Do I need a charge controller to save AC appliances

SlowLearnerSlowLearner Registered Users Posts: 6
SYSTEM DESIGN/CONFIGURATION QUESTION

Off grid NO BATTERY system to provide just the very basics for a primitive cabin during daylight hours.
Refrigeration approx................1 Amps
Microwave approx.............................. 15 Amps
Cistern Pump approx.......................... 1.5 Amp
Washing Machine approx..................... 10 Amps
Random Outlet approx...........................15Amp

All appliances are 120VAC


If required disabling all appliances but the one needed at a time would be acceptable.

Non-installed system currently consists of:
12 Kyocera KD205GX-LP 205W 18V Solar Panel
1 Outback FX3048T Inverter
Estimate 5.45 kWh/sq m/day Central Florida

My original thought was to closely monitor loads and only turn on appliances as needed and weather permitting. Refrigeration taking precedence over most everything else. But even this 'critical' appliance would not be turned on if the inverter wasn't putting out 100-300% more than required for the load.

However, others have told me that constant and dramatic oscillations in output from the inverter due to passing clouds would GREATLY reduce the useful life of the refrigerator or whatever other appliance I would put on the system because it would often be rapidly cycled on and off due to normal weather induced output oscillation even on a good sunny day.

Is this true?

Do I NEED a charge controller?

Do I need a charge controller and a small battery bank to provide a small buffer to protect against these oscillations?

Or no charge controller or battery but something like a $350 Smart UPS perhaps?

Does no one install off-grid systems WITHOUT batteries anymore?



Any advice and the reasoning behind the recommendations would be greatly appreciated.

Thanks in advance-
SlowLearner

Comments

  • BB.BB. Super Moderators, Administrators Posts: 28,185 admin
    Re: Do I need a charge controller to save AC appliances

    For 120 VAC appliances... I am not aware of any PV Inverter Only that is available... It is possible to make one--but there are lots of issues why it would probably not be a very popular device.

    In general, there are two major classes of AC inverters:
    1. Off-Grid--Your classic inverter that runs from a battery bank
    2. Grid Tied/Utility Interactive--A GT inverter connects directly to the solar PV array and pumps all available energy from the solar array out to the Utility Grid... There are some "other" configurations--But those would involve a battery bank and/or an AC generator.
    If you want to make a DC only system without any battery bank/generator... The best way to do that is DC only.

    There are Off-Grid Refrigerators that you can connect to a solar PV panel and the DC motor will simply run whenever there is enough sunlight (and the thermostat demands cooling).

    Also, another popular solar panel only application is well pumping. There are Linear Current Boosters, or specialized well pumps, that can basically cause the pump to output as much water flow as there is sun.

    Most other Solar Panel Only uses are going to be charging cell phones, running a small radio or TV, charging a laptop computer, etc...

    Very few AC appliances can take the variable power from the sun/solar panel combination... And the AC appliances don't like being "turned on and off" while operating. Many will could be damaged (AC motors) or not make much sense (microwave turning on and off multiple times while cooking, running a sowing machine that turns on and off with the sun would be dangerous, etc.).

    There are some specialized "inverters"--Aka Variable Frequency Drives that can drive motors with available power (such as water pumps)... Motors turn slowly with little solar power, or faster with lots of sun power. A VFD would not make sense to most 120 VAC devices that expect 60 Hz fixed frequency AC power.

    If you have a specific thing you want to run only when the sun is up (solar thermal pumping water, running fan for fruit drying, etc.)--Then no-battery systems can make very good sense.

    Roughly, adding a battery to a well pump will double the cost of the system and can reduce power output from the solar array by another 50%...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Do I need a charge controller to save AC appliances

    sl,
    i think you want something that did not and does not exist unless it is a straight gt which does not apply to off grid. the inverter and ups both need a battery to operate. putting pvs straight to the inverter or ups won't work either as the voltage is unregulated and apt to blow out the inverter or ups. even the charge controllers that regulate the voltage need a battery, but even if they made this for you that didn't require a battery or cc then you have the dilemma of the sun going in and out so this no cc or battery thing is not a wise thing to strive for.
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Do I need a charge controller to save AC appliances
    SYSTEM DESIGN/CONFIGURATION QUESTION

    Off grid NO BATTERY system to provide just the very basics for a primitive cabin during daylight hours.
    Refrigeration approx................1 Amps
    Microwave approx.............................. 15 Amps
    Cistern Pump approx.......................... 1.5 Amp
    Washing Machine approx..................... 10 Amps
    Random Outlet approx...........................15Amp

    This will not work, you NEED the batteries.

    Solar power is not constant, every time a cloud passes over it will drop out. This means that your AC voltage will be dropping in and out and providing a variable amount of power which means your voltage will be fluctuating all over the place.

    If you fridge is running when the cloud passes it will stop running.
    Every time the fridge wants to start up it needs a lot of current to get going, either your array won't be able to produce this current, or you'll have to massively oversize the array to provide startup current that isn't needed the rest of the time.

    Batteries make the system work and work better. While it might be possible to build a system that can run without batteries, it will be MUCH cheaper to builds a system that uses batteries. Besides with batteries you can run stuff at night.

    That said, it is possible to build some stuff that will work without batteries. You can build or buy a Eutectic (cold plate) refrigerator that runs directly from a panel.
    Switch to solar cookers instead of the microwave. Get a solar pump current booster to run the cistern and pump into a raised storage tank for water pressure. Switch to a hand crank manual washing machine.
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Do I need a charge controller to save AC appliances
    Does no one install off-grid systems WITHOUT batteries anymore?

    Thanks in advance-
    SlowLearner
    As far as I know, nobdy ever did. Off grid systems HAVE to have a battery, or at least some type of storage system. And currently batteries are the only one that makes economic sense.
  • SlowLearnerSlowLearner Registered Users Posts: 6
    Re: Do I need a charge controller to save AC appliances

    WOW ! :blush:

    I am really glad I asked the question on this board. Thank you ALL for the very comprehensive explanations. And so FAST even. This sounds like a fantastic forum/resource.

    I sourced the panels and inverter from Northern Arizona Wind & Sun, now it appears I am going to be in the market for some deep cycle batteries as well...
    Which opens up a new set of questions/concerns that I hope the board can guide me through.

    I figure I am NOT terribly concerned with the storage of amp hours. I intend very minimalistic living by modern standards.

    I want to be able to extend the shelf life of food during the long hot humid summers of Florida. Yes, a eutectic based refrigeration system is vital but anything else I power like a hand tool OR a washer OR a microwave; would just be nice-to-have weather permitting.. I am good with no power when no sun.

    Although my original intent was, as PeterV put it,
    to massively oversize the array
    however, I obviously didn't consider the massive minute-to-minute fluctuations of output from the array.

    ADDITIONALLY i had NOT considered startup current.

    So here is my current conundrum...
    Everything I read is based on adding up total load and calculating amp HOURS to size the battery bank.

    It doesn't seem this approach really applies to my system.
    I am not interested powering 45 amps for 12 hours. I just want a way to buffer the array fluctuations so I am not wearing out electric motors and be able provide the start up capacitor a kick.

    HOWEVER at the same time I don't want to excessively drain the batteries every day. I don't know how to properly, optimally SIZE the battery bank given my unorthodox design parameters.

    I can understand the "buy-as-much-battery-as-you-can-afford" method since this will assure the batteries a never drawn down and will equate to a LONG battery life but at the same time, my understanding is that just sitting unused a battery is degrading.. What is the shelf life of a unused but constantly charged deep cycle marine battery?

    Could I get 20-30 years out of battery if it never goes below 98% charged? If not, I need to try and determine at what point the extra amp hours of storage are just going to decay unused and wasted.

    Additionally- should I ASSUME that I do NOT need to purchase a separate charge controller if using a Outback FX3048T Inverter. Is this in fact so??
    "Each OutBack FX inverter / charger module is a complete power conversion system - DC to AC inverter, battery charger and AC transfer switch."

    At least that is how I interpreted the above statement. Is anyone on the board familiar with OutBack's FX series Inverter/charger that can verify whether or not I need to purchase a separate charge controller?

    I appreciate your time and knowledge,
    SlowLearner
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Do I need a charge controller to save AC appliances

    Ah, no. There's only one way off grid inverter systems work and that is this:
    The inverter runs off the battery, the panels recharge the battery through the charge controller.

    The Outback inverter reference is to the fact it has a built in battery charger, but that charger requires a 120 VAC input to work. It does not connect to solar panels directly.

    The basic formula for sizing equipment is like this:
    Step 1: size the loads. The maximum Watts will determine the size of the inverter. The daily Watt hours will determine the size of the battery bank.
    Step 2: size the solar array for recharging. This is based on two factors; 1). being able to achieve a peak charge current of 5% to 13% of the Amp hours of the battery, and 2). being able to 'harvest' the Watt hours used daily. This will also tell you what size and type charge controller you need.
    Step 3: work out the details of wire sizing, fusing, mounting, et cetera. Fine tune the system to suit your particular installation and use.

    If you try to design a system any other way it will end in heartache. Large numbers of posts here are from people who did it some other way and were terribly disappointed with the result.

    Remember you don't need a huge battery bank; just one that's the right size. Without batteries it simply won't work, and without enough battery you won't have power 24 hours a day.

    As for how long a battery will last with light use and maintained charge, ten years would still be a stretch. Batteries degrade whether they are used or not. Deep cycle batteries actually need an occasional cycle to keep them functioning optimally (unlike automotive batteries which prefer to stay at a constant Voltage).
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Do I need a charge controller to save AC appliances

    1st i guess we should be sure if you have grid power or not. if you do and are just looking to backup some appliances then that inverter/charger will work, but you need batteries for it and there's no getting around that. for small outages a generator is probably best. if you go with the inverter then the size of the battery bank will depend on the size of your loads (limited by the inverter's max output of course) and the length of time you expect to run this without going below 50% soc on the batteries. at the very minimum it will most likely have 4 100ah batteries in series. this can be made higher if need be by larger battery capacities or paralleling more battery strings. the 100ah string example will have 48v x 100ah = 4800wh. in keeping with preserving battery life by not going below 50% soc you could use 2400wh.

    once you've figured out the battery bank size you can use solar to charge the batteries if you would like to and we generally recommend between 5% and 13% of the ah capacity rating as a charge rate and this can vary somewhat depending on the battery type, model, and manufacturer. for instance trojan would prefer you charge with 10%.

    hope this helped some.
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Do I need a charge controller to save AC appliances

    HOWEVER at the same time I don't want to excessively drain the batteries every day. I don't know how to properly, optimally SIZE the battery bank given my unorthodox design parameters.

    What is the shelf life of a unused but constantly charged deep cycle marine battery?

    Could I get 20-30 years out of battery if it never goes below 98% charged?

    Well simple way to size your battery, figure out how many Amp Hours you need on an average day and multiply that by 5. This means that normal days you only drain the battery to 20% which is generally the best for maximizing life vs costs.
    You'll also have enough battery to handle 4 days with no sun (during a bad storm for example) without draining the battery more than 80%

    Do NOT use Marine batteries!!
    Do NOT use Marine batteries!!
    Do NOT use Marine batteries!!

    Marine batteries are not really deep cycle batteries and probably won't last more than a year, maybe two.

    If you want 20 year battery life then buy a battery designed specifically for long life in solar applications, something like a Rolls-Surrett (VERY expensive!!)

    Another much cheaper option would be something like a Deka Dominator. I have some of those that are over 15 years old and still working (though no where near what they were like new)
    The Deka Dominators run about $180-$200 for an 8G24 which is a 12V 84AH Gel Cell battery.
  • SlowLearnerSlowLearner Registered Users Posts: 6
    Re: Do I need a charge controller to save AC appliances

    From Cariboocoot-
    The basic formula for sizing equipment is like this:
    Step 1: size the loads. The maximum Watts will determine the size of the inverter. The daily Watt hours will determine the size of the battery bank.
    Step 2: size the solar array for recharging. This is based on two factors; 1). being able to achieve a peak charge current of 5% to 13% of the Amp hours of the battery, and 2). being able to 'harvest' the Watt hours used daily. This will also tell you what size and type charge controller you need.
    Step 3: work out the details of wire sizing, fusing, mounting, et cetera. Fine tune the system to suit your particular installation and use.


    My attempt to follow this framework yields for me:
    Size the loads: Daily Load = 3930 watt hours
    Depth of Dischard = 20% so Battery will need to be 5 * 3930 or 19650 Watt Hours

    Inverter Size is GIVEN: Outback FX3048T
    DC Input Range = 42 - 68 VDC (i read this as 48Volt System)
    Continuus Batter Charger Output = 35amps
    Step 2: Size of solar array IS GIVEN: 12 panels at 205watts each or 2461 watts for 5 hours of daily "peak sun" = 2461*5= 12305 daily watt hours


    What size and type of charge controller do I need to use an array that generates 12305 daily watt hours to charge a 19650 watt hour battery bank that is drawn down 3930 watt hours per day?





    From (and i promise not to use marine batteries) Peter_V -
    Well simple way to size your battery, figure out how many Amp Hours you need on an average day and multiply that by 5.

    I am not sure I understand AMP HOURS?? The energy content of a battery is usually expressed indirectly by its capacity in ampere hours; to convert watt hours (W·h) to ampere hour (A·h), the watt hour value must be divided by the voltage of the power source. This value is approximate since the voltage is not constant during discharge of a battery.

    But how about:
    3930 WATT HOURS / 48 = 410 DAILY AMP HOURS
    FOR 20% DEPTH OF DISCARD 410 AMP HOURS X 5 = 2050 AMP HOURS BATTERY BANK REQUIRED.

    Is that correct logic ??


    Additionally, after reading some Rolls Surrette Spec Sheets I realize I do not even understand how to purchase 19650 watt hours of battery capacity or 2050 amp hours of battery capacity. For instance :
    a 12 CS 110 yields 357 amp hours at 20 hour rate. Meaning what exactly? That the battery reaches 100% depth of discharge after 20 hours of drawning 357/20 amps per hour or 20 hours at 17.85 amps per hour = Total Discharge.
    IS THAT what this is saying???



    More confused the further I read...
    SlowLearner
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Do I need a charge controller to save AC appliances

    Yes, it is daunting isn't it? :blush:

    Okay for converting Watt hours into Amp hours you divide by the nominal system Voltage:

    3930 Watt hours divided by 48 Volts = 81.875 Amp hours that you expect to use.
    At 25% Depth Of Discharge this means a battery bank that is four times that: 327.5 Amp hours.

    Now comes the fudge factor, as there's no such thing as a 327.5 Amp hour battery. You could go down to 320 Amp hours (L16 'A' size) and count on not always using full power or you could go up to 390 Amp hours (L16 'B' size) and need perhaps a tad more panel. For the sake of example let's go down:

    A 10% potential peak charge rate would be 32 Amps @ 57 Volts charging, or 1824 Watts. Less typical derating of panels @ controller (77% efficiency) = 2368 Watt array. So your 2460 Watt array works there. Since it is the output current that matters most with charge controllers, and MPPT type capable of handling 32 Amps or more would suit. This would include the Tristar 45 Amp MPPT on up to a 60 Amp Tristar, Outback, Xantrex, or Midnight.

    Analyzing your array for daily Watt hour 'harvest' using the "quick method" we get:
    2460 Watts * 4 hours "equivalent good sun" = 9840 Watt hours / over-all 50% efficiency (usually) = 4920 Watt hours per day, which is about 1 kW hour above your expected use.

    Does that help any?
  • SlowLearnerSlowLearner Registered Users Posts: 6
    Re: Do I need a charge controller to save AC appliances

    To design off a single 320 Amp hours (L16 'A' size) battery

    A 10% potential peak charge rate would be 32 Amps @ 57 Volts charging, or 1824 Watts.

    32A * 57VDC = 1824 Watts good, clear.

    32A is 10% of 320 Amp Hours

    57VDC Where did this come from? I don't understand.


    A typical derating of panels @ controller (77% efficiency) = 2368 Watt array

    Meaning 2368 * .77 = 1824 watts, the real-world Array and controller CAN provide what the battery will require daily. Ok, makes some sense.. thank you.


    For the sake of practice let's go up:

    To designing off a 390 Amp hour (L16 'B' size) battery

    39 * 57VDC (still??) = 2223 watts

    My 2460 watt array would require an unrealistic 90.4% efficiency between array and controller to charge a single 390 Amp hour battery... Therefore I should NOT use a 390 Amp hour battery.

    Would a battery bank composed of 4quantity of 100 Amp hour batteries work in this exact same scenario?


    Additionally, in this design we used a 10% potential peak charge rate. Would lowering this rate down to only 5% peak charge current INCREASE battery life??

    19.5 A is 05% of 390 Amp hours

    19.5 * 57VDC = 1111.5 watts

    In this scenario a much smaller 1450 watt array would work with a single 390 Amp hour (L16 'B' size) battery

    Perhaps I don't understand potential peak charge rate.

    I know i am still missing the big picture but yes this helps ALOT.

    Daunting yes, but this forum is light at the end of the tunnel.

    I really appreciate your time and knowledge,
    SlowLearner
  • mike95490mike95490 Solar Expert Posts: 8,030 ✭✭✭✭
    Re: Do I need a charge controller to save AC appliances
    To design off a single 320 Amp hours (L16 'A' size) battery

    A 10% potential peak charge rate would be 32 Amps @ 57 Volts charging, or 1824 Watts.
    57VDC Where did this come from? I don't understand.

    57V is needed to force power back into a 48V battery. However, when the battery is low, I've seen 30amps going into my bank, but it's usually at 53v or so, when the charger drops out of Bulk mode and switches to Absorb, the voltage goes up to 57, but amps go down to about 10 or so. Of course, my battery bank is pretty sick, so maybe it's not behaving correctly, but it's what i can see. I figure my 400A bank actually works like a 100a bank, since i bought used batteries, and planned on replaceing them.
    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 ,

  • BB.BB. Super Moderators, Administrators Posts: 28,185 admin
    Re: Do I need a charge controller to save AC appliances

    57 volts is the equivalent of charging a 12 volt battery bank at 14.25 volts...

    You could use 59 volts (14.75 volts) to quickly recharge the battery bank.

    Look at the charging specification for your battery bank... Different manufacturers and different types (flooded cell / AGM) have different recommended charging voltages/profiles.

    Also, the higher you crank the charging voltage, the "rougher" the charge is on the battery bank--So, you tend to shave a bit of life off the battery bank with very high charging voltages...

    But, the down side is that you only have X hours of day to recharge from the sun.

    "Dave Sparks" (poster here) really likes tracking arrays for his customers--allows him to have more hours per day to recharge and keep the peak charging current/voltage down a bit).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Do I need a charge controller to save AC appliances
    Would a battery bank composed of 4quantity of 100 Amp hour batteries work in this exact same scenario?

    Theoretically? yes.
    In real life? Not so much. Paralleling two batteries or battery strings is fine. Paralleling three strings can cause problems and is the maximum recommended number of parallel strings.
    Four in parallel is pretty much guaranteed to cause problems and you'll most likely end up with a battery going bad, which will usually kill it's buddies.
    Single strings are the best.
    For your use the L16 is the best bang for the buck.
    Additionally, in this design we used a 10% potential peak charge rate. Would lowering this rate down to only 5% peak charge current INCREASE battery life??

    Probably not. 10% is the recommended charging rate, much lower and you'll not have enough current to properly recharge the plates. You'll end up with sulfation and very short battery life.

    Charging Lead-Acid batteries is something of a compromise, charge at too high a rate and you get grid corrosion and shedding, too low of a rate and you get sulfation..
    The precisely correct rate is somewhat variable depending on manufacturing methods, temperature, etc.
    However, 10% is generally the best compromise.
  • BB.BB. Super Moderators, Administrators Posts: 28,185 admin
    Re: Do I need a charge controller to save AC appliances

    I am not speaking for Peter--But I am usually the guy talking about 2-3 being the maximum "I would" recommend for paralleling multiple battery strings from my own experience in generic electronics and power supplies.

    There are people who have 4 or more strings and are happy with them.

    If you don't mind the X times battery cells to check/refill and the extra fuses/cables/balancing issues--Paralleling >3 strings can be done.

    Also, with a DC current clamp meter, it is much easier to check your strings once a week or once a month to ensure that they are properly sharing (check both under heavy charge and heavy load for proper current sharing) and look for open/shorted cells/bad wiring/bad connections.

    However, if you can go with one series string (typically going to 24 or 48 volt battery bank for larger systems), I think you will be happier.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: Do I need a charge controller to save AC appliances

    Could you please post the link that described and illustrated the different ways of connecting multiple batteries? Thank you.
    BB. wrote: »
    I am not speaking for Peter--But I am usually the guy talking about 2-3 being the maximum "I would would" recommend for paralleling multiple battery strings from my own experience in generic electronics and power supplies.

    There are people who have 4 or more strings and are happy with them.

    If you don't mind the X times battery cells to check/refill and the extra fuses/cables/balancing issues--Paralleling >3 strings can be done.

    Also, with a DC current clamp meter, it is much easier to check your strings once a week or once a month to ensure that they are properly sharing (check both under heavy charge and heavy load for proper current sharing) and look for open/shorted cells/bad wiring/bad connections.

    However, if you can go with one series string (typically going to 24 or 48 volt battery bank for larger systems), I think you will be happier.

    -Bill
  • BB.BB. Super Moderators, Administrators Posts: 28,185 admin
    Re: Do I need a charge controller to save AC appliances

    Here is one:

    www.smartgauge.co.uk/batt_con.html

    Does not include wire sizing/fusing information.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SlowLearnerSlowLearner Registered Users Posts: 6
    Re: Do I need a charge controller to save AC appliances
    Would a battery bank composed of 4quantity of 100 Amp hour batteries work in this exact same scenario?

    Theoretically? yes.
    In real life? Not so much.Paralleling three strings can cause problems...
    Single strings are the best.

    I understand that if I would wire 4quantity of 100 Amp hour batteries in parallel i would now have 400 amp hours.. But do I really NEED to wire them in parallel to achieve/use 400 amp hours of power from my system??

    Meaning if :
    3930 Watt hours divided by 48 Volts = 81.875 Amp hours that you expect to use.
    At 25% Depth Of Discharge this means a battery bank that is four times that: 327.5 Amp hours.

    I do NOT understand exactly how a charge controller works but can't I program/setup a single charge controller to:
    Bring Battery A down 5%, then
    Bring Battery B down 5% while starting to re-charge Battery A
    and while that is happening begin drawing down Battery C once I have used up 5% of the Battery B etc.....
    Aren't they basic logic programmable with parameters like this?

    Or am I expecting too much from a charge controller? They can only SEE one battery or one bank of batteries as a single solitary unit. All or nothing?

    I hope my question makes sense...
  • BB.BB. Super Moderators, Administrators Posts: 28,185 admin
    Re: Do I need a charge controller to save AC appliances
    I understand that if I would wire 4quantity of 100 Amp hour batteries in parallel i would now have 400 amp hours.. But do I really NEED to wire them in parallel to achieve/use 400 amp hours of power from my system??

    Normally, that is how it is done... You take 4 smaller batteries and wire them in parallel (or series) and they are now 1 big battery.

    You could do it differently (wire each battery behind a switch and turn on the battery you would want to use)--but I have not seen it done on a small scale.
    I do NOT understand exactly how a charge controller works but can't I program/setup a single charge controller to:
    Bring Battery A down 5%, then
    Bring Battery B down 5% while starting to re-charge Battery A
    and while that is happening begin drawing down Battery C once I have used up 5% of the Battery B etc.....
    Aren't they basic logic programmable with parameters like this?
    Normally, when you wire all the batteries together, they all behave like one large batteries... They all discharge and charge together.
    Or am I expecting too much from a charge controller? They can only SEE one battery or one bank of batteries as a single solitary unit. All or nothing?

    Normally, the batteries act all together.

    There are special ways of using shunt and distributed chargers to help balance the load on individual batteries... And some battery chemistry (like Lithium type) actually have small "smart modules" on every cell to prevent over/under charging... But this is not usually done on a normal lead acid bank.

    This is why every battery bank should be made from "matched" batteries that are wired in such a way that they share voltage and current equally.

    If not, then some batteries carry more of the load or get over/under charged.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SlowLearnerSlowLearner Registered Users Posts: 6
    Re: Do I need a charge controller to save AC appliances

    Is anyone on this board familiar with a charge controller than can be programmed to logically address individual batteries to discharge/charge according to a parameters such as use 5% of Battery A then 5% of Battery B while charging Battery A then use 5% of Battery C etc.??

    Additionally, since battery longevity is a primary concern for me I am hoping someone on the board could further explain the voracity of this statement from
    http://www.firemountainsolar.com/learn-more/learn-about-products/batteries/#4
    Depth of Discharge and Battery Life
    Standard Deep Cycle Batteries (L16 type): 4-8 years
    Premium Deep Cycle Batteries (Surrette, Trojan L16RE-A & L16RE-B): 7-15 years
    Industrial Deep Cycle Batteries (Surrette 4KS & Trojan L16RE-2V): 10-15 years
    Solar One Batteries with patented HuP Technology: 15-25 years

    Is this just a Solar One advertisement or is the median lifespan of a Solar One Battery really 81% GREATER than a Surrette or Trojan L16RE-B

    Thanks,
    SlowLearner
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Do I need a charge controller to save AC appliances
    Is anyone on this board familiar with a charge controller than can be programmed to logically address individual batteries to discharge/charge according to a parameters such as use 5% of Battery A then 5% of Battery B while charging Battery A then use 5% of Battery C etc.??

    Not likely, as charge controllers can't really tell how depleted a battery is. They basically just sense its Voltage, and feed it available current to reach a higher Voltage set point (with variable parameters like time and temperature). Additionally, such a configuration would rely on their being a charge source present at all times - which is not the case with solar. Controllers with AUX functions like the Outback's can be set up to switch charging to a secondary bank once the primary bank is full. Usage switching would still be manual unless you really know how to design some complicated circuitry capable of twitching a relay at appropriate times. In theory a battery monitor could do this, but I don't think any of them are actually designed with this function.
    Additionally, since battery longevity is a primary concern for me I am hoping someone on the board could further explain the voracity of this statement from
    http://www.firemountainsolar.com/learn-more/learn-about-products/batteries/#4



    Is this just a Solar One advertisement or is the median lifespan of a Solar One Battery really 81% GREATER than a Surrette or Trojan L16RE-B

    Thanks,
    SlowLearner

    See this thread about HUP's: http://forum.solar-electric.com/showthread.php?t=10977
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