More battery talk

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Bow42

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I have 2x 100 solar panel and 3x100AH battery's bank plus an 75Ah engine battery .
my battery monitor in good sun light will show up to 9.5 A but the Voltage only every go up to 13.5 Vdc
read other posting on charging , talk of 14.2 are mentioned ,
does this mean that my battery's are not getting enough volts to get fully charged ?
 
13. 5 V is a pretty good charge on a battery.

Maybe if brand new you might get more. I won't my cheap charger only gives about 13.5 V.
Though I have read some claims if you can put over 14 V at low amps for a long time it may de sulphate some weak cells.
I have also read this claim is BS.
 
Bow42 said:
my battery monitor in good sun light will show up to 9.5 A but the Voltage only every go up to 13.5 V...does this mean that my battery's are not getting enough volts to get fully charged ?
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Probably, assuming the 13.5V is when there are no other drains on the batteries. What sort of controller do you have?
Depending on power usage (obviously), and sophistication of controller, it's possible to fully charge a bank with solar, but many boats rely on alternator* and/or shore power to reach 100%. It's important that lead-acid batteries reach 100% charge periodically if they're not to degrade. If they're open lead-acid, a hydrometer is the most reliable means to test for state of charge.

* Most modern alternators can put out 14.4V or so; older ones produce rather fewer unless fitted with some sort of boost regulator.
 
Hi
The alternator pushes out 14.4 , no problem there .
The 13.5 v is when its on the panels .
The reg is an MPPT , if I understand It correctly if it pushing in amps then the battery isn't fuller charge other wise the amps would be zero or very little ( am I right )
I am assuming that the 13.5v is what coming from the panel the higher of the two ( battery / panel volts ) and that's what's showing on the monitor .
 
Bow42 said:
Hi
The alternator pushes out 14.4 , no problem there .
The 13.5 v is when its on the panels .
The reg is an MPPT , if I understand It correctly if it pushing in amps then the battery isn't fuller charge other wise the amps would be zero or very little ( am I right )
I am assuming that the 13.5v is what coming from the panel the higher of the two ( battery / panel volts ) and that's what's showing on the monitor .
Click to expand...

Some MPPT controllers are 'smart' (i.e. offer staged charging in response to battery status), some not.

Yes, you should expect the amps to fall away as the batteries approach full charge, simply due to the rise in internal resistance of the batteries. That's why the final 10% or so of charge is so laboriously slow -- but, as said, necessary from time to time. If the batteries are taking 10A or so, then they're not at full charge.

If the 13.5V is showing on your battery monitor, then that's battery voltage. As suggested above, if there any loads on the system, then this can be expected to be lower than the output of charging panels. From the sound of it, when charging under engine there's no problem reaching higher voltages.
 
Saying that solar panels won't fully charge batteries is incorrect.

Some details of your controller would be useful.

The controller should regulate voltage and amperage. An MPPT controller should be multi stage, the final stage will be float and that will be around 13.4-13.6 volts. You might want to keep an eye on things and see what voltage it's putting out first thing in the morning (once the Sun is up).

My panels are currently showing 37v, 117w and are charging at 14.4v ("Absorption" mode).

If your controller is suitably rated and you don't have big shading problems, try connecting the panels in series.
 
macd said:
If the 13.5V is showing on your battery monitor, then that's battery voltage. As suggested above, if there any loads on the system, then this can be expected to be lower than the output of charging panels. From the sound of it, when charging under engine there's no problem reaching higher voltages.
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I don't understand that bit of your post. :confused:

If the batteries are connected to the charger and a voltmeter is connected across the battery terminals, then the 13.5V is going to be the controller output voltage as the OP is suggesting, rather than the battery voltage. A lead acid battery is never going to output 13.5V unless it is being charged or has just been disconnected from charging.

Whether 13.5V is "right" can only really be decided by looking at the manual for the controller and seeing what voltage it is supposed to produce when charging a partially discharged battery. In absolute terms 13.5V is low by modern standards but if that is what the controller is designed to produce and there is no switch to alter it, then that's the best that particular controller will ever do.

Richard
 
PaulRainbow said:
Saying that solar panels won't fully charge batteries is incorrect.
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I don't know who you think wrote that, Paul, but it certainly wasn't me: "it's possible to fully charge a bank with solar" (post #3).
I agree that so far the OP's "MPPT controller" is a bit of a pig in a poke. What does it's handbook say it's capable of?

RichardS said:
I don't understand that bit of your post. :confused:

If the batteries are connected to the charger and a voltmeter is connected across the battery terminals, then the 13.5V is going to be the controller output voltage as the OP is suggesting, rather than the battery voltage. A lead acid battery is never going to output 13.5V unless it is being charged or has just been disconnected from charging.
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Richard: in post #1 the OP indicated that he was reading both A and V from his battery monitor, not from a voltmeter across the terminals, in other words nett of any loads. But clearly, unless those loads are substantial, it will be elevated whilst under charge from the panels. As you imply, it will not, of course, indicate rested battery voltage, much less state of charge. I think we're talking about the same thing.
 
RichardS said:
If the batteries are connected to the charger and a voltmeter is connected across the battery terminals, then the 13.5V is going to be the controller output voltage as the OP is suggesting, rather than the battery voltage.
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Absolutely correct.

Whether 13.5V is "right" can only really be decided by looking at the manual for the controller and seeing what voltage it is supposed to produce when charging a partially discharged battery. In absolute terms 13.5V is low by modern standards but if that is what the controller is designed to produce and there is no switch to alter it, then that's the best that particular controller will ever do.

Richard
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Hopefully the OP will post some details about his controller.

13.5 would be OK if the controller is in float mode, but is too low for normal charging. But, with 12v panels wired in parallel it might not be possible to get enough volts from the panel for the controller to maintain a high enough charging voltage, except in the brightest of Sunlight. This is where (as you know) a decent MPPT controller and series wired panels come into there own.

For those who think that solar panels cannot fully charge batteries, my controller went into float mode at 1100. The panels are at 41.45v. Output has been shut down to 13.4v and the panel yield is now only 13w. If i turn something on the controller will increase the solar yield to maintain float mode and simultaneously run the equipment. For the rest of the day my batteries will remain fully charged and all onboard power requirements will be met by the solar panels, providing i don't exceed the max available yield of course.

As above, the battery monitor shows 13.4v to match the solar controller output.
 
macd said:
I don't know who you think wrote that, Paul, but it certainly wasn't me: "it's possible to fully charge a bank with solar" (post #3).
I agree that so far the OP's "MPPT controller" is a bit of a pig in a poke. What does it's handbook say it's capable of?
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Not aimed at anyone in particular, but i have often read people saying the solar won't fully charge batteries.

Richard: in post #1 the OP indicated that he was reading both A and V from his battery monitor, not from a voltmeter across the terminals, in other words nett of any loads. But clearly, unless those loads are substantial, it will be elevated whilst under charge from the panels. As you imply, it will not, of course, indicate rested battery voltage, much less state of charge. I think we're talking about the same thing.
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My battery monitor shows net amps, if 10a is being produced by the solar panels and 2a being used by onboard systems the monitor will show 8a.

The voltage that is shows is the output voltage from the controller. As you say though, a heavy load will give a reduced reading, such as turning the water pumps on.

I can also monitor the controller output directly, so can see at a glance what the panels are sending to the batteries.
 
This it?

df0l6Vc.png
 
GHA said:
This it?

df0l6Vc.png
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Yes.
It seen by this that mine isn't getting to Bulk 14.3 .
So is it the case that the panels aren't given out enough V or is it the case where my battery's are never that low , which can't be the case , as first thing in the morning my BM1 reads 12.4 v 75% .
 
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Couple thoughts ....

Can you bypass the controller and watch what's going on? Keeping an eye on things in case the voltage gets too high..

If 300Ah of batteries are actually accepting nearly 10A at 13.5v then it doesn't sound like they're getting very close to fully charged.
 
Bow42 said:
Now now children , no fighting

Its a 25A 12v 300w
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No scrapping intended. Greatest respect for Paul and Richard.

From your link it looks able to take up to 50V input, which would allow two 20V panels in series, as suggested above. Lots written about the pros and cons of this. On balance, it's probably a bad idea if the panels are located in such a way that one is often in shade (even partial shade) and the other not. If they generally experience equal shading, it might be the way to go. Makes fewer demands on cabling, too.

It looks like optional cabling makes the unit programmable by a PC. That might be worth exploring as a means of increasing the output voltage, whether you keep the panels in parallel or link them in series.
 
Bow42 said:
Yes.
It seen by this that mine isn't getting to Bulk 14.3 .
So is it the case that the panels aren't given out enough V or is it the case where my battery's are never that low , which can't be the case , as first thing in the morning my BM1 reads 12.4 v 75% .
Click to expand...

Actually, it isn't. Yours is the 3012, but the voltages are the same, so good enough.

If the batteries are down to 12.4v the controller should go through the bulk and absorption phases, if the batteries get charged then it should go into float mode.

I can't fine a manual for the controller for more info. The LED display shows panel voltage, i'd expect to see this higher than 13.5v, closer to 20v should be more like it.

Do the panels get shaded much ?
 
macd said:
No scrapping intended. Greatest respect for Paul and Richard.
Click to expand...

Likewise Mac :encouragement:

From your link it looks able to take up to 50V input, which would allow two 20V panels in series, as suggested above. Lots written about the pros and cons of this. On balance, it's probably a bad idea if the panels are located in such a way that one is often in shade (even partial shade) and the other not. If they generally experience equal shading, it might be the way to go. Makes fewer demands on cabling, too.
Click to expand...

If shading isn't a big problem i'd definitely try wiring in series. I have a pair of 30w panels on the coachroof that suffer with shading and output is poor. The pair of 100w panels at the pushpit do not get shaded and they work extremely well in series.

It looks like optional cabling makes the unit programmable by a PC. That might be worth exploring as a means of increasing the output voltage, whether you keep the panels in parallel or link them in series.
Click to expand...

That would be a good idea. My Victron controller is fitted with the optional Bluetooth dongle, which allows remote monitoring and custom changes. All very useful.
 
PaulRainbow said:
Actually, it isn't. Yours is the 3012, but the voltages are the same, so good enough.
Yes it's a 3012
If the batteries are down to 12.4v the controller should go through the bulk and absorption phases, if the batteries get charged then it should go into float mode.
So your saying it's going straight into float mode 13.4 instead of Bulk mode 14.2

I can't fine a manual for the controller for more info. The LED display shows panel voltage, i'd expect to see this higher than 13.5v, closer to 20v should be more like it.
It's a 12v controller it I wire panels in S 24 v won't that harm the MPPT !
Do the panels get shaded much ?
Click to expand...
 
Bow: if it's the panel you linked to, it specifically states it can handle 50V, which effectively amounts to two 20V panels in series. (We have four panels in series, pumping out 80V, albeit with a controller different from yours. Still well under what it's rated for. For shadowing reasons I'm considering changing this to two pairs of parallel panels, each pair in series. But, as ever, there are other jobs first...)
 
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