Perhaps the next battery room is not the perfect choice?

softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
Currently using the sun room for the batteries. Yearly temp range is about 38F to 86F. This is a cold part of the Colorado mountains.

The charge controller/inverter are a bit harder to get to. They are towards the bottom of the root cellar staircase. That has never exceeded 59F to my knowledge and I can remotely read the temp from bed. Currently perched at 45F. Temp rarely varies more than 1-2 degrees/week. It is very stable.

Made sense to use the cool storage room just another 12" wall beyond the sun room. Egads - It has been reading temps in the 20s (F) this week. Had no idea that the storage room gets that cold, this early, in the colder season.

The great news is that it is always cool in the storage room. I doubt that it ever exceeds low 60's.

I'd use the root cellar for the batteries but space is at a real premium down there. Plus the eight AGM solar batteries weigh over 170 pounds/each. Tripping on the staircase would not be pretty.

The batteries should last a L...O...N...G time in the cool to cold storage room. With eight massive batteries, they *should* still offer more than enough energy.

Everything else is great. Good lighting. Plenty of space. Great access. Strong battery rack in place. Distance to inverter is about 8' this time. Has been about 5'. Using 4/0 of course.

Can I expect unexpected problems?

First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    Get a remote temperature sensor and bury it in the middle of the battery bank (foam insulation if needed to prevent air flow from affecting the temperature). See if the battery bank is in a "happy range". There is a lot of thermal mass and a few hours of afternoon heat will not affect the average temperature much.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    I have mine in an insulated crawlspace, likely similar temps or even colder in winter. The only downside I've found so far is capacity is reduced with temp. 350ah bank gets to be more like 300 when really cold.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    BB. said:
    Get a remote temperature sensor and bury it in the middle of the battery bank (foam insulation if needed to prevent air flow from affecting the temperature). See if the battery bank is in a "happy range". There is a lot of thermal mass and a few hours of afternoon heat will not affect the average temperature much.

    -Bill
    I probably conveyed too much at once. The old and current battery bank is in the sun room which can get pretty warm for several hours/day.....almost every day that it is sunny (very often).

    Being certain that cool batteries tends to equal happy batteries that enjoy prodigious lifespans, I made the decision to relocate the next battery banks in a cool to cold storage room. While the storage room is only 12" away (wall thickness when I do stuff), the batteries will face away from the inverter so I can easily service them. Thus increasing the distance (from inverter) from ~5' to ~8'.

    What I failed to realize is just how cold it gets everywhere but the bedroom and sun room. I expected temps in the 40's....just like the root cellar. Found temps in the low 20's. Winter isn't even here yet.

    Perhaps everything will turn up roses so long as the Outback temp sensor performs adequately.

    Or.....are you gently implying that the current sun room location is the better choice?

    I could mount a door on the storage room. The batteries would likely raise the room temp a bit. I could install a pilot light about ............no.

    Battery bank "happy range?" For max performance then 70s are ideal...sure. With a larger bank than needed (currently), I am geared towards battery longevity.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    Estragon said:
    I have mine in an insulated crawlspace, likely similar temps or even colder in winter. The only downside I've found so far is capacity is reduced with temp. 350ah bank gets to be more like 300 when really cold.
    We have found that our Canadian friends enjoy solar battery lifespans much longer than those in southern environs. How are the batteries holding out? Do they also stay pretty cool in the summer?

    I am a bit concerned that most of my place may hover around 10F within a month. I always knew it was cool but I was shocked when my FLIR was reading low 20's everywhere my dogs weren't sticking their hot little noses.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 32,997 admin
    From what a few of our cold climate friends have said--An insulated battery box with cycling batteries stays acceptably "not cold" during hard winters (self heating from charging/discharging).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    BB. said:
    From what a few of our cold climate friends have said--An insulated battery box with cycling batteries stays acceptably "not cold" during hard winters (self heating from charging/discharging).

    -Bill
    Good idea. I have reams of insulation. Rooms of insulation Stacks of insulation.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    softdown said:
    BB. said:
    From what a few of our cold climate friends have said--An insulated battery box with cycling batteries stays acceptably "not cold" during hard winters (self heating from charging/discharging).

    -Bill
    Good idea. I have reams of insulation. Rooms of insulation Stacks of insulation.
    The batteries were in the crawlspace before it was fully enclosed and insulated, so ambient would have been as low as -35 or so.  They were/are in an uninsulated plywood box, so the mass of the batteries would have kept them somewhat warmer than that, but still in the minus 20s (C)..  I'm not there as much in the winter, so self heating was minimal.  

    As mentioned, capacity drops but fully charged electrolyte won't freeze at ambient temps (well, maybe Antarctica?).  Last year, unusual early winter weather delayed freeze-up so I wasn't able to get out until Feb.  The unusual weather also resulted in panels covered with sticky snow early on, which later sun couldn't melt.  The tare load from charge controllers ran the batteries down well below LBCO, and although electrolyte was sort of slushy it didn't freeze hard enough to burst batteries.  I suspect the cold temps also slowed down the chemistry to the point that even having sat for at least a couple of months in a discharged state, there was little if any permanent damage.

    Now that the crawlspace is fully enclosed, I don't expect the batteries will get much below -15C.  In the summer with ambient > 30C and regular cycling I rarely see batteries get over 20C.  

    Even with the incident last winter, I'm not seeing any apparent drop-off in capacity (beyond what I'd expect from the lower temps).
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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