how i know whether my car battery is full charging??

Thread Starter

hcchuar

Joined Nov 8, 2008
23
Lefty.
The OP, among other things in his (her) circuit needs is regulating. Part of any charging circuit, mechanical or solar needs a way to stop. The dump load is part of that circuit.
Dan
is LM350 perform as a voltage regulate? or which part need regulating as u means? this circuit does not have any controller to stop the voltage when the battery is full charging, may b i make a switch button so that i can switch off the charging, or do u have any circuit to auto switch off the charging?
 

Thread Starter

hcchuar

Joined Nov 8, 2008
23
Lefty.
The OP, among other things in his (her) circuit needs is regulating. Part of any charging circuit, mechanical or solar needs a way to stop. The dump load is part of that circuit.
Dan
Your new circuit has a lousy old 741 opamp with its input voltages too high. The circuit probably used an obsolete opamp that worked fine with its inputs near its positive supply voltage. A newer TL081 opamp will work.


So TL081 will be work better than 740 opamp?
 

Thread Starter

hcchuar

Joined Nov 8, 2008
23
Lefty.
The OP, among other things in his (her) circuit needs is regulating. Part of any charging circuit, mechanical or solar needs a way to stop. The dump load is part of that circuit.
Dan
Your new circuit has a lousy old 741 opamp with its input voltages too high. The circuit probably used an obsolete opamp that worked fine with its inputs near its positive supply voltage. A newer TL081 opamp will work.


So TL081 will be work better than 741 opamp?
 

SgtWookie

Joined Jul 17, 2007
22,230
So TL081 will be work better than 741 opamp?
A 741 opamp will not work in the circuit the students attempted to simulate.

The original circuit called for an LM301 opamp, which did allow inputs as high as +V. The TL081 will also allow inputs as high as +V.

There are a number of other mistakes the students made, such as calling an LM324 a comparator, which it is not.

If you wish to see the original circuit that the students were attempting to re-engineer, go to the National Semiconductor website, and download the datasheet for the LM150/LM350 regulator. Look on page 10, where you will see a schematic for a 12v battery charger.

However, that charger circuit is not designed for continuous use; it would attempt to charge a battery to nearly 15v and keep it there, shortening the battery's life.

A good charger would have a "bulk charge" phase where the battery was charged at a constant current until it was approximately 80% to 90% charged, then an "absorption charge" phase where the input voltage was held at 14.4v until the battery was nearly fully charged, and then drop to a "float charge" phase where the voltage was maintained at around 13.4v, adjusted for the battery core temperature. Most off-the-shelf chargers completely ignore the battery core temperature. This makes them cheaper to buy, and keeps the charger users buying new batteries every few years.
 

Thread Starter

hcchuar

Joined Nov 8, 2008
23
A 741 opamp will not work in the circuit the students attempted to simulate.

The original circuit called for an LM301 opamp, which did allow inputs as high as +V. The TL081 will also allow inputs as high as +V.

There are a number of other mistakes the students made, such as calling an LM324 a comparator, which it is not.

If you wish to see the original circuit that the students were attempting to re-engineer, go to the National Semiconductor website, and download the datasheet for the LM150/LM350 regulator. Look on page 10, where you will see a schematic for a 12v battery charger.

However, that charger circuit is not designed for continuous use; it would attempt to charge a battery to nearly 15v and keep it there, shortening the battery's life.

A good charger would have a "bulk charge" phase where the battery was charged at a constant current until it was approximately 80% to 90% charged, then an "absorption charge" phase where the input voltage was held at 14.4v until the battery was nearly fully charged, and then drop to a "float charge" phase where the voltage was maintained at around 13.4v, adjusted for the battery core temperature. Most off-the-shelf chargers completely ignore the battery core temperature. This makes them cheaper to buy, and keeps the charger users buying new batteries every few years.

So do u have have any better circuit that can show to me....? because i found that a lot of charging circuit through the internet,i do not know whether which 1 can be perform well........
 

floomdoggle

Joined Sep 1, 2008
217
Saw this place today. It is called cirkits.com. They have a good charger contoller circuit that allows you to build while learning.
Also, listen to Wookie, he knows what he is talking about.
Dan
 
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