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Thread: Cold Air Feed to the Battery... IS IT REALLY NEEDED?

  1. #21
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    If you mean the one that exploded - Dumb bum me. I had a set of jumper leads connected directly to the starter motor cranking the car over. I had no ignition keys, It was hot wired) it an old Austin A40 convertible that I pulled out of a paddock. I had done all the usual checks spark, fuel and compression. It just wouldn't fire. I had it cranking over so I could turn the dizzy (no timing marks on engine).

    As I leant over to disconnect the jumper leads I bumped one of those wing nut terminals on the battery which was loose - consequently it came off and on with a huge spark because it was still connected to the cranking starter motor - 300 plus amps current draw.

    BIG BANG - I'm covered in battery acid - so loud a bang my next door neighbour heard it from his loungeroom. Blew bits of the battery over the top of my house. As I said - dumb shit - I did EVERYTHING wrong I should have known better.

    The other batteries all but one were from car accidents where the positive battery had shorted out. The other was one of my part time teachers who was just driving down the street when he heard a bang under the bonnet. When he got back to his workshop he opened the bonnet to find battery acid everywhere. By the way this guy is proprietor of a long established Tyre & Battery outlet and taught Auto Electrical modules for me at TAFE.

  2. #22

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    Quote Originally Posted by rd415 View Post
    I don't mean to be rude but - no speculation, FACT - the battery has to be kept as cool as possible. Just read any book on batteries, Auto text books and even on the internet the battery talk on electric cars is all about cooling the batteries.

    .
    Wrong. You're talking about a general principle. If you were quoting the Mazda engineer responsible for designing the duct and having it approved for production then you might be entitled to claim that it's a fact. But you're not, so you can't.

    As a matter of "FACT" batteries need to be kept at an optimum operating temperature, not simply cooled. There are some applications where batteries are heated so they'll work efficiently. I've dealt with battery risk management issue in various forms of transport from buses to trains to aircraft and it's been my experience that managing hydrogen output, and the perceived liability associated with it takes precedence in terms of design criteria.

    The "FACT" is that no one here knows why the duct is there.

    Gone to Volvo


  3. #23
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    egads.. what have i started :P suppose there is nothing like a good debate huh?

  4. #24
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    Quote Originally Posted by kmh001 View Post
    Wrong. You're talking about a general principle. If you were quoting the Mazda engineer responsible for designing the duct and having it approved for production then you might be entitled to claim that it's a fact. But you're not, so you can't.

    As a matter of "FACT" batteries need to be kept at an optimum operating temperature, not simply cooled. There are some applications where batteries are heated so they'll work efficiently. I've dealt with battery risk management issue in various forms of transport from buses to trains to aircraft and it's been my experience that managing hydrogen output, and the perceived liability associated with it takes precedence in terms of design criteria.

    The "FACT" is that no one here knows why the duct is there.

    I wasn't going to comment initially on battery cooling, but I couldn't help myself becuase the responses were so far off track.
    It is FACT - It is well documented by the manufacturers as to why the cooling ducting is placed over batteries. Optimum temp for electrolyte in a lead acid battery is 27 degrees - when testing specific gravity you add .004 for every 5 degrees celcius that the electrolyte temp exceeds 27 degrees celcius.

    Listed in the 2005 Mazda 3 workshop manual as a battery cooling duct see extract below

    "b) Remove the plastic screw connector holding the battery cooling duct in place. Remove the battery box cover and remove the battery cooling duct."

    I think Mazda know the answer don't you????????

  5. #25

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    I can certainly testify that if a battery get's too cold it won't work right either nothing more embarassing them telling workers to move their truck cos they are blocking your car in and then have it not start (thank god second attempt was the charm!). Interesting side note this is also why storing your batteries in the freezer may prolong their shelf life.

    Also its good to hear Im not the only person to ever short a car battery. The heat shield on my pod filter was made of steel and cut through a positive wire on my battery and then touched the battery mount earthing itself. I almost shat myself when sparks started shooting everywhere, lucky I didnt have any problems with hydrogen gas honestly. End result was that the battery literally vaporised a chunk of the heatshield and left scorch marks on most of the rest!

    Ranton I think a good summary would be, yes you can remove the duct going to your battery and it might not have an effect, but Mazda probably put it there for a reason. It might only shorten the life of your battery but on the other hand if you are wrong and it does serve an important purpose you could risk an engine fire.

  6. #26
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    hmmm

  7. #27
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    Yes if it's too cold the battery won't work properly.
    But the cooling duct is there to stop the battery from getting too hot when the car is running and overcharging.
    I'd much rather have a flat battery on a cold morning that a battery explode while driving down the road.
    It's not just Mazda that have a cooling duct for the battery or at least some sort of insulation.
    Every manufacturer does. So it must have a point.

    I know through racing radio control cars we try to keep all the electronics as cool as possible. And the pros have special battery charging trays with cooling fans and have experimented with dry ice to keep the batteries cool when charging

  8. #28

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    I guess there is some distinction to be made between keeping electronics cool and keeping batteries cool. As noted above, batteries should be kept at an optimal temperature and the other ventilation consideration is to reduce gas build-up to minimize risks of explosion as well as corrosion.

    Electronics (as distinct from electrics) need to be kept cool (but not necessarily as cold as possible, which would have a different set of cooling requirements, including refrigeration) firstly to continue to function as designed and secondly because conductivity improves with reduction in temperature. The fan in you laptop or heat dissipating fins on your inverter are examples.

    The same applies to battery and electrical leads but in the normal range of temperatures experienced in automotive use this is not a big consideration. I've worked on drill rigs whose start batteries are in the sun at over 50C air temperature, plus they are right alongside a pile of mechanicals and hydraulics bellowing away at full power for 12 hours continuously. There is no way they are at their optimal temperature, yet under normal use and charge parameters they don't boil or fail to perform.
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