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  1. Join Date
    May 2014
    Posts
    920
    #21
    Quote Originally Posted by Vodka View Post
    what you're doing is risky as well. the battery buffers the raw output of the alternator, protecting all your electronics from spikes etc

    the proper way is to use a memory saver cable. plugs to OBD2 port.
    I am honestly curious why it would be dangerous, if you are not connecting the positive and negative terminal together or 'completing a circuit' that should not be completed?

    I would like to know where info would be on this matter is could be read up? It would be helpful.

    Https://mechanics.stackexchange.com/...car-is-running

    In the link above, the guy saying the same thing was basically just promoting his own ebook, as noted by another user.

    Replacing the battery while it is running shouldnt take longer than a minute or two and everything else is technically off, other than the car idling.

    The battery is there to start the car, the alternator to run it, right (as well as keep the battery chsrged as best it can)?

    As for the obd memory saver, it might not specifically pertain to the time you need to replace just the battery but since it is reading material, il link it as well as a source

    Memory savers not recommended by industry experts | Search Autoparts

    Again, id like to reiterate, they were just mentioning in when discussing other work like needing to weld or repair the car and not just swap out to a new battery.

    Thanks for taking time to reply.

    I am curious, but i dont see a valid reason yet for why it should pose a problem to start the car and swap out with a new battery under 2 minutes.

  2. Join Date
    May 2014
    Posts
    920
    #22
    Here is a link that says what you mentioned to support use of the memory saver.

    Using a Battery Code Saver? — Auto Expert by John Cadogan - save thousands on your next new car!

    But also, looking at the post. It does mean thst if you unplug the batteries from a 'dead' car, you need to have it reset and recalibrated which most regular owners dont do, i think.

  3. Join Date
    Mar 2004
    Posts
    8,850
    #23
    Quote Originally Posted by 17Sphynx17 View Post
    7) For my case, when replacing the battery, I specifically run the car first before the battery is removed so that all electronics are running off the alternator, avoiding any electronics to suffer a reset or "error" (just to be on the safe side). On my first battery replacement, I didn't know about the CVT might needing to be reset so I didn't start it before. So I did bring it to Honda to have it reset as I felt it was not "performing" the same (shifting wise) after my first battery change. Succeeding battery replacements, I made sure to start the cars (be it AT or CVT) after that happened, never had any issues after. If the battery is already dead, I have the new battery just connected to the old battery terminals so I can start the car when they are connected in series. Car starts, assuming no other issue is causing the "unable to start" issue.
    Should avoid doing this on modern vehicle withs a lot of electronics ... One spike from the alternator and it might fry a lot of things ...
    Last edited by Walter; May 22nd, 2019 at 09:23 AM.

  4. Join Date
    May 2014
    Posts
    920
    #24
    Quote Originally Posted by Walter View Post
    Should avoid doing this on modern vehicle withs a lot of electronics ... One spike from the alternator and it might fry a lot of things ...
    Automotive Charging Systems - A Short Course on How They Work | CarParts.com

    I would like some clarification on this specific topic then.

    Documentations I have read always mention that alternators (I assume especially the current car designs) have regulators as all alternators run Alternating Current.

    Now, there is a likelihood that the regulator "could fail". But even the documentation here says that if that is the case, lights on the dashboard would shop up indicating such an issue.

    So, based on that, my understanding it, don't do it if your car is showing other issues and not just a "dead battery" that needs swapping out. Since current AT/CVT batteries are the maintenance free types, once signs of hard-starting are showing (meaning the car can still turnover) I usually buy new batteries already to change it out.

    Thoughts?

    EDIT:

    1) please consider that all other electrical components are turned off when I'm doing the swap with the car running. A/C, Lights and radio/Head Unit are turned off. No revving of the car engine during the "swap" to a new battery
    2) By doing #1, I am not introducing any unnecessary load to the electrical system during the swap. Just need to car to idle "low"
    3) the car does not present any other issue when it was in use prior to the "Swap"
    4) During the "swap", I will keep presence of mind to keep the battery terminals/wires (positive and negative) completely isolated and separate, and not contact with any other metallic component of the vehicle or tools that could cause a completion of the circuit (other than when they connect with the new battery)

  5. Join Date
    Nov 2009
    Posts
    64
    #25
    Quote Originally Posted by 17Sphynx17 View Post
    Automotive Charging Systems - A Short Course on How They Work | CarParts.com

    I would like some clarification on this specific topic then.

    Documentations I have read always mention that alternators (I assume especially the current car designs) have regulators as all alternators run Alternating Current.

    Now, there is a likelihood that the regulator "could fail". But even the documentation here says that if that is the case, lights on the dashboard would shop up indicating such an issue.

    So, based on that, my understanding it, don't do it if your car is showing other issues and not just a "dead battery" that needs swapping out. Since current AT/CVT batteries are the maintenance free types, once signs of hard-starting are showing (meaning the car can still turnover) I usually buy new batteries already to change it out.

    Thoughts?

    EDIT:

    1) please consider that all other electrical components are turned off when I'm doing the swap with the car running. A/C, Lights and radio/Head Unit are turned off. No revving of the car engine during the "swap" to a new battery
    2) By doing #1, I am not introducing any unnecessary load to the electrical system during the swap. Just need to car to idle "low"
    3) the car does not present any other issue when it was in use prior to the "Swap"
    4) During the "swap", I will keep presence of mind to keep the battery terminals/wires (positive and negative) completely isolated and separate, and not contact with any other metallic component of the vehicle or tools that could cause a completion of the circuit (other than when they connect with the new battery)
    Voltage regulators do not output pure DC voltage/current. They can only do so much in converting AC to DC. Your battery as someone here said makes sure that pure DC is fed to your system electronics. Remember also that your ECU is powered electrically. Eventhough you are not turning electrical loads, directly feeding power from the alternator to your ECU without going through the battery may cause problems specially in modern cars. Just my two cents.

  6. Join Date
    Jan 2008
    Posts
    3,643
    #26
    Quote Originally Posted by whiteb16a View Post
    Voltage regulators do not output pure DC voltage/current. They can only do so much in converting AC to DC. Your battery as someone here said makes sure that pure DC is fed to your system electronics. Remember also that your ECU is powered electrically. Eventhough you are not turning electrical loads, directly feeding power from the alternator to your ECU without going through the battery may cause problems specially in modern cars. Just my two cents.
    Conversion of AC to DC of the alternator is done by the rectifier composed of 4 diodes... the voltage regulator controls the DC output to maintain the voltage range not to exceed 14V along the RPM range.

    But to be safe, better to turn it off and place a back up battery while replacing the old one..

  7. Join Date
    May 2014
    Posts
    920
    #27
    During lunchtime been reading up.

    There are 2 camps, but with more modern vehicles, yes. They do say just to avoid any issues altogether, don't do it. You could but "why risk it".

    So, I guess I'll change the approach and try and see if I can use jumper cables when swapping out batteries instead.

    Regarding the memory saver, there are also 2 camps. Most say it is okay while some say it could preserve error codes in the system as some cars do detect battery removal/disconnection. Not sure where I should stand on that department.

    Lastly, it still stands, if you do disconnect your battery to change to a new one without doing anything else, go to have your computers reset and recalibrated to be sure everything is running or being run by the computers as it should be. =)

  8. Join Date
    Jun 2011
    Posts
    323
    #28
    Dati nagpa-deliver kami ng car battery for replacement. Iyong technician may dala din na extra 12V motorcycle-size battery. Kinabit niya muna itong small 12V battery in parallel, bago nag-palit ng battery.

    Iwas reset daw.

  9. Join Date
    Feb 2007
    Posts
    41
    #29
    [QUOTE=17Sphynx17;3077334]It may not be written in the manual, but i rather not rrisk running the transmission while there could be an error in the computer box after battery removal (without running off the alternator).

    Im just saying what i do to avoid needing a cvt reset.

    I also own a sylphy cvt. When nissan serviced the sylphy, they removed the battery over the course of repair work (i posted this in the thread for sylphy).

    When i got the car back, the transmission was behaving differently. I brought it back for a reset. Nissan doesnt have the same like honda. So they installed the latest firmware they had on hand for the cvt. Basically equivalent to a reset.

    The transmissiom behaved the same after it as well.

    So, you could see it as anecdotal. But that has been my personal experience with cvts and i would rather not risk it. [ “ lately my honda cvt 2014 behave diffently after the battery was disconnected , during downhill it reduces cvt setting to lower setting causing high revs ranging from 3000-4000 rpm & on straight highway its rpm goes up & down at speed more than 80-100kph. I brought it to honda casa & they test drive it , after that they recommend to change transmission!!! Im insisting if they can do first to reboot or update the ecu but they not considering my opinion, my gash new transmission will cost 360K��. Has any one of you do the ecu update on thier honda cvt? Please kindly inform me , id like to have a second option. Thanks for any one who will response and will give me positive feedback�� “ ]

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Honda CVT transmission concerns, have you had any? How did the dealership handle it?