Hello Again,
Still not much luck I'm afraid. I followed your suggestion Mike and I connected the circuit to a 12v transformer instead of using the wind turbine controller power supply. I then connected the negative side of the battery bank to the ground of the 555 circuit. However, when I connected the positive side of the battery bank to the circuit there was a large spark and quite a bit of smoke. It looks like the voltage division resistors have got cooked, probably not surprising since they were connected directly between the two battery bank terminals...
...
As I mentioned in an earlier reply, neither of the battery bank cables are tied to the wind turbine controller ground; there's about 100 volts difference. However, I have tried putting a pair of voltage dividing resistors between ground and the terminal marked 'L'. When I first tried this the 100v dropped to almost zero; I don't know why, but the system continued to function, nothing got hot or started to smoke. The right resistors will have to be selected to obtain a 4v or 8v output but it might be possible to get the circuit working like this. I'm just guessing of course, I'm really out of my depth so if someone's got some sound advice I'd be glad to hear it!
Thanks everyone for your consideration and helpful ideas.
OK Mike, I follow your what you're saying. The resistors I used were all 1/8 watt 5% and must have been far too weak for the circuit. I'll have to look around to see what else I've got, otherwise I'll have to order some sturdier parts.
This raises another issue. The LM7812 regulator has a dropout voltage of 2V, so to get the rated 12V out, the input voltage must be 14V or higher. If the voltage sags below 14V, the 7812 might be dropping out of regulation.The transformer was a mains powered device giving out just over 13 vdc; it was connected to the regulator as in your design.
I'll continue in the morning and keep you up to date as I go along.
Here you go. I used a LED as a temporary load. You can use a small relay. I would put a snubber diode around the relay coil. If you want it to be ON when the LED is OFF, you can return the other end of the relay to 12V instead of ground. Use a 12V relay with a coil resistance greater than about 100 Ω
doesn't the 555 have a "push pull" output meaning that the diode would short the out put when it is "off" i may of course be talking out of my hat
I looked up the specs on Fluke's web site. In the DCVolts mode, the input impedance is 10megΩ, meaning that the leakage in your battery bank which is "earthing" the bank is pretty high. Probably just moisture on the surface of the battery casesSorry Mike, but I can't answer your question about the impedance of the meter. The one I've been using is a Fluke digital multimeter 8022A that I've had for many years.
I am beginning to suspect that there is some problem coming to the surface in the battery bank because these days it won't hold a charge as long as it did a few months ago; maybe the connections need to be checked out; maybe a battery has gone "bad". This though is another subject and not the 555 controller circuit we've been building.
I'll take your advice and change the capacitors to eliminate the ripple. After that all should be set. I've adjusted the resistor values and installed a couple of trim pots; all are fairly beefy components to handle the power. The indicator LED has been removed and the output from pin 3 now goes to drive the low voltage relay. When the circuit is connected the output is high and so the relay will make contact, this then is connected to a second more powerful relay that switches the house supply between inverter output and the national grid.
I assume that when the pin 3 output is high the batteries are charged up and that the system can be left connected to the inverter/battery bank? When the battery output level falls low (below 240v) the 555 will trigger the two relays to switch the house across to the national grid and allow the batteries to charge up again without any load. When the batteries reach 260v the system will trip again, pin 3 will go high, the relays will change state and the batteries will begin to discharge via the inverter as the house uses up energy.
If this isn't the way things work please point me in the right direction! I'll try wiring it up today and the only way I can really try it out is to wait for low voltages or high wind.
I'll keep you posted.
Use a 555. Feed the Vcc pin with a 10V regulator. The trip points of the two comparitors will be 3.333V and 6.667V, respectively. Now make two voltage dividers off the sensed voltage input such that one produces said 3.333V when the sensed voltage is at your lower trip point, and the other divider so that it produces 6.667V when your sensed voltage is at your upper trip point. The 555 can drive a small relay, or buffer its output as ne
I built a battery charger using this trick. The two voltage dividers utilize trim pots, so the upper and lower trip voltages are easily adjustable. I can post an LTSpice schematic if you want.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?