Solar panel downside

[Robin2]

You have taken account that the panels during the day have input amp hours so maybe the batts are better than they were before solar with loads masking the true voltage at engine start up?

 

That's an interesting thought. A lot more useful than the answers from the resident expert!

 

Part of the problem is that I don't like to get up sufficiently early to measure voltages in the dark. As the seasons march on this will be less of a problem,

[Gibbo]

A lot more useful than the answers from the resident expert!

 

The fact that you don't like my answer is utterly irrelevant. It is the truth. What I said is correct.

 

You can choose to disbelieve it as many times as you want. It won't affect reality.

 

Edited to remove pointless insult.

Edited August 23, 2011 by Gibbo

[WotEver]

That seems to be enough to raise the battery voltage to 12.6 / 12.8 volts and the alternator charge current starts at only 15 to 20 amps.

What part of that don't you want to happen?

 

The Solar has raised the charge on the batteries so that the alternator has to work less hard to finish off the charging.

 

Why is that a bad thing?

 

Tony

[Robin2]

What part of that don't you want to happen?

 

The Solar has raised the charge on the batteries so that the alternator has to work less hard to finish off the charging.

 

Why is that a bad thing?

 

Tony

 

The impression I have is that the increased voltage is just superficial and does not reflect extra amp-hours that have been added.

[blodger]

The impression I have is that the increased voltage is just superficial and does not reflect extra amp-hours that have been added.

New GT Power LCD RC 130A Watt Meter Power Analyzer Ver.

 

I can recommend this item on Ebay right now for 22.09.

 

I have used them for gennies/chargers; I have not used them on my solar setup as I have a switched diode 4 feeds to the battery banks and to record the wattmeters need a direct connection to the batts.

[Smelly]

Right, as a humble bystander I may have noticed an out... I remember this from when I fitted my solar...

 

The panel voltage is clamped by the batteries; that is a given. It could provide 20 volts open circuit, but with a big battery in the middle that 20 is clamped to 12.6/8... That is not the resting voltage but the charging voltage.

 

An alternator will want to do the charging job with loads more amps and hence generate, eventually, much higher (relatively) voltages; in the 14 .4 volt range. Raising the charging voltage that high reflects lots of charging, whereby a charging current of 12.6 reflects hardly any.

 

Hence; despite a small effect from the PV; it is insignificant compared to the job the alt is doing, and proportionately the effect of the alt is so massive as to render a couple of amps from the PV as virtually unnoticable in a decent charging regime.

 

I always try and save my engine run until the end of the day to maximise the PV yield BTW...

Edited August 23, 2011 by Smelly

[sebrof]

 

Thank you, Tone, for a characteristically helpful response.

[dor]

Early in the morning the solar panels produce, say, 2A most of which is consumed by the inverter but some goes into the battery - say 0.5A for an hour or so. That seems to be enough to raise the battery voltage to 12.6 / 12.8 volts and the alternator charge current starts at only 15 to 20 amps.

 

OK, so the panel has increased the apparent voltage on the batteries.

 

But as soon as you start the engine, the alternator will increase the voltage seen at the batteries, probably to over 13V straight away. How is this voltage different to that which the solar panel has put on the battery, as far as the alternator or controller is concerned?

 

That's why I don't think that my panel affects the charging rate once the engine is started.

 

My voltage can drop to about 12.3V at the batteries overnight. A nice bright morning will see the voltage rise to 13.2V by 9:00am say. However I know that if the panel was disconnected and the batteries allowed to stabilise the true voltage would still be less than 12.5V. Although there is 13.2V showing when I start the engine, the alternator soon works out that it needs to charge the batteries so puts out the 50 or so amps that it can put inot the batteries at that stage.

[blodger]

OK, so the panel has increased the apparent voltage on the batteries.

 

But as soon as you start the engine, the alternator will increase the voltage seen at the batteries, probably to over 13V straight away. How is this voltage different to that which the solar panel has put on the battery, as far as the alternator or controller is concerned?

 

That's why I don't think that my panel affects the charging rate once the engine is started.

 

My voltage can drop to about 12.3V at the batteries overnight. A nice bright morning will see the voltage rise to 13.2V by 9:00am say. However I know that if the panel was disconnected and the batteries allowed to stabilise the true voltage would still be less than 12.5V. Although there is 13.2V showing when I start the engine, the alternator soon works out that it needs to charge the batteries so puts out the 50 or so amps that it can put inot the batteries at that stage.

 

I still think that Robin2 is benefiting from fitting solar more than he realises and that the batteries are now healthier than they were with all that solar input so that all other things being equal his alternator does not now have to work that hard.

[WotEver]

I still think that Robin2 is benefiting from fitting solar more than he realises and that the batteries are now healthier than they were with all that solar input so that all other things being equal his alternator does not now have to work that hard.

Absolutely. He was told in post #4 that he's not experiencing what he thinks he's experiencing. All the subsequent posts have been arguing for argument's sake.

 

Tony

 

Thank you, Tone, for a characteristically helpful response.

In your predictable style you demonstrate once again that you're unable to read and comprehend a thread.

 

Well done - I would be so disappointed if you'd let me down.

 

Tony

 

edited for carp tryping

Edited August 24, 2011 by WotEver

[sebrof]

Absolutely. He was told in post #4 that he's not experiencing what he thinks he's experiencing. All the subsequent posts have been arguing for argument's sake.

 

Tony

 

 

In your predictable style you demonstrate once again that you're unable to read and comprehend a thread.

 

Well done - I would be so disappointed if you'd let me down.

 

Tony

 

edited for carp tryping

 

Let you down? There's no further you could go in that direction, old chap.