new camp setup

[blackbear199]

long time small scale user(20 yrs).
wanted to upgrade system at my camp.
currently 3x100w panels series connected to a epever 30a controller with 2S2P 6v 225ah lead acid.

i am upgrading to this..
2 x longi 405w - voc 37.00 - lsc 13.83 in series connected to a epever 40a
2 x longi 545w - voc 49.65 - lsc 13.92 in series connected to a epever 60a

reason i went with 2 strings is space where panels to be mounted,i cant fit 4 x 405w or 4 x 545w

i got a good deal on some used gel batteries
12v alphacell 220 glx 110ah battteries.
they came out of cell towers so i assume they havnt been cycled much.

i am going to connect them in parallel as per a iota diagram i found(see pic)

i dont use much power but what i wanted is storage for cloudy/rainy days.
a 1200w inverter runs all i need and prob only using half its output max at that.

i know with a bank this big i should have went 24 or even 48v but my loads are low and i have stuff that runs off 12v so didnt want to go with a down converter also.

so i decided to get with awg 4 for battery cable everywhere.
from my calculations between the 2 arrays(i am over paneled) on paper i shud get full 40 and 60 amps charging from each controller.realastically more like 85% from each.

i dont ever expect to see anywhere close to the full charging capacity as i watch my battery state carefully and when they get 12.4-12.3 i shut it down as i never over discharge.
i got easily 7-8 years out of lead acid batteries doing this along with always keeping them topped up with distilled water.

i know i shudn have went with awg 2 but the price diff didnt seem worth it to me as i rarely if ever expect to see max charge capicity(batteries dead).

i am also using a iota 90a when needed from generator.14.2v bulk and 13.6 float.

i built a panel during the winter and am going in a week to install at the camp.
i connected everything at home and everything looks fine.
the batteries were near full charge.
after powering it put max currect was like 5 amps and slowly dropped to less tham 1 amp.
i left it connected for a week to let batteries equalize.

just like some thoughts if i under doing it with cable size.

 

[seneysolar]

8 batteries?

The diagram looks more complicated than it needs to be, but yest it will work. Depending on layout and space, id consider using bus bars.

Slow discharge (light use) and slow charging with long periods of absorbtion, you wont have balance issues.

Wire size is on the small side for a 1200w/12v inverter . Depending on the style, 4 awg is generally rated for 75-95a. Just be sure to fuse it accordingly. Fuse protects the wire. If you have long duration of high use, you may blow the fuse or notice it getting warm.

What size wire does your dls-90 specify?

Note, if you do use bus bars , you can use the 4awg for the individual batts to the bus. Then you can use heavier from bus to inverter.

 

[blackbear199]

thks for the repy.
yes i thought about bus bars but couldnt find any for 8 bats.
i found 4 connection busbars and thought about doubling each one.
bus bars are expensive(i sure u know this).

thats why i figured i'de go with the 8 battery connection.
even at that the wire and lugs still cost enough.

i think i ok for the dls-90.
the manual states 8-4 awg.i assume depending on lenght.
my bank is going to be right below my panel so wires from battery bank to bus bar(inverter/iota connected) is short.
guessing maybe 3ft max.

i was worried about being close to the upper amp limits for 4awg.

 

[blackbear199]

btw i did buy 10 ft of 2awg.
i was planning on using it for the 90a iota to busbar where inverter connects and to the first run to battery bank as this is where the highest current will be,after that the amps are split across the bank.

the problem i had was i couldnt get the 2awg to fit into the iota lug.
its uses a set screw and didnt like the way it felt without a furrule,after adding a furrule it wouldnt fit in the hole.

so i had to use 4awg which fits with a furrule.
after that i though whats sense of using 2 awg anywhere.

 

[seneysolar]

I always recommend using larger wire on 12V inverter systems. One issue is the small voltage range for operation at 12V. If you are sitting at say 11.8 and the inverter calls for a surge, having too small of wire might drop the voltage at the inverter terminals enough to hit low V cutoff. Just something to watch for. Sounds like your use is low enough to not have this problem.

Yes, bus bars are pricey for a good set, but you are really only dealing with 100-150A so you could actually use some of the cheaper ones.

Something like this would be fine.

Batteries could be parallel with the 4 awg wire in sets of 2, then run the opposite + and - to the bus only taking 4 spots instead of 8. This would leave you a set of studs for the inverter and the charger. Just an idea.