Powering DC Powered Fans for Battery Enclosure: Suggestions

DickyDckDickyDck Registered Users Posts: 139 ✭✭
Hi all, I'm looking at fans to cool and vent an outside (out of house) battery enclosure. I was looking at DC powered fans, some running anywhere from 40w to 80w per fan. However I wasn't sure how I was going to be powering them. The battery bank will consist of 2 strings of 8 batteries, 6v batteries. So while they are in my finished garage which is climate controlled, putting this enclosure outside now creates a at the mercy of the weather scenario. Anyone have suggestions on how I could power the DC powered fans, I was thinking possibly using the batteries themselves as the power source but that brought up more questions in my head that was worth the hassle so I'm opening up to the experts here for other possible alternatives.

Comments

  • mike95490mike95490 Solar Expert Posts: 8,875 ✭✭✭✭✭
    Burushless DC fans are the way to go.   Here's a batch of 48V fans
    https://www.digikey.com/products/en/fans-thermal-management/dc-brushless-fans-bldc/217?k=48VDC+fan&k=&pkeyword=48VDC+fan&sv=0&pv14=167&sf=0&FV=ffe000d9&quantity=&ColumnSort=0&page=1&pageSize=25
     you may need to rig up a voltage limiter, as 48V banks can sometimes hit 60+ volts when equalizing


    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • DickyDckDickyDck Registered Users Posts: 139 ✭✭
    Sweet thanks!!! what, juicing a 48v fan to 60v isn't like adding a turbo to a naturally aspirated car? :p
  • mcgivormcgivor Solar Expert Posts: 3,438 ✭✭✭✭✭
    Using a 12V computer fan powered by a 10W panel will allow ventilation when needed most, during charging. This is something I have done, mot for battery box ventilation but to create airflow across a passively cooled charge controller.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • TecnodaveTecnodave Registered Users Posts: 418 ✭✭✭✭
    I use Metacrylic roofing compound on my entire external battery box, this stuff reflects 95% of solar heat gain, really meant for roofing, it sticks to about anything, wood, bare concrete, fiberglass, old roofing, you name it, very durable, the insides of my battery boxes are also coated with Metacrylic, my battery boxes are repurposed commercial fiberglass laundry tubs from our local university....I use some fans controlled by the aux output on charge as well as a thermostat, it does get rather hot here on the left edge at times. I use only brushless fans around hydrogen gas, the fans are low on the battery boxes forcing air in..
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • DickyDckDickyDck Registered Users Posts: 139 ✭✭
    edited June 2019 #6
    mcgivor said:
    Using a 12V computer fan powered by a 10W panel will allow ventilation when needed most, during charging. This is something I have done, mot for battery box ventilation but to create airflow across a passively cooled charge controller.
    I'm thinking about doing the same for my 2 Charge Controllers, as I'm considering adding more panels to both of them. They are rated at 3500w with I think around 4200w surge, and my array is total rated at 7200w.... but I average a lot less due to my area, I think I've ever only seen it hit 6000w maybe 2 times ever, usually hovering between 4.5 - 5.5 on normal sunny days.
  • DickyDckDickyDck Registered Users Posts: 139 ✭✭
    Tecnodave said:
    I use Metacrylic roofing compound on my entire external battery box, this stuff reflects 95% of solar heat gain, really meant for roofing, it sticks to about anything, wood, bare concrete, fiberglass, old roofing, you name it, very durable, the insides of my battery boxes are also coated with Metacrylic, my battery boxes are repurposed commercial fiberglass laundry tubs from our local university....I use some fans controlled by the aux output on charge as well as a thermostat, it does get rather hot here on the left edge at times. I use only brushless fans around hydrogen gas, the fans are low on the battery boxes forcing air in..
    Gonna have to check this stuff out, available at the standard hardware store? Home Depot / Lowes type places or specialty roofing places only?
  • DickyDckDickyDck Registered Users Posts: 139 ✭✭
    @Tecnodave
    For an outdoor enclosure, do you ever have to worry about it getting too cold? obviously heat is a concern, but is there a too cold temp to avoid, I would think so with FLA batteries since I'm sure the acid has a freezing point? I'm considering all potential factors for an external enclosure. I'm thinking maybe having the box against the house but outside, and routing a pipe into my garage to funnel cooler air to the box, and exhaust it into open air, which then could also be used to funnel warm air in during winter if it gets too cold, which may or may not happen. I guess each battery type and manufacturer has their own range of temperature for the specific battery.
  • BB.BB. Super Moderators, Administrators Posts: 30,740 admin
    As always, the answer is "complicated"... A quick list of issues:
    1. When Lead Acid batteries get cold, their apparent capacity drops.
    2. Lead Acid batteries when fully charged, won't freeze until something like -70F to -90F.
    3. A fully discharged lead acid battery freezes fairly close to 32F (electrolyte is mostly water--20% SoC 19F freezing)
    4. AGM batteries are freeze tolerant (they will generally not be damaged when frozen)
    5. AGM batteries should not be cycled when frozen.
    6. One person here used battery heaters and small genset to heat up bank when opening for winter. Once above freezing, normal use of cabin/cycling kept above freezing (not a heavily insulated box/under cabin if I recall correctly? I live in California--Let one of our friends in Canada answer the insulated box vs cold weather question)
    7. For storage, cold batteries last longer. With 77F/25C as "room temperature", for every 10C/18F drop in temperature, aging is cut by 1/2 (during 5C storage, 2*2=4x longer "aging life" for battery bank).
    8. For Li Ion/LiFePO4 and other chemistry batteries, check the manuals. Most Lithium batteries should not be cycled as temperature drops near freezing.
    9. Running lead acid batteries hotter than ~110-120F--shortens life of battery bank.
    10. Hot/gassing (Equalizing charge) FLA batteries--Heat and gassing causes electrolyte to expand... Do not fill FLA batteries to brim... When getting ready to charge, just make sure plates are covered with a bit of electrolyte--And fill when batteries are hot/gassing (not overfill).
    11. AGM and GEL batteries do not like EQ or high charging voltages (in general). Can cause to gas/vent/overheat catalyst and shorten life.
    http://www.windsun.com/Batteries/Battery_FAQ.htm
    http://www.batteryfaq.org/
    http://batteryuniversity.com/

    https://www.trojanbattery.com/pdf/WP_DeepCycleBatteryStorage_0512.pdf (freezing temp of electrolyte)

    http://www.windsun.com/Batteries/Battery_FAQ.htm (percent of rated capacity vs temperature)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • littleharbor2littleharbor2 Solar Expert Posts: 1,526 ✭✭✭✭
    mcgivor said:
    Using a 12V computer fan powered by a 10W panel will allow ventilation when needed most, during charging. This is something I have done, mot for battery box ventilation but to create airflow across a passively cooled charge controller


    I did exactly this to circulate air over my 5th wheel propane fridge/freezer coils. Made a huge difference in how fast it cooled and how cold my fridge got.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • TecnodaveTecnodave Registered Users Posts: 418 ✭✭✭✭
    edited June 2019 #11
    In Fairbanks Alaska glue on battery heaters are attached to the sides of auto batteries to help in the winter, these are about 80-100 watts, AC powered, 8" X 8" square, 1/2 thick encased in plastic,  they are common along with percolating engine block water heaters. Temps often fall below -70 F for extended times. So yes at temps below -40 degrees supplemental heating helps a lot. Plug in cars are common in Fairbanks, parking lots have meters on each spot......burrrr, that's why I left for Sunny California , not going back home in the winter, I'm spoiled now.
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • TecnodaveTecnodave Registered Users Posts: 418 ✭✭✭✭
    McGivor,

    later models of Dometic propane referigerator have two small fans under those coils, increases effeciency a bunch, I always add them when I use Dometic refrigerators. 
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
  • EstragonEstragon Registered Users Posts: 4,478 ✭✭✭✭✭
    If I was building an outdoor battery shed I'd try to excavate a few feet, and insulate above ground.  This would reduce the daily temp range.  Mine are in an insulated crawlspace, and the temp doesn't vary much at all.  They're currently 14°C, and will stay about there despite a number of upcoming days of >30°C highs.  They might get to low 20s in August.  The reverse happens in winter, with a slow decline to ~ - 15ish °C despite lows of around -40.
    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
  • DickyDckDickyDck Registered Users Posts: 139 ✭✭
    Estragon said:
    If I was building an outdoor battery shed I'd try to excavate a few feet, and insulate above ground.  This would reduce the daily temp range.  Mine are in an insulated crawlspace, and the temp doesn't vary much at all.  They're currently 14°C, and will stay about there despite a number of upcoming days of >30°C highs.  They might get to low 20s in August.  The reverse happens in winter, with a slow decline to ~ - 15ish °C despite lows of around -40.
    I had briefly thought about doing underground with tube ventilation with fans, but I thought someone here would have the blank stare of "why would you bury your batteries" :p so partial or complete underground could be a viable option....
  • DickyDckDickyDck Registered Users Posts: 139 ✭✭
    in the settings for the battery temperature on both the inverter and the charge controllers, there is cold/warm/hot. does anyone know the what range in celsius each one is? 
  • BB.BB. Super Moderators, Administrators Posts: 30,740 admin
    My guess:

    under 10C is cold
    10-30C is normal (could be "room temperature" is 15-25C)
    over 30C is hot

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EstragonEstragon Registered Users Posts: 4,478 ✭✭✭✭✭
    If they show target absorb voltage at each setting, you could infer temperatures from that.

    Absent more info, I'd guess something like cold = < ~15°C, warm = ~ 16-29°C, hot = >30°C.

    It's also possible the setting could be an offset relative to temp as measured at the controller (eg if batteries are outside while CC is in conditioned space), but it's likely just a simple absolute setting.
    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
  • DickyDckDickyDck Registered Users Posts: 139 ✭✭
    it is set to Warm on both CCs and the inverter so I figure thats about accurate. my batts stay in the 22-27 range, I am still researching fans to get them lower. and my extra batteries came in today so I'll be charging them up today, and adding them maybe tonight/tomorrow
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