Battery-box questions

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VolcanoSolar
VolcanoSolar Solar Expert Posts: 56 ✭
in General Solar Power Topics #1
Two battery-box questions, for a unit that will be outside, behind the house, on its own little patch of concrete, with a total of 24 L-16s wired at 48 volts:

1) I've heard advice -- from two friends -- that lead-acid batteries shouldn't sit directly on concrete, because "it drains them down." Having found nothing in any literature on this, am I correct to assume it's not true? When I queried the Interstate sellers they said there was some very minor effect, but not to worry about it. (I *have* seen how battery acid can etch the concrete over time, and have primed it with POR-15 paint, then cover-coated it with oil-base exterior paint -- fairly bullet-proof, as paint goes.) Any comments on concrete and batteries?

2) How critical is sealing the box up and/or venting? I was planning to use corrugated fiberglass siding over a painted-wood frame, such that the corrugations would allow a bit of natural ventilation. Need I worry about either sealing it up tight (not too many critters other than spiders and small lizards), or actively venting it with a fan? Given that it's outside and breezy most of the time.

Thanks for comments.
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #2
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    Re: Battery-box questions
    1) I've heard advice -- from two friends -- that lead-acid batteries shouldn't sit directly on concrete, because "it drains them down." Having found nothing in any literature on this, am I correct to assume it's not true?
    It's not true. Here's a link to Interstate Battery's discussion of this subject: http://www.interstatebatteries.com/www_2001/content/faqs/tech_talk/maintenance/storing.htm#a-4
    2) How critical is sealing the box up and/or venting?
    Since the box is outside, power venting probably wont be required. You should include an intake vent or two near the bottom of the box, and another exhaust vent or two near the top and above the tops of the batteries to allow for natural convection air flow.

    I recommend you place a label on the box warning others of the dangerous contents.

    HTH,
    Jim / crewzer
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  • System2
    System2 Posts: 6,290 admin
    #3
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    Re: Battery-box questions

    The Battery-on-concrete myth is a religion with many people. If they believe in God, you can't change their mind, the same with the battery and concrete thing. One time I helped a student with his HS science fair project, it involved totally encasing a car battery in concrete for a month, except for the vents and terminals. Of course the battery didn't care, but the teachers did. They failed him - - because what he proved - - was wrong! It's interesting when students know more than the teachers. So sad.
    I've also been "educated" that one must never place a chain saw on concrete. Seems those magical properties of concrete "will take the CD ignition right out of it". Humm, perhaps that's why everyone living in concrete housing gets brain cancer.
    On a more serious note, if one lives through cold winters, the concrete floors in outbuildings tends to stay cold longer than other things, so at times, the bottom portion of a battery sitting on that concrete could stay colder than the upper portion which could present a problem with acid stratification etc.
    I've had batteries sitting on concrete for years with no ill effects, just to prove it to others. But even that didn't change the minds of true believers.
    Wayne
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
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    Re: Battery-box questions

    to be clear a battery sitting on concrete does not drain a battery. now if the concrete is on the ground (like as in a basement) the thermal temperature of the battery will be reduced closer to the temperature of the ground rather than ambient air. a colder battery will perform slightly worse in respect to the one at the usually warmer ambient air temperature. my point is that thermal characteristics could effect the battery performance somewhat. if that concrete is hotter than ambient air temperatures(usually not though quite possible) it will perform slightly better as the battery would be hotter. if you take a piece of plywood or other insulating material and place it between the battery and the concrete you will control the thermal characteristics slightly better. as i have said many times, use a battery temperature sensor and equipment that can accomodate them as battery temperatures are usually not at ambient air temperatures.
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #5
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    Re: Battery-box questions

    Hi all

    Wayne, I understood that the Chanisaw on concrete had to do with the alkali nature of concrete interacting with the metals (usually cast aluminum alloys) of saw bodies. i've always had mine sit on wood pallets (eventually covered with oils) and never had a problem. my batteries sit on chipboard with that black plastic air gap stuff on it's bottom...keeps the cases safe from alkalai poisining :p and the temps not affected as Neil noted.

    rlaph
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  • System2
    System2 Posts: 6,290 admin
    #6
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    Re: Battery-box questions

    I always thought the "dont set down chain saw on concrete" was for the idiots that cant put the saw down with out ramming the teeth into the concrete and dulling them....
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  • VolcanoSolar
    VolcanoSolar Solar Expert Posts: 56 ✭
    #7
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    Re: Battery-box questions

    Gosh, I have chainsaws, and I have concrete, and I've never heard of this. I'm forwarned!! :D

    Thanks for answering the questions.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #8
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    Re: Battery-box questions

    MY batteries sit in a separate building. They often times go through extended periods of my absense in the winter, and the temp can fall to -35f. I have built battery boxes that are lined with 2" styrofoam insulation, top, bottom and sides. A little experimentation with thermometers reveals that the batteries generate a fair bit of heat both during the charging phase as well as the discharge, keeping the batteries tens of degrees above outside air temp. They sit in an insulated but un heated building, protected from the wind. They still get cold, but my winter sun is great, and my loads are small so they have suffered no ill effect in more than ten years.

    As to concrete floors, I too grew up with that myth and still put any battery on a board or a piece of styrofoam. As said elsewhere, it does keep the battery warmer that the surrounding floor.

    Icarus
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  • System2
    System2 Posts: 6,290 admin
    #9
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    Re: Battery-box questions
    SKYWLKR wrote: »
    I always thought the "don't set down chain saw on concrete" was for the idiots that cant put the saw down with out ramming the teeth into the concrete and dulling them....
    I love it, that's an excellent point. But where I live, the reason behind this religious belief is the supposed magical qualities of concrete to reach up inside the guts of the saw and destroy the electronics inside the CD ignition module. Nothing else is harmed, only the ignition module. Ha Ha. Much the same as the ability of concrete to "SUCK THE JUICE RIGHT OUT OF IT", referring to a battery. Of course stupid me, never having believed such things, have been getting away with such things for 40 years. By the way, here's another one: Never park your car on grass for an extended time, as the grass, in it's desperate need for oxygen, will suck the air out of the tires.
    Icarus, thanks for the bit on your insulated battery box. I'm in a similar situation and am just building my battery box now, complete with 2 inches of foam insulation. Great news that they generate some heat on their own etc. Makes me feel much better.
    Cheers
    Wayne
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #10
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    Re: Battery-box questions

    Great news that they generate some heat on their own etc.
    Yep... that's related to charging efficiency discussions that we enjoy from time to time. Using flooded-cell lead-acid batteries' ~80% recharge efficiency as an example, supplying the batteries with ~1,000 W (i.e., 25 V x 40 A), they'll radiate away ~200 W in waste heat.

    Make sure you have the remote battery temperature sensor plugged in when using a well insulated battery box!

    HTH,
    Jim / crewzer
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #11
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    Re: Battery-box questions

    I don't have a remote temp. monitor, nor any temp monitor. (I should, but my batteries are almost always cool, if not cold). I set my charge point accordingly. When it is -35 out, there is little worry that the batteries are going to overheat.

    As a side note, It's pretty cool on this site that there are people who can back up with science and calcs. what we discover through trial and error. I must admit I tend to be a trial and error guy,,, some might argue an error guy.

    (It is supposed to go to -6c tonight, our first freeze of the year, a few weeks late).

    Icarus
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #12
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    Re: Battery-box questions

    "When it is -35 out, there is little worry that the batteries are going to overheat."

    we aren't talking about a car here as overheating wasn't the point. the voltage that you are setting your controller for based on temperature will not stay the same be it ambient air temperature changing or battery temperatures changing. heck even if the air temp stayed one temp night and day the batteries will change anyway because some of the charge power is dissipated into the batteries as waste heat. the batteries will be totally different early in the morning when getting their first charge as compared to a few hours later on after the batteries have warmed somewhat due to charging and also because of ambient air temps rising later. i feel it is impossible to set and forget for one voltage based on one temperature as the temp changes constantly and the battery charge voltage requirements also change accordingly.
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  • System2
    System2 Posts: 6,290 admin
    #13
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    Re: Battery-box questions

    Good explanation Niel, that's why, when I bought my MX-60, for a very little extra $, got the remote temp sensor for the batteries. Now the MX-60 will know what adjustments it needs to make to the battery voltage to both properly charge them and prolong their life, no matter their temperature.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #14
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    Re: Battery-box questions

    thanks wayne,
    crewzer and i are not pushing battery temp sensors because we want somebody's sales to go up with accessories here. it is a necessity in our point of view for proper operation and prolonging battery life. costwise, you won't beat the little you put into the bts as compared to the battery costs incurred sooner when not doing the bts.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #15
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    Re: Battery-box questions

    Neil,

    I understand the concept of electrolite temp visavis charging voltage. In my case, my system(s) have been built piecemeal over the years. As such I don't have the sophiticated hardware I might like. (Not having the information and the knowhow of this site until late, is part of it as well)!

    It has only been in the last six months that I have gotten a 'real' battery charger to upgrade the automotive one I have used for years. I didn't know the difference. Not only that I didn't know that it wasn't putting out full amperage on my floating neutral generator!

    Having said all of this, I am ten years on a set of l-16 type batteries. My drawdown is minimul, and I watch the sg and the water carefully. In my next live I will get more fancy stuff.

    This system started as a way to have emergency lights 24/7. We are on an island waaaay off grid. It evolved into, using the 12vdc for the fridge igniter, then the radio, then a few more lights. Now with a pure sine inverter we use it 24/7 for lights, radio, telephone, sewing maching, and yikes! sattelite internet service! Things that didn't even cross our minds ten years ago. With nice cfls, we use about 16-20 amp/hours 12vdc a day. We charge the computer batteries and other stuff on full sun days.

    Thanks one and all for the great information.

    Icarus
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  • System2
    System2 Posts: 6,290 admin
    #16
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    Re: Battery-box questions

    10 years on a set of L-16's, that's awesome!
    I don't expect mine will last that long, because for the last 3 years, I believe they have been almost constantly overcharged. I paid more attention to the info that came with my Morningstar TS-60, re special recommendations for L-16, than I did to the battery manufacturer, East Penn. 14.8 \ 14.1
    I guess it's no wonder my SG was always way high. Should have trusted the SG more. Live and learn I guess. Also didn't like the way the TS-60 transitioned to Float - - it almost never did. Regardless of the battery voltage, regardless of the hours at the adsorb voltage, it wouldn't transition until the charge from the PV's had been reduced by the controller, to 30% for some hours. With 660 watts PV and six L-16's that rarely happened, especially with the fridge starting every hour or so, putting the boot to that magical 30%, thus starting the timer all over again, so the batteries continued to boil merrily all day long at 14.8 volts.
    I've learned a lot in the last 3 years, much of it from the great people on this form. I now have an MX-60, a few more PV's and from everything I've read, it's what I should have had in the first place, but the money just wasn't available back then.
    All the best
    Wayne
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #17
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    Re: Battery-box questions

    My only "secret" is having only small loads. In the evening with everything on we draw 3-5 amps 12vdc. This is all lighting and the radio. We do most of our computer work when the sun is up, (not all) No fridge load, (l/p) and no water pumping loads, (gravity with a honda pump, buckets when it's below freezing (Oct-May)

    We are building a new building and as such we will have more loads, but mostly lighting. I am going to a pressure water system, (Shurflo pump into a BIG pressure tank). My theory is that I can pump the tank(s) up during the day when the sun is out and I have excess panel capacity, and then draw down at night for dishes, showers etc. No bath tubs, only a wood heated hot tub, no toilets (flush) means no large water use. We use about 20 gallons a day currently. (Dogs drink from the lake!)

    I guess this is off topic, but in the new place, I am going to build the battery box under the work bench on (big) casters so I can roll them out to clean and check.

    Icarus
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #18
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    Re: Battery-box questions

    Icarus,

    what type/size batteries. I've got 6 455pound Surrettes, I'd need a small tractor to move a wheeled box arounnd:p.

    Why going for the Surflo pump, cost, etc? I'm needing to rplace a jet pump and am looking at the various booster pumps. Not sure i'd like the buzz of the diaphram type, but i've never heard the rotary vane type working. Any thoughts?

    ralph
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  • System2
    System2 Posts: 6,290 admin
    #19
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    Re: Battery-box questions

    Wow, Almost a ton and a half of batteries. Man, you want to look after those babies. Ha Ha. Are they inside, kept warm, or is that not a problem in your case?
    Just curious - what do you have for PV watts, controller etc? or is it PV?
    I know this is drifting a bit from battery boxes, but it's an ongoing discussion.
    Wayne
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  • GreenerPower
    GreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    #20
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    Re: Battery-box questions
    crewzer wrote:
    I recommend you place a label on the box warning others of the dangerous contents.
    Add to this, a bucket or plenty of baking soda boxes handy at the site.

    GP
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #21
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    Re: Battery-box questions

    Hi Wayne

    The batteries are in the basement in a box, the box is vented 24/7, hydrocaps. 2.1kw Sharp 175 and 180's, MX60, H80 and 10kw diesel genset. I have an added 48v lift truck charger by Vulcan (canadian co) which when run in conjunction with my SW4048 utilizes the full wad from the genset. It's easy to see where the power loss goes when charging...the electrolyte will warm up enough to lower the setpoints unlike when it;s cold.

    I keep tabs on the SG readings with pilot cells, full complement readings and log of water usage per cell (getting more thourough after 3+ years.

    This forum has been helpful on several fronts...now i'm looking at booster pump to replace an old jet pump. Earlier i've found valuable information on charging, meters, everything. I watch a couple of forums but this one regularly. Glad to see Joe Bennet packed his tent and left the park.

    ralph
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  • System2
    System2 Posts: 6,290 admin
    #22
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    Re: Battery-box questions

    Man! Quite the setup you have there! Ya gotta love it.
    All the best
    Wayne
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #23
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    Re: Battery-box questions

    Along the same lines. I'm building my new battery box an wish to vent it with a power vent to be on the safe side since the batteries will be in a small occupied building: gas range with pilots, wood heat etc.

    What I would like to know is what is the minimum safe voltage to trigger a vent van, ie have the fan come on before the batteries start to gas. (12 volt nominal). I don't want the fan to come on any sooner than needed. I intend to build a voltage control switch to trigger just BEFORE gassing voltage.

    Thanks again for all the help.

    Icarus

    PS. I did a search hear and elsewhere and haven't had much luck finding this info.
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #24
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    Re: Battery-box questions

    Icarus,

    what's your inverter and charge controller setup? I have an always running 48vdc vent fan on my battery box...it helps with the air exchanges in the house too. There are 2 or 3 unused relays on my Xantrex 4048 inverter (yours?) and an Aux function on the MX60 charge controller which can also be used.

    I use a heavy duty relay on the MX to route house power to a dedicated outlet. IT runs an oil filled space heater...when there's excess power to use. Right now i'm still waiting for a little sun to melt the accumulated ice off the PV panels and the wind turbine blades. the turbine blades aerodynamics are toast with even a small amount of ice on them, no way they'll spool up to speed. The weight is negligable, it's the surface contamination on the airfoil surfaces that do it. Usually after an ice storm there's some sun in a day or two, but not so far:cry:

    Ralph
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #25
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    Re: Battery-box questions

    Ralph,

    I have a morningstar 300 puresine inverter. I have ~1000amp/hrs 12vt of batteries and 220 watts of panel. At present I just have a simple controller and am planning an upgrade to an mppt type.

    Wiring a simple voltage controlled switch is pretty simple, rather than having the fan run 24/7. (I really don't need any more fresh air in the building!).

    Tony
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #26
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    Re: Battery-box questions
    icarus wrote: »
    Along the same lines. I'm building my new battery box an wish to vent it with a power vent to be on the safe side since the batteries will be in a small occupied building: gas range with pilots, wood heat etc.

    What I would like to know is what is the minimum safe voltage to trigger a vent van, ie have the fan come on before the batteries start to gas. (12 volt nominal). I don't want the fan to come on any sooner than needed. I intend to build a voltage control switch to trigger just BEFORE gassing voltage.

    Thanks again for all the help.

    Icarus

    PS. I did a search hear and elsewhere and haven't had much luck finding this info.

    I'll try once more. Does anyone have any idea what the minimum safe voltage to set a battery box fan?

    Icarus
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #27
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    Re: Battery-box questions

    I found this link: http://www.powerstream.com/SLA.htm

    It seems to have some useful information. The gist seems to be ~2.4v per cell @ 20c (68f). Anyone agree, or disagree?

    Icarus
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  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    #28
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    Re: Battery-box questions

    SysV..................Fan On.................Fan Off
    12v................13.2 VOLTS............13.0 VOLTS.......0.2v
    24v................26.4 VOLTS............26.1 VOLTS.......0.3v
    48v................52.8 VOLTS............52.2 VOLTS.......0.6v

    From Zepher Power Vent site http://zephyrvent.com/Inst.html

    HTH;)
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #29
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    Re: Battery-box questions

    Nigel,

    Thanks a bunch. I don't know how I missed that on the Zepher site.

    Thanks once again,

    Tony
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  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
    #30
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    Re: Battery-box questions

    something like

    "WARNING! LOW VOLTAGE!"
    well, i thought it was funny
    crewzer wrote: »
    I recommend you place a label on the box warning others of the dangerous contents.
    HTH,
    Jim / crewzer
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  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    #31
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    Re: Battery-box questions

    Warning Low Voltage !
    But Watch Out for the Amps ?
    They Can Melt Metal !!!

    ;)
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