Charge controller

rake1
rake1 Solar Expert Posts: 173 ✭✭
I have wind and solar my question is my solar charge controller. I just added another solar panel so I now have 265 watts of panels putting out about 17 amps on a good day. My question is any way to keep the amps up longer before my controller starts cutting the amps to my batteries? My controller is showing 17 amps but being that my batteries are about 80% charged it is only allow 4 of the 17 amps to my batteries.These are still charging but very slowly and most times the clouds roll in and I lose the amps and don't get fully charged.My controller is set from the factory at 14.2 volts anything I can do to make better use of that high amperage when it is available to charge my batteries? Would an MPPT controller help this situation?
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Charge controller

    An MPPT controller, I believe, will not increase charging current...

    So, some questions/suggestions:
    • What brand/model of battery do you have. Typically AGM/Sealed are 14.2 to 14.4 volts charging. Deep cycle flooded cell are typically around 14.5 to 14.8 volts. Higher voltage will push more current.
    • When the current reduces, is the voltage at the battery bank (on the battery lugs or bus bar) actually 14.2 volt when measured with an accurate volt meter.
    • You should have very short/heavy gauge cable from the charge controller to the battery bank. For a 12 volt bank, I would suggest you want no more than ~0.05 to 0.10 volt wiring drop (too much wire resistance will drop the voltage at the battery bank even more when heavy current is flowing).
    • If you have flooded cell batteries... Do you measure/log the temperature corrected specific gravity for each cell once in a while?
    • What is the Vmp of the solar array (Vmp~17.5 to 18.6 volts or so ideally for a PWM 12 volt battery bank).
    • What is the gauge/length of wire run from the array to the charge controller (don't want too much voltage drop).
    • If you have a deep flooded cell battery bank--They should need distilled water every couple of months. If you are not adding water--then raise charging voltage/absorb time. If you are adding water every month or less, cut back on voltage and/or absorb time (if your controller has an absorb time/float setting).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    Welcome to the forum.

    Okay, a little short on details but we can surmise a bit from what you've said. :D For instance the system Voltage is 12. But we don't know the capacity.

    It is perfectly normal for the current to decrease as the battery charges. This is how it is supposed to work. In the Bulk stage the controller should supply all the current it can until the batteries reach the Absorb stage, where Voltage is held steady (in this case at 14.2, kind of low if they are FLA's) and the current will decrease until the batteries are fully charged.

    It sounds like you are saying that you sometimes don't get a complete charge, due to fall off in available sun. This is where we need to know the battery capacity. Frankly if it's more than 170 Amp hours (@ 12 Volts) you're likely to have this trouble.

    A different charge controller may help, as it seems that one is locked to a low Absorb Voltage. Normally flooded type batteries would Absorb at 14.4 to 14.8 Volts. An MPPT controller would be a waste of money in this case. It may grab a little extra current, but the problem is most likely too much battery for the amount of panel.
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Charge controller
    rake1 wrote: »
    I have wind and solar my question is my solar charge controller. I just added another solar panel so I now have 265 watts of panels putting out about 17 amps on a good day. My question is any way to keep the amps up longer before my controller starts cutting the amps to my batteries? My controller is showing 17 amps but being that my batteries are about 80% charged it is only allow 4 of the 17 amps to my batteries.These are still charging but very slowly and most times the clouds roll in and I lose the amps and don't get fully charged.My controller is set from the factory at 14.2 volts anything I can do to make better use of that high amperage when it is available to charge my batteries? Would an MPPT controller help this situation?

    An MPPT controller might help you finish charging your batteries faster by providing more current early in the morning when the panels are not yet getting full light. But there is nothing you can do to reduce the "waste" of energy from the panels when the batteries do not need or will not accept a higher current. It would also possibly help you to get more charge to the batteries when the clouds roll in. The degree to which it will help depends on what the Vmp of your panels is compared to your battery voltage.

    One thing you can do is plan to run your heavy loads (like washing machine, tools, etc.) at times when you have output to spare from the panels rather than running them off the batteries alone at a later time.

    You can also look for "opportunity loads" like pumping or heating water which you can turn on automatically when you have power to spare.

    There are ways to try tweaking your CC settings to stay in the Bulk phase longer, but that would need to be done with knowledge of your battery characteristics and monitoring of the battery temperature. I am not going to advise you on that.
    SMA SB 3000, old BP panels.
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    Ok this is at my camp and I only run lights and a TV they take about 12 amp when on. My batteries (six of them) are not the correct ones for solar they come from a UPC system that change out every two years so the price was 20 bucks for $450.00 batteries I COULDN'T PASS THAT UP.I WAS JUST WONDERING IF THERE WAS A CONTROLLER THAT HAD SOME ADJUSTABILITY TO IT. I would like to be able to dump more amps in on certain days to get a full charge hence the question about the MPPT. I just hate to see all that power going to waste. My wind turbine controller has this feature can change it up to 15 volts before it dumps.PS my battery charger will bring these batteries up to full once I disconnect the wind charge controller.


    Welcome to the forum.

    Okay, a little short on details but we can surmise a bit from what you've said. :D For instance the system Voltage is 12. But we don't know the capacity.

    It is perfectly normal for the current to decrease as the battery charges. This is how it is supposed to work. In the Bulk stage the controller should supply all the current it can until the batteries reach the Absorb stage, where Voltage is held steady (in this case at 14.2, kind of low if they are FLA's) and the current will decrease until the batteries are fully charged.

    It sounds like you are saying that you sometimes don't get a complete charge, due to fall off in available sun. This is where we need to know the battery capacity. Frankly if it's more than 170 Amp hours (@ 12 Volts) you're likely to have this trouble.

    A different charge controller may help, as it seems that one is locked to a low Absorb Voltage. Normally flooded type batteries would Absorb at 14.4 to 14.8 Volts. An MPPT controller would be a waste of money in this case. It may grab a little extra current, but the problem is most likely too much battery for the amount of panel.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    There are lots of controllers that have some "adjustability" to them, ranging from being able to select Absorb Voltage between some presets http://www.solar-electric.com/ss-20l.html to ones that can adjust almost every parameter there is http://www.solar-electric.com/mnclassic.html

    Your UPS batteries are probably sealed of the AGM or even gel type, so it is not a good idea to push the Voltage and/or current up too much. You really need to have the specifications for the batteries being used in order to determine proper charging profile. Pushing them to 15 Volts may be a very bad idea (sealed batteries can vent if too much Voltage is applied for too long; this will damage them). Likewise putting more current to them could be a problem (as a rule AGM's are forgiving of current but not Voltage, FLA's are forgiving of Voltage but not current, gel's are picky about both).

    Without actually knowing the specifications of the particular batteries we're just shooting in the dark here.
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    Thanks for the info you are correct they are AGM batteries Sprinter 370F Here is a link to the batteries if you are interested thanks for the info. Ps I have the TS-45 now just not a MPPT I use it for my wind turbine.

    http://www.gryps.si/opisi/baterije/pdf/agm/Sprinter_S.pdf
    There are lots of controllers that have some "adjustability" to them, ranging from being able to select Absorb Voltage between some presets http://www.solar-electric.com/ss-20l.html to ones that can adjust almost every parameter there is http://www.solar-electric.com/mnclassic.html

    Your UPS batteries are probably sealed of the AGM or even gel type, so it is not a good idea to push the Voltage and/or current up too much. You really need to have the specifications for the batteries being used in order to determine proper charging profile. Pushing them to 15 Volts may be a very bad idea (sealed batteries can vent if too much Voltage is applied for too long; this will damage them). Likewise putting more current to them could be a problem (as a rule AGM's are forgiving of current but not Voltage, FLA's are forgiving of Voltage but not current, gel's are picky about both).

    Without actually knowing the specifications of the particular batteries we're just shooting in the dark here.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    If you look at those specs you can see these batteries were definitely not intended for RE use. For one thing the charging is all about constant Voltage (Float) and the maximum V given for "equalization" is 2.35 per cell, or 14.1 for a 12 Volt battery. Given that info, increasing the Voltage is probably not a good idea; they are likely to vent.

    The extremely small capacity time listed of 15 minutes is another indication that these weren't meant for RE. And they expect to drain them down to nearly 10 Volts in that time! If you want to try to calculate the 20 hour RE capacity take a look at these links: http://forum.solar-electric.com/showthread.php?12093-Re-AGM-battery-capacity-interpolation
    Without doing the actual math, it looks like about 120 +/- Amp hours for the 20 hour rate. If you have six of these in parallel (bad idea: see this wiring info http://www.smartgauge.co.uk/batt_con.html ) that would be 720 Amp hours and your 17 Amps peak current is an abysmal 2% charge rate.

    Here's a suggestion: disconnect three of the batteries and see how the bank performs.
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    Yes I have them wire the same as method # 3 hopefully that is correct. I knew when I got these that they were for a UPS system not meant to be charged and discharged. I talked to the manufacture a couple of years ago and he said that they were closer to 75ah so I figure I have about 450ah. I have run these type of battery for two years and they did work good just had to charge them about once every 6 weeks to get them back up to full. But as stated I change these every two years when the company changes out theirs. I will not fool with the voltage as you stated 14.2 is what the controller is set at from the factory.14.3 is what the wind turbine is set at. One other question if I were to replace these batteries with say 3 120 AH batteries 360AH total would that work better than the 6 at 450AH? Now I am talking 120ah deep cycle batteries?
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    Discounting the contribution from the wind turbine, what you have for a peal charge current from your existing panels is 17 Amps, correct? Using the standard rules-of-thumb that would be best for 170 Amp hours @ 12 Volts with the battery bank discharged no more than 25% on a daily basis. Your wind turbine could up that, of course, depending on what output you can count on from it.

    On a 450 Amp hour battery bank that 17 Amps represents a peak charge rate of 3.7%, which is still well below the recommended 5% (with no loads) minimum. This I think is your basic problem; deficit charging caused by too much battery for the amount of panel. When you have that peak charge current around 10% you can get a full charge more often (daily if conditions are right) and you don't have to worry about the batteries being below 70% SOC for too long (with resulting premature terminal sulphation).

    So it comes back to the load demand and sizing the battery bank so that is met. Then adjust the charging availability to handle the battery capacity. I suspect you could get more than two years out of those AGM's if they were charged up faster, more fully, and more often.
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    The percentages you talk about are all new to me, and I agree 100% that I probably have to much battery for my charging capability of the solar panel. But my six batteries on a good night are going from 12.8 to 12.7 maybe 12.6 if I watch tv for 5 hours so 12.6 is still 80 % charged correct? The following day if a good day these batteries will surface charge back up to 14.2V and when I turn on the 10amp TV, they drop in 10 minutes to 12.8 and hold that for a couple hours then 12.7 for the rest of the evening and maybe 12.6V. But I agree my problem arise if the following day I don't have a good sunny day then I have to really watch my batteries that night, that is when I start seeing 12.5 or 12.4V. Three days of bad sun and forget the TV that night. Now going back to my old question about the 3 120ah batteries would they do a better job. Where can I find this info you supplied about charging % and peak charge current this is great info I didn't realize I new as little as I do HeHe. It is funny you talked about only using 3 batteries I told my brother inlaw the exact same thing the other day. He has six batteries but only a 60 watt panel,his was obvious to me. But again he only uses lights.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    Voltage is not a good indicator of SOC unless it is at rest: no current in or out for at least two hours. Proper charging consists not only of bringing the battery up to Absorb Voltage but also keeping it there until the charging process is complete. Depending on the size of the battery and the depth of discharge this could be one hour - or four. Here's a little light reading about deep cycle batteries: http://www.solar-electric.com/decybafaq1.html

    Now if you are using these batteries to power an inverter you can get a Kill-A-Watt meter and measure your actual power consumption under normal use. Then you have to include the power that the inverter itself uses and include that as part of the consumption. There is no better way to figure out how much battery you need.

    Example: a TV might use 120 Watts. Run for an hour that's 120 Watt hours. Converted to 12 VDC (efficiency losses) it would use about 12 Amp hours in that time. The inverter in the same time may consume an additional 2 Amp hours. So one hour's TV watching uses up 14 Amp hours @ 12 VDC, necessitating a minimum 28 Amp hour battery. Larger is better, especially as the actual capacity will diminish over time no matter what. But you have to have enough charging capacity to properly recharge the battery. This is where the 5% to 13% peak charge current comes in, but it also depends on battery type and depth of discharge. When you use 10% peak rate & 25% maximum DOD it tends to fall into balance for most situations.

    Let's say you pick a 60 Amp hour 12 Volt battery for the above example. Then you calculate 6 Amps peak charge current against the minimum (or system) Voltage and see you need about 72 Watts of panel to provide it. But panels only operate at an average 77% efficiency (+/- depending on circumstances) so you need a bit more for it to actually work: 94 Watts. If you cross-check that for AC harvest during a short day (4 hours of equivalent good sun) using the Icarus formula you get: 94 * 4 * 0.52 (over-all efficiency) = 195 Watt hours, enough to cover the TV and the inverter's consumption as well as system efficiency losses.

    I recommended cutting down on the battery bank because more than once that has worked out for the best; reducing the capacity to where the panels can fully recharge it daily even if it means the depth of discharge goes up some (although not exceeding 50%). There's a lot of trade-offs to balancing a system so that it works for you, and it takes a bit of adjusting to get it right.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Charge controller

    The 5% floor is based on some assumptions that may not be true in your case:

    First is that AGM batteries are much more "efficient" at charging vs flooded cell (~90-98% eff vs 80-90% for flooded cell).

    Second, self discharge--Fork lift batteries at the end of their life can self discharge as much as 1-2% per day--If you recharge ~4-6 hours per day (from solar), that means a 5% rate of charge for 5 hours just about equals the 1% self discharge over 24 hours. AGM's which have much lower self discharge, will eat much less into your "minimum" rate of charge (needed to keep ahead of self discharge in old flooded cell batteries).

    Third, many of the calculations we do assume charge during daylight and discharge at night. In the case of a "mixed use" off grid power system--You may discharge during the day too (especially if you work during the day and use a computer/etc.). So, that 5% rate of charge, and take out a couple percent for running daytime loads--and you are looking at very near available current for charging.

    So--the 5% minimum rate of charge is really weighted around flooded cell batteries. For example, many companies have a minimum recommended rate of charge of 5% (Trojan says 10%). And for equalization, 5% rate of charge is the maximum recommended by Rolls/Surette (batteries during equalization convert all charging energy into heat and H2+O2 gases--Too much charging current can over heat the batteries and cause excessive "wear" on the plates from gasing--as well as driving oxygen into the positive grid causing corrosion).

    The 13% maximum cost effective is a combination of "efficient" battery charging (more energy to charging, less to heat). And using the solar array during much of the day... A "Huge" array could take the battery bank to float in the morning--and just "do no more charging" during the day. Plus heavy charging currents can be a bit hard on the battery and require heavy copper cables to carry the current.

    If you go above 13% rate of charge (with flooded cell), should probably have a remote battery temperature sensor for the charge controller to reduce the threat of thermal run-away (battery gets hot from lots of current, battery charging voltage falls, accepting more current and controller thinking battery needs more charging, battery gets hotter, repeat, melt down).

    I have been "guilty" of using lots of rules of thumbs hear for several years instead of asking detailed questions on power usage, battery construction, etc... Saves lots of time and usually works very well for everyone (gives answers on the conservative side of design).

    If you have special needs, are very cost sensitive, etc.--Then we can fall back to asking for more details and recommend alternative design solutions.

    You are doing OK because you are not using a lot of power, and probably using most of it after dark (all solar power during daylight is going into charging the battery bank). If either of those change, there is a chance the battery bank will "have issues".

    Given that you are using AGM, they are probably pretty happy with the "soft" charging parameters you are currently using. And, the seem to be "good enough" to recharge your bank on an average day (after average use).

    -Bill "lots of hand waving" B. :blush:

    PS: And you will probably blow a bunch of holes in my assumptions--I can take it. :p:D
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    WOW lots of info one thing I forgot to mention was I usually come home from the camp Sunday so my batteries do have3 or four days to get back to full charge before I come back and are usually showing 13.2V on my meter when I walk in the door at night.If I come in the afternoon they show 14.2 about if it is a good sunny day. Again that 14.2 v only last until I turn on my inverter and a light then right to 13,2v.With my current set up I wasn't concerned with the heat issue because even 17 amps int 6 batteries is less than 3 amp per batteries so I felt pretty safe with that. I will try pulling two batteries of for a weekend see what happens, I assume the remaining 4 should charge quicker correct??? I will just have to see how much they drain down through the evening. Now my only concern is if I use 4 of them and they drain down to 12.5v that is fine,but if a have a real poor day sun wise I may be stuck with draining them real low the following night correct? This is the plus of having the six batteries, I have a lot more reserve. But I know the answer use 4 and get them fully charged or use 6 and maybe only get to 95% charge. Now as far as equalization goes I can do that with my TS-60 controller but was told not to equalize AGM batteries is that also correct.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    As I said before, Voltage is not a good indicator of SOC unless the batteries are at rest. What you are describing is a situation where the batteries and/or panels can not maintain Voltage when load is applied. The charge Voltage dropping from 14.2 down when load is applied shows the panels do not put out enough power to handle both charging and load. The battery Voltage dropping quickly under load can indicate either that the load is too much for the batteries or the batteries are not fully charged or both.

    Reducing the battery bank capacity should result in a faster and more complete charge. The panels may even be able to maintain the Absorb Voltage against the load draw. If they can't you have to either increase panels or decrease loads or else you will be deficit charging still. If that issue is resolved you will then be able to get the batteries fully recharged and they should be able to maintain Voltage against the load longer (normally you expect an immediate but small drop, followed by the Voltage 'holding' for a while, followed by rapid decline after they pass their optimum point). If not then they still have insufficient capacity for the loads.

    There is no point in trying to equalize these batteries. You can not check the specific gravity per cell on an AGM so you have no way of knowing if they are too different and know way of knowing if they improve. Most likely the EQ recommended for these was a regular timed cycle at the higher Voltage. Without knowing that recommendation you can't duplicate it. As it is the Voltage given for EQ is about the same as what you are charging at.

    Another incident of why bargains aren't necessarily. :roll:
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Charge controller

    The problem with taking 5 days to recharge a battery bank--The longer they sit at less than full charge (some people use less than 75% state of charge), the faster they sulfate.

    But--In reality--At this point, with a cheap supply of AGMs every two years and not a lot of discharge--I don't think you are doing too badly at all.

    Other than making sure you have the batteries wired correctly and a good fuse or breaker on the battery bank output (for reduction of possible fire hazard with a short, and you should have a fuse/breaker per string if more than two parallel battery strings), why not continue the way you are.

    AGM's tend not to have a real long float/storage life (compared to higher end flooded cell)--So if you have to replace them every 4-6 years--adding more solar panels is not probably going to prolong the life that much more (if any).

    If you add more loads/longer times in cabin--Then more panels would be a good idea anyway.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    When I mentioned they drop from 14.2 to 12.8 and hold I thought that was normal. Isn't the 14.2 just a surface charge since the batteries have just been charged by my panels? I also thought that 12.8 is a fully charged 12 volt battery at least that is what I understood from reading. Bill I just added the new panel that brought me up to 265 watts and haven't had enough time to really tell how long it take to recharge. The other day was real sunny I probably got 6 hours of good sun and it did charge fully. When I mentioned 5 days to recharge I might of mislead you, what I meant was I may not use the batteries for five days until I am back to my camp. I am hopping that they fully recharge in two days of 4 hour sun or one day of 6 hour sun.I also, 90% of the time only bring them down to about 12.6V which I believe is still 80% charged. Am I correct in saying bringing them down to say 12.3 is still 50% charge, and still OK if I get a good charge the next day. Again thanks for all this info.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    14.2 Volts is the charging Voltage; the minute it is removed the V will go down and yes 12.8 is fully charged. I wasn't clear in my statement about sudden V-drop; it applies when not being charged or when being charged but not as a result of the change between the two states.

    At 12.3 Volts while under load you still have more than 50% capacity. If you leave the batteries unattended with the panels & controller connected they probably won't take five days to charge but will be charged when you return in five days. That's a different thing. :D What you want to watch out for is if they are below 70=75% SOC for days on end as it will accelerate sulphation and shorten life. We're not talking immediate battery death here, just years shaved off.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Charge controller

    Rake1,

    I understood what you were typing... I was just trying to clarify that you don't want to take 5 days to "slowly" recharge the battery bank as this increases sulfation rates (like Marc said). Many people with cabins believe they can use power over the weekend and use a small solar array to recharge over the next week or two--Not a great idea.

    One thing about deeply cycling a weekend use battery (such as a cabin/RV)... Even if you discharge to 50% or lower SOC, most good quality batteries will still have something like a 500+ cycle life--50 weekends a year for 10 years--Most batteries will die for some other reason anyway before cycle life failure (age, oops, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    Thanks guys I think I am up to speed on this topic now great info thanks.
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    Hi guys I am at it again well the two solar panels are working good 265 watts, I took your advice and disconnected two of my batteries to try to get a more complete charge that worked but I don't seem to have the reserve to run my Tv two nights in a row. Same problem I had when all six AGM's were connected. I now believe these batteries are toast and should be replaced. They are about 70AH each which means I have 420AH if they are new and working proper. If I buy 4 six volt 225 AH batteries that will give me 450 AHs correct? Would this be better than say four 12 volt 125 AH batteries? What about @ 225 12 volts I am just trying to get you thoughts on the best way to go if I change these out.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    Battery arrangement: four 12V in parallel has a greater chance of uneven current sharing than two strings of two 6V.

    Do you have any way of seeing how much current those panels are putting out? I'm guessing somewhere around 15 Amps, maybe 17 at most?

    So 420 Amp hours getting 15 Amps is a 3.5% charge rate. This will take a long time to charge up, even if the batteries are still good. If they've been chronically under-charged they won't be 420 Amp hours anymore, so you would not have the capacity needed to keep the TV going on 1/2 the bank.

    225 Amp hours getting 15 Amps is a 6.5% charge rate. If they were charged without loads drawing at the same time these batteries would last for many years and have their capacity diminish slowly (it always diminishes; you can't stop that, only slow the rate).

    If you put together two such strings you're right back at 450 Amp hours @ 12 Volts and the same low charge rate as before with resulting shortened battery life.

    You need to measure that power usage and see how much battery is required to supply it and how much panel would be needed to charge it. Otherwise you have to adapt to whatever limitations it's not practical for you to overcome.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Charge controller

    Do you have the Watt*Hours (or AH at what voltage) you are using per day/per night?

    I would prefer 4x 6 volt golf cart batteries connected in 2x series (for 12 volts) and then 2x parallel (for 450 AH @ 12 volts). I am not a fan of more than 2-3 series strings (more connections, more things to go bad, more fuses/breakers, more cells to check electrolyte levels, etc.). Plus the golf cart batteries may end up being a lot cheaper to buy (and if they don't last too long, you are not out lots of money for experimenting).

    A Battery Monitor, or a DC Clamp / Digital Multi-Meter, or Shunt+Amp meter, Kill-a-Watt meter (for 120 VAC loads), a DC WH/AH meter (smaller DC Loads) (one or more combination of the previous), and a hydrometer are some of the basic tools that can help you understand your loads and charging situation.

    A DC Clamp DMM + Hydrometer is probably the minimum to figure out what is going on.

    A Kill-a-Watt type meter is cheap and great to use around the home too for conservation projects.

    Battery Monitor is great for AGM and just over all monitoring of a battery bank (and much easier to use for spouse/kids/guests to monitor vs a volt meter or hydrometer--Plus a few Battery Monitors can be setup to trigger an alarm).

    The Shunt+Amp meter--Just a less expensive way to monitor what is going into/out of the battery (no "Hours" measurements--so not a replacement for a battery monitor).

    DC WH/AH meter--Good for smaller systems/DC loads (used by a lot by hobbyists who work with electric radio controlled vehicles).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    I am taking out about 12 amp per hour at night watching TV for say 4 hours. During the day their is very little power used usually only a radio. The panels will put out 17 amps in good sun. My meter is connected to the batteries and shows amp going in amps going out % charged and battery voltage and other functions. My Dc clamp meter is always the same as the trimetric 2020 meter very little difference. I believe it is my batteries because I only had on panel last year with the same type of battery and didn't have this issue. Changed batteries (same brand exactly) problem started. Put up another panel helped but not enough. Keep in mind the batteries were used AGM out of a UPC system each time.
    PS charging batteries up full with a charger takes hours and helps slightly but real low again in 3 nights. I feel it is a battery problem, but that is why I am asking. So where is a good spot to buy batteries, and also a good web sight where I can get the panel vs battery calculations?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Charge controller
    rake1 wrote: »
    I am taking out about 12 amp per hour at night watching TV for say 4 hours. During the day their is very little power used usually only a radio.

    Amps is already a "rate" (Ampere = Joules per second)--The per hour is not used...

    So, math:

    12 amps * 4 hours = 48 Amp*Hours per night

    To recharge:

    48 AH per night * 1/12 amps in full sun * 1/0.90 eff AGM battery charging = 4.44 hours of full noon time equivalent sun per day for recharging

    You appear to be about breaking even (many places in North America will get 4 hours of sun minimum per day for ~9+ months of the year). If you are heading into winter, 4 hours of sun may be pushing it and you are probably "deficit charging"--For example, replacing 80% of the power used every day, and slowly, on average, discharging the battery bank...

    Using PV Watts for a random town "Greenwood" in Nova Scotia Canada (guess for your location):
    Month Solar Radiation (kWh/m2/day)
    1 2.58
    2 3.59
    3 4.65
    4 4.88
    5 4.83
    6 4.99
    7 4.97
    8 5.49
    9 4.86
    10 3.83
    11 2.87
    12 2.14
    Year 4.14
    The panels will put out 17 amps in good sun. My meter is connected to the batteries and shows amp going in amps going out % charged and battery voltage and other functions. My Dc clamp meter is always the same as the trimetric 2020 meter very little difference.

    So--It would appear that you are simply drawing more power from the battery bank than your present solar array can resupply.
    I believe it is my batteries because I only had on panel last year with the same type of battery and didn't have this issue. Changed batteries (same brand exactly) problem started. Put up another panel helped but not enough. Keep in mind the batteries were used AGM out of a UPC system each time.
    PS charging batteries up full with a charger takes hours and helps slightly but real low again in 3 nights. I feel it is a battery problem, but that is why I am asking. So where is a good spot to buy batteries, and also a good web sight where I can get the panel vs battery calculations?

    While the batteries may be old/damaged--It still sounds like you are under charging (putting on AC charger makes the problem "go away" for a few days).

    Review your connections from the charge controller to the battery bank. Cables should be short and heavy with solid/clean connections. Measure the voltage at the charge controller contacts and at the battery bank... For a 12 volt bank, my personal recommendation is 0.05 to 0.10 volt maximum voltage drop (at full current).

    If the controller is holding ~14.2 volt to 14.4 volts (typical AGM charging voltage for room temperature batteries) for 2-4 hours minimum--then the controller is doing its job.

    If the battery bank voltage is not reaching 14.x volts, then either the bank is too far discharged (or not enough charging current/time/sun) or the charge controller is (incorrectly for your needs) limiting absorb charging voltage (i.e., current is falling back to below 12 amps at 13.8 volts even though there is plenty of sun available).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    If the battery bank voltage is not reaching 14.x volts, then either the bank is too far discharged (or not enough charging current/time/sun) or the charge controller is (incorrectly for your needs) limiting absorb charging voltage (i.e., current is falling back to below 12 amps at 13.8 volts even though there is plenty of sun available).

    This is exactly what bugs me about this set up EX. My batteries may read 12.6 in the morning sun comes out putting in 17 amps that is great, 1 hour of this then the batteries start excepting only ex 8 amps then less and less. I know that is normal but I sure wish I could keep that 17 amps for say 2 hours before it starts cutting back. In good sun 17 amps My 2020 meter is reading within the hour 14.4 and my Tristar 60 is dumping to my dumpload and my solar controller is limiting amps to the batteries at 14.2. It seems that these agm batteries take a surface charge way to fast. Or at least that is my thinking. I know I am stuck on the battery thing but I have seen batteries act like this in the past in cars, charge up full in no time but have no staying power if needed.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Charge controller

    Using dump loads can be difficult--They do not do as good of job of charging a battery bank vs a standard "series" controller.

    Can you set your TS dump load to delay longer (2-4 hours) before turning on?

    What is your dump load--Is is something "useful"? Or can you turn off the dump load and see how everything performs?

    I made a mistake and used 12 amps for charging instead of 17 amps... The corrected numbers would be:

    48 AH per night * 1/17 amps in full sun * 1/0.90 eff AGM battery charging = 3.13 hours of full noon time equivalent sun per day for recharging

    Anyway--If you can turn off the dump load (at least during winter) and see what happens next.

    Your batteries may not be perfect--But I would not replace them until you can get the system stabilized first. No reason to stress a new set of batteries while these are still functional.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Charge controller

    If you are not holding ~14.4 volts for 2-4 hours (absorb), then you are not fully recharging the battery bank (or until the batteries are down to 2% or 1% of rated capacity (i.e., a 100 AH battery bank down to 2 amp or 1 amp--then batteries should "be full").

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    Charging up quickly can indicate diminished capacity. If the batteries are still good then even a fast Bulk charge will be made up for by sufficient time in Absorb. Sounds like your charging is just 'zooming through to Float', which is not good.

    I'm a bit lost here: why do you have a dump load connected to solar? Maybe disconnect this and see how long you can keep them at 14.4 Volts. Failing that, set up an EQ charge, limited to the same Voltage, so that you can manually maintain the higher Voltage for an hour and see if it improves.

    Frankly, I think you're right that these batteries have had it. But as I explained with the charge rates before, merely replacing them won't necessarily fix the underlying problem. New batteries might work better for a while, and then they too will suffer from chronic deficit charging.

    Some people dismiss my "10% rule of thumb" saying it is unnecessary, but since it is based on a sunny day it does give room to maintain charge levels on those days that aren't so sunny.
  • rake1
    rake1 Solar Expert Posts: 173 ✭✭
    Re: Charge controller

    No timer on the TS 60 but I can adjust it up to as high as 15 VOLTS before it dumps. But my Steca solar charge controller is where it all starts it limits the amps to the batteries before the TS 60 starts dumping. The problem with raising the TS 60 is I can damage the batteries with it set so high. Remember my ts 60 is there to control my wind turbine if set to high and it is real windy then I am charging at 15 amps. My dump load are 300 watt resisters designed for wind turbine. Here is a pic not pretty but here it isAttachment not found.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Charge controller

    Looks like this is one of those rare instances when two different charge controllers don't want to work together. This would be due to the limitations of the Steca I think.

    This is mostly more of the familiar solar-electric problem of having to control things by Voltage when what is needed is current control (harder to do).

    That wiring is messy even by my Mad Scientist standards, but it looks as though you've tried to bring equal length positives and negatives from each battery to common connection points.

    Try this: disconnect the TriStar/turbine/dumpload provision and see if you can get the batteries to perform better off solar alone. If you can get that to happen then the system is working, and the wind power becomes gravy and will help out when the sun doesn't shine but the wind does blow.

    I have this horrible feeling you're going to have to replace the Steca controller with something more flexible (expensive).