Trickle Charge AGM Battries

jbdpark
jbdpark Registered Users Posts: 16 ✭✭

I have 4 new spare Agm batteries 100HA/ea. Currently they are not being charged.

I am looking into purchasing a 10 watts ALTE panel/ 4.5A sunguard charge controller

to trickle charge them. Would that system will be sufficient or do I need a more elaborated one.

The batteries will be unattended for months at the time. Also how to arrange the array so all batteries are charge

at the same time, and do they need to be fully charge before the trickle charge can be connected.

Any advise will be appreciated.

Comments

  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,144 ✭✭✭✭
    edited December 2016 #2
    If they are not dead now, give each one a simple boost to 100% state of charge, then set them up in parallel at the constant Float voltage specified by the manufacturer.  The correct voltage will generally between 13.2v  and 13.8v at room temperature, depending on the brand. 13.3v will undercharge some and 13.8v will cook some others. It is critical to get this part right!

    Temperature compensated charging/floating is important unless the batteries will stay at a constant temperature.

    What is the standing voltage now?
    What brand are they?
    Where will they be stored?

    Marc
    I always have more questions than answers. That's the nature of life.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    Assuming the batteries are 12v they would be a 400ah parallel bank. At 10w the panel will put out less than 1a. The charge controller apparently outputs 14.1v, which seems high but may not matter given the low current.

    AGMs have a low self-discharge rate so depending on how many "months at a time", storage temps, etc. it may make more sense to just charge them properly periodically?
    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
  • jbdpark
    jbdpark Registered Users Posts: 16 ✭✭

    They are trojan 100 ah 12v batteries, they are stored in a room at 80 degree average temperature.

    For what I understand , the 10 watts solar panel and 4.5 A charge controller will not properly do

    the trickle charge process to keep these batteries in constant 100% charge. Would  a bigger panel and Charge

    controller devices do the trick?  The batteries will be unattended for 6 to 8 months at a time, and in use for

    2 to 3 weeks when attended. please advise.

  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    AGMs self-discharge quite slowly so 10w might be okay if there's good sun. You should check on the recommended float voltage for your battery though.
    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
  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,144 ✭✭✭✭
    edited December 2016 #6
    In general, Trojan advertises 13.5v as the required float voltage for their AGM labeled batteries.

    Exceed their spec by more than a few tenths long term, and you will shorten the life. However, this is far less critical for PV charging than grid charging - because the sun goes down every night with extreme reliability!

    I have no inside information on this, but it appears that they may have changed AGM partner/manufacturers in the past,so be sure to check what their current guideline says for your particular battery.

    I do know that they are not manufactured by Concorde, Fullriver or East Penn. Shenzen/Ritar maybe now? But if were Concorde or Fullriver batteries, the current draw on long term float would be between 0.25a and 0.45a per battery at the float voltage, so 1.0 amps to 1.80amps total.

    Remember that temperature compensation is critical.
    I always have more questions than answers. That's the nature of life.
  • jbdpark
    jbdpark Registered Users Posts: 16 ✭✭

    Thank you Marc for your advises. The float charge for my batteries is indeed 13.5. I am not sure who manifacture them for Trojan.

    The question I have now, would I need a 10 watts solar panel and a 4.5A controller to trickle charge each battery separately or can I mount them in series an use one 10 watts panel and one 4.5A controller. whould this setup be powerfull enough to trickle charges the 48volt string?

  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Sorry, the simple answer is no, that is not going to do anything to a 48V battery bank....  You will need at least 4 panels,  at '12 volt' designation, that each will create 17 - 18 Volts Vmp (not Voc) .  More later
     
    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
  • mvas
    mvas Registered Users Posts: 395 ✭✭✭
    jbdpark said:

    They are trojan 100 ah 12v batteries, they are stored in a room at 80 degree average temperature.

    For what I understand , the 10 watts solar panel and 4.5 A charge controller will not properly do

    the trickle charge process to keep these batteries in constant 100% charge. Would  a bigger panel and Charge

    controller devices do the trick?  The batteries will be unattended for 6 to 8 months at a time, and in use for

    2 to 3 weeks when attended. please advise.


    You said, "... the 10 watts solar panel and 4.5 A charge controller will not properly do the trickle charge process ..."
    WHY not ?

    I think, YES a 10 Watt Solar Panel can FLOAT four (fully charged) 100AH Trojan AGM's in parallel.

    Per Trojan  ... A 100AH 31-AGM battery will self discharge at about 3% per month.

    Assuming 8 hours of sunlight per day (adjust as needed) ...
    3% Discharge per Month x 100AH = 3AH per Month
    3 AH per Month / 30 Days per Month = 0.1 AH per Day
    0.1 AH per Day / 8 Hours per Day = 0.0125 Amps or 12.5 miliamps

    If my math is correct then very little amperage is required to Float your AGM Battery
    0.0125 Amps x 14 Volts = 0.17 Watts per battery
    0.0060 Amps x 14 Volts = 0.08 Watts for the Charge Controller 

    4 AGM Batteries  + SunGuard Charge Controller requires: ( 4 * 0.17 Watts ) + 0.08 Watts ~= 1 Watt

    But, NO I do not think the 4.5A Sunguard Charge Controller is designed to FLOAT an AGM battery.
    It appears to be a SIngle-Stage 14.1 Volt PWM Bulk Charger.
    Is that really appropriate to FLOAT your  AGM batteries ??? 
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2016 #10
    @mvas is correct the Sunguard is not the appropriate controller for your application, you would need a 3 stage CC with an AGM setting such as the Sun Saver or similar, see arrachment.
     Without attempting to discredit mvas in any way, 10W, mathermatically and in theroy may be enough, however in reality there are variables, 8 hours of full sun is unrealistic and depending on location, season and weather, cloudy sky's etc. this figure would most likely  be significantly lower, could be as low as 2 to 3 hours or even less in high latitudes during winter, and panel output is never what its ratings state, even in full direct sunlight.
    @Marc Kurth, whom I don't know personally, appears to be  very knowledgeable with regards to batteries, read his post #2 & #6 again
    Sometimes it's better to over build and be on the safe side, than to minimize, have problems and lose the batteries, the cost of which far exceeds the equipment needed  to properly protect them. Perhaps a 30W or larger panel would afford you a wider safely margin. My opinions.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • jbdpark
    jbdpark Registered Users Posts: 16 ✭✭
    Thank you Marc Kurt, Mvas, mcgivor, Estragon, westbranch, etc. You guys have been very helpfull guiding me toward getting the right sets of solar panel and charge controller to trickle charge my four 12v 100ah Agm batteries.I understand even thaugh the 10watt panel can do the trick, but now I am leaning more toward abigger one 30 to 50watt instead, which maybe will allow me in the future to add a 15.5watt Led motion security light.But I am still puzzle about the CC. Some of you guys think the sungard 4.5A is adequate, but concern about availibility of 3 stages charging and selection switch for  AGM battery. Below is the features of the sungard 4.5A. Does it includes all I should look for?  Plse advise
    "• BATTERY CHARGE REGULATION: SunGuard uses an advanced series PWM charge control for constant voltage charging. A true 0 to 100% PWM duty cycle is very fast and stable for highly efficient charging. • TEMPERATURE COMPENSATION: A sensor measures ambient temperature and corrects the constant voltage setpoint by –28 mV per °C with a 25°C reference. This works best if the SunGuard and battery are in a similar thermal environment. • The SunGuard prevents the battery from discharging through the solar array at night. There is no need to install a blocking diode for this purpose."
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    JBDpark,  please read up on the difference between a PWM and an MPPT charge controller and the different types of solar panels  to be able to make the most out of the following..... 
    Simply, a PWM CC will only be able to deliver power (watts) to the battery at the batteries nominal voltage. 
    You can NOT get the full output from a, for example, GT (grid tie) panel that might produce 30volts! 
    You would only get ~ 17 volts into your 12 volt battery, the PWM CC has fixed outputs..
    The same would apply to using 3 x '12 volt' panels hooked up in series..  BUT a MPPT CC can use the full output from a GT panel or the 3 '12v' panels because it can output at the battery voltage by dropping the voltage to the setting you give it, that is 12, 24 or 48 volts depending on the battery configuration. MPPT also raises the amperage depending on the battery bank configuration when it decreases the voltage.
    hth
     
    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
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    @Jbdpark - I'm still not clear on some of your details.

    Is your bank wired in series (48v) or parallel (12v)?

    Have you determined the manufacturers recommended charging regime, especially float voltage and temperature compensation?

    I'm assuming the controller and batteries will be in the same room and temps will be fairly constant. If either of these assumptions is wrong, you should really be looking for a CC with external temp sensor.

    Personally I'd avoid putting a security light on a bank that will be unattended for such a long period. Maybe you plan to only plug it in when you're there?
    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
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2016 #14
    Estragon said:
    @Jbdpark - I'm still not clear on some of your details.

    Is your bank wired in series (48v) or parallel (12v)?

    Have you determined the manufacturers recommended charging regime, especially float voltage and temperature compensation?

    I'm assuming the controller and batteries will be in the same room and temps will be fairly constant. If either of these assumptions is wrong, you should really be looking for a CC with external temp sensor.

    Personally I'd avoid putting a security light on a bank that will be unattended for such a long period. Maybe you plan to only plug it in when you're there?
    Reading though the questions my understanding is that they were going to be 12V in parallel, a query into the possibility of a series connection, 48v using a 12v cc was made, and this I believe  is where the confusion of intent may have been misinterpreted.

    A 3 stage 12v  PWM CC with bulk, absorbtion and float, along with a panel rated with VMP 17-18v would  work.
    The Sun Guard is only a 2 stage, bulk and absorbtion, which could be used on an attended application where there are daily loads but on an un attended application it is a different story, the PWM voltage  (absorbtion ) will always be at approximately 14.4v in pulses, getting shorter in duration until a full charge is achieved  .The current would be extremely low but the voltage would still be 14.4v, too high over extended periods.What is needed is the 3rd stage, float, which once the 14.4v absorbtion time is satisfied, will drop the voltage to around 13.7v, float.

    Here is a n explanation from Morningstar when I asked why my PWM controller rarely went into float, my system has loads and is attended.

     The duty cycle is The duty cycle is used to determine when to transition into float.  The duty cycle is derived from a square waveform and the percentage of time - out of each complete cycle - when current is allowed to flow. Current is regulated by opening and closing the PV-battery circuit -- the essence of a series charge controller. A 50% duty cycle means that current is flowing, and interrupted for, half of the cycle. Our controllers pulse with a frequency of 300 Hz, so each cycle lasts 1/300th of a second. By varying the duty cycle, we can control the average current going into the battery so that the regulation voltage is maintained but not exceeded. As the battery reaches full charge at a particular voltage, it will require less and less current to maintain that voltage and the duty cycle will decrease. The duty cycle will approach zero %, but will never actually get there because losses and battery self-discharge require at least some current to maintain regulation voltage. A Morningstar PWM controller's float transition algorithm waits for the duty cycle to reach 30% or less before starting a one hour timer. When the timer expires, the controller moves from absorption to float voltage. A 30% duty cycle simply means that 30% of AVAILABLE charging current is allowed to pass. Duty cycle is the best measure we have to determine how deep a battery may be in regulation. Factors affecting the accuracy of this method include: 1. Reduced radiation and current. With less available charge current, the duty cycle will inevitably be higher making the transition to float more difficult; 2. Load on the battery. Loads on the battery drain current from the battery which causes a higher duty cycle. If the load is large enough (greater than the amount of solar current ) it can pull the controller into 100% duty cycle and out of absorption - into bulk charging; 3. Aging batteries. Old batteries tend to absorb more current at regulation, keeping duty cycle high. Sulfation leads to higher internal resistance, and more energy loss in the form of heat, which leads to excessive water loss. us
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • jbdpark
    jbdpark Registered Users Posts: 16 ✭✭

    The batteries will be setup in 12 volt parallel. They will be in the same room with the CC at an average temperature of 80 degrees. Trojan recommand for12 volt battery a bulk charge of 14.40, absorption charge 14.10 - 14.70, float charge 13.50. Temperature compensated rule is 5.0 mV per cell/ centigrade or 2.8mV per cell/ farenheit, which I think the charge Controler will automatically handle. I have access to a Midnite Solar Classic 150 MPPT Charge Controller, 150V 96A, but, that might be an overkill for trickle charge 4 12v AGM batteries. My real concern is to identifyand purchase the proper PWM CC which will safely do the job.

  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2016 #16
    Any good quality PWM controller from Midnight, Morningstar or Outback, to name a few would  be good choices , check the host's store, avoid the cheap Chinese models.The Midnight Clasic 150 is perhaps overkill for the current purpose. Attached is some more infothat you may find helpful, especially the section regarding  PWM vs MPPT and size of system.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2016 #17
    To add to the previous post, I checked and most of the controllers will satisfy the bulk and absorbtion but they seem, the ones I checked out, have a float of 13.7V, however as @Marc Kurth mentioned it is probably not that much of a big deal as the "sun goes down every night with extreme reliability " .....got to like that statement.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    The MN classic is a good controller with a lot of potentially useful features. It's not only overkill for this application though, it also takes power to support the functionality. In my case the sun is too low in the sky for panels to provide power but classics are using battery power just being on. During the month or so this will be the case, the total power used will be a considerable fraction of capacity. I will go to the cabin in early January to charge with generator and clear snow so batteries should be okay. If I wasn't going to be there until spring I would disconnect the banks rather than risk having the classics drain banks dead.
    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
  • jbdpark
    jbdpark Registered Users Posts: 16 ✭✭

    I want to thank everyone who participated in this post. I have concluded a 30 watt solar panel and a Sunsaver CC will satifty my requirement (trickle charge 4 Agw 100 Ah 12v battery in series). Morningstar offers the best for the buck of PWM 4 stages. The Sunsaver line offers different size and features of CC. I am seeking ADVISES  to determine if a 6A or 10A is best for me and which  models (With( SS-10L 12V ) or Without LVD ) to considere. Thanks