Re: sealed (air tight) rechargable battery technology

"Mook Johnson" <mook@xxxxxxxx> wrote in message
news:Ktc8e.3399$h6.360@xxxxxxxxxxxxxxxxxxxxxxx
> Also,
>
> I can monitor the battery temperature while they are charging and reduce or shutoff the charging currents if the temperature gets
> too high.
>
> Would that be sufficient to prevent venting in nimh or nicad batteries?


The battery will not vent if you can avoid overcharging
it. The would include responding to the terminal voltage.
Keep in mind that if a cell fails shorted, the battery voltage
will still not suffice to help avoid overcharging. Venting is
due to a reaction other than the normal charging reaction
which results in simple rearrangement of the species. Gas
production to the point of venting depletes something and
should be strictly avoided for longevity.

Making the "fully charged" voltage depend on the
average cell temperature is a refinement that may or
may not be useful depending on your ambient range.
You might also use the temperature difference between
the cells and the outside as a means of detecting the
onset of overcharging. When that happens, "charging"
current result in more heat than when the battery is
actually accepting charge. (Some of this heat arises
from the evolved gas recombining instead of venting.)

You should also be aware that hydrogen can be
evolved during overcharge. That gas can collect in
explosive concentrations depending on the space
in which the battery sits. (This is a big concern in
airplanes for engine starting batteries.)

--
--Larry Brasfield
email: donotspam_larry_brasfield@xxxxxxxxxxx
Above views may belong only to me.


.

Relevant Pages

  • Re: Charging NiMHs
    ... The heating is what indicates that battery is fully charged. ... detect this heat dissipation and switch over to trickle charging. ... changes in ambient temperature could fool the simplest form ... It's normal for NiMH to release heat on normal charge, ...
    (sci.electronics.design)
  • Re: schottky tempco
    ... temperature characteristic of the circuit right. ... Don't run an LM35 from over +5 volts! ... Whatever kind of temperature sensing element used, be it a diode, LM35 ... needs to be screwed on to the battery terminal. ...
    (sci.electronics.basics)
  • Re: schottky tempco
    ... temperature characteristic of the circuit right. ... Don't run an LM35 from over +5 volts! ... Whatever kind of temperature sensing element used, be it a diode, LM35 ... needs to be screwed on to the battery terminal. ...
    (sci.electronics.basics)
  • Re: Inverter/Charger recommendations
    ... charging voltages in high temperature environments. ... you or the engineering documents describing the ... engineer who supports the battery. ...
    (rec.boats.electronics)
  • Re: Charging NiMHs
    ... The heating is what indicates that battery is fully charged. ... detect this heat dissipation and switch over to trickle charging. ... changes in ambient temperature could fool the simplest form ... It's normal for NiMH to release heat on normal charge, ...
    (sci.electronics.design)
Quantcast