Ultracapacitors parallel to houe battery.

[stevensuf]

I was just watching a video on ultracapacitors, the guy had replaced his start battery in his car with a capacitor bank, but also was using them in parallel with his house batteries , the reason being they help with high start loads, eg motors etc when running his inverter, reasoning it was extending his battery life by a fair extent by reducing damage done by high demand loads.



Anyone think there is any truth in it? they are cheap enough nowadays? worth an experiment?

[Nicholson58]

Probably reduce the high draw as the starter is engaged.

[a64pilot]

They are sold very often to people who put together car stereo’s that just make noise, in other words very high power bass producers, not music.

They are snake oil as a battery is in effect one truly massive capacitor.
You would be much, much better off adding another battery.
Plus I believe caps discharge is extremely short, like a strobe, things lie starters and windlasses etc are much longer duration.

My opinion of course

[skipmac]

Unless there is something new in capacitor technology I don't see how they would completely replace a starting battery. Capacitors leak down their charge rather quickly so would be dead within hours or even minutes after they're charged so worthless for starting an engine in normal usage

[DeepFrz]

Originally Posted by skipmac

Unless there is something new in capacitor technology I don't see how they would completely replace a starting battery. Capacitors leak down their charge rather quickly so would be dead within hours or even minutes after they're charged so worthless for starting an engine in normal usage

" A supercapacitor (SC), also called an ultracapacitor, is a high-capacity capacitor with a capacitance value much higher than other capacitors, but with lower voltage limits, that bridges the gap between electrolytic capacitors and rechargeable batteries. It typically stores 10 to 100 times more energy per unit volume or mass than electrolytic capacitors, can accept and deliver charge much faster than batteries, and tolerates many more charge and discharge cycles than rechargeable batteries. "

Tesla must find them interesting as they have bought Maxwell. Speculation is that they will be used in the Tesla Semi which is due to go into production in 2020.

[dougweibel]

I did some research on ultracapacitors a few years ago trying to spec one that could replace a battery. They can be useful for meeting a very short peak load but they can't come close to competing with a battery for energy storage. If you actually have spike loads that are shortening the life of your batteries then perhaps they would be useful but I expect that is an unusual case. Start batteries are designed to deal with the load of starting an engine.

[a64pilot]

I believe there have been some hybrid race cars that harness tremendous energy during braking, to sort of launch the car out of the turn just a few seconds later.
I believe they have used super capacitors to do this.
But that’s huge loads in both directions and short durations, something that would be tough on a battery.
I think maybe Porsche may be using the Williams flywheel now? Seems you can dump more power into a flywheel in a shorter duration into a flywheel than a super capacitor?

[DeepFrz]

Originally Posted by a64pilot

I believe there have been some hybrid race cars that harness tremendous energy during braking, to sort of launch the car out of the turn just a few seconds later.
I believe they have used super capacitors to do this.
But that’s huge loads in both directions and short durations, something that would be tough on a battery.
I think maybe Porsche may be using the Williams flywheel now? Seems you can dump more power into a flywheel in a shorter duration into a flywheel than a super capacitor?

Just a guess because I have no knowledge but I would suspect that overcoming the inertia of a flywheel, plus the mass and gyroscopic effect would put a flywheel in second place behind Super Caps.

[AedanC]

Formula 1 teams are using both at the moment, https://en.m.wikipedia.org/wiki/Kine...ecovery_system

[cal40john]

Self discharge weeks to months depending on which of the 3 technologies you use.
Capacity 5-10% of Lithium batteries per weight (milliWattHours/gram).
Can supply 2-6 times the power per weight (Watts/gram).

https://en.wikipedia.org/wiki/Supercapacitor

For something like a car that you don't expect to sit for weeks seems like it would work to replace a battery.

[Rapanui]

I have been considering for some time adding a large car type 'boom box' capacitor at my 12v house panel. Very occasionally like maybe 2 or 3 times a week, my autopilot drops into standby, and the only reason I can think of is that there has been a momentary volt drop probably when the fridge starts. Not a super capacitor but something like 1-2 Farads should do it to reduce the voltage dips. I cannot see any downsides and there should be a positive gain.

[a64pilot]

Originally Posted by DeepFrz

Just a guess because I have no knowledge but I would suspect that overcoming the inertia of a flywheel, plus the mass and gyroscopic effect would put a flywheel in second place behind Super Caps.

Depending on how the flywheel was oriented, It’s inertia may well be an advantage. Position it so that it resists roll?
I think Porsche who has sort of led the hybrid race car thing, started out with Supercaps. And has abandoned them in favor of the flywheel.
I don’t know anything about them either, but would suspect magnetic coupling and running in a vacuum.

I’ve not kept up with auto racing though so I may well be wrong.

[a64pilot]

Originally Posted by Rapanui

I have been considering for some time adding a large car type 'boom box' capacitor at my 12v house panel. Very occasionally like maybe 2 or 3 times a week, my autopilot drops into standby, and the only reason I can think of is that there has been a momentary volt drop probably when the fridge starts. Not a super capacitor but something like 1-2 Farads should do it to reduce the voltage dips. I cannot see any downsides and there should be a positive gain.

The downside is money and maybe a fire hazard.
If’s very unlikely that your fridge is dropping bank voltage much at all, it’s much more likely that you have a loose ground or wiring that is too small.

You have a battery bank that is capable of providing short time duration amps likely measured in the thousands, and your 5 or 6 amp fridge compressor is causing a significant voltage drop?

For whatever it’s worth my B&G plotter occasionally alarms on voltage drop when there is no such voltage drop, I even ran new 10Ga wiring to no avail, I finally just disabled that alarm.

[DeepFrz]

Just a hunch but I have a feeling that Formula 1 will be all electric in the not to distant future. I'm really interested in what Tesla will use them for.

Originally Posted by Rapanui View Post
I have been considering for some time adding a large car type 'boom box' capacitor at my 12v house panel. Very occasionally like maybe 2 or 3 times a week, my autopilot drops into standby, and the only reason I can think of is that there has been a momentary volt drop probably when the fridge starts. Not a super capacitor but something like 1-2 Farads should do it to reduce the voltage dips. I cannot see any downsides and there should be a positive gain.

Have you run separate wiring from the main power bus to your autopilot or is it wired from your main switch panel? If from the panel I would suggest you try running power from the main bus bar to the autopilot.

[a64pilot]

Originally Posted by DeepFrz

Just a hunch but I have a feeling that Formula 1 will be all electric in the not to distant future. I'm really interested in what Tesla will use them for.

I don’t follow racing anymore, but I believe there is a formula electric or something similar.
My SWAG is Tesla would use the Caps to get the truck broken loose if you will, to get it moving from a stop, normally Caps are only good for a very short time.
The best example of what caps are good for is I think a Camera strobe, very short duration high current.