Solar controller voltage output

Gus1949 · Senior Member

Solar controller voltage output

Jaahn · Guru

Gus1949 wrote:
I recently purchased a 120watt portable solar panel for use with my caravan.
Today I used a multimeter to measure the voltage output and found while I was getting 20V on the input to the controller I was only getting about 2.5V on the out put side. Does the panel have to be connected to a load (e.g. a battery) to obtain a correct measurement or is there a potentential problem with the controller?

Hi Gus smile

Did your panel and controller come with any instructions ?? Read them !

Generally it is recommended that you connect the controller to a battery BEFORE you connect the solar panel, to protect the controller. Doing it that way powers the output 'transistors' so they do not burn out. So yes you need to be connected to a battery to get a sensible reading.

Jaahn

Gus1949 · Senior Member

Yes I did read the instructions but they don't deal with the question I asked. With the portable panel the controller comes already attached on the input side so there is not much that can be done about attaching the battery first.

If the panel is attached to a battery won't the multimeter just measure the voltage in the system, not the voltage flowing from the regulator? Would the battery need to be down on charge for the multimeter to detect the voltage coming from the controller?

Jaahn · Guru

Gus1949 wrote:
Yes I did read the instructions but they don't deal with the question I asked. With the portable panel the controller comes already attached on the input side so there is not much that can be done about attaching the battery first.
If the panel is attached to a battery won't the multimeter just measure the voltage in the system, not the voltage flowing from the regulator? Would the battery need to be down on charge for the multimeter to detect the voltage coming from the controller?

OK smile

If you connect the battery to the output of the panel/controller, with the multimeter reading the battery voltage, then turn the panel to face the sun, the battery voltage should go up from the resting voltage to a higher voltage as it charges the battery. Perhaps to 14+v after a while if sunny.

Jaahn

Gus1949 · Senior Member

Thanks Jaahn, its going to be sunny tomorrow so I will leave a light on overnight to run the battery down a bit from its fully charged state at the moment.

Dreamcaster51 · Senior Member

Sorry to hijack the thread Gus1949, I just purchased two fold up panels and hooked up my multimeter to check, both 22 volts into controller at @ 4.9 amps, after controller only 7.48 volts @ 4.8 amps. Being a little bit slow I always thought you needed around 10 - 14 volts to charge a deep cycle battery any advise please

Peter_n_Margaret · Guru

EXACTLY where are you putting the multimerer probes?
Cheers,
Peter

Whenarewethere · Guru

My 120 watt (6 x 20w running as 6 panels in parallel in this photo, normally run in series for 43v input). The controller is near the battery.

The amp meter is before the controller, as the Bluetooth data on the phone only shows amps out of the controller & I wanted to know the amps out of the panels.

The voltage meter is after the controller, even though the Bluetooth data showed this already, this was to be able to see battery voltage at a glance without having to get out the phone.

Amps out of the controller according to the bluetooth data on the phone on a good day is typically around 9 amps with the battery fairly well charged & voltage controller output gets up to about 14.4 volts depending on the stage of charging. I do get up to 11.3 amps out of the Victron MPPT 100/20 controller.

I do get a whisker more out of the Victron MPPT 75/10 controller but it cuts off at 10 amps output so I then miss out on another 1.3 amps.

Bypass the cheap third rate controller on the back of the panels, it is in the wrong place to start with, & install a quality controller near the battery.

To be on the safe side always connect the controller to the battery first, plug in or turn on etc first, then after that connect the panels, plug in, turn on, or turn to face sun. Fire up the panels last.

Dreamcaster51 · Senior Member

If the question was for me, I put the probes into the input side of the controller (22.2v & 5.1a) then on the output of controller (7.1 v & 5.1a ) . As I said or asked is this voltage enough to charge ??

kgarnett · Senior Member

What is the voltage across the battery terminals?

Peter_n_Margaret · Guru

Dreamcaster51 wrote:
If the question was for me, I put the probes into the input side of the controller (22.2v & 5.1a) then on the output of controller (7.1 v & 5.1a ) . As I said or asked is this voltage enough to charge ??

EXACTLY where and in what conditions?

The terminals are connected directly to the battery too.

Maybe the controller thinks it is a 6V battery. That is why connection sequence is important.

Cheers,

Peter

Dreamcaster51 · Senior Member

Ok Peter for you,
The panels and controllers are brand new, I put the probes directly on to the input side of the controller from the panel, then the out side of the controller. Input volts 22 amps 5.1 then on the battery side of the controller 7.1volts & 5.1 amps. This was in direct sun in the s.a. Riverlands at 3 degrees, panels set to the correct angle as per the legs.
I had not connected the battery at this time as I wanted the readings from the panels and controller. If I hooked a battery up would it not show the battery voltage onto the battery side of the controller.
My question was this enough voltage to charge a battery, I always thought around 10 to 14.2 volts to charge, if you can help with an answer I would appreciate it if not no worries.
I can not find a user manual for these controllers and am awaiting a reply from suppliers, just thought I would short circuit the system

Dreamcaster51 · Senior Member

https://s3-ap-southeast-2.amazonaws.com/sharepoints/image/yhec04-f-h%20sp-f160-oc-v/design/sp-f160-oc-v_e.jpg?refrish0106

This is the controller

Peter_n_Margaret · Guru

I don't know your controller, but the battery must usually be connected before the panels so that the controller knows what it is and with no battery, nothing is happening, so the readings will all be meaningless.
Connect it up and you may get some sense.
Cheers,
Peter

Mike Harding · Guru

Two points come to mind:

1 - the controller may be faulty, you can easily test this over a couple of day by observing whether it charges the battery.

2 - the controller is a PWM type and your digital multimeter is being confused by the pulsing waveform the controller is producing. This is harder to confirm and needs both knowledge and test equipment. Try borrowing another multimeter and see what that reads.

Edit:

Just reread your original post: yes, it probably needs to see a battery before it produces any significant output.

-- Edited by Mike Harding on Saturday 22nd of January 2022 05:34:45 PM

Jaahn · Guru

Hi

My suggestion is the same as other have said AND was said EARLIER IN THIS THREAD TOO. Disconnect the solar panel, and any load connections, then connect the battery and see what the reading are and if they are close to your multimeter. Then connect the solar and see what the readings are then.

I cannot say why the readings were showing a current before. BUT that regulator does say on the front "will not charge when the voltage is below the discharge stop voltage" I would say 0 Volts(no battery) is below that whatever it is set to.

Good luck. Jaahn

Dreamcaster51 · Senior Member

Thanks to all, will hook up battery and see how it goes, unfortunately the battery is showing 13 volts but I will run the fridge for a while then check.
Great place for help as it always was.
Cheers, see you out there some time

dorian · Guru

How can there be 5.1A of charging current when the battery is not connected?

Dreamcaster51 · Senior Member

Not sure my friend Dorian, must be the force
Any how I finally hooked up the fridge to the battery I installed in van and turned on, then hooked up the 160 watt solar panels, reading 18.7 volts input and 14.7 volts output @ more amps than my little 10 amp multi meter could handle. The wires on my meter started to heat very quickly and no readings on amps, bugger, but the panels seem to be working. My question now is how many amps input can an AGM battery take ?

-- Edited by Dreamcaster51 on Friday 4th of February 2022 05:53:53 PM

Whenarewethere · Guru

About 0.2 to 0.3C

DeBe · Guru

The quickest way to destroy those regulators is power it up with out a battery connected. The battery needs to be connected first for the micro processor to determine what voltage the battery is. I have actualy wrecked one.

DeBe · Guru

This is the instructions typicaly for those solar regulators. Note connect battery first in instructions.

Hylife · Guru

no battery connected = no regulated output from the controller

jegog · Senior Member

Peter_n_Margaret wrote:
Dreamcaster51 wrote:
If the question was for me, I put the probes into the input side of the controller (22.2v & 5.1a) then on the output of controller (7.1 v & 5.1a ) . As I said or asked is this voltage enough to charge ??
EXACTLY where and in what conditions?
The terminals are connected directly to the battery too.
Maybe the controller thinks it is a 6V battery. That is why connection sequence is important.
Cheers,
Peter

5.1A input and 5.1A with differing input and output voltages? The input voltage is about three times the output voltage so one would expect the output current to be about three times the input current.

I can only assume that you are not making the measurements correctly or that the output current you are measuring is the battery discharge current and not the charging current.

ps The abbreviations for volts and amperes are V and A, not v or a

Long Weekend · Guru

Volts and Amps are named after persons, hence always in capitals.

Murray

Dick0 · Guru

dorian wrote:
How can there be 5.1A of charging current when the battery is not connected?

Magic? confuse confuse confuse

Mike Harding · Guru

Long Weekend wrote:
Volts and Amps are named after persons, hence always in capitals.

No. Otherwise, amongst many others, pasteurise would be capitalised.

Only words which still have a strong association with their original noun retain a capital eg. Shakespearian.

The volt and the ampere have stood as words in their own right for a very long time.

Source: The Oxford Style Manual, section 4.1.12.

Ram Man · Veteran Member

How's it Go'in

So without getting too deep into this, my Solar outputs are low when connected up I see little charge going into the system.
Because the batteries are charged, but turn on the 2000W inverter and start drawing down power the Solar goes off.
Pumping out 285W at 15 amps, it's all related to draw.

RichZen · Newbie

Do you still have the user manual for that controller / regulator?

How many amps is it?

I have the same regulator and have lost the instruction.

I need the "battery type" settings.

TimTim · Guru

If you scroll back up then that is the general manual for the cheap PWN controllers. The are no other pages to it.

Press the left hand menu button to scroll through the different interface. When you come to battery type hold the menu button down for a few seconds until it flashes then press either the middle or right hand button to scroll through the different battery types b01, sealed b02 and flooded b03.

https://www.youtube.com/watch?v=4S-79eGSCKE

You can see at 8.10 in the above video.

Tim