24v system battery options.

mendocino_beano
mendocino_beano Registered Users Posts: 5 ✭✭
in General Solar Power Topics #1
For a small 24v bank is there any discernable difference in efficiency between using 2x 12v 200ah (4D-8D) vs 4x 6v (near equivalent ah)?  Aside from more connections on the 6v end and a hernia on the 12v end, what are the pros and cons of either? Cold weather and mounting dictate agm batteries.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Especially with AGM, parallel connections are frowned upon.   Save your back and go with the 4x 6V.   And if one cell turns out to be a dud, and has to be replaced, it's easier
    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 ,

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  • mendocino_beano
    mendocino_beano Registered Users Posts: 5 ✭✭
    #3
    Where would there be a parallel connection?  Your point on ease of replacement is valid though, if a cell were to fail I would rather replace one quarter of the bank than half.
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,102 ✭✭✭✭✭
    #4
    Are the 12 volt , 4D or 8D batteries true deep cycle batteries? If not then definitely 6 volt deep cycle.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #5
    mendocino_beano said:
    Where would there be a parallel connection?  Your point on ease of replacement is valid though, if a cell were to fail I would rather replace one quarter of the bank than half.
    my bad, I had a brain fart
    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 ,

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  • mendocino_beano
    mendocino_beano Registered Users Posts: 5 ✭✭
    #6
    littleharbor2 said:
    Are the 12 volt , 4D or 8D batteries true deep cycle batteries? If not then definitely 6 volt deep cycle.
    Depends what you mean by "true" deep cycle. I'm certainly not referring to an ag or marine battery, but I am not sure Trojan or Crown are in the budget.  Perhaps something heavy and chinese? I guess my original point  was: all things being as equal as they can be is there any performance difference between the two options?
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #7
    @BB.  I flagged you because I think the outside link might toss this in the spam folder.

    Hard to beat the price and life span for cost per watthour of in-expensive golf cart batteries from Sam's Club or Costco. About $85 + core. they are very liberal on the core you use, you can bring a lawn tractor battery! I've done it!

    Don't have a membership or a friend with a membership, buy a gift card and go in and ask to use that. You can also get a 1 day trail sometimes. I think one of them charges an extra 10%. Might also find a Groupon 'deal' on a Sam's club membership (I don't think I've seen Costco do this) I don't see one running now, but they often are, buy a membership $45 and receive a $10 gift card, a roasted chicken $5, a couple other items $10-15 free.

    There is a $20 gift card, but it comes 7-10 days after you sign up;

    https://slickdeals.net/f/13036885-sam-s-club-join-today-get-a-20-gift-card?src=SiteSearchV2_SearchBarV2Algo1
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,102 ✭✭✭✭✭
    #8
    littleharbor2 said:
    Are the 12 volt , 4D or 8D batteries true deep cycle batteries? If not then definitely 6 volt deep cycle.
    mendocino_beano said:
    littleharbor2 said:
    Are the 12 volt , 4D or 8D batteries true deep cycle batteries? If not then definitely 6 volt deep cycle.
    Depends what you mean by "true" deep cycle. I'm certainly not referring to an ag or marine battery, but I am not sure Trojan or Crown are in the budget.  Perhaps something heavy and chinese? I guess my original point  was: all things being as equal as they can be is there any performance difference between the two options?

    Being that many sealed lead acid batteries are back up, UPS, high rate or Telecom batteries which aren't designed to be cycled daily is why I ask. If they are deep cycle batteries they should state that on the battery somewhere. The long term performance would be considerably better with a battery that was designed to be cycled on a regular basis.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #9
    Photowhit,

    For members in good standing, your posts should never go into the spam folder.

    Only new members with a few (or zero) posts are checked for "spammy" posts.

    6 volt (and 8 volt) "golf cart" batteries are usually the cheapest (best bank for the buck) for deep cycle storage batteries. Look around for local distributors that supply golf courses and such with electric vehicles).

    The 6 volt batteries are typically more available in deep cycle vs 12 volt batteries... And are 1/2 the weight for an "equal" AH rating (2x 6 volt @ 200 AH = 1x 12 volt @ 200 AH battery in weight/size).

    AGM batteries are going to be much more expensive, and will (in my humble opinion) probably last a couple years less than equal quality flooded cell batteries (which have their own issues of monthly water check, electrolyte SG measurements, etc.).

    Will the system be operating in the winter or just in storage? A fully charged FLA (or AGM) battery will not freeze. And if cycled daily, in an insulated space, should remain above freezing (which gives you higher AH storage capacity).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • billybob9
    billybob9 Registered Users Posts: 141 ✭✭
    #10
    Photowhit said " Costco $85 + core ". They are now $91 + core but not the same 6V battery as before. They discontinued the 225AH battery for a 210AH battery which on a load cell will discharge to week when activated. I bought one and brought it back thinking it was defective but they all did the same thing. Then went to the Interstate store and they let me test their 6V 225AH battery with the same load tester I have and the results were the battery stayed the same voltage and did not go into the week reading. So I guess the 225 is just better then the 210.
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #11
    More like the Costco battery is cheeper......not nearly as good a quality as interstate. One of my battery banks is Interstate traction L-16 batteries now 6-7 years old and doing just fine, test at full capacity.  The L-16 is very much like the GC-2 golf cart battery but way taller at 16"  these are used in floor sweepers as seen in grocery stores and twice the capacity, I think mine are 378 a.h.,  about 150 pounds and as big as I want to lift. L-16 are also available as 4 volt and 2 volt....the 2 volt units are about 1150-1180 a.h. capacity.  L-16's are my go to battery choice. My other bank is Rolls-Surette S-530 L-16  328 a.h. shipped from Rolls on June, 26, 2005. They will be 14 years old next month, still testing at full capacity. I will get 20 years out of them.
    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,
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #12
    billybob9 said:
    Photowhit said " Costco $85 + core ". They are now $91 + core but not the same 6V battery as before. 
    I'll be honest and say I've never bought through Costco, I am surprised by them dropping voltage though. I've used the 'Energizer' 6 volt from Sam's club quite a bit, been close to 2 years but I've been in Sam's and saw 215 amp GC "Energizer" batteries, I assume the same. On the Atlantic coast they get a Dura cell version GC battery.

    I don't know how you tested, Charge first, then load applied, after initial drop should hold voltage...?

    I'm sure I'll be setting up another system end of summer, I'll keep an eye on them.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • billybob9
    billybob9 Registered Users Posts: 141 ✭✭
    #13
    Tecnodave
    The Costco batteries are Interstate. Both the 210AH and the 225AH. They are cheaper at Costco by about $50 and when I bought them about 5 years ago, this was a really good deal. Paid $76 a pop. 
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    edited May 2019 #14
    Billybob, 
    i suspected that they were interstate brand, but did not know for sure. There is a big difference in big box store handling as opposed to battery company handling of batteries. I have interest in an auto repair dealer and we are interstate dealers. Interstate puts batteries on our shelf and swaps them out if we don't sell within 90 days, they take them back to their warehouse where they charge them , test them and put them out again. They have always been there if we need some special battery or if we have a problem with them. I formerly owned an automobile electrical shop specializing in automobile dealers and fleet service. They put batteries on my shelf, maintained them and we paid for them when we sold them. 20 commonly sold batteries on the shelf with no bucks out to have that stock. Electrical Specialty Shop has Since has been sold. I do not need to buy from Costco as I pay less than they sell them for. Dealer confidential I can't say what I pay for them. Costco buys them outright and does not get the same service that small dealers get.  They buy in huge quantities and If they let them run dead its on them. In automobile type batteries there are only 4 manufacturers of all the labels out there. They will build to your specs if you buy enough.....Most Interstate batteries are built by Johnson Controls as are the Die-Hards.  Exide is one of the big four.   Rolls-Surette, Trojan, and North Penn Deka all build their own batteries but these are not automobile batteries, the others I do not know who builds them.

    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,
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  • billybob9
    billybob9 Registered Users Posts: 141 ✭✭
    #15
    Photowhit
    Glad you mentioned Sam's Club was just there yesterday looking at batteries and shopping. Lots of different options as far as batteries. It's Dura Cell here on the West Coast Too. I tested the Interstate batteries both ways charged and right off the shelf getting the drop from only the 210AH. 
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #16
    Billybob,

    Interstates premium GC-2 is the 225 amp hour version, they also build a 195 a.h. version
    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,
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #17
    I can (could?) get the cheap Trojan GC battery (605?)for the same price as the Sam's club GC battery. but they require a 'real' core. I can't just take in any old lawn tractor battery for a core, making them $15 more expensive...lol.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • billybob9
    billybob9 Registered Users Posts: 141 ✭✭
    #18
    Tecnodave
    WOW ,  thanks for the run down on how the Big box stores operate and the different battery companies. You are so right about being in business and having a franchise to get things cheap. Yes, when I was in the Interstate store they had many different battery choices.The manager was very helpful and I told him about this forum. I said why don't join up and call yourself Battman. Maybe someone has that one already LOL ? 
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    edited May 2019 #19
    Billybob,

    Interestedly enough...the 210 a.h. version is not on my supply list. Available to me is the 195, 215, 225, and 245. Maybe the 210 is only for big box stores.....they have buying power that small shops do not. I move only 60-100 batteries/year it's a small one person operation. I only diagnose  electrical problems, teaching co-owner the tricks I've learnt.  Trying hard to retire but taxes, govt regs......
    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,
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  • billybob9
    billybob9 Registered Users Posts: 141 ✭✭
    #20
    Tecnodave
    Your  right again there is something " Interestedly Enough " .  When I first tested the 210 AH battery I noticed that the Interstate tag was in the wrong place on the battery. In that place on the other Interstate batteries was the warning about acid. The 210AH is on the right.
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    edited May 2019 #21
    I have bought batteries from Interstate that were not manufactured by Johnson Controls, they had U.S. Battery markings on them.....and when I requested data sheets ...charge profiles....they were clearly labeled U.S. Battery. Interstate remarkets  batteries from other sources as they now supply batteries that are not auto batteries, even flashlight batteries, Ni cad cells etc., phone batteries etc.
    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,
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #22
    In comparing AH ratings, keep in mind that although the 20hr rate is common, some are promoted at other rates (eg 24hr).  

    Or maybe the big box just labels a 225ah battery as 210ah because they know they leave them sitting around, and the resulting sulfation reduces capacity.
    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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  • billybob9
    billybob9 Registered Users Posts: 141 ✭✭
    #23
    From my photo above you can see the size of the 2 different batteries are the same. The case on the 225ah is different having extra support on the bottom. The 210ah case is the same all the way down to the bottom. Since I have tested both batteries with a load tester It's obvious to me this is just like the egg rolls that were once very tasty and now are mini egg rolls that have no taste at all. The golf cart people will be the first to notice the difference in longevity.
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