The Longest Night

Well it is quite cloudy right now with some thunder rolling. My concerns are back due to only feeding 51 volts to the batteries from incoming voltage that is fluctuating in the 60's. Concerned again - of course. It is very rarely this dark and cloudy though. You can'r charge batteries with the same voltage they have. 

Disconnected the 8D's in effort to save the far more valuable batteries by maybe 7 : 1. 

Hard to diagnose absolutely cloudy conditions. Bit like analyzing a light bulb that is almost off. 

Idea seems very jerry rigged but here it is nonetheless: Serial three panels two times for much higher voltage to increase entire array voltage. Almost certain this will not work. 

Dave Angelini said:

Use a genset. I do not understand your set-up in your sig below. You have to complete charge somehow Good Luck!

Tomorrow is mostly sunny. I'm thinking that ought to help considerably.

boB said:

Not sure where the FM80 shuts down at these days.  WAS 140V but might be 145V now ?  Maybe Darren Emons remembers.  I'll ask him next week since he is working for us now.

Think mine was made in 2012. Sat in its box for several years while I continued building. Building. can. take. a. while. 

BB. said:

Remember that you want to hold ~57.6 volts (AGM) for something like 6 hours for full absorb (and drop below 1% or even below 0.5% rate of charge). Making float 57.6 volts is probably not going to hurt anything for your solar power system... I would worry if float was >2% (enough to cook a battery bank, and really an indication of an end of life battery bank that needs to be replaced soon).

From Marc Kurth regarding Concorde--But would not be bad for AGMs in general:

https://forum.solar-electric.com/discussion/comment/401301#Comment_401301

...

First: I will categorically state that almost every early Concorde battery failure that we see is from undercharging. Undercharging is the enemy and always has been forever. Undercharging can include too low of an Absorb voltage, too short of an Absorb time, too low of a charge rate and not reaching 100%  SOC often enough. Way behind undercharging on the list is high temperature. Overcharging is rare to the point of being almost non-existent.

Second: It is MY opinion that Concorde has gradually ratcheted up their support of “conditioning” because customers are so afraid of “over charging” their batteries, that they undercharge them. MOST people do not read (or perhaps ignore) the fact that Concorde batteries must be charged at the Absorb voltage until they are only drawing one half of one percent of the battery bank C/20 rating. Simply put, 0.50 amps per 100 AH of battery capacity.

Dropping to Float before reaching this point is a form of undercharging and will cause sulfation. Their manual also provides suggested Absorb time settings to be used as a starting point to fine tune. Two hours is minimum for very shallow cycling and four hours for deeper cycling.  Remember that “end amps” is the key and that lots of Float time brings strings into balance.  We often read the internet megaphone about overcharging AGM’s.  Think about a typical 1200 ah bank. At 100% SOC, the entire group of 24 batteries is only drawing 6 amps!  I assure you that it will take a very long time to cook them. Especially when the sun goes down with great regularity.

There is much, much more to discuss, but I will say that if our battery banks are charged per the manufacturer’s instructions, equalizing is not required for the first 5-7 years. Yes, it is a slightly destructive process, but less so than sulfation! 

OK that was wordy! But go ahead tell me what I missed!

-Bill

I figure that using FullRiver numbers is good. They take slightly more aggressive charges. 

Loving your suggestion about the BMS. Seven strand thermostat wire is great for hooking up BMS units. 18 gauge and solid strand with seven colors. 

There is a downside to mounting the inverter and CC out of the way. But keeping it cool with stable temperatures will certainly help a lot with longevity.

Dave Angelini said:

Yes use the OEM numbers! What is being conveyed is to make sure your FM80 is not going out of absorb to early. Being able to read the 1% or even as Marc and Bill are saying .5% is really the ball game here. That is why I used the picture of the  battery system to show everything in one shot. A battery monitor is good also but,

Really all you need is a voltmeter and a way to read end of charge amps for AGM's.

And the most important thing, you have to do it daily offgrid. This should not have happened in summer. Sorry to be frank about it.
Call me the bad cop!

"read end of charge amps for AGM's."  I'm not sure what that is conveying. 

Not many old timers are going to check battery voltage every day, after the excitement wears off, unless the CC readouts are extremely convenient. Much like checking oil levels with every fuel up - likely not going to happen. Whether or not it should? Well of course we should all spend several hours/day monitoring everything we own.

With my BMS next to the TV remote, I can read it with a 3" twist of the head. Actually it would be hard not to read it. 

Outback has a DC monitor for $278. Some folks may be better off just easily reading battery bank voltage. I can do the other figuring in my head.