Cloud Edge Effect and MPPT Solar Charge Regulator

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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby jules » Sun Sep 06, 2015 10:07 am

It's surprising that your batteries can have such a sharp voltage rise in such a short time. Could this be a wiring problem? How is your inverter wired into the system?

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Spares; 5 x 12V, 1,000 Ah batteries plus a couple of regulators
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby Gordon-Loomberah » Sun Sep 06, 2015 11:19 am

I think it's just the combination of overdriving the charge controller and using an inverter with a very low high voltage disconnect. 15.5V is a normal equalising voltage in mild weather for flooded Lead-acid batteries, and it's higher in cold weather, making this inverter a bit unworkable in cold climates, even with a regulator that didn't have any high voltage excursions. However, I'm pretty sure that most CCs will take a small period of time to adjust to sudden large changes in load or charging, it's just that that it's not a problem with most inverters, due to HVD of around 17V.
And as Jules says, I would have thought that 560AH of battery should deaden any large voltage spikes, when you are only at 14.4V to start. I remember a thread on the Outback Forums a few years ago about Flexmax CCs having high voltage spikes with AGM batteries, and I think it was suggested the problem was worst with AGM.
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby grell72 » Mon Sep 07, 2015 6:14 am

As you guys have pointed out I think its a combination of events.

Wiring wise the inverter is connected to the opposite set of battery poles the charging regulator is. The charging regulator is connected to the positive on one battery and the negative on the other. Hence the inverter goes on the opposite set of poles.

The unique thing about Tassie will be the colder but sunny weather.

Its funny about the voltage protection level of the inverter. I have been searching high and low and the only inverter I could find with a 17v cut off that wasn't hugely expensive is the Victron range. Just about all others sat at around 15/15.5v, a couple where 16v. I guess that might be the difference in quality or something. Any advice on what you would use?

I'm just getting quotes to double the size of the system using a Midnite solar classic 150. They have a sizing calculator which works well.

Thanks heaps for your comments.
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby Gordon-Loomberah » Mon Sep 07, 2015 8:44 am

We might have a Victron 2kW 24V inverter (C24/2000) available for Trade price, ie way under RRP, in the very near future, it's somewhere on its way from Tas back to Victoria I think.
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby Bthree » Mon Sep 07, 2015 9:29 am

Wiring has not really be mentioned but even a small 12 volt system like yours should have min 70mm2 to the inverter and short runs
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby grell72 » Mon Sep 07, 2015 5:39 pm

Out of curiosity how does the Outback FM80 rate as a possible replacement charging controller? I like the Midnite Solar Classic 150 but I'm open to suggestions at the moment. Both are about the same price.

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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby Gordon-Loomberah » Mon Sep 07, 2015 5:47 pm

I've been using FM80s for a few years and am quite happy with them, although you have to spend more money if you want to synchronise them and use Outback's data logging add-ons. I use a different, much higher resolution and accuracy data logger, and run the FM80s independently, rather than synchronised, which still works ok.
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby grell72 » Mon Sep 07, 2015 5:53 pm

Thanks Gordon...

On a specification basis the Midnite Solar Classic 150 definitely has more "standard" features. However specifications are one thing performance and durability is another!
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby jules » Tue Sep 08, 2015 9:30 am

The options you choose now might depend on where you plan to go with the system in the future. You'd probably be better off to go up to 24V with the batteries in series, not parallel. You'd have to replace the inverter of course but it sounds as though you're prepared to do that anyway. Given the size of the system, I don't think it's worth spending a fortune on a charge controller. A Plasmatronics PL 40 would be totally reliable and you should be able to pick one up for $150, used or refurbished. [Disclaimer ... I use one :) ].

If your only aim is to resolve the voltage spike problem, then you really should eliminate any possibility that you've got a wiring problem before you go ahead and spend money.

Jules
Last edited by jules on Tue Sep 08, 2015 10:57 am, edited 1 time in total.
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Re: Cloud Edge Effect and MPPT Solar Charge Regulator

Postby davidg » Tue Sep 08, 2015 9:32 am

grell72 wrote:On a specification basis the Midnite Solar Classic 150 definitely has more "standard" features

I have installed Midnite Classic's a number of times for DC coupled systems, work a treat. Warranty for both is excellent and the STD features really do work, for the Midnite some of the STD features are basically essential, I find it irritating they are extra's with the Flexmax products. I have both an FM80 and Classic 150 here. I them use for "testing" there's no question they both work well. The Midnite's config system is easier. It's also easier to reconfigure them to do all sorts other "cool" stuff. 8-)
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