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  • Aux. Battery oops :S

    So I did bad and didn't mount my aux battery in the trunk. It was situated between my sub box and the sidewall. There wasn't much room to move, but I guess there was just enough to cause badness.

    On the way home from lunch a few days ago my subs went out. I found out today that my battery had tipped over and melted itself to the chassis of the car. It was only the plastic from the connecting forks that melted but still. luckily the 30A fuse blew that connects the aux from my main battery.

    I secured my aux so it won't happen again and replaced the fuse. I'm noticing that there is a bulge now in the side of the battery. Should I be worried about this? The last thing I want is a battery to explode.

    Any thoughts?
    Former author of LinuxICE, nghost, nobdy.
    Current author of Automotive Message Broker (AMB).
    Works on Tizen IVI. Does not represent anyone or anything but himself.

  • #2
    Yes - it could be a worry....
    It's physically damaged so there can be internal shorts and bad cells.
    Even if not initially hazardous (shorts & thermal runaway etc), the cells are probably mismatched hence uneven charging then collapsed cells, then gassing etc....

    You were lucky the battery didn't explode of start a fire etc - those AGMs typically have at least double the short-circuit current or wet cells.

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    • #3
      I wouldn't trust it. Get a new one and chalk it up to experience.
      Originally posted by ghettocruzer
      I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
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      • #4
        Yes there is an excellent chance it will explode. It is gassing which is caused it to bulge which flammable hydrogen gas has built up and could explode. Read here http://en.wikipedia.org/wiki/Car_bat...ding_batteries
        Replace the battery, btw what is the difference between a normal and your car audio battery?

        Andrew

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        • #5
          Can't be much if the fuse is only 30A.... (ie, under 500W of audio)....

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          • #6
            Yeah, i'm not pulling over 500W. I took the battery out and I'm getting a new one. I'm planning on building a proper mount for all this stuff so I can avoid this moving forward.

            btw what is the difference between a normal and your car audio battery?
            My "normal" is a optima yellow top. The second battery is about half the size and I'm guessing, won't last as long as the bigger battery when drawing from it. I got it because it was smaller and thus easier to place in the wrong spot :P.
            Former author of LinuxICE, nghost, nobdy.
            Current author of Automotive Message Broker (AMB).
            Works on Tizen IVI. Does not represent anyone or anything but himself.

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            • #7
              What did you use to secure the new battery? I just put a Marine Deep Cycle in my trunk and am using a cheap $8 vented battery box from Wal-Mart secured down with a metal strap. The battery is about 40lbs or more and was just wondering if that's enough or I might need more.

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              • #8
                If you corner hard or stop hard, or hit another car, will it break loose?
                If it breaks loose, will it short out and start a fire, or will you have a permanently embedded battery for later pacemakers?
                They are the issues....

                (I assume everyone has fuses or circuit breakers at each end of the interconnecting battery cable?!!)

                And I for one hope they are not paralleled when not charging....

                That reminds me - OptimaJim still hasn't substantiated.....

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                • #9
                  Originally posted by OldSpark View Post
                  And I for one hope they are not paralleled when not charging....
                  I don't know if those questions were for me, but I do have fuses all over the place. I did have them linked when not charging. I am not running anything when it's off yet, when I do, i'll add in my 80A relay.
                  Former author of LinuxICE, nghost, nobdy.
                  Current author of Automotive Message Broker (AMB).
                  Works on Tizen IVI. Does not represent anyone or anything but himself.

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                  • #10
                    My original about cornering and being fixed was in response to nst6563's $8 vented box. (Over here I have seen tests that show a box of tissues from a rear parcel tray is enough to kill in an accident, though other permanent damage is more likely. But that's a box of tissues which IMO is not as heavy as a battery...)


                    The fusing & paralleling is a general comment....
                    Many forget to have protection (fuses or breakers) at BOTH the 2nd battery and the 1st/main battery (on circuit/cable line that joins them).

                    Paralleling of batteries should not be done except when charging else when being used.
                    Paralleling of idle batteries of different types, ages and temperatures should NOT be done.
                    Now even though OptimaJim (eCare Manager for Optima) stated that Optima's could be paralleled, he hasn't come back with any evidence to support it... but thanks to this thread reminding me, I emailed Optina lastnight....

                    Paralleling idle batteries is just a means of prematurely destroying good batteries. (I've likened it to the old practice of tyre rotation except that one bad wearing tyre won't effect thye other good ones (until AFTER the rotation).)

                    Paralleling new & matched batteries is usually okay for a while, but when one battery starts its decline, they all go. And the problem is that could be hazardous - especially for AGM batteries (thermal runaway... some people claim LEDs are bad - but they aren't power sources....).

                    The frustrating thing about not-paralleling except when charging is so easy to solve....
                    Simply use your alternator's charge-lamp circuit to control a relay that connects the 2nd battery.
                    When not charging, the 2nd battery stands alone and powers whatever it needs to.
                    If the 2nd battery flattens, who cares? - the primary battery is still there as normal.
                    If you want more 2nd battery reserve (for audio at the campsite etc), then you add more secondary batteries... How they are paralleled may not be as significant if they are all matched, cross connected, and in the boot etc (rather than one hot battery in the engine bay....)

                    If you are NOT running anything of the second battery, leave them disconnected - especially since they are AGMs.

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                    • #11
                      hmm... Just curious, how does leaving both batteries parallelized kill the battery prematurely? When i get the replacement, I'll hook up my relay and connect it to ignition or something.
                      Former author of LinuxICE, nghost, nobdy.
                      Current author of Automotive Message Broker (AMB).
                      Works on Tizen IVI. Does not represent anyone or anything but himself.

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                      • #12
                        hmm... Just curious, how does leaving both batteries parallelized kill the battery prematurely?
                        Because the gimpier one [and there will always be a gimpier one] is basically sucking electricities out of the better one, and throwing them away. That's why it's the gimpy one :-)

                        Gary (-;
                        OBDGPSLogger, for logging OBDII and/or GPS data
                        OBDSim, an OBDII/ELM327 software simulator
                        mp3car forums: obdgpslogger, obdsim

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                        • #13
                          Thanks Chunky....

                          Yep - well documented.
                          And in many ways quite obvious....

                          Any load discharges a battery.
                          A battery has its own discharge rate (like a parallel resistor) albeit small.
                          The battery deteriorates and those resistances decrease (discharge increases).
                          Add a parallel battery - it increases its discharge through the other battery.

                          The rest is a combination of stuff - individual cell resistances (series and parallel), cells collapse, hence causing the overcharging of others, more damage etc. One parallel battery feeds the failing battery hence compounding its damage as well as discharging itself and damaging itself.

                          Consider a battery with a failed cell (10V instead of 12V). Connect a 12V battery. Eventually the 12V gets dragged down to 10V which is under the lowest allowable voltage for that battery (ie, a cell is ~2V; what battery allows discharge from full (12.7V) to 2 Volts less?). That's another damaged battery.

                          Hence why - if you cannot monitor the batteries, they should NOT be paralleled - except when charging, or - because it may be the reason for wanting to parallel - when being discharged/used.
                          But they should not remain parallel connected when not in use (well, not for long...)

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                          • #14
                            The $8 box wasn't really what I was referring to as holding it down, it's the steel straps which are screwed into the chasis of the car in the trunk. They are thin enough to bend with your hands (if you don't have girly hands and can stand the edges) yet they're thick enough that they were used on shipping crates of electronics (ironically...they came off the same pallet of battery isolators that my isolator came off of )

                            You mention the charge lamp... I've looked through all kinds of documentation on my 2004 Maxima and can't find any mention of WHERE the charge lamp wire is. I have a SurePower 130A solid state isolator (http://www.translectricinc.com/catal...?PartNo=13023A) that is waiting to be hooked up...yet when I look at the documentation and match the connector to what's on my alternator - the surepower documentation states that my alternator is "not compatible with battery isolators".

                            So really until I figure out how to connect that to my Maxima I'm sorta SOL on my isolator while the deep cycle battery just sits in the trunk waiting for the wiring to be attached. People with Stinger isolators are able to hook them up to the Maxima... I'm just curious what makes it "incompatible" since the wiring has to be there somewhere to make it work if it's not directly on the alternator itself.

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                            • #15
                              Yeah - diode isolators. IMO the worst of the lot - the alternator has to up its output by the diode drop to maintain proper charge voltage - and which battery does it pick for that? Does it overcharge one or undercharge the other....?
                              And then the huge heatsinking - the diode (voltage) drop x current - say 0.7V x 10A = 70W.
                              And you cannot parallel the batteries....
                              Diode isolation is for signaling and small power - not big!

                              It's probably incompatible since you have a D+ (single wire) alternator, hence your batteries will undercharge (the D+ alternators reference their own output voltage - not that of the battery).



                              The charge lamp circuit is simply the D+ else L output from the alternator (regulator).

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