Battery Minder

tcvb
tcvb Solar Expert Posts: 44
Got a question,will hooking up a Battery Minder to your battery bank do any harm to your panels or your solar charger?I recently got a VDC 8 amp minder and was going to install because of the pulsating feature.Any suggestions?

Thank's

Tim

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    Re: Battery Minder

    You can parallel battery chargers without any problem (assuming the other battery chargers do not overcharge the battery).

    If you install a "desulphator" type device (one that puts high frequency energy into the battery bank) (I don't know specifically about the Battery Minder), it is possible that the radio frequency noise can cause other battery chargers problems.

    There has been a poster here who found that a desulphator was causing his Outback Solar Charge controllers to get confused and supply less energy. When the desulphator was turned off, the output of the Outbacks went up significantly.

    Interaction of desulphator and MPPT charge controller

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Battery Minder

    Over the years, I've read much about how desulphator devices just do not work as claimed, and are basically a waste of money. Has something changed?
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Battery Minder

    no, nothing has changed with that subject. it is still a very opinionated topic area so that would be best discussed in one of the upper topic areas if you'd like to continue on the desulfator subject.
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: Battery Minder

    Pulsing chargers do help soft sulfation and can be used to avoid equilization cycles that do significantly stress the batteries. I would not refer to them as 'desulfators' however.

    Pulse charging allows higher peak currents while keeping the average current to a level that does stress battery.

    As to original question, the pulse charger may make the solar controller to back off on its charging a bit early, depending on how great the current pulse is and the series resistance of the batteries. It won't damage anything.
  • BillBlake
    BillBlake Solar Expert Posts: 49
    Re: Battery Minder
    niel wrote: »
    no, nothing has changed with that subject. it is still a very opinionated topic area so that would be best discussed in one of the upper topic areas if you'd like to continue on the desulfator subject.

    niel,

    Where are the "upper topic areas"? There are a few desulphator items that the Group may enjoy bearing witness to. :p
    It really doesn't matter if they work or not - Long as they sound cool. :cool:
    Batterymart.com talks highly about BatteryMINDer. Normally, eventually, so goes Batterymart - so goes the Nation.

    Bill Blake
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    Re: Battery Minder

    I think Niel is referring to the Forum Topics near the top of the lists:

    Solar Product Reviews & Opinions
    Solar Skeptics, Hype, & Scams Corner

    Depending on your thoughts regarding the subject(s).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Battery Minder

    yes, bill has it right as to what i was saying.
  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    Re: Battery Minder

    At 8 amps output on a discharged battery, it looks like the smallest size you can go for the initial current surge with FLA would be 64ah (C/8 max), and for AGM's, 32ah (C/4 max) unless you are running other types that can take more than this according to the manufacturer.

    Speaking of sulfation, I size my chargers to meet the minimum 5% (C/20) spec, so that the battery won't sulfate faster than I can charge it, and make sure it will overcome an FLA's higher impedance.
  • bills
    bills Registered Users Posts: 1
    Re: Battery Minder

    is this true?
    If you connect a solar panel directly to a battery, the battery will clamp down the voltage of the solar panel to about 13-14V(max) and absorb all the solar energy in the process. If the battery's plates are fully charged, the additional energy will go into a process generally referred to as boiling. Is boiling a bad thing? Not necessarily and certainly not in stationary deep cycle batteries. You will need a certain amount of boiling to keep the electrolyte from settling. Your car battery doesn't have that issue if you drive through the odd pothole or across other bumps but for stationary batteries it is a real problem.
    Secondly the boiling that occurs from potential (over voltage) is different than the boiling that occurs from high current. It sounds different (small bubbles instead of big bubbles) and doesn't boil off
    the water. I am not sure what is being released but a marine battery that I bought at Wal-Mart (three years ago for stress testing) has been through many[short duration] boils and I have yet to add a drop of water to it as its cell's water levels are still as high as when it was new.

    As you can see from the table above a 12V battery is fully charged (max capacity) at 6 * 2.4 = 14.4V. But there is one entry after that for cell balancing. This happens at 6 * 2.6 = 15.6V. In short cell balancing is fixing a bad cell by over potentializing it. Generally speaking if your battery's capacity drops, its because 1 cell has gone bad and drains the others. For a more detailed description you can google the term "cell balancing".
    Cell balancing process:
    Simply connecting a solar panel directly to a battery seems to accomplish this cell balancing (= restoring the battery's capacity) under the following conditions:
    - battery is in decent shape = resting voltage reads 12.3V or higher.
    - battery is not discharged during the process (i.e. you cannot use the battery)
    - the process takes time; at least a few weeks if most days are sunny.

    I told you that it was easy to maintain your batteries!
    I 'bumped into' this process last winter when it was too cold to work in the yard. 1 bank of 4 T-1275 batteries was sitting at about 12.35V so I connected them to a 60W solar panel to avoid discharging them further and walked away. Six weeks later as temperatures started to rise I opened the battery box and found all batteries softly boiling. My volt meter showed 14.4V. I unplugged the solar panel and the next morning the resting voltage was 12.80V! Using the batteries this spring I noticed their capacity is much higher than it was last summer: no more instant collapse from 12.6V to 12.3V. What's most special is that I got the batteries used. They had spent the first three years of their life powering golf carts around a local golf course and were replaced because they couldn't get the job done any longer.
    So lets do some math. At my elevation a 60W panel delivers about 3.5 Amps for a few hours on a bright sunny day in the middle of the summer and also on a sunny winter day with a fresh layer of snow on the ground. Spread over 4 batteries that is .9A per 150Ah battery. Which is barely a trickle charge for them and roughly 12% of their C20 capacity making it highly unlikely I would overcharge them even if left unattended. I think its most likely that the batteries were fixed by the high voltage generated by the solar panel. It is possible that this method works better in colder climates because my solar panel voltage is de-rated at -.5%/degree Celsius. This means that on a cold winter day it puts out 17% higher voltage than its rated capacity. For my panel that translates to about 20V in a closed circuit.
    Coming back to charge controllers; it seems to me that as long as you keep your charging current below your battery's C20 rate by matching panel to battery, you cannot destroy (but only improve) your battery by applying the solar panel's full voltage to it. No need for a charge controller that cuts out at 14.4V, thereby eliminating the possibility to equalize your cells.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    Re: Battery Minder
    bills wrote: »
    is this true?
    If you connect a solar panel directly to a battery, the battery will clamp down the voltage of the solar panel to about 13-14V(max) and absorb all the solar energy in the process. If the battery's plates are fully charged, the additional energy will go into a process generally referred to as boiling. Is boiling a bad thing? Not necessarily and certainly not in stationary deep cycle batteries. You will need a certain amount of boiling to keep the electrolyte from settling. Your car battery doesn't have that issue if you drive through the odd pothole or across other bumps but for stationary batteries it is a real problem.

    "Boiling" a battery--there is some reason to do it--mixes electrolyte in tall batteries, can help sluff off inactive materials that insulate the plates, and for cells in series--the "low specific gravity cells" need to be recharged while the "high/fully charged cells" will gas.

    Bad side is excessive gassing of a battery drives off hydrogen/oxygen gases and electrolyte mist, drives oxygen to the positive plate causing positive grid corrosion, and erodes plates. For AGM/sealed batteries, this can cause excessive pressure in battery--forcing venting--and loss of electrolyte (which cannot be replaced). For GEL batteries, >C/20 ~5% rate of charge causes gas pockets in the GEL--which reduces battery capacity permanently. Sealed batteries may have a catylist in the cap--running lots of equalizations will erode the catalyst and make it run hot--shortening the battery life. Running lots of current (5% or more typically) also raises battery temperature--again reducing battery life. So--I would suggest that high charging currents to nearly full batteries (aka equalization) is something that should be minimized (necessary evil).
    Secondly the boiling that occurs from potential (over voltage) is different than the boiling that occurs from high current. It sounds different (small bubbles instead of big bubbles) and doesn't boil off the water. I am not sure what is being released but a marine battery that I bought at Wal-Mart (three years ago for stress testing) has been through many[short duration] boils and I have yet to add a drop of water to it as its cell's water levels are still as high as when it was new.

    Maintenance free batteries (automotive--perhaps your marine batteries) have additives (like calcium?) to reduce the amount of water loss. In standard deep cycle batteries, not adding water every ~2-4 months may indicate the batteries are being chronically under charged. So monitor resting voltage/specific gravity of your marine batteries and make sure they are fully charged (>90% state of charge) around a couple times a week.
    As you can see from the table above a 12V battery is fully charged (max capacity) at 6 * 2.4 = 14.4V. But there is one entry after that for cell balancing. This happens at 6 * 2.6 = 15.6V. In short cell balancing is fixing a bad cell by over potentializing it. Generally speaking if your battery's capacity drops, its because 1 cell has gone bad and drains the others. For a more detailed description you can google the term "cell balancing".

    We typically call that "equalizing" a battery (bringing all cells to full charge). Usually done with flooded cell. AGM's maybe once a year (basically a long absorb cycle).

    If you are noticing your battery loosing capacity--That may be an indication that the battery/cell is near end of life anyway (whether from age/cycling, or some mistakes like cycling too deeply, not fully recharging battery, storing with less than 75% state of charge for weeks/months at a time, etc.).
    Cell balancing process:

    Simply connecting a solar panel directly to a battery seems to accomplish this cell balancing (= restoring the battery's capacity) under the following conditions:
    - battery is in decent shape = resting voltage reads 12.3V or higher.
    - battery is not discharged during the process (i.e. you cannot use the battery)
    - the process takes time; at least a few weeks if most days are sunny.

    Can work--but nothing is defined... A maximum voltage, type of battery (flooded, AGM, GEL), maximum current rate, etc. If you have a "dead/dying battery" it is sort of "why not"--But be careful... For current >5% rate of charge, you can overheat the battery. Also check the water / temperature often to make sure you are not killing the battery in other ways.
    I told you that it was easy to maintain your batteries!
    I 'bumped into' this process last winter when it was too cold to work in the yard. 1 bank of 4 T-1275 batteries was sitting at about 12.35V so I connected them to a 60W solar panel to avoid discharging them further and walked away.

    That sounds about like a 0.5 to 1% rate of charge (~600 AH battery bank at 12 volts)--That is "floating" a battery and can be done pretty safely without a charge controller (check water often to make sure you are not "boiling dry"). If it works for you--Great. But it will not quickly recharge a partially discharged battery bank at that rate.
    Six weeks later as temperatures started to rise I opened the battery box and found all batteries softly boiling. My volt meter showed 14.4V. I unplugged the solar panel and the next morning the resting voltage was 12.80V! Using the batteries this spring I noticed their capacity is much higher than it was last summer: no more instant collapse from 12.6V to 12.3V. What's most special is that I got the batteries used. They had spent the first three years of their life powering golf carts around a local golf course and were replaced because they couldn't get the job done any longer.

    Sounds interesting.
    So lets do some math. At my elevation a 60W panel delivers about 3.5 Amps for a few hours on a bright sunny day in the middle of the summer and also on a sunny winter day with a fresh layer of snow on the ground. Spread over 4 batteries that is .9A per 150Ah battery. Which is barely a trickle charge for them and roughly 12% of their C20 capacity making it highly unlikely I would overcharge them even if left unattended. I think its most likely that the batteries were fixed by the high voltage generated by the solar panel. It is possible that this method works better in colder climates because my solar panel voltage is de-rated at -.5%/degree Celsius. This means that on a cold winter day it puts out 17% higher voltage than its rated capacity. For my panel that translates to about 20V in a closed circuit.

    More than likely, the output current of the solar panel was not impacted one way or the other by temperature... And it should easily bring the batteries over 15 volts (if the batteries are so inclined with that amount of current). 20 volts is probably unlikely unless you had an open cell.
    Coming back to charge controllers; it seems to me that as long as you keep your charging current below your battery's C20 rate by matching panel to battery, you cannot destroy (but only improve) your battery by applying the solar panel's full voltage to it. No need for a charge controller that cuts out at 14.4V, thereby eliminating the possibility to equalize your cells.

    Around here, we use the 1% rate of charge as the rough number to trade between no controller vs a "cheap" controller. Also--if charging sealed batteries, I would suggest using a controller anyway as you cannot replace electrolyte if they vent.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset