Keeping a battery charged between two voltages - Electronic Circuits Projects Diagrams Free

Jules · 22nd July 2004, 09:12 AM

I want a simple way to keep a 12 volt gel cell charged between a range of voltages (approx 10.5 volts and 13.8 volts), and to disconnect the load when it falls below 10.5 volts, and reconnect at 13.8 volts. I am using an 18 volt solar cell as the power source, and this has an amplified zener to regulate its voltage to a fairly stable 13.8 volts, but it can fall below this when dark!
I have looked at a window comparator circuit, but it needs a stable supply voltage. Any ideas? Thanks

Russlk · 24th July 2004, 02:13 PM

As you noted, your need a stable reference. Try a programmable zener like the TL431.

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22nd July 2004, 09:12 AM	(permalink)
Jules	Keeping a battery charged between two voltages I want a simple way to keep a 12 volt gel cell charged between a range of voltages (approx 10.5 volts and 13.8 volts), and to disconnect the load when it falls below 10.5 volts, and reconnect at 13.8 volts. I am using an 18 volt solar cell as the power source, and this has an amplified zener to regulate its voltage to a fairly stable 13.8 volts, but it can fall below this when dark! I have looked at a window comparator circuit, but it needs a stable supply voltage. Any ideas? Thanks

24th July 2004, 02:13 PM	(permalink)
Russlk	As you noted, your need a stable reference. Try a programmable zener like the TL431. __________________ see my website: www.geocities.com/russlk