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DarkSkySeeker

Freestone, California

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Posted: 01/14/20 10:11am Link  |  Quote  |  Print  |  Notify Moderator

I've read about solar charging systems, and am impressed when the owner boasts of the current generated. What I don't understand is how a system that generates 20-50+ amps doesn't fry the batteries. In these high current systems, is the charge being passed through a bank of batteries in parallel so each battery sees reasonable current?


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2oldman

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Posted: 01/14/20 10:20am Link  |  Quote  |  Print  |  Notify Moderator

The controller handles the current that's needed.

DarkSkySeeker

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Posted: 01/14/20 10:21am Link  |  Quote  |  Print  |  Notify Moderator

2oldman wrote:

The controller handles the current that's needed.

Whazzat? The controller knows how much current to pass depending on battery capacity?

2oldman

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Posted: 01/14/20 10:23am Link  |  Quote  |  Print  |  Notify Moderator

Yeah, that's why it's there.

DarkSkySeeker

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Posted: 01/14/20 10:36am Link  |  Quote  |  Print  |  Notify Moderator

2oldman wrote:

Yeah, that's why it's there.

So - here's a silly example.

If I had a big array and one battery, the charge controller would limit the 50+ amps to perhaps 4 amps to the one battery?

red31

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Posted: 01/14/20 10:50am Link  |  Quote  |  Print  |  Notify Moderator

Battery and/or bank of batteries will accept all they can until a voltage set pt is reached. Then the controller limits power to the battery to maintain the set pt voltage.

High current into a small bank will cause the bank's voltage to rise quicker and then be limited by the constant voltage set pt.

time2roll

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Posted: 01/14/20 10:52am Link  |  Quote  |  Print  |  Notify Moderator

DarkSkySeeker wrote:

I've read about solar charging systems, and am impressed when the owner boasts of the current generated. What I don't understand is how a system that generates 20-50+ amps doesn't fry the batteries. In these high current systems, is the charge being passed through a bank of batteries in parallel so each battery sees reasonable current?
Same way your 55 amp converter does not damage the battery or your 130 amp alternator does not burn out your vehicle battery.

Just like any charger... the voltage is controlled and as the battery comes up to the same voltage the amps taper off to zero at full.


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2oldman

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Posted: 01/14/20 11:03am Link  |  Quote  |  Print  |  Notify Moderator

DarkSkySeeker wrote:

If I had a big array and one battery, the charge controller would limit the 50+ amps to perhaps 4 amps to the one battery?
That's what a decent controller is designed to do. As said above, they're just like any other charger.

BFL13

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Posted: 01/14/20 11:10am Link  |  Quote  |  Print  |  Notify Moderator

2oldman wrote:

The controller handles the current that's needed.


No, the controller controls the battery voltage. The controller has an amps rating. Some controllers have a current limit so they don't over-heat by amps going above the controller's rating..

The battery itself controls the amps going into it by its "natural acceptance rate", which is higher at higher voltage. It accepts more amps at 14.4v than at 13.6v.

Current to the battery depends on whether it is an MPPT or PWM controller. With PWM you can get the panel's Isc rating worth of amps, but with MPPT you get the controller's output watts divided by the battery's voltage at the time. The battery doesn't care where its amps are coming from though.


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twodownzero

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Posted: 01/14/20 01:09pm Link  |  Quote  |  Print  |  Notify Moderator

My controller knows how large my array is and what kind of batteries (conventional lead acid) are attached to it. I can adjust the charge voltages as well. I expect my batteries will last many years since they are never dead or even close.

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