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  1. #21
    Junior Member level 2
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    kingtal0n's Avatar
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    Jun 2016
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    Re: Car battery STARTER voltage help (not charger) using variety of methods (possibly

    I feel like you didnt read it or I worded it improperly. I said I replaced 18AH battery with typical actually a Group "35" size 525~CCA style lead acid unit already.
    Also 18AH did just fine for a year, no issues yet. It cranked the engine ran it fine even had a higher/better charge charging 13.5v instead of 12.8v I charge at now with the battery relocated (and fuse box relocated. There are two relocations here to make room in the engine bay for turbocharger)
    Only reason I took it (18AH) out was because I was trying to do a 'proper' relocation to the trunk using large battery.
    The 18AH was so small it almost fit in the front but eventually a corner melted on turbine flange and I said thats enough and replaced it. If it didn't melt I would probably be still using it.

    here are the terminal, I get alot more response for this than imagined so I think less words at this point and more pics would be useful to save time

    Ill try to find and post more relevant pics... lets see
    the big ground that goes to the other side of chassis

    dare you to say 'done wrong' here

    That is separate 60 amp relay for fuel pump, and feeds the computer directly from battery, separately from large starter power wire which starter inductor kinda owns

    I think capacitor in the front next to the starter will do it but I am not crazy about having more than a couple farads available for very long, so I think I want to over-charge something (16volts) with less capacity temporarily as opposed to simply have a large reservoir. It seems like an accidental discharge waiting to happen.
    Need a couple days now to work on the solenoid current first. Its a 240sx btw and very common ignition switch issues etc... so I am step by step replacing every single wire and upgrading every single component, especially known weaknesses. Like power brace for the chassis, indestructible door panels, special coated oem-shape fuel tanks, hmm this car doesn't have many thats why I picked it lol
    Last edited by kingtal0n; 27th June 2019 at 03:10.

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  2. #22
    Super Moderator
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    Apr 2011
    Minneapolis, Minnesota, USA
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    Re: Car battery STARTER voltage help (not charger) using variety of methods (possibly

    Quote Originally Posted by kingtal0n View Post
    I keep thinking I want to store energy in a magnetic field
    You are referring to the concept of a boost converter:
    1) Switch on the inductor
    2) Let current flow build for a few seconds
    3) Divert current (while adding battery power as well) to the starter.

    Click image for larger version. 

Name:	boost converter concept 12V car bat'y 50mH coil 5 second buildup sends 15V to starter.png 
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    The inductor must be constructed to carry 500 Amperes with little voltage drop. (This means 000 or 0000 gauge.) The timeframe is 5 seconds of build-up, then the switch transfers current to crank the engine. By experimentation the value of 50mH works (in simulation and theoretically, that is). The starter receives 15V initially, declining quickly to about 8v.

    The low-ohm resistors depict some amount of parasitic resistance in the wiring. It is optimistic to hope it might be as low as 1/100 ohm.

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