NiCad long term trickle charging

[Keith Soldavin]

I have an application where I am using a two cell 2300 mAh NiCad
battery as a backup power supply for a sensor. The system will be out
in the field and running off AC power most of the time but when the
power is disconnected that battery will keep the system alive. I want
to be able to recharge the battery and keep it maintained but I am
trying to avoid a smart charging system. Would it be OK to constantly
trickle charge the battery at a rate of around C/50 and not risk
overcharging? I'm not concerned about how long it will take to
recharge the battery nor am I concerned about shortening the battery
life significantly. I doubt this will be used for longer than a year
before the entire system is replaced. If the C/50 rate is not
appropriate then what charge rate would be acceptable for my
application?

Thank you
Keith

 

[Tilmann Reh]

I have an application where I am using a two cell 2300 mAh NiCad
battery as a backup power supply for a sensor. The system will be out
in the field and running off AC power most of the time but when the
power is disconnected that battery will keep the system alive. I want
to be able to recharge the battery and keep it maintained but I am
trying to avoid a smart charging system. Would it be OK to constantly
trickle charge the battery at a rate of around C/50 and not risk
overcharging? I'm not concerned about how long it will take to
recharge the battery nor am I concerned about shortening the battery
life significantly. I doubt this will be used for longer than a year
before the entire system is replaced. If the C/50 rate is not
appropriate then what charge rate would be acceptable for my
application?

AFAIK, C/30 is suggested for long-term NiCd trickle charge.

In discussions with a product manager from panasonic, I was told
that high-temperature cells are better suited to this operating
mode, even if they have lower capacity. Their inner construction
is different to that of "standard" high-capacitance cells.

--
Dipl.-Ing. Tilmann Reh
Autometer GmbH Siegen - Elektronik nach Maß.
http://www.autometer.de

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