Re: shorted (?) lead-acid battery
From: Art (plotsligt_at_comcast.net)
Date: 01/29/05
- Next message: Winfield Hill: "Re: Logic level HV fet..."
- Previous message: Patrick Cheung - townt.com: "Electronic Components Supplier"
- In reply to: Kim Clay: "Re: shorted (?) lead-acid battery"
- Next in thread: William: "Re: shorted (?) lead-acid battery"
- Messages sorted by: [ date ] [ thread ]
Date: Sat, 29 Jan 2005 08:39:16 -0500
"Good Container" ?? Ever see one of these batteries blow up tossing
residue, poison, acid, etc all over the place when someone attempts to apply
a high charge rate to "Blow Off the slight shorts"??
Not a nice sight exp when it comes in contact with someone's face or
exposed skin. Not a right pleasant experience in the least. Personally know
at least one person who lost one eye and has facial burns as a result of
trying to do what others are implying may work. Buy a NEW BATTERY!
"Kim Clay" <kimclay@myrealbox.com> wrote in message
news:4tvlv0h5r66qn128gj8lieuqm71fp8dsan@4ax.com...
> On Fri, 28 Jan 2005 18:01:54 -0800, "aurgathor" <spam-me@if-you.com>
> wrote:
>
>>
>>"Kim Clay" <kimclay@myrealbox.com> wrote in message
>>news:c4jjv0hc94hi6mamo3ui5pomt1qr85s298@4ax.com...
>>> On Thu, 27 Jan 2005 11:41:56 -0800, "aurgathor" <spam-me@if-you.com>
>>> wrote:
>>>
>>> >Yesterday I started to charge a car battery that was sitting unused
>>> >for quite a while with a 1A charger. (my other one is broke)
>>> >Initially, the battery was around 6V,
>>> Three discharged (but not completely) cells = 6V, the other three cells
>>> are at 0.0V each due to internal shorts.
>>
>>That is not correct.
> It is correct! Your original question was about a car battery that had
> been "sitting unused for quite a while" which you measured at "around
> 6V".
>
>> A discharged battery can go down that much,
>>or even more without the cells having internal shorts.
> Yes, one can deeply discharge a "good" battery down to 0.0V & after
> the load is removed the cells _may_ recover. A new battery discharged
> accidently to 0.0V & promptly recharged will probably be OK. A old
> battery discharged in the same way may not make it.
> The one key point is that the battery is not left in the discharged
> state for long. Once the load is removed the cells start to recover. A
> non-defective battery will bounce back (even without any charging
> applied) to around 11-12V within 24 hours & probably less. I have never
> timed it :)
>
>>Case in point,
>>a couple daysbefore this one I had a battery that measured 1.7V!
>>(in car, with a light left ON). In a couple of days, that battery was
>>measuring 14V, and worked just fine. I just checked it today --
>>12.85V.
> Ran the battery down & it got promptly recharged.
>
>>Based on the voltage measurements after a few hours of charging
>>(10.40V -> 8.40V -> 6.40V) some cells must've become shorted
>>during the charging process.
> The cells were shorted from the beginning. These are not 0.0 ohm
> internal shorts but some higher resistance that have bridged the plates.
> It seems your ~1A charger was enough to overcome the internal cell
> short (or bridging resistance) of two of the cells but not the third.
> This resulted in the 10.40V reading early in the charging process.
> During the rest of the charging process the internal shorts within the
> other two cells slowly decreased in value resulting in your 8.4V reading
> & the ending 6.4V.
>
>> Alas, I no longer remember the voltage
>>after the first 10 - 15 mins of charging -- that may have been close to
>>12V.
> Indeed it may have been "close to 12V" near the start. If the charger
> can overcome the internal short a cell will attempt to recharge. The
> plates just fell apart & created a harder short. It took a while for all
> three cells to end up the same way - hard short internally.
>
>>> Because (from your first sentence) "battery that was sitting unused
>>> for quite a while". Car batteries self discharge just sitting on the
>>> shelf. A discharged battery that sits is quickly self destructing
>>> internally, as you have found out.
>>
>>I expected sulfation, and while that's no good either, it's less
>>deadly, and it's easier to reverse than an internal short.
> If you have a lead acid (12V) battery that is at ~10.5V or better it
> has a chance of becoming useful no matter how long it has set. If it is
> <10.5V it may (probably) have a shorted cell. These are measurements
> taken of an unknown battery that has been sitting for >24 hours.
>
>>I guess material fell from the plates, created a highly conductive
>>sludge in the bottom, and that's what shorted the cells out.
> You were attempting to recharge a battery in which 3 cells already had
> internal shorts (or the battery would have been closer to 12V to start
> with). These cells had been in this condition for an unknown length of
> time. The shorts just became more solid as the charging progressed.
>>
>>One of my friend got a 100A or so charger, so I wonder if
>>I can blow the shorts with that. ;-) Of course, I'd need to
>>find a good enough container first incase the whole battery
>>blows.
>>
> Even if you could magically make the shorts disappear the basic
> trouble is still there. The cells are falling apart internally.
>
> Kim
- Next message: Winfield Hill: "Re: Logic level HV fet..."
- Previous message: Patrick Cheung - townt.com: "Electronic Components Supplier"
- In reply to: Kim Clay: "Re: shorted (?) lead-acid battery"
- Next in thread: William: "Re: shorted (?) lead-acid battery"
- Messages sorted by: [ date ] [ thread ]
Relevant Pages
|
|
