circuit needed.

[snake21]

hi friends,i have a small question.
i have a ups which doesnt work,in fact,the battery is damaged.i have a 12v 100a/h battery which i connected a wind turbine ans i will connect 250w solar panels.

i just want to know if there is any type od circuit or method that works the opposite way of a ups?

i mean that,the primary power supplier of bulbs will be batteries and then the voltage of the battery drops,the circuit disconnect power from batteries and connect power from grid.

is there any way to do that?

thanks

[ghurd]

Are the light bulbs 12V, or 120 / 240VAC?

Could use a ghurd controller LVD, in reverse.
When the backwards LVD triggered because of a low battery, a grid powered battery charger would charge the battery.
It would be opposite of a UPS.

"i mean that,the primary power supplier of bulbs will be batteries and then the voltage of the battery drops,the circuit disconnect power from batteries and connect power from grid."
Disconnecting 120/240VAC devices from the inverter, then connecting to the grid, or the other way, will cause problems.
It would be possible if the devices were Only regular incandescent light bulbs, but anything else could be blown up.
The inverter and grid will not be in phase.  The change will make voltage and current spikes.  Motors, transformers, CFLs, possibly the inverter, will all be ruined.

G-

[snake21]

hi,i was planning that for ac 240v for bulbs only.
how should be the ghurd lvd connected?

[ghurd]

This description is ONLY suited to 12V systems.
24V systems require it to be done a bit differently.

It will require another kit.  Can not do it with a kit that is already doing another task.

It also require a power P-channel mosfet to do it the simplest way.  And a relay with 12VDC coil, and contacts rated more than the battery charger uses from the grid.
The relay coil requires a Schottky flyback / freewheel diode.

The kit is assembled as an LVD, with the hysteresis maybe about 0.6V.

The circuit boards output goes to a P-channel mosfet.  They are wired differently than N-channel mosfets!
P-channel mosfets also operate differently.

The P-fet is connected to the relay coils.
The relay contacts are between the grid and battery charger.

If the battery is above the controller's set point, the output to the P-fet Gate is high.  The P-fet is Off. The relay is Off. The battery charger is Off.

If the battery voltage drops below the controller's set point, the output to the P-fet Gate is Low.  The P-fet is On. The relay is On. The battery charger is On.
Everything stays On until the battery voltage rises the 0.6V hysteresis, when the controller shuts everything Off.

G-