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Boatdave

Hi and a solar controller question

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Boatdave

Hi there, my name's Dave, I'm new here.
I live on a narrow boat in the middle of England. I have a bank of 3 x 12V leisure batteries which power my led lights, water pump, inverter (which I very rarely use,) etc.
I have inherited a 265W LG MonoX PV which I want to use to help keep my battery bank topped up.
I have wired the PV into the system but am getting no solar (sunny icon) charge symbol on numerous 30A solar controllers I've tried, despite getting voltage readings from the PV with a multimeter and the same readings at the controller PV terminals and the controller(s) otherwise seemingly working (battery/temp/etc readings seem fine?) 
What am I missing?
Many thanks in advance.

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binky

is polarity correct? How many other panels do you have?

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Boatdave

Hi there, cheers for your reply. Yep, polarity is correct. I have 2 other 100W panels on a different controller (but to the same x3 batterybank) I figured it'd be easiest/most efficient to leave them alone and get a new controller for the new 265W panel.

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Geoff1946

Is your battery fully charged? 

Presumably the controller cuts off charge at some pre-set voltage. I'm just wondering if your new controller cut-off is set lower than the older one, which is fully satisfying the demand on its own. 

If my theory is valid it does call into question whether you can have two controllers one the same battery.

Edited by Geoff1946
typo

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Boatdave

Hi Geoff, I did wonder that, and played about with the controllers settings (each one I've tried is a cheap Chinese one off eBay labelled MPPT which I doubt is correct?) but the battery voltage has dropped as per normal (before adding the new 265W panel and controller set up) which makes me think it would have kicked in at some point?

the existing controller I have is an old one with no screen or seemingly adjustable settings? 

Is it not possible to have more than one controller per battery bank do you think?

Cheers.

Dave

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Boatdave
26 minutes ago, Geoff1946 said:

Is your battery fully charged? 

Presumably the controller cuts off charge at some pre-set voltage. I'm just wondering if your new controller cut-off is set lower than the older one, which is fully satisfying the demand on its own. 

If my theory is valid it does call into question whether you can have two controllers one the same battery.

But also, thinking on about it, regardless of what the existing array/controller are doing, shouldn't the new controller and panel show that it's sunny/there's power going from the new panel to the new controller if it is (sunny)?

cheers, as ever...

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binky
57 minutes ago, Boatdave said:

 

Is it not possible to have more than one controller per battery bank do you think?

 

 yes it is, you can link as many controllers as charging inputs to one set of batteries. So single panel which will be about 30V / 36V  in 'stalled'condition (ie not connected) - what is the minimum voltage for the  new charge controller to work at? 

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Boatdave

Hi binky, I think the draw from the SCC is tiny, like 0.02V. Is that what you mean by min voltage for it to work at?

cheers

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binky
5 hours ago, Boatdave said:

Hi binky, I think the draw from the SCC is tiny, like 0.02V. Is that what you mean by min voltage for it to work at?

cheers

 

OK, I mostly work with 240V grid tied inverters. All of these have a minimum voltage at which they start working, like 90V. Now I noticed you say you've tried several 30A MPPT controllers,  your panel will only be outputting about 8A. Now, the only controller I can find that states minimum voltage is a Victron unit, which works from 15V , cheap chinese stuff may require a higher voltage than that? Once running the stalled voltage of the panel will drop as the controller tries to find the optiumum voltage / ampage balance to maximise power output (MPPT means Maximum Power Point Tracker.) So maybe I'm wrong, but perhaps your single panel isn't man enough to get the charger controller working?  If your multimeter has DC amp setting check how many amps you are getting from the panel.  It might also be just that the panel is knackered. 

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Boatdave

Thanks blinky, much appreciated. I'll check the amps, but I think you might be on the money about the panel not being powerful enough. Thanks so much for the knowhow. Much appreciated.

dave

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binky

You could probably wire it in with the exising panels, just remember panels in series, voltage increases, amps stay the same, panels conncted in parallel, voltage stays the same, ampage increases. eg panel that outputs 30V and 8 amps, 2 panels in series gives 60V and 8 Amps, 3 in series gives 90V and 8 Amps, 2 in parallel gives 30V and 16 Amps, 3 in parallel gives 30V and 24 Amps. Check the spec of the current battery charge controller. 

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david056

Is your battery fully charged? 

Presumably the controller cuts off charge at some pre-set voltage. I'm just wondering if your new controller cut-off is set lower than the older one, which is fully satisfying the demand on its own. 

If my theory is valid it does call into question whether you can have two controllers one the same battery.

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Geoff1946

How odd. That's word for word what I wrote a month ago. Is it meant to be a "quote", and the follow on comment has got lost?

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Sharpend

Perhaps it’s your twin or doppelgänger? 

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