I am trying to make a simple battery float charger for a 12V lead acid battery into a simple power supply. I have a test design that you can veiw at;Lust print this in landscape form
First I would like to thank all you for responding to my problem at the link listed above. I have reposted this again (Above) with the changes and I hope I will not fry the transister is this curcuit.
I have made the following changes do to the spacs of the 12 volt 5 amp/hour battery I will be using for the backup. This battery is sealed and has a standbye charge current of 1.5A maximum. I am now useing a ballest resistor39 ohm 10W (R2) The transeformer will be now a 15VAC 3A instead of the 28 VAC one. This should reduce charge current even if the battery is flat to about .750 I hope well within the 2N3055 I will be putting Q1 on the outside of my metal case. The hole case should act as a heatsink. I will be fan cooling.
R2 the bias and D2 the zener will be a 13V 1N4743 this will give me a output at the emitter of Q1 of 13.7 volts (well with float specs of the battery). But D4 (There is a mistake in the schematic d4 should be a 1N474313v zener) D3 looks like a .6 volt drop. Iahve installed a blue LED (Just looks cool) on the power line side of the curcuit. I have also put a green led in this curcuit to show that the battery is holding a charge and stays on when the 120 volts is lost. I have put a yellow led to show when cutoff/standbye is hit.
I am useing a 741 for U2 because they are rugged and can opperate up to 36V for the comparator. R6 and R7 that bias Q2 are to saturate it it because U1 does not go rail to rail ot floats 2.5v above and below rails. R8 is the hystersis that prevet the relay from chattering when cut is hit bt making the "No Zone" several volts from trigger point.
Please direct replys to the URL below; (Because my e-mail is munged because of spammers)
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