Ricky327

Alot of member here have noticed the big 1F question kept comming up. Newbies come and ask the same question over and over again. No one has really proved that this circuit can survive a crank.

So for those who have built one, please post your success story so we can point this thread to the newbies whos needing help.

Exact setup details, inverter, PSU, m/b used...etc.

Cheers

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Ricky327

Wow 41 views and not a sausage?

Anyone comming forward?

SjLucky

I think they are too scared to post...

they need to drink like me... that way fear has nothing to do with posting it just has to do with weither or not you feel like it

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robiewp

I couldn't tell you who but someone was kind enough to post the calculations. It came out that the 1f should be able to power the mini itx system for 1/4th seccond of cranking. Not enough if you ask me!

I'm a HUGE fane of the seccond battery with an isolator circuit that kills power durring cranking (and in my case engine off aswell). 1fs are expensive too! my rig cost me less than 50 bucks and it can run my computer for over an hour.

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car computer rev 5: 8" lilliput and usual suspects

SjLucky

Im a big fan of the second battery too

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Ricky327

It was me who posted that calculations, good old physics book it was

I started this thread to clear things up because that damm 1F question kept bothering me

Ricky327

Im a big fan of second battery too,

I bought 12V 0.8Ah, 12V 2.8Ah and 2x6V 1.2Ah

The plan with the 2 x 6v 1.2Ah was to put them in series side by side in a low profile case...disnt work as I expected

robiewp

at places like U do it electronics you can get really nice low profile 12v (13.blah)batteries. I was able to meet the 'run your headlights for 1/2 hour' spec in converting a dirtbike with two batteries zip-tied to the inside of my leadlight casing.

I, on the other hand, have an SUV and no problem carrying a seccond full size battery

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none

Nobody has tried a 1F cap, that wasn't the idea. Someone mentioned a 1F cap when someone else said the 2200uF caps wouldn't last long enough - neither poster having tried anything (and missing the point btw.)

The tank circuit doesn't need to power the whole setup for any time at all - it's just there to smooth out the voltage dips. The calculations being thrown about are irrelevant. Capacitors aren't meant to fully power things, but they are more than capable enough to smooth an engine-cranking voltage dip to the point that a well designed and efficient PSU won't "tank."

The pw60/70/120 and ITPS combo are not efficient at all.

Ricky327

Ok...maybe I misunderstood what tank really meant :

So that tank circuit was just there to smooth out the "AC" components of the supply during cranking. Just as found in a power supply circuit where you have a smoothing capacitors...it will not keep the 12V during cranking.

If smoothing was all needed then that diode shouldnt be there at all as the voltage never goes negative.

I thought the whole idea was to survive a crank due to heavy load from the starter motor?

Correct me if Im missing something here

none

Yes that is what it is supposed to do, but it doesn't need to supply the full 12v - the starter doesn't take ALL the juice. Smoothing is all that is needed with a good dc-dc PSU.

Not sure what you mean by "AC" - I'm talking about dc-dc PSUs here.

Ricky327

AC components = the waves on top of the DC voltage, noise, hums whatever mixed on a DC.

What I meant was to smooth any dirty bits on the DC and keep it 100% DC.

Ok no more confusion

shakes

i'm still waiting on the proof ... i've had enough of people saying "yeah man it works" ... do it ... and if it works post the details so we can close the books on this one.

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Ricky327

Well...

From what I was told this 1F tank doesnt work unless you have a good PSU. All it does is smooth out the "roughness" during cranking.

So all in all its not designed to survive a crank...its main purpose is just to smooth.

Dont ask me why someone call it a tank circuit which alot of people here still believe its there to survive a crank. As I did say the diode is NOT needed if smoothing is all that required.

Getting clearer?

starfox

I'll echo what the other guys above said, a second sealed lead acid battery is probably easier to use (with an isolator), and definately safer!!

1F caps are extremely dangerous, you wouldn't want to be in an accident where one of those was squashed >_< 1F of charge is a huge amount of energy, and it'll probably drain your car battery charging the thing.. actually i still have no idea why 1F caps are even legal in most countries as it'd be pretty easy to build a bomb out of one....

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