ghurd controller question

[snake]

hi friends,i just need some advice and clarifications using ghurd's controller.when i bought ghurd controller kits,i thought that it can be used for bothe an LVD and a dump load controller at the same time in a wind turbine system

but after some research,i have found that one controller is to be used for either an lvd or a dump load controller but not for both at the same time

i wanted to have it as both lvd and dump load controller due to the wind conditions in my area.sometimes there is lots of wind and sometimes there is no wind at all.

i wanted to know if i can use 2 ghurd controller, 1 for LVD and 1 for dump load controller in my wind turbine system.

if yes,then how the controllers should be connected to the system.

how must i connect the circuit to the batteries so that it works as an lvd

i thought that ghurd's controller need to be connected in series with the battery bank where there is 1 input from the turbine and one output to the batteries but after having studied the circuit well,i saw that it should be connected in parallel to the battery banks with only one output to the dump load.

IN ANY CASE,I AM NOT SAYING THAT GHURD'S CONTROLLER IS NOT GOOD,PLEASE DONT MISUNDERSTAND ME.

please do help me

thanks

[Flux]

I am sure Ghurd will help you here, but it is a shunt controller and must never be put in series with a wind generator, nor must any other controller other than one specifically designed as a mppt wind controller.

No controller can be used for diversion and lvd at the same time. You might be able to buy a box to do this but it will have 2 controllers inside.

The voltages are different so the sensing circuit can't be common and there is no way that a series control device can be used in 2 places at once.

Yes you can certainly use one controller for each. I don't want to get too involved with this , I know Ghurd will help anyone buying his controller but basically both connect to the battery. The charge controller connects a load resistor to the battery when it exceeds a certain voltage.

The LVd feeds your load from the battery as long as it is above a limiting voltage and cuts off below it. The logic works backwards but the control mosfet feeds from the battery to a resistor or the load depending on the mode you use.

Flux

[snake]

how the lvd need to be connected with the battery banks?

[Flux]

The lvd is connected to the battery just like a charge controller. The terminals that go to the dump on a charge controller become your load connections. Your load replaces the dump, the logic is reversed so that the load stays on until the volts drop to a set value.

Flux

[Flux]

Actually the logic is not reversed, you just lower the set point to your lvd voltage. There is no change to the controller, you use the dump terminals as load and lower the set point.Sorry for the confusion, it's the logic of the process that's reversed not the circuit.

Flux

[ghurd]

Flux has it covered.

Using the circuit as an LVD is simply placing the load where the power resistors go in a dump load circuit.

The RX resistor controls the hysteresis (the difference between On and Off).

The RX resistor needs to be a much lower value, or the load will oscillate.

The voltage is set lower in an LVD.

Load shuts off at maybe 12.2V.  Turns back on at maybe 12.8 or 13.0V.

Need to consider the battery AH compared to the amps the load uses.  A large load on a small battery needs a larger hysteresis than a small load on a large battery.

G-

[electrondady1]

so if you google LVD you get a sheetmetal working company from holland

so what is a lvd in this instance

[ghurd]

Low Voltage Disconnect.

It protects the battery from being excessively discharged.

Say a system is used for an automatic security light.

But the RE charging was not so good for a few days.

The LVD will shut off the light when the battery gets low, and not allow it to turn back on until the battery has received some charging.

G-

[snake]

so with what i understood,the turbine should be connected directly to the battery banks,then both controllers are connected in parallel to the battery.the wire going to the dump load in an LVD is connected to the inverter

is this right?

[bzrqmy]

I started out with a Ghurd controller as a diversion controller.  This took care of my over production problem.  Recently, I added another Ghurd Controller ad an LVD.  I am tired of plugging and unplugging my load when my battery gets too low.  Now, when my battery starts getting low, the LVD kicks in a relay that turns on a battery charger.

One question:

For 24V, and a 60 Watt continuous load, what voltage should I kick my charger on at?

[snake]

thats a nice idea.....i must think about it

anyways,i got another question.

normally,wind doesn't blow at a constant speed which makes the turbine to produce high voltage or low voltage.is there any DIY circuit which will control this voltage to the battery?i believe that low voltage will not cause a problem because the batteries will not get charge.but what about high voltage to a 12 volts system

for exam if my batteries need only 14.5 volts and my turbine is producing 20 volts.is that a real problem?what can be done to avoid this problem?

thanks

[bzrqmy]

The battery acts as a natural voltage regulator, until it gets fully charged, then the voltage will start to rise.  If left uncontrolled, the battery will become damaged.  This is why we use dump or diversion controller to switch on a load to use the extra power being produced.  The 20 volts you are referring to from the turbine is what is called open circuit voltage.  It's voltage, but it's not doing anything if not connected to a load.   When hooked to a battery, the turbine will spin until it reaches the "Cut in" voltage.  This is the voltage that the battery begins to charge.  You will see current flow into the battery and therefore generate watts.  You should notice a slight humming noise when this happens.  This is a good sound as it means your turbine is generating.

[ghurd]

Depends on the use, battery size, and charger size, partly.

If it is cycling less than maybe 12(?) times per hour at the worst, and the battery charger is reasonably suited to the battery size (not a 20A charger on 7AH batteries), probably all is good.

Personally, I do not like to take the batteries below about 12.2V on a 12V system, regardless of lead-acid battery type (flooded, SLA, gel, AGM).

Naturally if the load is vital I would not have a problem taking the battery a lot lower.

If the load is large compared to the battery capacity, the voltage will "Bounce back up" without any charging.

Could take the battery lower in this case, maybe 12.1V?

A small battery capacity and large load will cause the charger to cycle pretty fast, as in maybe once every minute or 2.

Once every minute or 2 will not hurt anything, but it means something in the system is too big or too small.

(I have to say those are nice answers you gave, thanks)

G-

[ghurd]

"for exam if my batteries need only 14.5 volts and my turbine is producing 20 volts.is that a real problem?"

It is not a problem.  It is a necessity if you want to charge batteries.

The "extra open voltage" is converted to charging amps.

If the turbine never made more than 14.4V, the battery would never over charge.

If the turbine never made more than 14.4V, the battery would never reach full charge.

If the turbine never made more than 14.4V, the battery would almost never get any charging amps at all.

It is important the turbine makes more than 14.4V open circuit, or the batteries will not charge.

G-

[wooferhound]

The battery will always try to keep the voltage going into it, at the voltage level of the battery itself. The battery will be sitting at 13 volts, and your Wind/Solar power will be 22 volts open circuit. As soon as you connect your open circuit Wind/Solar power to the battery, POOF ,everything is now running at 13 volts. It pretty much doesn't matter what voltage you want to charge the battery with, Your genny may be making 65 volts open, but connect it to the battery and then everything is at the battery voltage.

What happens to all that extra voltage? It's converted to amps and that is where you start to worry about your stator burning up. Once your wind genny reaches Cut-In (battery voltage) the measured volts will be the battery voltage which should be increasing slowly as it is charging. As your genny speeds up past cut-in the voltage doesn't increase, but the amps do. Under most circumstances you don't have to worry about the voltage of the device you are connecting to the battery, your worry will be with the ability of the charging device to deliver the Amps without burning up.

When Charging a battery try to keep the current going in to less then 10% of the capacity of the battery. For Example: a 100 amphour battery should be charging at 10 amps or less.