Electronics > Beginners
12v Battery Charger Circuit using LM317 (12v Power Supply)
digsys:
--- Quote from: queennikki1972 --- MarkF that makes more sense to me. I assume that 1R0 is 1W means 1 WATT resistor.
--- End quote ---
errr nope. 1R0 = 1.0 ohms (at 1W as stated)
Working with V=IR, as current increases, voltage across the resistor also increases following that formula. At near 0.6V ~= 600mA, it will start to conduct
and start bringing down the Vop. If you need more current, decrease the resistor value and vice-versa
Note: That type circuit is really only for "Trickle charging" at ~ 13.8V, it has no boost capability, as usually ~14.4V. That gets trickier :-)
Zero999:
--- Quote from: queennikki1972 on April 30, 2019, 11:15:27 pm ---http://www.ti.com/lit/ds/symlink/lm317.pdf page 13 battery charging circuit "RS" means current sensing resistor? Im sorry for asking such dumb questions
--- End quote ---
I thought it meant series resistor, but the naming is arbitrary.
--- Quote from: MarkF on April 30, 2019, 11:36:41 pm ---Here is a circuit I found online some time ago. There was a description but I didn't save the URL.
I have not built it but looks interesting to play around with.
--- End quote ---
It's probably based around the one on the datasheet I referred to above.
http://www.ti.com/lit/ds/symlink/lm117.pdf page 26.
--- Quote from: digsys on May 01, 2019, 06:14:20 am ---
--- Quote from: queennikki1972 --- MarkF that makes more sense to me. I assume that 1R0 is 1W means 1 WATT resistor.
--- End quote ---
errr nope. 1R0 = 1.0 ohms (at 1W as stated)
Working with V=IR, as current increases, voltage across the resistor also increases following that formula. At near 0.6V ~= 600mA, it will start to conduct
and start bringing down the Vop. If you need more current, decrease the resistor value and vice-versa
Note: That type circuit is really only for "Trickle charging" at ~ 13.8V, it has no boost capability, as usually ~14.4V. That gets trickier :-)
--- End quote ---
He's right. It should be a 1W resistor, to allow some leeway.
queennikki1972:
Typo, 1 Ohm at 1 watt is actually what I meant to say. 1R0 1W = 1 Ohm at 1 watt
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