so I need to know if my method/circuit of charging a 6V Lead Acid Battery is safe or even workable! so this is the circuit and battery info!


simulate this circuit – Schematic created using CircuitLab

  • 6V/2Ah Lead Acid Battery
  • Model - SD620
  • Type - VALVE Regulated
  • Voltage Charge Type - Constant - "Also it writes Constay, I think it's a typo!"
  • Cycle Use - 7.25V - 7.45V
  • Standby Use - 6.8V- 6.9V
  • Initial Current - Less Than 1.2A
  • 1
    \$\begingroup\$ It is suboptimal due to power loss in regulator with 1.2A and about 4W when discharged to 5.75V, then exceeds standby voltage. or 6.9V. Safe? probably ? reliable? too hot for regulator so it will cut in and out. reduce battery life?, yes somewhat, efficient? no, slow? yes.. good? not really... you want an SLA charger or a 6V 6W light bulb and watch the voltage never exceeds 7.4 and disconnect immediately \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Sep 29 '17 at 23:33
  • 2
    \$\begingroup\$ related: BU-403: Charging Lead Acid on Battery University \$\endgroup\$ – Nick Alexeev Sep 29 '17 at 23:42
  • \$\begingroup\$ the thing is that the regulator is not even hot, I got a small heatsink on it and it's cold! \$\endgroup\$ – Xios Sep 29 '17 at 23:42
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    \$\begingroup\$ Check the input voltage on the 7807. They generally need a few volts more on the input pin than on the output. The datasheet will give you details on that. Don't omit the recommended capacitors or the device may oscillate. \$\endgroup\$ – Transistor Sep 29 '17 at 23:47
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    \$\begingroup\$ It won't hurt the battery as long as you don't leave it there indefinitely. If the regulator is cold to the touch, it is probably not charging, either because the battery is full, or because something is broken or wired wrong. Some power adapters are always warm when plugged in. May not indicate any problem. I would expect the regulator to get hot at some point during the full charge cycle. \$\endgroup\$ – mkeith Sep 30 '17 at 1:47

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