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mitiempo · 07-08-2017, 19:39

Quote:

Originally Posted by foojin

And that was my original point and question. It seems, if I understand the replies, that we agree there is no accurate way to determine true SOC with the panels connected to the batteries.

Jim, I think that is who you are.

A battery monitor counts amps in and out of the bank. They are not perfect but the best we have during charging.

On a cruising boat with varying loads there is rarely a time that the bank is rested enough for an accurate voltage reading. The refrigeration alone is a problem. Amp counting along with reading the current going into the battery bank will tell you all you need to know. I rarely recommend testing specific gravity as it can be messy, especially when batteries are under a bunk for example, and it also risks contaminating the batteries.

A64's post above concerning premature float can also be a large charging issue. My recommendation for a boat cruising with loads is to eliminate float from the solar controller if possible. Victron and many other controllers allow this. Batteries, as A64 stated, do not really charge after the controller is in float.

Brian
Trotac

mitiempo · 07-08-2017, 19:41

Quote:

Originally Posted by smac999

The battery monitors (victron 700). Work great for boats often plugged into shore power. As they will self reset with a fully charged battery. From what I hear they will start to drift off if a boat is never plugged in and fully charged.

All the boats I work with are always plugged unless on a short trip. They work great.

If not plugged in the battery SOC can be easily determined by the current going into the bank. A battery monitor considers the bank full when it is accepting less than 2% of its capacity. Truly full is less than .5% of capacity.

**newhaul** · 07-08-2017, 20:23

Quote:

Originally Posted by mitiempo

If not plugged in the battery SOC can be easily determined by the current going into the bank. A battery monitor considers the bank full when it is accepting less than 2% of its capacity. Truly full is less than .5% of capacity.

So if I understand correctly I am definitely fully charged by noon every day then . I have 220ah bank (gc2's) and my solar controller shows less than a half amp going into the bank by noon at the latest daily in summer and at least an hour before sundown in winter. ( im sure when I finish my refer build that will become later in the day.)
For now I only use about 10 ah at anchor and about 13ah on a night sail/ pasage. (Everything is led.)

john61ct · 07-08-2017, 20:32

Quote:

Originally Posted by newhaul

So if I understand correctly I am definitely fully charged by noon every day then . I have 220ah bank (gc2's) and my solar controller shows less than a half amp going into the bank by noon at the latest daily in summer and at least an hour before sundown in winter. ( im sure when I finish my refer build that will become later in the day.)
For now I only use about 10 ah at anchor and about 13ah on a night sail/ pasage. (Everything is led.)

Yes, **if** those low amps are being pushed at Absorb voltage, **no** if the SC dropped prematurely to float.

And using only 5% of your capacity each day is an exception that proves the rule.

**newhaul** · 07-08-2017, 20:36

Quote:

Originally Posted by john61ct

Yes, **if** those low amps are being pushed at Absorb voltage, **no** if the SC dropped prematurely to float.

And using only 5% of your capacity each day is an exception that proves the rule.

Yes that is at absorption . Also it proves what rule?

mitiempo · 07-08-2017, 21:04

Quote:

Originally Posted by newhaul

Yes that is at absorption . Also it proves what rule?

You probably use a smaller percentage of your battery bank on a daily basis than anyone I have ever come across.

**newhaul** · 07-08-2017, 21:13

Quote:

Originally Posted by mitiempo

You probably use a smaller percentage of your battery bank on a daily basis than anyone I have ever come across.

I expect my nightly usage to likely double in the near future ( when I finish my refer build)

john61ct · 07-08-2017, 21:28

And then getting to that 100% full on solar only may require lots more panels, especially in hotter weather.

**newhaul** · 07-08-2017, 22:10

Quote:

Originally Posted by john61ct

And then getting to that 100% full on solar only may require lots more panels, especially in hotter weather.

Not really once my bank acceptance drops below 4 amps I will be running my refer on the "excess" solar being generated. ( plan on a holding plate system)

john61ct · 08-08-2017, 06:31

Will your system have so much 'platage' you can skip a day charging them?

**newhaul** · 08-08-2017, 07:09

Quote:

Originally Posted by john61ct

Will your system have so much 'platage' you can skip a day charging them?

? What " platage " are you referring to I am estimating a daily usage of about 30 ah with the fridge . And I currently have 220 ah house bank. I am currently working with a couple of refrigerator manufacturers on the design and capabilities for me and my systems. The plan is to be able to go for up to three days without charging my house bank . ( the chances of not getting anything out of the solar for 3 days is nill.) I get some even when its stormy and raining all day.

softdown · 08-08-2017, 07:52

Quote:

Originally Posted by newhaul

? What " platage " are you referring to I am estimating a daily usage of about 30 ah with the fridge . And I currently have 220 ah house bank. I am currently working with a couple of refrigerator manufacturers on the design and capabilities for me and my systems. The plan is to be able to go for up to three days without charging my house bank . ( the chances of not getting anything out of the solar for 3 days is nill.) I get some even when its stormy and raining all day.

He is referring to battery capacity as "platage".

For some reason he likes to talk to solar newcomers as if they are solar pros. Gets pissy if you question that proclivity. We are going to arm wrestle for the CF cantankerous award...I can hold my own from time to time.

Perhaps I missed it....are you 24 volt or 12 volt or? 220 Ah means little without knowing the voltage the system runs at. Perhaps I just missed it...

**newhaul** · 08-08-2017, 08:08

Quote:

Originally Posted by softdown

He is referring to battery capacity as "platage".

For some reason he likes to talk to solar newcomers as if they are solar pros. Gets pissy if you question that proclivity. We are going to arm wrestle for the CF cantankerous award...I can hold my own from time to time.

Perhaps I missed it....are you 24 volt or 12 volt or? 220 Ah means little without knowing the voltage the system runs at. Perhaps I just missed it...

First I am a 12 volt system. As far as his platage comment I was not sure what he was referring to due to my stating that I will be Installing a holding plate refrigeration system.
Just to bring you up to current on my boat. 220 ah gc2 bank 2 100 watt mono 12v solar panels and a p30l pwm charge controller. I have been able to harvest up to 60 ah on a consistent basis in summer.(from late april to to mid september. )

john61ct · 08-08-2017, 08:12

Sorry no, I meant the holding capacity of the eutectic fridge plates.

They store energy as cold, exactly the same as a bigger battery bank would.

Think the blue freezer packs, but made of metal with evaporator coils inside.

They are much more expensive up-front than normal evaporator-based units. Also heavy and take up a lot of space.

Not inherently more efficient, but some excellent vendors like Rich Boren @ Technautics and his "Cool Blue" combine other efficiency features with top-notch service.

Advantage is the compressor runs less frequently, usually once or twice a day.

If there is a charge source regularly putting out more energy than what is being used the holding plate system can act as a useful load dump.