6v or 12v Battery. Confused

Zakarume
Zakarume Solar Expert Posts: 143 ✭✭
Was getting bored today and was looking at different batteries for solar. I have theses right now http://www.trojanbattery.com/product/t-105_plus/. There are 8 of theses wired in series/parellel for a 450 AH 24v battery bank. I am now seeing these https://www.batteriesexpressinc.com/...int-srm-29.htm. It says they are at 210 AH battery. If i read this right then 6 of these would be 630 AH 24v battery bank and be bigger than mine. Would this be correct? Would it be better than what i am using now? It says it is a Deep Cycle battery, but it is confusing me
1460 Watts Solar @24v. 675 AH Battery Bank using 12 6v Trojan T-105. 1 Midnite Classic 150. 1500 Watt 24v Samlex Pure Sine Inverter

Comments

  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Hi Zak..,

    There is a Typo on the site that you Linked. There is NO AH Capacity noted, at all. The Reserve Capacity is minutes of run time @ 25 A. Instead of listing this Reserve Capacity in Minutes, they mistakenly list the RC as AH.

    In looking at the Interstate site, there is NO AH Capacity listed for this battery either.

    It might be about 100 AH, but suggest that you RUN AWAY!

    In general, buying the lowest voltage battery that you can will give better results, IMO. Because, if a battery goes bad, and you must replace it, you will be throwing away fewer good cells, usually. And higher voltage batteries have less capacity for a given weight, so, you would wind up with more parallel strings, which is not goos.

    Just my opinions, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • Saipro
    Saipro Solar Expert Posts: 74 ✭✭
    I'm new to this RE thing but traditionally, RE batteries usually come in 6V and 2V offerings,with plenty of good reasons. Marine batteries are invariably deep cycle batteries too but aren't manufactured for use in RE applications and typically would not stand to the test. The ones which can double as RE batteries are typically way more expensive yet once again rarely appear in offerings of greater than 8V per battery. I'd say you're better of with your T105-RE batteries (distinctly different from the T105 batteries). Notice the RE suffix? It's common nomenclature you'd find these days and it specifies that the batteries are engineered for RE applications.
    Semi off-grid

    255W Canadian Solar × 12, 200AH 48V US 185 XC2 bank, Victron Bluesolar MPPT 150/85, Victron CCGX, Victron MultiPlus 48V/5kVA/70A inverter (primary system) Victron Phoenix 48V/375VA inverter (backup for critical loads)

    300W Yingli × 2, Midnite Brat, 200AH 24V bank (powers DC LED security lights)

  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Saipro wrote: »
    I'm new to this RE thing but traditionally, RE batteries usually come in 6V and 2V offerings,with plenty of good reasons. Marine batteries are invariably deep cycle batteries too but aren't manufactured for use in RE applications and typically would not stand to the test. The ones which can double as RE batteries are typically way more expensive yet once again rarely appear in offerings of greater than 8V per battery. I'd say you're better of with your T105-RE batteries (distinctly different from the T105 batteries). Notice the RE suffix? It's common nomenclature you'd find these days and it specifies that the batteries are engineered for RE applications.

    If you just look at the weight of the T105 compared to the T105RE, you will see that it has a lot more lead in the plates for long term stability.
    Cranking batteries have more thin fragile plates to be able to deliver high current "off the top". But if you discharge them too far the plates will suffer cumulative damage. Same if you chronically overcharge them.
    Hybrid (and most Marine batteries, even if they say Deep Cycle) batteries have fewer thicker plates and the active chemicals on the plates are structured to withstand a deeper discharge, but still not the cycle life of a real RE battery.
    RE/Deep Cycle batteries have a higher internal resistance than the other two types, but are designed to deliver a lower current through many more discharge/charge cycles for longer life. In some cases the chemical composition of the active material on the plates may be different too.
    SMA SB 3000, old BP panels.
  • Zakarume
    Zakarume Solar Expert Posts: 143 ✭✭
    It was just confusing as to why they say i is deep cycle when overall it is not. Just got done watching a youtube video and it explained it better also
    Link is here https://www.youtube.com/watch?v=xELqluPUsuQ
    1460 Watts Solar @24v. 675 AH Battery Bank using 12 6v Trojan T-105. 1 Midnite Classic 150. 1500 Watt 24v Samlex Pure Sine Inverter
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Vic wrote: »
    Hi Zak..,

    There is a Typo on the site that you Linked. There is NO AH Capacity noted, at all. The Reserve Capacity is minutes of run time @ 25 A. Instead of listing this Reserve Capacity in Minutes, they mistakenly list the RC as AH.

    In looking at the Interstate site, there is NO AH Capacity listed for this battery either.

    It might be about 100 AH, but suggest that you RUN AWAY!

    In general, buying the lowest voltage battery that you can will give better results, IMO. Because, if a battery goes bad, and you must replace it, you will be throwing away fewer good cells, usually. And higher voltage batteries have less capacity for a given weight, so, you would wind up with more parallel strings, which is not goos.

    Just my opinions, Vic
    I just looked at the Trojan site and it shows both RC (although not explicitly labelled as that) and the AH at 5 through 100 hour rates. The 225 AH at twenty hours (C20 = 225) looks right for this 6V battery.

    Using six volt batteries, you can get a 24V bank using just four in series to get 24 volts and two strings in parallel to get more capacity (550AH).( If you were starting from scratch, I would recommend a 48V battery bank instead, using all eight batteries in a single series string.)
    If you try to get the capacity you need at 24 using 12V batteries, you will end up with four series pairs in parallel, and that is generally accepted as a bad idea. It will be hard to get even current distribution over the four strings during both charge and discharge, and that will reduce battery life and require more maintenance attention from you.
    You can see a good discussion of batteries in parallel at this site. The rest of the technical pages on the site are great too.

    SMA SB 3000, old BP panels.
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    inetdog wrote: »
    I just looked at the Trojan site and it shows both RC (although not explicitly labelled as that) and the AH at 5 through 100 hour rates. The 225 AH at twenty hours (C20 = 225) looks right for this 6V battery.

    Hi inetdog,

    If the above was responding to my statement that there IS NO AH rating in the Linked site's data, I was referring to the Subject battery from Batteryexpress.

    It is THAT battery that has NO AH rating stated. It is THAT battery that has the Typo, where Reserve Capacity is stated in AH, rather than the correct Reserve Minutes.

    And it was that battery that I was referring that Zak.. RUN AWAY FROM, NOT, his existing bank of Trojan batteries.

    As noted in my previous post, there IS NO AH Capacity listed for the same battery on the Interstate site either. So, seems that that battery merits no attention for RE use, FWIW.

    Should have been more specific that I was referring to the Interstate Battery SRM-29, and the site with the bogus R C Data was Batteryexpress ... FWIW, Thanks, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.