Solar charging problem, anyone understand the electronics?

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cliffdale

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Hi folks

I have a 100w solar panel connected to mppt 30A charge controller.

I have 330 Amp of batteries, 3 110A in parallel.

My BM1 monitor shows 12.8v and 0.1A charge. The battery indicator shows 80% capacity.

I'm wondering why I am not getting at least 4 amps of charge in this strong sunshine. Do these figures show a problem?

Are there any checks to make? I'm thinking the controller is not working as it should.

Any suggestions greatly appreciated.

Cliff
 
cliffdale said:
Hi folks

I have a 100w solar panel connected to mppt 30A charge controller.

I have 330 Amp of batteries, 3 110A in parallel.

My BM1 monitor shows 12.8v and 0.1A charge. The battery indicator shows 80% capacity.

I'm wondering why I am not getting at least 4 amps of charge in this strong sunshine. Do these figures show a problem?

Are there any checks to make? I'm thinking the controller is not working as it should.

Any suggestions greatly appreciated.

Cliff
Click to expand...

I don't particularly understand this stuff completely, but nitial thoughts are:

Is the BM1 shunt the 1st thing in the negative cables from the battery? i.e. the negative from the solar controller is not connected directly to the battery, or between the battery and the shunt?

Have you got a clamp ammeter? If so, you could check the current in the solar and controller cables.

Even with a simple voltmeter you could check the voltage where the panel wires enter the controller, and where they leave the controller.
 
As Richard suggests check negative connection from the solar charger is correct. It mus not go direct to the battery ( or to the end of the monitor shunt that is connected to the battery) It must go to the end of the shunt furthest from the battery connection.

However

Even if the solar charger is incorrectly connected, so that the BM1 does not register the charging current, one would expect a higher voltage reading than 12.8 volts. that suggests a fully charged battery which is not receiving any further charging.

Check the output volts from the solar panel at the input to the MPPT controller. That should be appreciably higher than 12.8 volts.

It might also be worth discharging the battery somewhat to see if the solar charging then resumes.
 
VicS said:
As Richard suggests check negative connection from the solar charger is correct. It mus not go direct to the battery ( or to the end of the monitor shunt that is connected to the battery) It must go to the end of the shunt furthest from the battery connection.

However


Check the output volts from the solar panel at the input to the MPPT controller. That should be appreciably higher than 12.8 volts.

It might also be worth discharging the battery somewhat to see if the solar charging then resumes.
Click to expand...

The voltage going into the charger is 20.2v.

Can I connect this to the battery directly?
 
OK, the voltage going into the solar controller is 20.2v

I have connected this directly to the battery and the BM1 still shows 0.1A to 0.2A charge. Voltage on the BM1 shows 12.7V.

Does this suggest a poor solar panel?

Cliff
 
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I have had similar problems with my solar panel.

Can you connet an amp-meter in series with either the regulator or the solar panel? It has to be able to cope with up to 10 Amps, so it might be difficult.

If not, can you connect a load of some kind to the regulator, instead of the battery? Like a (strong) lightbulb or -better- the cooling box or ... something.

Any of these would replace the BM1 as a test of the regulator + solar panel.

/J
 
It's very likely to be a defective controler. A lot of the cheap MPPT ones fail very quickly if they work at all.
Conect the solar panels direct to the batteries the 20v will not cause a problem. The solar panel voltage will drop to the battery voltage as soon as they are connected. Without the regulator monitor the battery voltage and disconect the panels if the voltage climbs too high.

Get a decent regulator.
 
Solar panel voltage

My 50 Watt panel is also only delivering 0.1 Amps under the Croatian midday sun. I thought it might have been the voltage regulator because the voltage at the input was 14v but the output was 12.8 and droping if the fridge was running. I connected the panel directly to the battery, with no improvement.
The panel has a junction box which I opened and are three wires (red, black and blue). The voltage between the black and red is +8v, and the voltage between the black and blue is -8v. This should be enough to to give me 16 volts for the battery, but when I connect the battery the voltage of the negative half goes down to 3 volts. I think this indicate my panel is due for replacement.
 
tawhiri said:
My 50 Watt panel is also only delivering 0.1 Amps under the Croatian midday sun. I thought it might have been the voltage regulator because the voltage at the input was 14v but the output was 12.8 and droping if the fridge was running. I connected the panel directly to the battery, with no improvement.
The panel has a junction box which I opened and are three wires (red, black and blue). The voltage between the black and red is +8v, and the voltage between the black and blue is -8v. This should be enough to to give me 16 volts for the battery, but when I connect the battery the voltage of the negative half goes down to 3 volts. I think this indicate my panel is due for replacement.
Click to expand...

Take your drive between red and blue to get 16v charge voltage, ignore the black wire
 
Testing solar panel

A simple test requires a 10 amp or more scale on a digital volt meter. Disconnect the panel from the battery and connect the amp meter across the output wires. Exactly the same way you checked the 20 volts.
This might seem hugely irresponsible and certainly is for a battery but short term it will not harm the solar panel and you should measure 5 amps for 100w panel. If you don't get 5 amps (watts divided by 20volts) in full sun she is cream crackered. If you do get 5amps then connect directly to the battery +Ve again you should find near 5 amps going in. If you do and the negative is via the BM-1 shunt you have a BM-1 anomally.
If BM-1 shows 5 amps then MPPT controller is "you know what" good luck olewill
 
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