Lifetime Capacitor, battery combo

I changed to lifepo4 long ago.

 

I mean to a larger lithium battery over the capacitor idea.

 

I'm no expert here, and OP seems to be pretty knowledgeable with 12v auto, however this seems like a very expensive, overly complicated solution to a rather simple "problem", that some could argue isn't even a problem. OP must be an engineer, no offense haha.

 

i am still using my OEM battery as a second for charging my wife’s (and my) toys

 

For now, 16 AWG wire yes. Which isnt an issue really because the small batt does very little work during startup. This last test was just with the Cap drained to 9v. So recharging that is no big deal. Next test is to drain both (batt and cap) and measure amps to and fro between them. See if wire gauge is an issue. There is some battery protection built into the small blue/red batt. It can only dump like 20 amps at a time so I dont think wire will be issue. If so, simple resister will limit the amps.

 

Modern electronics, aka computer/ecm have a certain voltage they need to turn on, that voltage is regulated by a transformer so only a constant (say 5 volts) is output to the ecm, no matter what battery volts are.

 

He is either very knowledgeable. Or very reckless. Only time will tell.

 

I thought that engineers were supposed to be practical? Maybe he's a physicist. OP, that tie-down of yours really needs some work.

 

Because if I ever end up with a dead capacitor, it can be fully charged in like 5 minutes to get me going and can be FULLY charged and discharged like 20,000 times. Which means it lasts forever in my use case. Plus Is not affected by cold or heat.

One can not find a solution without inventing a problem first. lol

We'll see.
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And wow, everyone jumps all over the tie down. Its temporary until I move the small batt inside or into the bed cubbie holes once I'm done testing the concept. This is no different than all you yahoos putting wenches, 300 lb bumpers, taller suspension, bigger tires on your trucks. Did you ask an engineer first! That's way more out of 'engineered spec' than my tie down. lol j/k

 

I would never put a wench on or in my truck! Besides, my wife would divorce me if I did!

 

Zip ties are stronger than a bungee that some people use. Look at my redneck shit, mad woodworking skills.

 

The nice thing about batteries, is they are both a source of a lot of power, but are also self-limiting in the amount of energy they will put out due to internal impedance. This is the CCA rating. It makes them safer than they might be otherwise, being inherently dangerous in so many ways. A battery cannot discharge it’s entire charge, instantly, even when directly shorted.

The crazy thing about capacitors, is they have no almost no internal impedance. That means that if you short anything out, it going see a huge surge of current that will drain the entire charge stored in the capacitor. If you short out a large “starting capacitor” in your truck, with say a wrench, you may or may not die, but you are guaranteed to shit your pants. Also, anyone within 20 feet will also either die, or shit their pants.

that set-up scares me OP. Be careful dude.

 

Did someone fall for the 40th Anniversary sale Oil fill cap?

 

Yeah, but at least he has a multifunctional zombie apocalypse survival power source- a field welder, jump starter, AED and electrofisher all in one!

 

You're thinking Civil. OP is probably Mechanical, we're all nutz. Cept those aviation guys, the lawyers scared them straight.

 

What about when the temps are below 0, will it still work ?

 

Interesting idea, though OP already spent more than most on batteries for the lifetime of the truck.

 

Yup, the cap can dump it all at once but has like 1/10 the total energy reserve that a batt has. But it would be a couple seconds of 'Big trouble in little China' if shorted. So I'm careful. Also been looking for like a 500amp fuse or resister to make it safer on the 'starting' side. Nothing found to my liking yet.

Not affected by the cold. Same uhmmph hot or cold. According to the stats anyway. But it rarely gets below freezing here., so I have no way to test that.

That lifetime is my lifetime, not the truck's. That's a group 51 size capacitor. (Honda civic size). Will go in any future vehicle.
Price is worth it to me to prevent cable corrosion, battery tray corrosion, fender corrosion.

 

So what's the purpose of this? Preventing battery terminal corrosion?

Solid A for effort, but as others have pointed out, it comes with a significant danger curve.

I made my own 100ah LiFePo4 pack out of surplus 32650 cells.

 

This scares me about capacitors too, they are not to be trifled with. But, one mitigating factor here is that its only 12V, so the resistance of your skin provides a pretty good barrier to getting shocked, same reason you don't get 100 amps to the heart when you put your arms across a car battery.

I still have mixed feelings on the project. It feels like a lot of risk of failing in certain scenarios for very little gain. I think there is a good chance the trucks electronics will be fine - automotive systems are designed to manage a variety of different funky transient scenarios (for an example, go look up "alternator load dump"). But, that doesn't mean Toyota tested against this particular scenario, so its really hard to say.

I think the biggest issue in my mind is the lack of reserve capacity. There are plenty of times where just having a big bank of electricity sitting under the hood is very handy.