General battery charging question for NiMH and Lead-Acid powered LEDlights for third world applicati

[[email protected]]

Hi there, I have a smattering of random small LED lighting solutions
from various countries, with either lead-acid batteries or NiMH
batteries inside. They all seem to have some sort of charging
circuitry (over voltage protection, etc.)

I'd like to measure the charging time of these LED lights (I have AC
adapters). Can I just monitor the current going into the light from
the AC adapter, or will this likely not reflect the battery state?
I've read that I have to monitor the battery voltage instead?

Thanks

 

[Wimpie]

Hi there, I have a smattering of random small LED lighting solutions
from various countries, with either lead-acid batteries or NiMH
batteries inside. They all seem to have some sort of charging
circuitry (over voltage protection, etc.)

I'd like to measure the charging time of these LED lights (I have AC
adapters). Can I just monitor the current going into the light from
the AC adapter, or will this likely not reflect the battery state?
I've read that I have to monitor the battery voltage instead?

Thanks

Hello,

Generally spoken, current that goes into the battery does not reflect
the charge state. How de current decays versus time depends on the
type of charger.

Some simple low current chargers do not even stop (as they don't have
a timer or other charge termination control) and distroy the battery
in the end.

A good measure can be: determine the capacity of the battery.
Discharge the batteries completely and monitor the current that goes
into the battery. Integral of current versus time is a good measure.
A good website on batteries and chargers: www.powerstream.com, click
on technical resources.

Best regards,

Wim
PA3DJS
don't forget to remove abc when using pm

 

[Raveninghorde]

Hello,

Generally spoken, current that goes into the battery does not reflect
the charge state. How de current decays versus time depends on the
type of charger.

Some simple low current chargers do not even stop (as they don't have
a timer or other charge termination control) and distroy the battery
in the end.

A good measure can be: determine the capacity of the battery.
Discharge the batteries completely and monitor the current that goes
into the battery. Integral of current versus time is a good measure.
A good website on batteries and chargers: www.powerstream.com, click
on technical resources.

Best regards,

Wim
PA3DJS
don't forget to remove abc when using pm

That's true for NiMH. Lead acid current tapers off at the end of
charge.

 

[ehsjr]

Hi there, I have a smattering of random small LED lighting solutions
from various countries, with either lead-acid batteries or NiMH
batteries inside. They all seem to have some sort of charging
circuitry (over voltage protection, etc.)

I'd like to measure the charging time of these LED lights (I have AC
adapters). Can I just monitor the current going into the light from
the AC adapter, or will this likely not reflect the battery state?
I've read that I have to monitor the battery voltage instead?

Thanks

Monitoring the current won't tell you what you want to know.
Charging time will depend on three variables:
the size of the battery, the degree to which it is discharged
when you start, and the charger design. You need information
on all three.

Ed