diy solar

diy solar

System can't keep up after upgrades and reconfiguration

The spec sheet for my GC2s says to charge them in the absorption phase at 7.65V. That's 15.3V for the bank. The bank floats at 13.4V. I've been using this bank in my RV with those settings for 6 1/2 years with good results.
Mine are the EGC2, which translates to East Penn/Deka GC15 - that's 230ah vs. 215ah w/ the plain GC2. Specs are as follows:

At 12V:

Max Charge Current = 30% or less of Ah capacity (20 hour)

Absorption Voltage = 14.4V - 14.7V
Absorption End Point = Current change over 1 hour period of less than 0.1A
Max Absorption Time = 12 Hours

Float Voltage = 13.8V - 14.1V
Float End Time = No Limit

Equalization = 15.0V to 15.3V
Equalization End Point = Current change over 1 hour period of less than 0.1A
Max Equalization Time = 12 Hours

Temp Compensation = -.018V for every degree °C rise above 25C

This is coming from here:

 
I've had it on 14.6v for months. It has been many days since the controller dropped out of bulk/absorption State.
You could go up to 14.8 for a few days and see how it gos
did you check your sg at the end of the day ? your cells read 1.280 or a little less the battery’s should all be the same
400 watts really is not enough power for 4 gc batterys
I have 16 battery’s with 4500watts of solar so about 1100 watts for 4 battery’s
heres some thing to try , check the sg and see how the battery’s read .
Then remove 2 battery’s and run the system , check your sg in a few days . I will bet at the end of the day
your sg will be up .
You really need to get the sg up to 1.275 every day.
I think your system dosent have enough power coming in , 400 watts would be ok for 2 battery’s I like to have 500 watts .
I think it’s just a coincidence that your power is going down At the same time you changed the CC .
The sun is dropping in the sky allso witch gives you less power .
 
Well, that was unexpected...

Here were today's State of Charge readings, based on my Victron BMV-712:

• Morning minimum - 74%
• 75% @ 7:50am
• 78 % @ 10:30am
• 79% @ Noon
• 80% @ 1:15pm
• 81% @ 1:45pm
• 82% @ 2pm
At 3:30pm I took a nap. After waking, I eventually checked the battery again:

100% @ 4:15pm

Wha??????? In two hours of partly cloudy skies it jumped to completely full? How can I trust this info? Right now, with a bit of sun still hitting the panels I'm seeing 8-9amps / 100W or so coming into the battery. Voltage is 13.4-5 or so. Controller has been in bulk state the entire day. Inverter has been off since yesterday evening, 20 hours or so. So yes, I expected this would help in recovery, but to go from a slow, steady progress to a sudden 20% jump in two hours just doesn't seem feasible.
 
You can’t trust it at all ? dip your acid and get a real reading .
The battery monitors don’t work
They can give you a idea of what is going on .
I think with 400 watts of solar you do not have enough power to charge 4 of the gg battery .
Plus you are using power during the day that steels from the charging ..
Check you acid it should bed 1.275 and up on all battery’s .
Get some power in them or they will need to be replaced , they are dying ☹️
 
OK, according to the Victron BMV-712 (w/ a smart shunt) -- hardware that has not changed for at least nine months -- my current battery bank voltage is 12.99, as the clouds and light rain move in removing the last bit of sun from the panels. Over the last 16 days, according to the Victron charge controller, the low voltage was 11.59v and the high was 14.63v. It left bulk stage and went to absorption and float on only two of those days.

Evidently I got behind on my battery maintenance. Water was low in all cells, average SG was 1.175. Refilled everything.
 
Just to clarify...

My inverter was off about 20 hours, starting last evening, including all day today. So no power draw at all today during solar charging.
 
you need to check sg every morning and every night To figure this out .
you do not have enough solar to charge the battery’s and it’s October here and that means less power in my area .
1.175 is 50% in sg world .
Less water gives a higher reading .
Low water dosent matter as long as the plates aren’t showing in side .
You need to check the sg on all the battery’s i would think it very different .
you need to charge The battery’s to full then start equalizing them , it mite take a few days .
 
Most battery monitors used with lead acid batteries are not very accurate.

The 20% jump may have happened because the voltage reached a reset point. My Victron smart shunt has one that is adjustable. I really like the smart shunt but I don't relay on it for accurate SOC.
 
You need to check the sg on all the battery’s i would think it very different .
you need to charge The battery’s to full then start equalizing them , it mite take a few days .
I checked all 12 cells.
 
ok, to wrap up this thread....

1. I need to watch water levels better. Tops of the plates were kinda/sorta exposed, maybe. Still wet, but way too low.
2. I need to possibly rethink some power draws, at least temporarily.
3. I need to reassess actual daily watts/amps usage and see how that positions us if/when a cloudy/rainy day hits.
4. I need to think about upgrading the total watts in our solar panels.
 
The water helps keep the battery’s cooler , and when full it cuts down on the acid concentration Sg
the acid could help Erode your plats . So keep it topped off .

If you can’t keep 4 battery’s above 1.265 every day they are being murdered .
You would be better off using just 2 battery’s and discharging more but charging to full every day .
on a bright sunny day with 400watts of solar you probably get 300watts for 4 hours in June so 1200 watts total
In December you will get about half that power .
Your inverter just being on with no load 24 hours can use 6/1200 watts by it self ☹️ depending on the unit
My system uses 50watts being on .

The 100watt panels are expensive , I bought my panels for 167 $ each locally
Check electrical supply houses .
I don’t know where you are it makes a big difference .

I was looking at your loads and my trailer uses the same System morning star 300 watt inverter
2 140watt 12v panels 30 amp morning star charge controller .
I would charge with a 12v generator early in the morning to get some power in ,then the solar would charge the rest of the day . In November the battery’s just did not charge . Eq your battery’s ?
 
5. measure SG and take appropriate action including a regular equalization charge.
6. check settings on BMV 712 are compatible with solar charging. I suggest 'charged voltage' set to 0.1 or 0.2 volts lower than the absorption volts setting on the solar charger. The usual recommended values are for a continuous charge such as provided by an AC charger, if used with solar charging there is often an early sync to 100%. My preferred use of the Victron BMV and smart shunt, is to use settings such that the unit will never auto sync, and manually set to 100% when I am sure the battery is at 100% state of charge. Its also necessary to set up the actual ( or a guess ) battery pack capacity rather the battery 'new ' capacity.
7. Its probable the batteries have lost capacity, equalisation may help somewhat. It would be useful to carry out a rough capacity test using the BMV readings and the rest voltage of the pack .
8. Accept that the batteries have aged and lost capacity, with daily cycling expect 3 to 4 years with shallow cycling, 20% discharge, and 2 to 3 years with 50% discharge, provided the batteries have had ideal attention.

Mike
 
I havent read the whole thread, just the first few posts so forgive me if this has been said already, but dont forget we are getting out of the summer months and our days are getting shorter, and the sun is at a greater angle than it was before. I had to adjust my panels last week as I was seeing 10-15% less output than I was 4-6 weeks ago. Might not be the equipment but just the days getting shorter all together.
 
Your inverter just being on with no load 24 hours can use 6/1200 watts by it self ☹️ depending on the unit
My system uses 50watts being on .
Not sure what the inverter does by itself. But there is *always* a load. Fridge control board, CO2 monitor.
I don’t know where you are it makes a big difference .
currently in S Central Colorado
I was looking at your loads and my trailer uses the same System morning star 300 watt inverter
2 140watt 12v panels 30 amp morning star charge controller .
I have 4 100w 12v panels, 30amp Victron controller (mppt), 1500watt inverter
I would charge with a 12v generator early in the morning to get some power in ,then the solar would charge the rest of the day . In November the battery’s just did not charge . Eq your battery’s
Generator not connected to solar battery bank, no way to charge except solar panels.
Definitely need to equalize.
 
8. Accept that the batteries have aged and lost capacity, with daily cycling expect 3 to 4 years with shallow cycling, 20% discharge, and 2 to 3 years with 50% discharge, provided the batteries have had ideal attention.
Two batteries are dated 3/20, put into service in 6/20. The other two batteries are dated 10/20, put into service 1/21. We mostly stayed in parks with only occasional boondocking so they weren't getting regular drawdowns until June of this year. We haven't plugged into shore power since June 6. I think the lowest drawdown has been down to 65-70% (based on BMV-712 State of Charge calculation)
 
I suggest that you add a charger that can be powered by the generator. Run it for an hour in the the morning when making coffee and hot water. This will give the batteries a much needed boost, you also get coffee and hot water. The generator will get the exercise that it needs too.
 
Ok not to bad, you loads seam low enough
it’s pretty damn Sunny in Colorado Compared to my location in NY . 4.5 vs6 sun hours .
you are under paneled if you can’t get the trailer to a outlet with cheep 12v car charger .
You need to hook up 2 battery’s to your solar and let them charge for a day then run a eq on just 2 batterys
Then do the second set .
You have enough solar to charge and EQ 2 battery’s by themselves if every thing is off.
June to September is just enough time to slowly kill the battery’s .
Every day you don’t get to full charge or part of the way thru absorb you are loseing capacity .
You should not buy battery’s at diffrent times or from diffrent lots .
The good news is since they are only a year old they should bounce back .
These battery are tough , for your next set Get the 215 ah battery’s they will last longer .
You don’t really want to jam extra lead in the case .
If you are on the road you could go to a gas station and ask if they can charge you up .
If you get a good charger on them for a few hours you mite get thru EQ in one day.
Side note , you charge controller is small , but I’m sure it can be over paneled 200watts more may
Be enough to keep you charged .
 
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