dump controller

[prasadbodas2000]

Hi All,

I have been reading on this board about the wonderful Ghurd controller.
However for me getting the parts here in my city (Thane, Maharashtra, India) had been a problem.

I then searched for similar circuits based on NE555 and found this one. http://gorum.ca/lvdisc.html
I built it and seems to be working fine with a setup comprising of below.
12V Battery 60Amp-Hr capacity
One number 14-18 V 60 Watt solar panel directly connected to battery.

The circuit built as per the details in the link above in my case uses STP55NF06 mosfet to switch on and off a load which is nothing but a automtive head lamp bulb 24V 100 Watt rated.
During daytime there is no load on the battery and also no MPPT for solar. At night time I use the battery to power the LED lamps approx 12Vx3Amp load for 6 hours.
So say 18 AmpHrs are drained from the battery everyday and say 20-30 AmpHrs pumped in by solar panel during day time when in healthy sunlight.

After about 11:00 HRS I see that the lamp starts a cyclic switch on-off sequence until about 15:00 HRS [cycle time 8 seconds on then 12 sec off], for rest of the daytime the lamp remains OFF.
I have not installed the capacitors C1 & C2 (becos I could not get low-leakage tantalums) as mentioned in the circuit.

I request comments from the seniors here, about if the said circuit is meaningful generally or not and any improvements recommended.

The main aim being to prevent battery overchanging, a dump load contoller basically.
Observed setpoints after whatever tuning/calib I could do are at 13.50 [load turns off] and 14.50 [load turns ON] volts.

Prasad

[ghurd]

Let me start by mentioning:
Ghurd will send his controller kit Anywhere in the world for the same price.

Someone else may have other ideas...

I believe the caps C1 and C2 could be polypropylene or polystyrene.
Use the highest voltage rating available to minimize leakage.  Or the highest voltage rating that fits in the space allowed.

I would only use a Schottky diode for CR2.  Change the 1N4004 to 1N5817 or 1N5819.

I am not clear about the fet and dump load, or if there is a relay in your circuit.
If the fet is powering the bulb directly (no relay involved), you may consider reducing C1 and C2 to 10uF.

1.0V of hysteresis (13.5V to 14.5V) is too much, in my opinion.  Might want to reduce that to 0.5V (14.0V to 14.5V).


"Observed setpoints after whatever tuning/calib I could do...." ?
That sounds like you are having trouble calibrating the circuit?
This will solve the problem.
Make 2 pairs of wires from the battery.
One pair for the controller circuit.
One pair for the fet and bulb.
Connect the 2 sections together with the R12 connection to the fet Gate.

Light bulbs are not good dump loads.  They have a high surge current.  Check the mosfet to make sure it is not getting hot.  Check at 12:00 to 14:00 HRS.
G-

[prasadbodas2000]

Thanks a lot for your kind comments.

I have not used a relay and the circuit is driving the lamp directly from MOSFET. The MOSFET has a 50 Amp datasheet rating and the lamp takes about 10-12 Amps peak current when starting from cold (I assume). The MOSFET and Sink temperature is very little warm I will say. So not an issue.

As you said, I could not reduce the hysteresis to less than 1V and this must be becos my cables that supply the 555 and MOSFET are same and not adequately sized.
So there must have been drop in the supply voltage to 555 when lamp turns on.
I will try to use separate set of wires and also will post a picture.

Regarding your open offer to ship the kit anywhere in the world, thank you very much. But I am afraid that cost of shipping will be excessive.
I will on the other hand try to look for the components for the Ghurd controller in other nearby cities here.

As an information the presently built circuit using 555 has costed me around (100 INR) 2 USD approx including MOSFET but excluding the lamp.
Also that the battery costed me around 90USD and the 60 Watt solar PV panel costed 1.8 USD per watt.

With many thanks again.

[ghurd]

Really, I will send a kit anywhere for US$3 shipping charge.

The separate wires will solve the calibration issue.
It is a problem all controllers have, and all controllers need 2 pairs of wires.

This shows wind, but the controller wires are shown.
G-

Edit-  If the circuit is still unstable after changing the wires, increase C3 to a larger value.  And might consider changing 555 to 7555.

[rumleyfips]

I am having a problem with a 96 volt ac permanent magnet generator.

I haven't been able to get it to furl quickly enough in 11+mps wind gusts ( probably swirling too.

The batteries charge and the charge controller diverter light comes on but the dump load is not heating. The inverter is shutting off at 120 v and disrupts my television time.

The dump load is constructed with three turned wire resistors in free air. One end of each resistor is connected to one of the three red wires from the controller and the other ends are connected together.  There is continuity from one end of the resistor array to the other. Ohm readings are all over the dial .

I have not been brave enough to test with the power diverted to the load. How should I do this? In suspect I shold be getting 120v+ readings across any of the three wires out of the controller when the diversion light is on.

Is there a better way?

Thanks:
John

[Rover]

Hi John,

Since your topic is different than this thread , you probably should have started a new post.

Rover.

[rumleyfips]

Rover:
Right. I found the new topic button, I had to log on first. I have to learn how to do it with every new site.

I'll repost as a new topic .

Thanks:
John