Need help please with Batteries

pacogpacog Registered Users Posts: 18 ✭✭
Hello New to the forum. Just got a group of 10 Deka Unigy 1 12avr170et. Can these be used for off grid application or should I return them right away? I've been reading a few different response's so I am a bit confused.

The guy I purchased them from knew exactly what my plans were for them and told me I should have no problems at all. As long as they stayed float charged at 13.5v and as long as voltage did not drop below 11.3v they should last? Was he correct or just saying that so I would buy the batteries?


Also what's the largest parallel string you recommend if using 12v batteries?

Thanks in advance.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,497 admin
    My suggestion--Return the batteries, if you can, and comeback here to discuss your needs (power, system, etc.).

    I could not find anything from Deka that listed the life of these batteries other than as 10 years in Float service. Many times, batteries designed for float service will have very poor deep cycle life (1-2 years to 3-5 years at best, a few 100 cycles of life sometimes).

    What your guy was telling you not to let the battery go below 11.3 volts (under load?) is actually good advice. You will see many batteries rated capacity down to 10.5 volts (and inverters with 10.5 volt cutoff voltage). Taking a lead acid battery to "dead" is usually going to result in a dramatically shorter life (can be as short as months or a few weeks of life remaining).

    Batteries are the "heart" of an off grid power system. Understanding your loads/power needs (daily amp*hour/Watt*Hour usage, emergency backup, full time off grid, peak power needs, etc.) are the first step in designing a system that will truly meet your needs cost effectively & low maintenance.

    Personally, I am not a big fan of lots of parallel strings of batteries... 1-2 is ideal, 3 is about the maximum I would suggest unless you have no other choice (although there are people that have done more parallel strings and are happy with the results). Another issue is, if this will be a 12 volt bank--It becomes much more difficult to monitor the "health" of your battery bank with a simple volt meter... All batteries have "bus voltage"--you cannot find a weak/under performing/failed battery by just using a volt meter on the terminals. Now with cheaper DC current clamp DMM (digital multi meters)--It is easier to monitor your battery bank--I still do not believe it to be ideal (better would be 6 volt batteries, 2 in series, so you can measure the voltage on each battery).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • KeithWHareKeithWHare Solar Expert Posts: 140 ✭✭✭
    I used three parallel strings of four 6-volt batteries in a 24volt battery bank. It has worked, but knowing what I now know, I'd prefer to use no more than two parallel strings.

    The issue is that it is very hard (impossible?) to get the resistance the same on all of the parallel batteries, so the batteries do not get evenly charged and discharged.

    If you have enough load to justify 10 batteries, consider moving to 48 volts which would be two parallel strings of four batteries each.

    A quick search for specs suggest that the "Deka Unigy I 12AVR170ET Front Terminal Telcom Battery" is designed for telecom usage which has a somewhat different profile than typical off-grid applications.

    What are you really trying to accomplish? What are you powering? How are planning on charging the batteries?

    Keith

  • pacogpacog Registered Users Posts: 18 ✭✭
    Thanks for the replies. Hopefully the guy is cool about it. I contacted him and let him know that the batteries will not work for my application. He is telling me that he has to look into it.He claims to have sold a lot of these batteries to people running them in long strings up to 12 and having no problems. So now I am a little worried. That's what you get for not doing your research I guess.

    If I only discharge the batteries 20-30% do you think I can make them work. What voltage would that be for 12v. These float at 13.5

    Stuck with my current 12v system so have to make it work.

    Have 3500w magnum energy inverter/charger,
    Magnum ME-RC remote control
    Magnum ME-BMK battery monitor kit
    1000w worth of panels(more coming)
    Midnite Solar Classic lite 150 charge controller.
  • BB.BB. Super Moderators, Administrators Posts: 29,497 admin
    Do you have a link to your inverter?

    I could not find that model.

    Back to the beginning, what loads do you need to run (watts and hours per day)?

    Where will the system be installed/used (nearest major city)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Solar Expert Posts: 4,994 ✭✭✭✭
    • "...Have 3500w magnum energy inverter/charger, ..."


    Magnum doesn't make a 3500 watt inverter charger in 12 volts, Their largest is 27-2800 watts in 12 volts.

    They do make a 3500 watt inverter in 24 volts...

    Everything else you have listed can be used on higher voltage systems.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • pacogpacog Registered Users Posts: 18 ✭✭
    edited June 2016 #7
    Thanks again guys, I know the system needs to be upgraded but funds are limited right now So i have to see if i can make it work. Trust me if i has the Cash things would be different.

    The inverter charger is the MS 2812 if that helps. I can take a pic of the specs on the info sticker if that would help?

    All the stuff listed below is 120v

    I have 2 Mini split Ac units that use 9Amps at start up. power draw varies Depending on which level it's set at.

    2 Tvs that use less than .5amp each.

    All LED lighting .

    Also have 12amp pump that runs for 3-4min a time when filling pressure tank. Only used this running the generator.

    My meter tells me when i have the AC on low, lights and Tv going i am using between 40-70 dc Amps.

    Closest city Ridgecrest Ca 93556

    Thanks again for everyones help.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    When talking about power use, WATTs are what is needed unless you tell us the Amps AND Volts .... amps alone tell us nothing. 
    thanks...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • pacogpacog Registered Users Posts: 18 ✭✭
    edited June 2016 #9
    2 900w Ac units , goes as low as 350w
    2 120w TV
    1 1440w Water pump, 4 min on time
    240w of led lights Dimmible so that varies
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    pacog said:
    Stuck with my current 12v system so have to make it work.
    pacog said:
    2 900w Ac units , goes as low as 350w
    2 120w TV
    1 1440w Water pump, 4 min on time
    240w of led lights Dimmible so that varies
    This system will not lead you to long term happiness.  You really need to be at 24 volts.
    pacog said:
    Just got a group of 10 Deka Unigy 1 12avr170et.
    <snip>
    Also what's the largest parallel string you recommend if using 12v batteries?
    pacog said:
    He claims to have sold a lot of these batteries to people running them in long strings up to 12 and having no problems.
    First a word about terminology.  A string is a number of batteries in series.  A long string of 12 batteries would have a voltage of 144 volts.  If you put your 10 batteries in parallel, the string length is 1 and the string voltage is 12 volts.

    Multiple strings of batteries can be put in parallel.  Parallel batteries are commonly used in telecom applications because the batteries are seldom cycled... they spend their lives in float.  In an application where the batteries are frequently cycled, parallel batteries are very problematic.  AGM batteries in parallel are even more problematic than flooded batteries.  Bill explained a bit about it earlier in this thread.  More to read here.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • bobertcombobertcom Registered Users Posts: 29 ✭✭

    Did you buy them from Joe in Hemet CA?

    I bought 12 Lucent/Alcants which are similar/same to the Deka's.  I have 10 of them, so far so good... but have only had them a couple months in my part time off grid cabin.

  • pacogpacog Registered Users Posts: 18 ✭✭
    Bobertcom, I did get them from Joe. I am currently in the process of re-wiring the system so I can properly run everything and get an even charge across all batteries or as best I can get. How are you running your system, what voltage and how are your batteries set up?
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