Looking to replace batteries and need help choosing

ABC1

Outback GS8048A Radian Inverter
Outback FLEXmax 80 Charge Controller
15–265-watt Canadian PVC= 3975 watts
adding soon 9–400-watt REC PVC = 3600 watts
17kw Diesel Generator
Rolls Battery 16- 428ah total 890ah L-16 S550


Been off grid for 9 years, all equipment, batteries and generator are inside an 8'x20' metal shipping container with vents.
Located in Hot Northern CA, batteries have been 123 degrees numerous times and been over 100 for days. Lowest battery temperatures are around 55 degrees.
Biggest electric use is the well, max at 3600 watt and air conditioning at 2800 watt.
The nighttime electric use is around 4000 watts without air conditioning.
Rolls Batteries held up to the abuse of being new to off grid, but the time has come to replace them. They are discharged 16% then generator kicks on and recharges them.
What battery will stand all this heat?


 

SumPower

ABC1 said:

What battery will stand all this heat?


 

Lead or LiPo4 will work in the enviroment.

For lead acid batteries the rule of thumb is for every 18°F you increase the temperture the service life halves. I would say your batteries have done pretty good in the shipping container!

Lithium also has some contraints to consider for temperature, but this is the direction I would go if I was replacing my AGM's.  Edit: lithium's life is rated at 77°F I believe. but many I have looked in the spec sheets will discharge up to 120°F.

You will only be able to do open loop with lithiums and the Outback equipment.

MariaA

Living off-grid for 9 years in a hot climate like Northern CA definitely puts your system—and especially your batteries—to the test. With internal temps hitting 123°F and staying above 100°F for days, heat tolerance becomes one of the most important factors when choosing a new battery.

In extreme heat, lithium iron phosphate (LiFePO₄) batteries tend to outperform traditional lead-acid types like your current Rolls setup. They’re more thermally stable, have a longer lifespan, and can handle deeper discharges with less wear. That said, high temps can still shorten the life of any battery, so improving ventilation or considering some passive or active cooling in your container would make a big difference no matter what you choose.

We’ve worked with similar setups on off-grid solar systems in hot climates like Pakistan, where dealing with high ambient temperatures is part of the design from day one. Choosing the right battery chemistry and managing heat makes a big difference in long-term performance and cost.

A rugged LiFePO₄ bank could be a solid next step for your setup, especially with your generator backing it up for heavy loads like the well and air conditioning. Just make sure to size it for both your daily use and to handle those hotter-than-usual days when system stress is at its peak.

manzanita2

I thought that LiFePo batteries don't like temps above 110-114F.

Dave Angelini

Build a proper insulated shed with ventilation and some cooling for really hot parts of the day.

Anything less is going to bite you long term. I know of 3 LFP battery fires in sheds. Nasty white dust everywhere that did not burn hot. I would post a picture but I need permission to do that. Client is away this week. He now has a proper power system location. 

ABC1

Decided on 4 Pytes V5, wanted Rolls LFP but they are hard to get right now.
Going to install them myself hopefully