Weird intermittent flat battery problem

We have a battery desulfator here that seems to work well. It's
a small power supply that generates a square wave of a voltage
considerably higher than the battery voltage, but very brief and of a
high frequency. The thing is connected to a tired battery and left
there for a week or two, and the effect is to break up the sulfate that
has accumulated on and around the plates and get it back into solution.
We've rejuvenated a few aircraft batteries with it as well as car
batteries.
That said, my experience has usually been that starting
problems are much more often due to bad connections. If the lights are
dimming when trying to crank on a supposedly good battery, it's
battery, solenoid or ground connections. They might look OK but the
crap shows up only after the connection is taken apart. Battery cables
will corrode inside the battery clamp itself, out of sight.

Dan

<snipped posting> You can also try a desulfator such as Pulsetech,
Batteryminder (or Battery Minder), Solarigizer, and other pulse
desulfators and oils and chemicals such as the ones by Battery Doctors.
These pulse desulfator devices, in my opinion, however, dry out the
batteries prematurely, causing shorter life than normal, which is not
stated in manufacturer's review or consumer reviews.



wrote:
> We have a battery desulfator here that seems to work well. It's
> a small power supply that generates a square wave of a voltage
> considerably higher than the battery voltage, but very brief and of a
> high frequency. The thing is connected to a tired battery and left
> there for a week or two, and the effect is to break up the sulfate that
> has accumulated on and around the plates and get it back into solution.
> We've rejuvenated a few aircraft batteries with it as well as car
> batteries.
> That said, my experience has usually been that starting
> problems are much more often due to bad connections. If the lights are
> dimming when trying to crank on a supposedly good battery, it's
> battery, solenoid or ground connections. They might look OK but the
> crap shows up only after the connection is taken apart. Battery cables
> will corrode inside the battery clamp itself, out of sight.
>
> Dan

On Wed, 21 Jun 2006 18:20:23 +0100, "Martin Underwood" <a@b> wrote:

>jeffcoslacker wrote in message
:
>
>> A little better explanation.
>>
>> As the plates in the grid detiorate over the years, conductive
>> material builds at the bottom of the battery. When it gets deep
>> enough to touch the bottom of the grid, and cause a conductive
>> connection between two plates, those two are effectively shorted. The
>> battery can't do much in this condition, there isn't correct
>> continuity within it. When the battery is moved, the debris will
>> sometimes resettle and the battery will suddenly come to life...
>>
>> Same with charging, the current applied to the battery causes an
>> overloading of the sediment connection, overloading it and causing it
>> to fail, like a fuse. The battery is now in correct condition, and
>> will test as if it is fully charged and fine.
>>
>> This can sometimes lead to explosions on jumpstarting when you produce
>> an arc, as shorting produces loads of hydrogen sulfide gas, so don't
>> fart around with it...replace it
>
>OK. I can see how this sediment could produce an intermittent problem.
>Presumably the sedimentation will build up when the car is not used for a
>few days, and then will be dispersed either due to the vibration of driving
>or by the act of charging it when the engine is running. I presume that the
>formation of sediment is irreversable.
>
>When I jump start, I always attach the final terminal of the jump leads at
>the donor battery rather than the dead battery in case hydrogen[*] is
>produced at the dead battery which an arc could ignite.
>
>Interesting that none of the garages or car-spares places that I've taken
>the car to have mentioned about sediment. You'd think they would have done,
>if they'd been aware of the concept, since it's in their interest to try and
>sell me a new battery. Unfortunately the battery is a sealed type (doesn't
>need distilled water adding to the electrolyte) so there's no way that a
>garage could test the electrolyte to see if there are traces of sediment, to
>confirm if this is the problem.
>
>However you've convinced me that the battery is dying, if not actually dead
>yet. I'll have to go out and buy a new battery - "only" £70 (about $110).
>And this time I'll go for one with a warranty that lasts for more than 2
>years ;-)
>
>
>
>[*] I *think* it's hydrogen rather than hydrogen sulphide - the latter is
>instantly detectable (by the nose!) and I don't think it's flammable. But I
>could be wrong.
>

Hi Martin,

I couple of quick points.

The last connection when jump starting should be to ground away from
the battery because the will be a small arc and you are trying not to
ignite the hydrogen gas produced during charging. Please see Section
6 in the Car and Deep Cycle Battery FAQ on www.batteryfaq.org for more
information about jump starting. The second point is that hydrogen is
flammable when it is exceeds 4% concentration when mixed with air.
Please see Section 14.4. Normally wet "Maintenance Free" batteries
only have a two year or less average life in hot climates because you
can not replace lost water and their overall service life is reduced
with deep discharges. Please see Section 7.1.3.

Kindest regards,

BiLL......