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Questions about Lead acid battery charger with LM317

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tong

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lead acid battery charger lm317

Need ugently your help. My car battery is out of voltage now.

This circuit can protect:

1. Battery inverse protection ?
2. No input voltage protecttion ?
3. Short output protection (battery) ?

(Short input protection --> I don't care because it can't human error.)


All diodes use 5A, right ? and we can remove 1N4001 above the IC, right ?
 

battery charger lm317

Another question How to make LED light on when battery connected properly.
 

lm350 battery charger

tong said:
Need ugently your help. My car battery is out of voltage now.

This circuit can protect:

1. Battery inverse protection ?
2. No input voltage protecttion ?
3. Short output protection (battery) ?

(Short input protection --> I don't care because it can't human error.)


All diodes use 5A, right ? and we can remove 1N4001 above the IC, right ?
Click to expand...

1) YES
2) YES
3) Only down to about 2 volts output. Not a Dead Short.

And Why would you want to remove the 1N4001?
Its not absolutely necessary, but can be useful in protecting the LM350.

Lastly, this is Not a very powerful charger, For a CAR BATTERY.

This would be More Suitable:
**broken link removed**
 

lm317k battery charger

I am newbie and would like to keep it easiest. Maybe I can sell this citcuit too.

I think I will remove the output capacitor and 1N4001.
 

lm317 lead acid

tong said:
I am newbie and would like to keep it easiest. Maybe I can sell this citcuit too.

I think I will remove the output capacitor and 1N4001.
Click to expand...

Big Deal, This will save you about 50 cents in parts.
BUT Leaving off that output capacitor can result in Oscillations on the LM317 or LM350.

It is recommended that you have a .1uF Bypass capacitor (or bigger) on the output. Even Better a 1uF Tantalum cap.
I suggest you check out the data sheets and application notes.
 

lm317 charger lead

what's the max current you can use to charge the battery? Would imaging a big transformer will be needed.
 

lm317 lead acid battery charger

IamnotJunk said:
what's the max current you can use to charge the battery? Would imaging a big transformer will be needed.
Click to expand...

The maximum charge current depends on the A/H Rating of the battery?
And it Not good to Exceed about 14.6 Volts during charge.

But YES, It could require a Big Transformer for larger batterys.
 

charger lm317

Hello,

regarding protection measures, I think that the 1N4001 could be used alternatively to output series 5A diode. When the output series diode is present, no current can't flow back to input, thus 1N4001 is superfluous, if the later is present, reverse current flow from battery won't damage the regulator and 5 A diode isn't necessary. The more serious issue is with protection against reversed battery, which blows the fuse at any case, cause battery current must be regarded as effectively unlimited. This results in a single design rule: The fuses melting integral should not damage the diode.

Alternatively, an invers operated MOSFET switch could be used as "non-selfdestructing" protection device.

Regarding bypass capacitors, National has a similar battery charger application without output capacitors. Don't know if it could show parasitic oscillations, but they wouldn't be an issue for a battery charger, I think.

Regards,
Frank
 

battery reverse protection through fuse

Thanks for all suggestions.

Most charger has 2 pincers,tewwzers for + and -. What's happen if the user short them together ( short output) ?

The Fuse is melted when

1. Inverse polarity of battery ?
2. Short output ?
 

battery charger diode protection

Hi,
The fuse will blow only for inverted battery. In case of shorting of the leads, the regulator output will go to 1.25V, which will get distributed across the series 5A diode and the current sense resistor R3. However a current within the maximum as set by R3 will flow and since the differential voltage across the regulator is maximum now, it will get hot for continued shorting of output. But, the Thermal cutout feature of the regulator should ptotect it.
Regards,
Laktronics
 

    T

    Points: 2
    Helpful Answer Positive Rating
can you hook an lm317 up to a car battery

You can remove IN4001 across the regulator IC Happily as this is not usefull if the serise diode is used with Fuse. This 5 amps diode will not allow reverse current through the regulator and hence no need of IN4001.
This has short circuit protection through the current sensing resistor R3. and Battery reverse protection through Fuse.

Apv1965
 

    T

    Points: 2
    Helpful Answer Positive Rating
lm317 current regulator lead acid battery

Thank I am building this circuit...looking for a box...

I use 4.5 x 3 inch heatsink. Is it ok ?
I plan to add cooling fan too.
 

lm3914 lead acid

Hi,
You can use the whole backpanel of your box as heat sink. Vertically mounted black anodised aluminium heat sinks with Fins is the best choice. You should actually measure the case temperature of the regulator at a given ambient temperature for Max. rated current and Max. expected input voltage and calculate the device's Junction temperature from the manufacturer's data of Θjc. Add to this temperature the difference between the Max. expected ambient temperature and the ambient temp. at which the measurements were taken. The total temperature should be well within the limits of the Max. Junction temperature of the device specified.
Regards,
Laktronics
 

battery charger with lm317

Nice Web page Chemelec
 

lm317 12 charger

Can anyone tell me how long it will take to charge a 35AH Battery if I use LM350? Also, can a "Charging Complete" LED be provided to indicate a fully charged battery?
 

maximum current through lm317 charger circuit

bipinravalia said:
Can anyone tell me how long it will take to charge a 35AH Battery if I use LM350? Also, can a "Charging Complete" LED be provided to indicate a fully charged battery?
Click to expand...

depend on capacity that remain on Battery and charging current.

a blank 35AH battery and 3A charging current = 35 / 3 = 11.6 hr
In real life it must add time for heat loss.


I am building a voltage monitor with LM3914 too.
 

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