Battery Capacity for Solar

[MtB]

2 minutes ago, Alan de Enfield said:

An 'amp' is an instantaneous  unit.

 

Or more accurately it is a rate of flow of electricity.

 

To be precise, one Ampere is said to be flowing when one Coulomb of electrical charge per second is flowing along a conductor.

 

IIRC.

 

 

[Alan de Enfield]

Just now, Mike the Boilerman said:

 

Or more accurately it is a rate of flow of electricity.

 

To be precise, one Ampere is said to be flowing when one Coulomb of electrical charge per second is flowing along a conductor.

 

IIRC.

 

 

 

I know that but I didn't see the need to further confuse the OP.

KISS.

[MtB]

2 minutes ago, Alan de Enfield said:

 

I know that but I didn't see the need to further confuse the OP.

KISS.

 

Strange, are you feeling ok? That's not your normal approach...

 

 

[Up-Side-Down]

8 minutes ago, Alan de Enfield said:

An 'amp' is an instantaneous  unit.

 

It is not a amp per minute or per hour or per day.

When you multiply it by time the unit becomes an Ah, so if you are generating 30amps for 5 hours the figure becomes 150Ah. (30amps for 30 minutes becomes 15Ah, 30 amps for 1 hour becomes 30Ah)

 

You will find that Solar will rarely give a constant figure over time.

You may get an instantaneous 30amps but as the Sun moves across the sky and the angles change the output will change, as a cloud crosses the sky the output will drop.

 

So "5 hours at 30 amps" will probably not produce 150Ah, more likely 120Ah. You can only tell by looking at your controller display at the end of the day.

Thank you Alan this is precisely the sort of education I'm looking for ......... and it makes perfect sense explained in the way that you have. So going back to the thrust of my very first question, what happens to the 'surplus' electricity generated if I have say 100 Ah of available battery capacity and the day's sun has just produced 120 Ah ....... assuming I'm using a MPPT controller? (you'll see from this just how electrically challenged my brain actually is!).

8 minutes ago, Alan de Enfield said:

 

I know that but I didn't see the need to further confuse the OP.

KISS.

Definitely of the KISS persuasion where electricery is concerned .......... but I'm not beyond looking up coulombs and flow on Wikipedia out of curiosity. I just don't expect to fully understand it!

[Murflynn]

it worries me a bit when someone is about to invest a lot of money and effort into panels, lithium batteries and suitable chargers, but is unfamiliar with basic electrical units, never mind coulombs and faraday thingummies..

Edited March 14, 2020 by Murflynn

[MtB]

2 minutes ago, Up-Side-Down said:

So going back to the thrust of my very first question, what happens to the 'surplus' electricity generated if I have say 100 Ah of available battery capacity and the day's sun has just produced 120 Ah .......

 

It won't have produced that much in the first place. 

 

It might help to consider what happens to an unconnected solar panel if daylight lands on it. NO electricity is produced, with no ill effect.

 

 

 

[Up-Side-Down]

1 minute ago, Murflynn said:

it worries me a bit when someone is about to invest a lot of money and effort into panels, lithium batteries and suitable chargers, but is unfamiliar with basic electrical units.

It worries me even more ........... which is why I'm here!

2 minutes ago, Mike the Boilerman said:

 

It won't have produced that much in the first place. 

 

It might help to consider what happens to an unconnected solar panel if daylight lands on it. NO electricity is produced, with no ill effect.

 

 

 

Thank you. Put like that it makes perfect sense. 

[Murflynn]

6 minutes ago, Up-Side-Down said:

It worries me even more ........... which is why I'm here!

 

fair comment. 

[TheBiscuits]

45 minutes ago, Up-Side-Down said:

It worries me even more ........... which is why I'm here!

Yes, this is an excellent place to come to get worried about boat electrics.

 

You keep coming back though, which is a better sign than running away because you didn't like the answers. 

 

[WotEver]

2 hours ago, Up-Side-Down said:

what happens to the 'surplus' electricity generated if I have say 100 Ah of available battery capacity and the day's sun has just produced 120 Ah ......

The same thing that happens to the 13A of 230V mains when nothing is plugged in

[David Mack]

 

2 hours ago, Alan de Enfield said:

An 'amp' is an instantaneous  unit.

 

It is not a amp per minute or per hour or per day.

When you multiply it by time the unit becomes an Ah....

 

2 hours ago, Mike the Boilerman said:

 

To be precise, one Ampere is said to be flowing when one Coulomb of electrical charge per second is flowing along a conductor.

 

... making one Ah equal to 3600 Coulombs.

[Murflynn]

2 hours ago, TheBiscuits said:

 

You keep coming back though, which is a better sign than running away because you didn't like the answers. 

 

which unfortunately happens more often than not.

[MtB]

58 minutes ago, WotEver said:

The same thing that happens to the 13A of 230V mains when nothing is plugged in

 

No, with the 13A sockets it dribbles and leaks out all over the floor surely, unless there is something plugged in to stop it?

 

Isn't that why they are called 'plugs'??

 

 

[Jen-in-Wellies]

11 minutes ago, Mike the Boilerman said:

 

No, with the 13A sockets it dribbles and leaks out all over the floor surely, unless there is something plugged in to stop it?

 

Isn't that why they are called 'plugs'??

 

 

You can't ever get electron stains out of the carpet. Worse than red wine.

Edited March 14, 2020 by Jen-in-Wellies

[MtB]

4 minutes ago, Jen-in-Wellies said:

You can't ever get electron stains out of the carpet. Worse than red wine.

 

I think you're making that up.

 

 

 

[Jen-in-Wellies]

1 minute ago, Mike the Boilerman said:

 

I think you're making that up.

 

 

 

Its a fair cop guv. You got me bang to rights. Completely made up. British Standards compliant mains sockets have automatic shutters over the live and neutral apertures that close when the plug is removed, stopping the electrons dribbling out. No risk of damaging your furnishings, or floors.

[peterboat]

3 minutes ago, Mike the Boilerman said:

 

I think you're making that up.

 

 

 

She isn't one of my Midnite controllers has gone for repair so I have had to put a big bucket underneath to save ruining the floor 

[MtB]

Just now, Jen-in-Wellies said:

Its a fair cop guv. You got me bang to rights. Completely made up. British Standards compliant mains sockets have automatic shutters over the live and neutral apertures that close when the plug is removed, stopping the electrons dribbling out. No risk of damaging your furnishings, or floors.

 

'Zackly. 

 

This is also why modern three pin sockets have a switch on them. To reduce yer leccy bills in case them shutters get jammed open, which is a common occurrence. 

 

 

 

 

[Jen-in-Wellies]

3 minutes ago, Mike the Boilerman said:

 

'Zackly. 

 

This is also why modern three pin sockets have a switch on them. To reduce yer leccy bills in case them shutters get jammed open, which is a common occurrence. 

 

 

 

 

With mains you have to be careful. Safety features for the safety features. No single point of failure. This is why you rarely hear of boats sinking after getting filled with electrons. With batteries there are only so many electrons that can leak out, but if you are on a shore line you could end up with the entire national grid trying to fill up your boat.

 

Edited March 14, 2020 by Jen-in-Wellies

[Richard10002]

3 hours ago, Mike the Boilerman said:

 

It won't have produced that much in the first place. 

 

It might help to consider what happens to an unconnected solar panel if daylight lands on it. NO electricity is produced, with no ill effect.

 

 

 

Assuming the batteries remain in the circuit, current continues to flow so, doesn’t their internal resistance mean that any “extra” Ah generated are dissipated as heat.

 

If the circuit is broken, (solar panel not connected, no plug in 13A socket), no current flows.

[MtB]

3 minutes ago, Jen-in-Wellies said:

With mains you have to be careful. Safety features for the safety features. No single point of failure. This is why you rarely hear of boats sinking after getting filled with electrons. With batteries there are only so many electrons that can leak out, but if you are on a shore line you could end up with the entire national grid trying to fill up your boat.

 

 

Oh fer goodness sake, a shoreline is AC innit, so them electrons just shuffle back'uds an for'ards, so then can't fill up the bote an sink it. 

 

This is WHY shorelines are always AC, as any fule kno. 

[Jen-in-Wellies]

Just now, Mike the Boilerman said:

 

Oh fer goodness sake, a shoreline is AC innit, so them electrons just shuffle back'uds an for'ards, so then can't fill up the bote an sink it. 

 

This is WHY shorelines are always AC, as any fule kno. 

Of course. It also shows what a con mains AC electricity is. The electric company, or marina sell you some electrons, then steals them back, then sells you the same electrons again that you've already paid for, fifty times a second. If you try and keep the electrons you've bought they cut off your supply and won't let you have any more. Everyone seems to accept this as normal and perfectly fine.

[WotEver]

1 hour ago, Mike the Boilerman said:

 

No, with the 13A sockets it dribbles and leaks out all over the floor surely, unless there is something plugged in to stop it?

 

Isn't that why they are called 'plugs'??

Bloody plumbers...

1 hour ago, Richard10002 said:

Assuming the batteries remain in the circuit, current continues to flow...

Does it?

 

Have you ever looked at a solar controller when the batteries are full?

1 hour ago, Richard10002 said:

doesn’t their internal resistance mean that any “extra” Ah generated are dissipated as heat.

No. 

[Murflynn]

1 hour ago, Mike the Boilerman said:

 

No, with the 13A sockets it dribbles and leaks out all over the floor surely, unless there is something plugged in to stop it?

 

Isn't that why they are called 'plugs'??

 

 

I thought that when it all dribbles out onto the floor it is collected on the earth mat.

[LadyG]

On 10/03/2020 at 22:48, Dr Bob said:

Firstly, I would go for one MPPT. We have 500W in 4 panels. 2 panels were on the boat with a 30A mppt and I added 2 panels with a further 15A MPPT. The MPPTs fought against each other so to stop that I wired them all into the 30A one. Works great and I get just about 30A on the best sunny days.

 

ooooh, that's my plan quashed, will my 40amp controller be OK with 2 x 275W, on domestic, and put the old 80W panel with controller to starter batt, or just rip it out, abandon starter battery charging by solar? Old solar is bodged, I'd rather get rid.

Edited March 14, 2020 by LadyG