The ideas about the LM317 are granted. I would also include a resistor to limit charge current, similar to what you showed a while back.Bill,
You can't charge a gel cell like that. You shouldn't charge a gel cell at faster than it's AH rate / 8, as it would cause excessive internal heating, bubbles in the gel, and permanent loss of battery capacity. It's much better to charge it as AHrate/20, as this causes less internal heating.
The combination of R1, R2 and R3 you have selected provides a maximum output of around 12.7v, which is not sufficient for 12v lead-acid nor gel cell batteries. If the battery internal temperature is around 77°F, the float would be around 13.37v for a 12v battery. As the internal temperature increases, the float voltage decreases.
Charging must be limited by current until the battery is nearly charged, and then regulated by voltage.
Also, you need to have 0.1uF and 10uF caps on the output of the LM317 to ensure stability and prevent oscillation.
The current sense resistor Rs needs to go between the output of the LM317 and the junction of R1 and the load. The value of Rs sets the output impedance of the charge circuit. Zout = Rs(1 x R2/R1).The ideas about the LM317 are granted. I would also include a resistor to limit charge current, similar to what you showed a while back.
Yes, I realize that. However, in rural areas power is less that completely reliable, and you have to figure that sooner or later there will be an outage, and the battery will need to be re-charged soon after.The core idea is the battery start charged and stay charged, and is used like a capacitor to provide surge currents. When I was a kid (30+) years ago that was the core problem I kept having, circuits like this require a large rush of current, even though the average requirements are modest. This not really meant as a battery charger in the traditional sense.
Leave out the 10 Ohm resistor on the input side of the 317. A small Rs will take care of it.So R2 needs to be 1.1KΩ, and a 0.1µF and a 10µF cap needs added on the output of the LM317. Maybe add a 10Ω resistor to the input of the LM317 in series with the power supply along with another fuse. This unit was fundimentally going to be outside, with a wall wart inside. Anything else you can think of?
|Thread starter||Similar threads||Forum||Replies||Date|
|S||DIY Electric indoors fence 9v||The Projects Forum||13|
|Help with an electric fence charger component||Technical Repair||5|
|B||Electric Fence Monitoring||The Projects Forum||8|
|D||Thoughts Please on "Electric Fence Circuit"||Power Electronics||26|
|Y||Electric fence problem of high voltage with chare||The Projects Forum||5|