Battery box indoors or outdoors

[Mike82]

I am getting ready to install a off-grid PV system and am using 2 strings x 4 T105 for a 24v system (system is for critical needs in power outage). I wonder whether to store the batteries in a box indoors or outdoors. I live on the coast in central FL with avg temp ranging from 90 deg peak summer to low 70s in the winter. I have a enclosed lanai where I can put the battery box and the temps range pretty steady at 75-80 deg, but the box takes up space and I have to put in an exhaust fan for the H2 fumes. Would I sacrifice too much battery life by putting them outdoors instead of the lanai? Thanks in advance.

[Sunking]

I am getting ready to install a off-grid PV system and am using 2 strings x 4 T105 for a 24v system, (system is for critical needs in power outage)

Do you have 4 or 8 batteries? If you only have 4 T105's configured as 24 volts can only be 1 single string with all 4 batteries wired in series. It would take 8 of the batteries to have 2 strings configured as 24 volts.

I wonder whether to store the batteries in a box indoors or outdoors. I live on the coast in central FL with avg temp ranging from 90 deg peak summer to low 70s in the winter. I have a enclosed lanai where I can put the battery box and the temps range pretty steady at 75-80 deg, but the box takes up space and I have to put in an exhaust fan for the H2 fumes.

What makes you think you need an exhaust fan?

I cannot imagine a Lanai made air tight in Florida without good air flow to outside air, that would be a room or house if fully enclosed. If the area has air circulation there is no reason to have an exhaust fan, and since you will be Floating the batteries, they never give off gas. You will be Floating at 27 volts, gassing does not occur until you reach 28.8 to 29 volts. Now if you put the batteries in a box, the box needs ventilated.

[Logan5]

If you already have 8X T-105's, why are you using 24 volts and why are you planning to parallel batteries?If you need that AH capacity then wire your batteries in series and get a 48 volt inverter. or get 4X L-16's and wire them in series for 24 volts. did you already buy a 24 volt inverter?

[Mike82]

If you already have 8X T-105's, why are you using 24 volts and why are you planning to parallel batteries?If you need that AH capacity then wire your batteries in series and get a 48 volt inverter. or get 4X L-16's and wire them in series for 24 volts. did you already buy a 24 volt inverter?

I already have a 24v inverter. I was looking at L16s, but they were almost 3x the cost of a single T105 (and less than 2x the AH cap) and since I have the space I got the 105s instead.

Sunking. As I stated, my lanai is enclosed with sliding windows so it stays air conditioned unless I open the windows. The lanai has a 10' ceiling and the H2 gas could build up in the upper 18" of the room, hence the safety measure of the inline exhaust fan thru PVC from the box to the outdoors.

My question is: Do I sacrifice battery life if I keep the batteries outdoors (in a vented box, of course) or should I keep them indoors?

[Logan5]

upgrade the inverter, there is no good reason to Parallel heavy expensive batteries.

[Sunking]

A 70 degree battery has twice the Calendar life of a 90 degree battery. Yes it matters. There are basements full of batteries in high rise building and no vents. None to speak of anyway. When I say full I mean a room the size of your average living room with 60,000 to 80,000 pounds of batteries. They do have Hydrogen Monitors with Exhaust Fans to meet strict building codes if ever needed. In my 37 years, never seen one fan come on yet. The Air Conditioning keeps th eroom ventilated.

If you are cycling daily where the charge voltage reaches gassing voltage of 2.42 to 2.45 volts per cell, there is some reason for concern. But you stated Emergency Standby which uses Float Charging of 2.2 volts per cell. Th eonly time you would exceed 2.2 vpc is if you EQ the batteries at 2.5 vpc. Open a window.

Makes me no difference, I do not care what you do. Inside or outside makes me happy. I am just here to give you the facts so you can make an informed decision you are comfortable with.