And because capacitors does not suffer the wear caused by chemical reactions, they also last a lot longer.


Normally if we drain our car battery to much and try to start our car it will cause more damage to the car battery and eventualy it will not charge back up to it's maximum again. However this is not true for super capacitors.

For example a capacitor the size of a D-cell battery, has a capacitance of about 20 microfarads. But if we take a similarly sized supercapacitor, it has a capacitance of 300 Farads. What this means is at the same voltage, the supercapacitor could in theory store up to 15 million times more energy. 

However a typical 20-microfarad capacitor would be able to handle as much as 300 volts, while an ultracap would be rated at only 2.7 volts. At a higher voltage, the electrolyte inside the supercapacitor starts to break down. So in reality an super capacitor have the ability to store about 1,500 times the energy of a similar sized capacitor. This would be something you would need to take into consideration in you're attempts on storing energy in a capaciator.

Supercapacitors are very effective at accepting or delivering a sudden surge of energy, and that makes them a good alternative for a regular 12v car battery.

With electric cars for example super capacitors provide the power or "boost" needed for acceleration, while a battery provides range and recharges the supercapacitor between surges. They normally also go by the name "Boost Capacitors" or "Boostcap" simply because that's their normal usage in industry. The Maxwell product line even have the name BOOSTCAP® ultracapacitors, and these are the ones you would normally find if you are searching for big capacitors.

While some electric vehicles are using super capacitors for acceleration. The devices also appear in hundreds of other applications, from cell phone base stations to alarm clocks to audio systems.

If you like to use supercapacitors instead of you're car battery they could provide power during stops (running lights, radio, air conditioner, etc.).” They would also provide power for the restart, and then be “recharged during the next interval of travel.”

Building you're own DIY car battery replacement with supercapacitors for automotive applications

So where can I really buy a +12 volt capacitor to replace a car battery?

Actually this is what you would need to do. Get 6 ultracapacitors connected together (normally they have about 2.5 Volts each)

What you would need are, 6 supercapacitors (normally they have about 2.5 Volts each)

So 2.5 Volts x 6 = 15 Volts fully charged. You could do with only 5 super capacitors giving you 12.5 Volts but it's not recommended, you need the extra volts to be there. Besides you're alternator will put out more than 12.5 volts when it's charging anyways. Most cars have some electronics that drain you're battery like the car alarm. So if you leave you're car standing for a week the supercapacitors might have drained to much and you will not be able to crank over the engine.

With 14-15 Volts you wont be having any problem starting you're car even if you leave it for 4-5 days. However any drain can be stopped with a simple solar panel to recharge the supercapacitors, so if that is done you always should always have them fully charged and ready to start you're car.

Another interesting thing replacing you're car battery with super capacitors are the weight. A normal lead acid car battery have a weight around 30 pounds. However installing supercapacitors in it's place you will actually save around 25 pounds in weight.

What all this boils down to is you will save weight = better gas milage
The ultracapacitor will charge up very quick and not load the engine as much = better gas milage
They will also probably last the entire life of the car = save you maintinance and money.
They will also prevent voltage drop when restarting the engine that could be causing aftermarket electronics to shut off like the stereo.

What About Using Lithium Batteries Instead?
Reply to a comment:

They only weigh 1.5Kg (3lbs), will stay charged for a year, survive 1000+ discharge cycles and can be fully charged in 1-2 hours. They cost around $300-500.

While it's true that the lithium battery does have some advantages over using supercapacitors. Like it can stay charged for a year, you also need to consider the life of the lithium battery (about 3-5 years max). And today the cost is about the same, today $300 will get you 6x 3000f farad super capacitors that can make you a very strong supercapacitor car battery replacement that in theory should last you over 200 years..

Here's a few things that are good to know. Porsche AG, Stuttgart was the first car maker in the world to offer a starter battery with lithium-ion technology. Weighing less than 13 lb or 6 kg, the new battery is more than 22 lb or 10 kg lighter than the conventional 60 Ah lead battery.

While the most used batteries today are rechargeable Li-ion, Li-Poly and Lithium Iron Phosphate (LiFePO4) batteries. Li-ion and LiPo batteries have a recommended per-cell safety zone between 3V (fully discharged) and 4.2V (fully charged), although they can normally discharge down to about 2.8V without any problems. Discharging below these levels may cause irreversible/irreparable damage.

Therefore, these batteries must have a built-in safety mechanisms, preventing over-discharging. Conversely, overcharging can also be very dangerous.

The Li-Po batteries have a lower number of recharging cycles than LiFePo4 (1000@0.2C rate, IEC Standard). The projected/estimated life of a Lithium-Ion battery is approximately 3 years from production.

The LiFePO4  batteries exhibit slightly different properties. The LiFePO4 is a kind of Li-Ion rechargeable battery intended for high power applications, such as EV cars , eBikes, electric bike, Power Tools and RC hobby.

The LiFePO4 batteries have more constant discharge voltage and are considered to offer better safety than other Lithium-based batteries.

Other advantages of the Lithium-based rechargeable batteries include the ability of a much faster recharge and higher discharge rates than other chemistries mentioned and usually higher number of recharge cycles (>2000@0.2C rate, IEC Standard) , meaning longer life when not fully discharged, but its energy density is lower than normal Li-Ion cell (Li-Co) LiFePO4 life expectancy is approximately 5-7 years.

The supercapacitors on the other hand can do 10 million times of charging/ discharging. The supercapacitor can be charged/discharged more than 20 times a day for 136 years of continuous usage. It is about 1000 - 2000 times of Li-Ion/Ni-MH/ Ni-Cd batteries. And to fully charge a supercapacitor takes seconds instead of hours for a lithium battery.




This can also be read on ☈ Ultra Capacitors VS Car Battery ☈

Read the full specifications to the most common 2600 farad Boostcap BCAP0010 supercapacitor below
☈ BoostCap BCAP0010 2600 farad Specifications ☈

12 comments:

  1. A lithium automotive starting battery is a much better option. They only weigh 1.5Kg (3lbs), will stay charged for a year, survive 1000+ discharge cycles and can be fully charged in 1-2 hours. They cost $300-500.

    ReplyDelete
  2. While it's true that the lithium battery does have some advantages over using supercapacitors. Like it can stay charged for a year, you also need to consider the life of the lithium battery (about 3-5 years max). And today the cost is about the same, today $300 will get you 6x 3000f farad super capacitors that can make you a very strong supercapacitor car battery replacement that in theory should last you over 200 years..

    Here's a few things that are good to know. Porsche AG, Stuttgart was the first car maker in the world to offer a starter battery with lithium-ion technology. Weighing less than 13 lb or 6 kg, the new battery is more than 22 lb or 10 kg lighter than the conventional 60 Ah lead battery.

    While the most used batteries today are rechargeable Li-ion, Li-Poly and Lithium Iron Phosphate (LiFePO4) batteries. Li-ion and LiPo batteries have a recommended per-cell safety zone between 3V (fully discharged) and 4.2V (fully charged), although they can normally discharge down to about 2.8V without any problems. Discharging below these levels may cause irreversible/irreparable damage.

    Therefore, these batteries must have a built-in safety mechanisms, preventing over-discharging. Conversely, overcharging can also be very dangerous.

    The Li-Po batteries have a lower number of recharging cycles than LiFePo4 (1000@0.2C rate, IEC Standard). The projected/estimated life of a Lithium-Ion battery is approximately 3 years from production.

    The LiFePO4 batteries exhibit slightly different properties. The LiFePO4 is a kind of Li-Ion rechargeable battery intended for high power applications, such as EV cars , eBikes, electric bike, Power Tools and RC hobby.

    The LiFePO4 batteries have more constant discharge voltage and are considered to offer better safety than other Lithium-based batteries.

    Other advantages of the Lithium-based rechargeable batteries include the ability of a much faster recharge and higher discharge rates than other chemistries mentioned and usually higher number of recharge cycles (>2000@0.2C rate, IEC Standard) , meaning longer life when not fully discharged, but its energy density is lower than normal Li-Ion cell (Li-Co) LiFePO4 life expectancy is approximately 5-7 years.

    The supercapacitors on the other hand can do 10 million times of charging/ discharging. The supercapacitor can be charged/discharged more than 20 times a day for 136 years of continuous usage. It is about 1000 - 2000 times of Li-Ion/Ni-MH/ Ni-Cd batteries. And to fully charge a supercapacitor takes seconds instead of hours for a lithium battery.

    ReplyDelete
  3. This comment has been removed by the author.

    ReplyDelete
  4. This comment has been removed by the author.

    ReplyDelete
  5. What is your solution to maintaining a charged capacitor when the car is not in use?

    ReplyDelete
  6. Hello Jacob,

    There are a few things that you can do to solve the car capacitors draining, the easy way would simply be to connect a small solar panel that will help keep everything charged if the car is not in use for a long time (like a week or two). You can get a 12V 4.5W Portable Power Solar Panel that would be more than enough to keep everything charged and these small solar panels are no more than 10-20 dollars and are small enough to fit on the dashboard.

    But before you do that the first thing I would check is to see if there are any unnecessary electronics that are draining the power when the car is not in use. If the power is draining overnight then you could have some electronics that are draining the power much more than they really should. This can be things you won't notice like a glove box, trunk, and under hood lights that do not automatically turn off. Clocks, security alarms and also radio presets can cause the same issues. If the alternator get warm when the engine is cold, it could also be shorted or leaking diodes in the alternator that are causing the drain.

    There is a good video on the topic by EricTheCarGuy on youtube that you can watch if you suspect this is something that's happening to you, it will help you find out if anything is draining the power.
    How To Perform a Parasitic Draw Test - EricTheCarGuy www.youtube.com/watch?v=KF1gijj03_0

    ReplyDelete
  7. Great article and alternative solution to traditional heavy lead battery. Can the supercapactors be damage from over charged by the alternator if you left it plug in while driving for miles and miles? If so, what would be the solution to this problem?

    ReplyDelete
  8. Hello Danny, the answer to your question is, no not really. The imporant thing is to make sure the voltage that you are charging the capacitors with stays at the same level the supercapacitors are rated for.

    Take the specifications for the BOOSTCAP Ultracapacitor BCAP0010 that is rated for 2.5 volts. When you have six of these supercapacitors connected instead of a traditional lead battery you have 6(supercaps) x 2.5(rated voltage) = 15 volts.

    So as long as the alternator charges at around 15 volt (normal car alternator output) then there is no problem or damage. These particular supercapacitors can also take a surge of 16.8 volts, so even in the case of an unlikely event there would not be any damage.

    If you for some reason do have an alternator that output more voltage than 15 volts, perhaps you drive a truck that use a 24 volt system and alternator. Then the simple solution would be to instad of using six supercapacitors like with a 12 volt system, use ten supercapacitors. 10 x 2.5 volts = 25 volts.

    ReplyDelete
  9. 2016=Maxwell now has 3.0wvdc at 3000F.
    Hey, the working volts is creeping up ...
    http://www.maxwell.com/products/ultracapacitors/k2-3-series

    ReplyDelete
  10. ’m trying myself to build a hybrid of a battery and a capacitor pack.

    The reason is weight balance in a car with forward-biased weight distribution. Battery is at the extreme front end, outside the wheelbase. Mass outside the wheelbase, even if very small, changes the polar moment of inertia. Mass inside of wheelbase doesn’t. About 34 kg (75 lbs) of non-essential parts were already moved backwards.

    Th project should use a small motorcycle battery (acid or AGM type) of 4 to 11 Ah (weighs 2-4 kg / 4.4 – 8.8 lbs) for current reserve, in parallel with a six pack of capacitors. Either Maxwell 350F (58 farad total) or Nippon 700F (116 farad total). Starter motor needs about 160 A for a start, as rated to 2 kW (158 A at 12.6 volts).

    This should result in a hybrid battery of no more than 5 kg / 11 lbs.

    ReplyDelete
  11. They are not so good in Diesel cars where glow plugs require a significant amount of energy, as well as the fact that diesel engines require more energy to turn them over anyway.

    Also, supercaps are still very expensive.

    ReplyDelete
  12. Well at $16.05 per Cap and only need six of them here in Arizona where car batteries die after 3 years. So an extra $25.00 to to last if atleast 6 years well worth it.
    Here is a link: https://jet.com/product/detail/d2584103a2984fefb042bc0a82113135?jcmp=pla:ggl:gen_electronics_a3:circuit_boards_components_passive_circuit_components_a3_other:na:PLA_348103020_24129139860_pla-161674411260:na:na:na:2&code=PLA15&ds_c=gen_electronics_a3&ds_cid=&ds_ag=circuit_boards_components_passive_circuit_components_a3_other&product_id=d2584103a2984fefb042bc0a82113135&product_partition_id=161674411260&gclid=Cj0KEQjw4_DABRC1tuPSpqXjxZwBEiQAhMIp6_VPfYTGXABOq_r2TjgYhGK2bOpICguhleq_VpYsYTwaAmEc8P8HAQ&gclsrc=aw.ds

    ReplyDelete