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Old 30-06-2014, 16:03   #16
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Re: Flooded lead acid solar charging voltage

Main Sail,

I have some questions on your info below...

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Originally Posted by Maine Sail View Post
*They need to know actual physical 20 hour capacity which is never the same as the factory rating for very long and is constantly changing. Many flooded batteries do not even achieve their full rating for 20-50 cycles...
Exactly what qualifies as I cycle? My mastervolt counts cycles but is that an industry standard?

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*The need to know the Peukerts exponent which is also changing with age.
Does this tend to go up or down with age? Should it be modified according to a schedule bases on the manufacturers estimated cycle life?

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*You need to know your Coulombic efficiency, which is also constantly changing.
By this can I assume you mean charge efficiency? Ours is calculated.



They are great informational tools, but not for pin point accuracy unless you really devote a lot of time to it....[/QUOTE]
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Old 21-09-2014, 18:30   #17
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Re: Flooded lead acid solar charging voltage

So a few weeks ago I changed the absorption voltage back to the 14.4V (from 14.6), but change the time to maintain to 2 hours (from 1 hour).

I can not really tell if the 14.4V at 2 hours is better/worst than the 14.6V for 1 hour.

I can tell based on the controller daily history that the system has done the 14.4V @ 2 hours more often than it was doing the 14.6V @ 1 hour. But the overall daily amp-hours the controller has been putting out is less because I changed the freezer temperature setting and it has been cooler.
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Old 27-09-2014, 11:03   #18
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Re: Flooded lead acid solar charging voltage

Voltage is only a good indicator if measured after 24hr rest, Using "the number" in return amps is inaccurate due to temp change, although watching the amps returning "flatline" is a good method,
Meters are only as good as they are set up and will drift over time, The only accurate way to decide charge is measuring SG,
Then what is your correct charge voltage, Wellll it depends, if you have long strong charging, use a lower voltage and a long absorb, If slow/poor charging, higher voltage to "fill em up quicker"
Absorb time, The correct way to determine this is by use of your hydrometer ( you don't have one ? you need to get 2, You will break one :-)) Set your absorb time to max, Check SG's every hour, When they stop rising, your batteries are full, add an hour (solar only) that is your absorb time,

Have a good one
Tim
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Old 27-09-2014, 11:57   #19
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Re: Flooded lead acid solar charging voltage

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Originally Posted by blackswan555 View Post
Voltage is only a good indicator if measured after 24hr rest, Using "the number" in return amps is inaccurate due to temp change, although watching the amps returning "flatline" is a good method,
Meters are only as good as they are set up and will drift over time, The only accurate way to decide charge is measuring SG,
Then what is your correct charge voltage, Wellll it depends, if you have long strong charging, use a lower voltage and a long absorb, If slow/poor charging, higher voltage to "fill em up quicker"
Absorb time, The correct way to determine this is by use of your hydrometer ( you don't have one ? you need to get 2, You will break one :-)) Set your absorb time to max, Check SG's every hour, When they stop rising, your batteries are full, add an hour (solar only) that is your absorb time,

Have a good one
Tim
Not disagreeing with anything you posted.

Just not sure how realistic it is to expect a 24hr rest.

My composting head requires a 24/7 fan and both my installed Frigaboat and portable Engel are both normally on. Normally have the anchor light on at night. When the boat is moving the nav stuff and auto pilot need power.

Wondering just how a liveaboard is able to rest the batteries for 24 hr.
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Old 27-09-2014, 12:09   #20
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Re: Flooded lead acid solar charging voltage

Yes agreed, My background is in off grid solar, Tell a customer that their gen has to run 24 hrs so I can take a (not very reliable) measurement, is a no :-)

Tim
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Old 27-09-2014, 18:37   #21
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Re: Flooded lead acid solar charging voltage

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Wondering just how a liveaboard is able to rest the batteries for 24 hr.
We have the individual 12V batteries (actually 2 6V in series for us) on isolation switches so that we can take individual batteries off line while the remaining batteries run the house. To get a 24hr rest voltage, we would take 2 of the 3 12V offline and run the house on one battery for 24hr. Then the next day, take the other battery offline.

It is rare that we do this - maybe once a number of years ago. But we have had to isolate bad batteries before, which was the primary purpose of the switches.

Mark
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Old 28-09-2014, 09:51   #22
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Re: Flooded lead acid solar charging voltage

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Absorb time, The correct way to determine this is by use of your hydrometer ( you don't have one ? you need to get 2, You will break one :-)) Set your absorb time to max, Check SG's every hour, When they stop rising, your batteries are full, add an hour (solar only) that is your absorb time,

I think it's not too easy to use a hydrometer with sealed AGM batteries

-Chris
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