Water Tank Cooled Batteries - Temperature Sensor Placement?

NicaSolNicaSol Registered Users Posts: 20 ✭✭

Having just built water tanks (see photos) to help control the ambient temp surrounding the batteries, I'm at a bit of a loss as to where the temperature sensors should be placed. This is complicated by two types of sensors: a single (normally) battery-side mounted pad sensor for the Xantrex inverter/charger, and two terminal mounted sensors (Morningstar recommended position) for  2 Morningstar MPPT45 controllers.

The batteries are submerged with the tops about an inch above water level. Questions:

1) Can the Xantrex sensor still be mounted on the side of a battery? Is it waterproof? If not, is there any benefit to placing it on top of a battery?

2) If the Xantrex sensor is waterproof and submerged, would it be accurately monitoring the internal temperature of the battery or be (heavily?) influenced by the temperature of the water? I have a feeling (correct me if wrong) that the internal temp of the battery would be greater to some degree that the surrounding water. This may be less of a concern if the sensor pad is surrounded by air (as it normally would be), but given the substantially greater conductivity of heat/cold by water, the sensor could be influenced (most likely cooled) when surrounded by water cooler than the internal temp of the battery.

3) Are the terminal posts still the best place for the Morningstar sensors? Comments in other posts in various forums recommend attaching temperature sensors to "center mass". If the concerns mention about about waterproofness and heat/cold transfer and sensing accuracy in water submersion are not an issue, can these eye terminal type sensors be attached to the side of a battery (and how)? 

A bit of background. The batteries are Ritar 200C lead carbon. The tanks have a circulating water system. Cooling the water bath is a work in progress. I am currently using frozen bottles of water. Even with this the bulk/absorption internal temps have reduced from 34-36 C to 29-31 C. I will be trying something related to modifying a minfreezer, dehumidifier or air conditioner to cool the water further. Any ideas or proven solutions welcome. Living in Nicaragua, there is no Amazon, no commercial/retail water chillers, no meaningful Craigslist, no Best Buy (etc) and the closest semblance of a Home Depot is an overnight trip away. Imagination and re-purposing is the norm.

Thanks for looking at the post and any comments/suggestion.







Comments

  • TecnodaveTecnodave Registered Users Posts: 418 ✭✭✭✭
    edited May 2019 #2
    Wow!  

    That is innovative!   Ok you do have a temperature problem there. 36c.  96.8 F... ...I'm native Alaskan and we had the opposite problem... how to keep them from freezing.  I would think attach the temperature sensors to the battery terminals....that would be the place closest to the internal battery temperature. Seeing that Xantrex bought Trace I'm going to assume the sensor is plastic encapsuled in a rectangular package maybe 1/4 inch thick.....same as used on Trace.
    These are waterproof but you need the battery temp, not the water temp. The water temp would affect the sensors reading.  The terminals would be closest to the temp of the battery internals. If not possible to place directly on terminals place them between the two terminals.  I think that I would surround the temp sensors with a bit of insulation to get them closer to battery temp. And yes keep the Mstar sensors on the terminals for the same reason.  I glue foam pads over my sensors to exclude external effects....

    ive survived winters in Alaska at 70-90 below...Fairbanks...but never lived in such heat.....I think that Alaskan blood is too thin to take such heat.  Interested knowing now you resolve this problem.

    just a thought....how is the temperature underground?  Is it moderated a bit?  Maybe a box underground a bit? I would think that would be a bit cooler......but I've never been to Nicaragua...I'm speaking with no real expereince with the heat, well rarely....Fairbanks did hit 109 F one summer but it did not last long....MidNite sun!

    david
    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,
  • mike95490mike95490 Solar Expert Posts: 8,755 ✭✭✭✭✭
    Describe the battery bank configuration, are these 6v cells wired as a 12, 24 or 48V system.

    if your terminal connections are good, and you are not running many amps through the terminals, those are a fine place, but if you run a 12V system and are pulling 50A all the time, you will get resistance heating from the terminals. 


    It looks like you are flowing water over the batteries and re-circulating it,  or are the batteries completely submerged in the water ?
    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 ||
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  • mcgivormcgivor Solar Expert Posts: 3,401 ✭✭✭✭✭
    This is something I've done with positive results, I used the terminal to reference the battery temperature with styrofoam as insulation to offset any ambient fluctuations. The cooling method used was a 90W water cooler with an aquarium circulation pump, just removed the dispensing valve so minimal modification to the cooler was needed. The cooler was run during daylight hours which reduced the battery temperature from ~45°C to  ~28°C, it did take a few days to reach a stable temperature.

    Some issues were animals, geckos in particular, were provided with a drinking source sometimes falling in, to reduce the possibility I used small styrofoam balls from a bean bag to float a few centimeters on top of the water, this had the added effect of providing insulation. The other was over time algae began to grow, a little chlorine bleach reduced that, the floating insulation also cuts light needed for its growth. 

    The energy consumption was ~500W per day so that needed to be considered, but it was well worth the effort to extend the life expectancy. Now with lithium I don't have the temperature gain associated with lead acid,  which loose approximately 15% of the energy passed through as heat. The LFP bank reached 36°C maximum during the hottest period of 45°C highs, not a major concern with the chemistry, most of the year they are significantly lower.

    When I was last in Nicaragua  during the Contra war years there were no private vehicles, one US dollar got 6.9 million Cordobas in the morning, by evening it was near 9 million, made the mistake of changing $20, nobody would accept the local currency, despite being a multi millionaire  all I got for my millions was a plate of rice and beans,to buy gas for my motorcycle I traded clothes, thins music be vastly different now.
    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 ✭✭✭✭
    edited May 2019 #5
    @mike90054,

    they are 12 volt batteries, and a 24 volt system.....these batteries are only available as 2 volt cells or 12 volt batteries, the 2 volt cells are more square......peeked at Ritar's  website,  it looks like 4 banks 24 volts at 800 a.h.
    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,
  • NicaSolNicaSol Registered Users Posts: 20 ✭✭
    david - yup, it's the Trace/Xantrex pad, about 1.5"x3.0"x.25". No chance for anything underground as we are practically on bedrock. Daytime temps hover around the low 30s (hi 80sF) on cool days and frequently hit high 30s (100+F) low 40s. A cool wave here is mid 20s (75ish) and the locals pile on sweaters and hoodies.

    mike - as David mentioned they are 12V in a 24 volt system; 4 strings of 2 cabled equidistant through buses. We may pull a max of 15 A for very brief periods and generally run at 5-8 A day/2-3 A night. The tops of the batteries sit about 1 inch above water level. The 4 visible tubes pass down between the batteries to the bottom of the tank. The batteries sit on spacers to allow water to circulate under them. Outlets to return water to the pump bucket are in the top edge of the tank sealed into 1/2"PVC tubing that runs along the edge.

    mcgiver - thanks for the idea about water coolers. Is that a compressor driven cooler or thermoelectric/peltier (the latter I would think not having enough oomf)? The system holds about 20 gallons of water and, at a guess, given the head and tubing resistance, the pump is probably operating at 40ish gallons per hour - complete change every 30 minutes. 

    One buck gets you 32 Cordobas now. Rice and beans are still a staple of every diet. Canned Starbucks Frappaccino has been spotted at times in the local grocery stores (pulperias). Mukul resort is the hit of the Hollywood crowd and $500 a night gets you a private cabana, pool and personal chef.
  • BB.BB. Super Moderators, Administrators Posts: 30,494 admin
    Thermoelectric/Peltier tend to be much less efficient than "compressor" based cooling systems.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mcgivormcgivor Solar Expert Posts: 3,401 ✭✭✭✭✭
    The water cooler is a compressor inverted 20 litre bottle type, it ran non stop for 5 hours per day, the insulated holding tank is about 1 litre, it was the cheapest way I could think of, about  $68 here in Thailand, now it's used for the purpose it was designed for.
    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.
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    What is the ambient temperature of the water?  Can you make up for a higher water temp by using more water, and spilling it away or using it for something else.  Well water or earth based cistern water might be cooler?  As TechnoDave suggests, those of us “further north” have a quite different set of issues.  Tony
  • TecnodaveTecnodave Registered Users Posts: 418 ✭✭✭✭
    Tony,
    One thing I have seen as a natural heater in a greenhouse,  milk cans, the kind that milk cow farmers use, about 10 gallons full of decomposing cocoa bean husk. This stuff gets really hot!  You won't pick up the milk can, it's way too hot. Temperature measurements in the core of the pile show 140-150 degrees F. It's so hot that the galvanizing on the milk cans is distorted, burnt! I have tinkered with it. Good 90 days to cool off and stop decomposing.  But cocoa bean husk is not available everywhere. I saw this in an organic farm in Palo Alto, CA.  The husk came from Ghiradelli Choclate in Oakland, CA. I haven't tried this in remote locations as I froze in my last winter in Fairbanks, Alaska and have been far south of there for quite a while now. I'm still thawing out....21 years in Alaska was quite enough...I was born there....Matanauska-Susitna Alaska. I go back home only  May through October to avoid the worst cold as I don't care to live in that environment , lovely to visit, but I'm spoiled with Bay Area Medeterrian climate.  I still would not recommend this for lithium but does work keeping AGM's warmer. Way too pricey to risk IMHO. (The Li's ) When I go to cabin in S.E. Alaska I take reconditioned cell tower AGM's with me and give them away to my neighbors when I leave. They have a better chance of using them than I would if I left them to freeze besides it makes for good neighbors. Love your photos posted, but no I will not go back to that remoteness.
    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,
  • NicaSolNicaSol Registered Users Posts: 20 ✭✭
    Icarus. Our well water is about 29C by the time it gets to the house. Using frozen pop bottles in the circulating reservoir cools it to about 27ish - using about 1 bottle per hour for 6-8 of the warmest daylight hours . That's getting pretty old but looking into a water cooler (a  la Mcgiver), or a modified minifreezer(fridge) or dehumidifier (see aquarium and weed growing forums), is an overnight trip to Nicaragua's only big city and not going to happen soon. The dehumidifier mod will actually freeze the reservoir water if not set/timered carefully. Anyway 27-29ish is better than 33-35ish ambient air temps. In the bulk/absorb stage the batteries used to get up to 35-36C internally. Now they hover around 29-30C internally.
  • WaterWheelWaterWheel Registered Users Posts: 337 ✭✭✭
    edited May 2019 #12
    I also went with a chilled water tank but use an aquarium chiller after looking at a thermoelectric cooler.     Thread here  https://forum.solar-electric.com/discussion/353721/cooling-the-batteries/p1

    As for where to place the tempature sensor I agree with Mike (post #3) in your situation, put it on the battery post.    
    I have doubled walled batteries and placed the sensor between the walls in the center of a cell (discussed post #36 and #69 in the thread).

    I believe that without some cooling of the batteries in a hot environment they gain more heat than they lose overnight growing slightly warmer throughout the summer until they are staying above 85 degrees even at night.       A chilled water bath stops that slow heating cycle.

    I'd never heard of Lead Carbon batteries.     Interesting low maintance choice.

    Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

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  • Dave AngeliniDave Angelini Solar Expert Posts: 5,180 ✭✭✭✭✭
    Outback has had the nano carbon for at least 5 years.
    https://www.wholesalesolar.com/9890060/outback-power/batteries/outback-power-nano-carbon-200nc-178-ah-12v-agm-battery

    Trojan has FLA smart carbon even longer.
    https://www.firemountainsolar.com/manufacturer/trojan/with-nre-smart-carbon-technology/

    The jury is out still on if they really have more cycles than conventional tech. I am a doubter from what i have heard from the field.

    How are the waterwheels spinning?
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
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