battery charger

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System
System Posts: 2,511 admin
in General Solar Power Topics #1
hello Great day here in NB. lots of sun and a light breeze. I'm looking to invest in a good battery charger. I have 6 batteries 600 A/H each. i would like to get a charger that will float charge (equalize) does anyone know of a good supplier here in New Brunswick. would an good charger from an auto parts store do the trick? Thanks for any help
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #2
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    Re: battery charger

    Tell us more about your batteries, i.e., brand, model number, voltage, flooded-cell or VRLA, etc.

    More later,
    Jim / crewzer
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  • System2
    System2 Posts: 6,290 admin
    #3
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    Re: battery charger

    Thanks Crewzer for your reply. The batteries are yasur I think that is spelt right, they were 24 volt, 625 AH. I split them into 12 volt they are acid, cant' say much more as i have them in an insulated box outside and cant see down onto the tag info. (yes they are vented) Hope this helps
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  • System2
    System2 Posts: 6,290 admin
    #4
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    Re: battery charger

    No,get three stage charger.Better for a car charger also.3 stage will fully charge ,as apposed to part charge or even over charge with car single stage.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #5
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    Re: battery charger
    bcarlstad wrote: »
    No,get three stage charger.Better for a car charger also.3 stage will fully charge ,as apposed to part charge or even over charge with car single stage.

    CAR CHARGERS are WRONG. They will UNDERCHARGE your battery, deep cycle batteries require an extra volt in the charge process, 13.8 V is NOT enough.

    Your charger should have about 1/5 of your battery capacity. If you have 600 amp battery, you should have a 120A charger.

    If you wire all the batteries (12) in parallel, @ 12V you will have a [ 625x12 ]
    7500A battery, needing a 1500A charger.

    Leavng them at 24V, [ 625 x 6]
    3750A battery, needs 750A charger

    wireing into a 48V bank
    1875A battery , 375A charger


    ** EDIT
    I meant NO MORE than 20% of battery capacity. So cut those # I gave above, in half.
    **


    Note : these all store the same amount of power, you trade voltage for amperage, which greatly reduces the wire size needed to carry the current.
    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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  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    #6
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    Re: battery charger

    Mike I will have to contest the figures your giving for charging rates.

    20 % is very high.

    My solar array puts out 60 amps into a 2100 amp hour bank and fully charges up the previous days use in 5 or 6 hours. Your 20 % rule indicates that I would need a 420 amp battery charger. The SW3024E only puts out 100 amps max. which would mean only suitable for 500 amp hour battery bank.

    I also thought most battery manufacturers usually spec around 10 % as safe max charging limit. In my case 210 amps

    Please advise.
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  • H2SO4_guy
    H2SO4_guy Solar Expert Posts: 213 ✭✭✭
    #7
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    Re: battery charger

    It is just fine to charge with a smaller charger especially if you are not using it every day, just for backup. There is also less heat and therefore less chance for plate warpage. I would reccomend getting a hydrometer if they are flooded batteries, and make sure that the level of water is at least over the plates before charging, then watering them after fully charging. You can always series up two or more auto type chargers to get the correct voltage. I have done this and run them through a Trace C-40 charge controller that will set the correct voltage. For a 48 volt pack, 5 auto chargers were used because the voltage wasn't enough, then the charge controller took care of the set voltage that I really wanted. Works great and is pretty cheap too. I bought 6 amp 12 volt and 6 volt chargers at Harbor freight for $19.99 on sale. Still using them, just using with a charge controller to set the desired voltage.

    Skip
    12K asst panels charging through Midnite Classic 150's, powering Exeltechs and Outback VFX-3648 inverter at 12 and 48 volts.  2080 AH @ 48 VDC of Panasonic Stationary batteries (2 strings of 1040 AH each) purchased for slightly over scrap, installed August 2013.  Outback PSX-240X for 220 volt duties.  No genny usage since 2014. 
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  • System2
    System2 Posts: 6,290 admin
    #8
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    Re: battery charger

    Again thank you everyone for your response. Its getting a little confusing, but it did start a good discussion. so in the end what kind of charger should i get. i am charging the batteries with one windmill and will be adding to more in the future. I need the charger untill i get all set up and then i assume about every 4 months after just to insure a good float charge. I have a c60 charge controller. my windmill is about 800 watts( never saw close to that output yet). Thank-you all for your info. Sorry one more question is it better to charge at a high amperage or low and slow.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #9
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    Re: battery charger

    It is an interesting idea to use a charge controller to control an auto type charger, not something I had thought about before. On the other hand, the idea of series or series/paralleling a bunch of them together must produce a tremendous amount of waste. If you are recharging from the grid, perhaps the waste is acceptable, but if you have to run a gennie it seems like there are more efficient alternatives.

    As to Mike's comment about the charger sizing ~20% of amp hour capacity. Most of the information that I have read, recommends a rate of ~12.5% (flooded batteries) so I differ with his opinion there . I actually prefer a bit smaller rate just to keep from overheating the bank if I'm not paying attention.(Sorry Mike) In the interest of attribution I suggest the following links.

    http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

    http://www.batteryfaq.org/

    Good luck,

    Icarus
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #10
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    Re: battery charger

    Yikes.
    I meant NO MORE than 20% of battery capacity. So cut those # I gave above, in half.

    I'm thinking of my own plan, where I may run a generator to bulk up my batteries, and let solar top them off.

    thanks for keeping me honest.
    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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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #11
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    Re: battery charger

    Tabers,

    You need a “24 V” charger, preferably a four-stage model (bulk, absorb, float, EQ). Considering your climate, a temperature compensated model would be preferable.

    5%, 10%, or 13% charge current values are handy numbers when dealing with batteries that are charged from PV modules, since there’s a limited number of hours of sunlight each day. Since you asked about an automotive charger, it would appear that you’re considering charging the batteries from the grid and/or a generator. You can get by with a charger that’ll supply ~3% of battery capacity.

    Six of your batteries connected together will result in a battery bank rated at 24 V x 3,750 Ah. That’s prodigious battery bank. 3% of 3,750 Ah = 112.5 A.

    One solution would be a pair of Outback FX2524T inverter/chargers. In charge mode, the two units together could supply 110 A DC to the batteries. Operation in inverter mode, the two together could supply up to ~5 kW at 120 VAC. Figure on ~$4K for the pair, including a Mate and a Hub-4.

    This appraoch will require a good-sized generator.

    HTH,
    Jim / crewzer
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