Too many amps?

[Salisburytree]

I'm full of questions ?

My home 240v charger uses 6 amps to charge my 100ah batteries. My solar charge controller is about to pump in 60 amps, this is a huge step up and leads me to wonder is this okay for my batteries (3x 100ah).

Of course charge time will be massively reduced in comparison to my humble 6 amp charger, which leads me to my next question... what does the charge controller so with all these volts and amps when the batteries are fully charged?

My charge controller for my wind turbine has a break which completely makes sence, no spinning no power, very simple concept. However we can't turn the sun off when its shining, where does that energy go?!

 

[sunshine_eggo]

1. What is the maximum charge rate of each battery?
2. Does 60A exceed this 3X this value?
3. Is the bank built in such a way that the current is shared equally?
4. Will you verify that each battery receives no more than what is specified with a clamp DC ammeter?

 

[sunshine_eggo]

My charge controller for my wind turbine has a break which completely makes sence, no spinning no power, very simple concept. However we can't turn the sun off when its shining, where does that energy go?!

The MPPT is a load to the panels. It only pulls only what it can use.

Same concept with the AC charger. Battery only pulls what it can accept.

THink of plugging a 13W lightbulb into a 1800W 110V outlet. The bulb only pulls what it needs. You're not worried about the other 1787W available at the outlet.

 

[Salisburytree]

The MPPT is a load to the panels. It only pulls only what it can use.

Same concept with the AC charger. Battery only pulls what it can accept.

THink of plugging a 13W lightbulb into a 1800W 110V outlet. The bulb only pulls what it needs. You're not worried about the other 1787W available at the outlet.

At the plug its connected to the grid and stays within the grid? The panel produces the electric, sends it to the mttp, the mttp says no thanks iv got enough or don't need anymore electric, thats where I'm lost, where does the constantly produced electric from the panel go? ? I have the feeling I'm asking a stupid question.

 

[Salisburytree]

1. What is the maximum charge rate of each battery?
2. Does 60A exceed this 3X this value?
3. Is the bank built in such a way that the current is shared equally?
4. Will you verify that each battery receives no more than what is specified with a clamp DC ammeter?

1, I havent managed to find or have seen the maximum change rate of the battey (dynamic deep cycle 100ah)

2, same as above I guess.

3, the bank is at 12volts, parallel I believe the term is.

4, I'm definitely in the beginners corner ?

 

[sunshine_eggo]

If these are AGM, most AGM can handle 0.2C or 20A in your case.

60A would be the maximum of 3 in parallel.

In most cases, if the array is capable of outputting 60A to the battery based on ratings, it's pretty rare to actually attain 100% output. Additionally, most systems that aren't overly discharged overnight are usually already in absorption phase by noon where solar is typically most intense. Once you're in absorption, you're voltage limited, and the batteries will only draw as much current as they need, so it will be less than 60A.

For a 60A charge controller to actually output 60A, you need:

60A * 12V = 720W of solar at minimum low battery voltage
60A * 14.4V = 864W of solar at maximum battery voltage.

Conditions also need to be perfect, i.e., high noon, crystal clear skies and perfectly tilted panels.

 

[time2roll]

20 amps into a 100 ah battery is fine.

 

[Salisburytree]

20 amps into a 100 ah battery is fine.

Ok so I need to think of st as 20 amps per battery as opposed to 60 amps going into each battery

 

[Salisburytree]

If these are AGM, most AGM can handle 0.2C or 20A in your case.

60A would be the maximum of 3 in parallel.

In most cases, if the array is capable of outputting 60A to the battery based on ratings, it's pretty rare to actually attain 100% output. Additionally, most systems that aren't overly discharged overnight are usually already in absorption phase by noon where solar is typically most intense. Once you're in absorption, you're voltage limited, and the batteries will only draw as much current as they need, so it will be less than 60A.

For a 60A charge controller to actually output 60A, you need:

60A * 12V = 720W of solar at minimum low battery voltage
60A * 14.4V = 864W of solar at maximum battery voltage.

Conditions also need to be perfect, i.e., high noon, crystal clear skies and perfectly tilted panels.

I'm going to be at a max of 750 watt, of course I'm not going to reach them numbers in sunny England ?

Thank you for your reply, that makes things more unstandable in terms of the battery handling the power.

I'm still abit lost as to where the electric from the panels goes after full charge however...

 

[Bud Martin]

I'm going to be at a max of 750 watt, of course I'm not going to reach them numbers in sunny England ?

Thank you for your reply, that makes things more unstandable in terms of the battery handling the power.

I'm still abit lost as to where the electric from the panels goes after full charge however...

It does not go anywhere, the Voltage potential is there but if no load is connected to complete the circuit for the current to flow then there will be no current flow.
I.E. you have an AA battery, it has 1.5V of Voltage potential sitting there waiting for the load to be connected and draw the current from the battery, same for your AC outlet in your home if you do not turn on your lamp then there will be no current flow.

 

[Salisburytree]

It does not go anywhere, the Voltage potential is there but if no load is connected to complete the circuit for the current to flow then there will be no current flow.
I.E. you have an AA battery, it has 1.5V of Voltage potential sitting there waiting for the load to be connected and draw the current from the battery, same for your AC outlet in your home if you do not turn on your lamp then there will be no current flow.

The battery isn't producing energy every second its exposed to light thought?

 

[Bud Martin]

The battery isn't producing energy every second its exposed to light thought?

Battery is the power source, the solar panel is the power source, your AC outlet is the power source they all have Voltage potential. I do not know how else to explain.

 

[Don B. Cilly]

Think of the charge controller as a switch. Which in a way it is. You might want to read this funny story By @Substrate which (sort of) explains how it works ;·)
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[upnorthandpersonal]

The battery isn't producing energy every second its exposed to light thought?

Neither is the panel if you don't take a charge from it. Think of it like an LED, in opposite form. Simplified, what happens at a physical level is that a photon knocks an electron out from the semiconductor material (the photons excites the electrons, creating free electrons). If you don't draw power (i.e., no current), you just end up with in a saturated position, and the electrons will go back to their original non-excited positions after some time, repeating the process while there is light. This unused energy just ends up being heat in the end, and no, it won't overheat a panel since it would be identical to just having a plate sit in the sun: the energy at most is what the sun can radiate on the plate, which is why you don't need a dump load.

Illustration:

 

[TorC]

Even a lowly 10A outlet in a grid-connected English home has, not merely 10A*240V=2400W, but the entire power of the whole grid behind it. That 10A is just how much a device can draw before a safety switch (AKA circuit breaker or, for older places, a fuse) cuts power.

What limits power is that any device has a certain amount of resistance. The 240V at your outlet can only push so much power through that resistance. Doesn't matter whether the source could feed it 2A or 200 000A. If the resistance will only let 1A flow, only 1A will flow.

The panel is like the grid here. Only if there's a load for the electromotive potential (voltage) to push up to the amperage it can produce through will anything flow. If the load is smaller because the battery is fully charged, less will flow.

 

[SamDeleted]

I'm still abit lost as to where the electric from the panels goes after full charge however...

From what I understand, the panels actually stop making power when there is no demand from your mppt.

Mppt switches off, opens the circuit, panels stop producing



But your wind turbine is constantly making power whether the batteries need it or not , so that's why you need a 'dump load' (basically a heater) somewhere for the power to go once your batteries are full

 

[TorC]

The open circuit panel produces voltage, but the heat of doing nothing with the power it could produce is insufficient to risk damage to the panel.

An open circuit wind turbine produces the same, but the heat ends up in a place that cannot dissipate it sufficiently, and will burn it up. Thus the dump load as a safe place to dissipate it, ideally doing something at least slightly useful with it.

 

[Salisburytree]

Right, thank you all very much!

I now understand how this works, explained in many different ways which has made life easier for this idiot.

So I can take from this, the solar panel isn't going to explode! ? ? ?

 

[sunshine_eggo]

I'm going to be at a max of 750 watt, of course I'm not going to reach them numbers in sunny England ?

Thank you for your reply, that makes things more unstandable in terms of the battery handling the power.

I'm still abit lost as to where the electric from the panels goes after full charge however...

Loads pull from sources. That's just how it is. Loads only pull what they need.

A battery is a load to a charger.

A charger is a load to the source (PV or AC).

Back to the lightbulb analogy...

A Type G plug in the UK is rated for 13A @ 230VAC. That's 13*230 = 2,990W of power.

When you plug in small light bulb, what happens to the extra available power? Nothing. It's not needed by the load, so it sits there doing nothing.

EDIT: in the case of PV, 80% of the energy coming into the panel generates heat. When no power is being drawn from it, 100% of the energy coming in generates heat.

 

[Gomez38]

The MPPT is a load to the panels. It only pulls only what it can use.

Same concept with the AC charger. Battery only pulls what it can accept.

THink of plugging a 13W lightbulb into a 1800W 110V outlet. The bulb only pulls what it needs. You're not worried about the other 1787W available at the outlet.

This is what I was just about to ask...about. Thanks!