solar regulator, how do they work ?

[simonfraser]

my solars measure 20.6V when disconnected.


with the regulator, i measure 12.8 on the solar input side and 12.5 on the battery side.
so, there is only 0.3V between the two, i can't see much current going into the battery like that.


i queried the above with the manufacturer:

Thanks for your enquiry.
The voltage is a potential difference between positive and negative references. The higher value (than the battery) at the charge source indicates that a current of charge will flow in the direction of the battery. At the same time of recording these voltages the charge LED should be illuminated green. It all sounds perfectly OK to me.



what do you guys think ?

 

[GeorgeTina]

The open circuit voltage from the panel will not tell you the amount of current that can be drawn from the panel. You need to measure the current flow into the battery which will depend on the amount of solor energy the panel is receiving. The green led is correctly showing there is some charge going to the battery but this may be a small amount unless the panel has bright sunlight and no shadows. Hope this helps.

 

[VicS]

There are different types of solar panel which work in different ways.
What type of regulator have you bought.

Also relevant facts are the size of panel (in watts) and the Ah capacity of the battery. also the incident light ... where are you in Northern Europe or in the tropics

I don't think much charging is going on at 12.5 volts unless the battery is deeply discharged or knackered.

As above really need to know the current as well in order to fully appraise.

Bull***t from the manufacturer!

 

[simonfraser]

good question, 1A going in at the time.

 

[Stu Jackson]

Are your batteries full or do they need a charge when you're doing what you describe?

 

[simonfraser]

they need a charge.

 

[VicS]

Grey cells churned this around a bit more.

Unless you have a MPPT controller a discharged battery may simply be taking so much current that the volts at the panel output /regulator input has dropped to 12.8 volts

if the battery is heavily discharged or knackered it may well be struggling to get past 12.5 at a low rate of charge

Still don't know the type of regulator, the size of the panels or the size of the battery. Nor the state of charge of the battery.

At least with one amp going in it is charging but if its a big battery it'll take forever.
If its a big panel to match then maybe the panel is duff .... (I hope this is not Uk in present conditions)

Disconnect the regulator, connect the battery directly to the solar panels and see what volts you then get and what charging current you get.

 

[simonfraser]

tnx vics, obviously a good idea to check the charging current, as it is now connected directly since last weekend, shall do so saturday.

was at boat tues, sunny, voltage then 13.10, at least an improvement over 12.5 with regulator.
most miffed the regulator is busted, imho, as it was nice and windy a week or so ago and the battery should have been full.

1A charging during the winter is common, panels mounted nearly vertical either side of the cabin.

battery 80Ah

 

[VicS]

It's a regulator controlling charging from solar panels and wind turbine then ?

Been connected as per the instructions... some require connecting in a particular sequence.

 

[nimbusgb]

What size solar panel? If its only a diddly one it may be working at capacity.

 

[William_H]

Solar regulators

Well I think the regulator is cactus. That is assuming that there is no wind turbine and no other charge source. Further the explanation from the manufacturer is a load of codswallop.
Regulators as far as I can figure can be a series regulator where a transistor passes current and is controlled by circuitry which compares the output voltage to a standard voltage and increases or decreases the effective resistance of the transistor to ensure that an appropriate voltage appears at the output.
That voltage would be about 14v. ie enough to charge the battery as fast as possible while not over chargeing it. The disadvantage of this type is that the regulator transistor always drops about 1 v so that if the solar panel voltage drops it will stop charging at 15v or more from the panel.
Some series regulators may use with more complexity a FET transistor which can reduce voltage drop.

Another method is to set up a regulator as a shunt regulator. This is again a power transistor with a voltage standard and circuitry to turn the transistor on when voltage exceeds 14v the transistor often with a large resistor sucks away the current when the battery volts reach 14v. So until the battery is charged and voltage has gone up to 14v the regulator does nothing but when voltage rises above 14v the shunt regulator passes current so that the voltage of the panel is pulled down to 14v by wasting current.

The last option is the MPPT regulator which takes the panel voltage ie 20v and converts it by switching and transformer to give 14v output. By reducing the voltage in a transformer it can actually produce more current into the battery than the panel provides. ie the power is the same 20v @ 1map is 20watts, 14v @ 20 w 1.42 amps. However losses in the switching reduce that a bit.

Note that in every case the voltage is 14v presented to the battery. Many regulators will njow use the step charge principle where this voltage is higher until full charge is reached then reduced for trickle.
But a voltage of 12.5 or even 13 will give very poor charge rate which will cease before the battery is fully charged.

A battery has an internal or inherent voltage which depends on charge state. It is in fact the voltage you measure with no load with a volt meter. Current can not flow into the battery until the charge voltage exceeds the inherent voltage. The current amount depends on the difference between the the charge voltage and the inherent voltage. So if charge voltage is 14v the current tapers off as the battery inherent voltage approaches 14v. Hence the last part of the batteries charge can be very slow compared to first part. Hence the value of stepped charge rate which can improve the top end charge time.

You can see that if the solar panel is capable no load of 20v then it will push in all its current even into a fully charged battery hence the need for a regulator. However if the max current the solar panel can produce is small (at this current the solar panel voltage drops) enough that it will not damage the battery over a long period of time then with no regulator every drop of current goes into the battery to give quickest charge.

So I would advocate send the regulator back. You might consider not using a regulator especially in winter when solar charge time is short compared to no charge time. good luck olewill