Hi!
The best thing to do is to consult the manufacturer's data sheet for the type &
model of the battery that you have. Then follow those recommendations.
Generally, the manufacturer will have the appropriate charger available for
sale as well. If not, find one that meets the requirements of the data sheet.
Most good chargers are 'smart' chargers that monitor the battery's charging
cycle and then regulate the outage and current accordingly.
For example, my charger for SLA batteries is an intelligent charger that has
three distinct cycles that it runs through before it indicates a full charge.
Note that the battery voltage straight off of the charger will be high at
first, then it will trickle down and settle out to a particular voltage after a
half hour or so. That voltage should be called out in the data sheet for that
battery. The lithium ion batteries that I have either have a built-in charger
or I put the cells in a recharging station that has been designed to
accommodate the proper charging cycle parameters under microprocessor control.
Don't even consider using a simple power supply for this purpose, especially
when you have any kind of lithium battery.
I hope that this helps.
Best regards,
Greg
Sent from my iPad
> On May 20, 2015, at 7:10 PM, " [naturerecordists]"
> <> wrote:
>
> > I looked for an answer in previous discussion but cannot find any. I am
> > interested in knowing your advice concerning a minimum voltage for
> > rechargeable batteries (to avoid over discharge).
>
> Amandine,
>
> It's an "all depends on" answer as there are so many types and variations of
> rechargeable battery available, but I'll hazard an answer.
>
> The old lead-acid batteries are still in widespread use as in cars and
> applications such as standby lighting and power backup as in telephone
> exchanges and other fail-safe applications but they are toxic and heavy.
> they should be stored fully charged.
>
> Nickel-cadmium batteries are more or less phased out now as they had minimum
> voltage and reverse charge problems as well as being toxic, like lead-acid.
>
> The battery of choice is now the Lithium-ion type which are reasonably
> robust and can stand being self-discharged when not in use, which wrecks
> lead-acid types. The recommendation is still to use a custom charger with a
> set maximum voltage and current. These are approximately 4.2V per cell
> charged and a rapid charge current giving preferably an hour or more charge
> time. After that, a good charger should drop to a low trickle charge to
> avoid overheating. A hot battery has a problem.
>
> The recommended end voltage is 2V for each cell, but this has to assume the
> cells are equal in capacity. If all cells are new, that is easy as an end
> point, but a higher end point is advisable on a well-used multi-cell battery
> which may have weak cells.
>
> The best advice is to watch the battery voltage or indicator, and when it
> begins to drop markedly, play safe and recharge. With a single 3.5v cell,
> the end point should be easy to see, but with a well-used multi-cell
> battery, the recharge point should be as soon as the total voltage begins to
> drop quickly, and well before the weakest cell reverse charges. That's why
> they often don't quote an end point voltage.
>
> David Brinicombe
>
>
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
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