Need some help from electronic friends, I know how to reduce voltage with resistors, what do I use to reduce amps? I want to branch off my 12v 5 amp source with a 12 v 300 mA for battery charging. I google it and the results are always that the source amps doesn't matter as the item draws what it needs except for battery charging. They mention a current limiter but I don't know what this is.
How do I reduce amps??
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If you where trying to apply juice directly to your batt, they would be destroyed from the fact that you
where putting 12V through a presumed 3.7V batt. The charger will regulate amps regardless of the source,
but you need to step down the voltage to 5v's if it is an USB charger. An AC adapter would presumably
step down voltage and regulate amps, but it sounds like you're using a 12V batt? Or, maybe a PC
power supply?
Think about it, the 5V 2amp wall adapter that most of us use for PT's and charging instead of
risking our PC's does not apply 2 amps to batt. The charger that you plug into it regulates that.
Duh!! I just seen where you said batt was 11.1V's, is 12V's what is required to charge that batt?
I would still think that a charger will regulate the amps, and on a side note, it seems to me
300ma's would take FOREVER to charge a batt that big.
where putting 12V through a presumed 3.7V batt. The charger will regulate amps regardless of the source,
but you need to step down the voltage to 5v's if it is an USB charger. An AC adapter would presumably
step down voltage and regulate amps, but it sounds like you're using a 12V batt? Or, maybe a PC
power supply?
Think about it, the 5V 2amp wall adapter that most of us use for PT's and charging instead of
risking our PC's does not apply 2 amps to batt. The charger that you plug into it regulates that.
Duh!! I just seen where you said batt was 11.1V's, is 12V's what is required to charge that batt?
I would still think that a charger will regulate the amps, and on a side note, it seems to me
300ma's would take FOREVER to charge a batt that big.
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No one is answering my question. How do I reduce 12v 5amp source to 12v 300 mA. Forget why I want to do it. And yes all I use for vaping is stepped down 11.1 v Li-Po batteries so all this abought 5v and 3.7v is irrelevant.
I thank you all for your suggestions but still haven't found the answer.
I thank you all for your suggestions but still haven't found the answer.
http://www.hobbyking.com/hobbycity/...Flightmax_850mah_3S1P_20C_Lipoly_Battery.html
This is one of the batteries I use
This is one of the batteries I use
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Maybe this will help..
I understand that you want to limit the current possibly to slow charge a battery.
I found this it says you can adjust the current by changing R2.
An Add-On Current Limiter For Your Power Supply
Ahh more studying..
I understand that you want to limit the current possibly to slow charge a battery.
I found this it says you can adjust the current by changing R2.
An Add-On Current Limiter For Your Power Supply
Ahh more studying..
Yor question was answered in post #5. Wait for the App to load and you will see exactly what you seek. Put a 40ohm resistor is series and you will have your 300ma. Make sure your resistor can handle the watts.
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I want to reduce my 12v 5 amp source to 12v 300ma to charge a 11.1v Li-Po
You want to charge a 11,1v lipo pack .
3 cells 3,7v = 11,1v --> you need 4,2v/elements = 12,6v max voltage during charging with a constant voltage first (12,6v) and constant current after (depend of your lipo pack capacity).
What do you use for charging ? I power supply with just current/voltage limitation is not sufficient
3 cells 3,7v = 11,1v --> you need 4,2v/elements = 12,6v max voltage during charging with a constant voltage first (12,6v) and constant current after (depend of your lipo pack capacity).
What do you use for charging ? I power supply with just current/voltage limitation is not sufficient
Pailpo my source is 12.6v 5amp, I have been in the RC hobby for many years and understand multicell Li-Po charging and balancing and have many expensive battery chargers to do that It was more a curiosity of how to reduce amps.
you need a current regulator.At that moment i don`t have ideea for a IC but try to find at maxim,TI or other sites
look out at http://www.ti.com/product/bq24450 have adjusting output, and regulat both voltage and current
look out at http://www.ti.com/product/bq24450 have adjusting output, and regulat both voltage and current
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