Emergency power

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  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Emergency power

    mike,
    if you are referencing to my post or to the user ham radio's post, i'm not seeing that either of us mentioned the subject of EQing. physical movement of the batteries will lessen the frequency of having to eq imo though. i am assuming we are in agreement on the battery expansion being undercharged if only using a 65w pv.
  • mike95490mike95490 Solar Expert Posts: 8,463 ✭✭✭✭✭
    Re: Emergency power
    niel wrote: »
    65w of pv will work ok (not within good charge range percentages) with an 85ah battery, but if you increase the battery capacity to about 220ah, there's no way you'd have enough current to properly charge the battery. the number of pv watts will need increased. you could roughly figure about a watt of pv for each ah of battery capacity at 12v and mind you that this is not a rule of thumb to go by in all cases as i'm only saying this as a rough idea for you. there isn't any good substitute for actual calculations. the general rule of thumb for most standard lead acid batteries, especially generic brands, would be a charge rate of about 5-13% of the total amp-hour battery rating based on about a 20hr rate unless the manufacturer would state otherwise. do know that many can take the higher rates, but even with that ok from the manufacturer, the farther it is above the 13% rate the higher the maintenance will be and a possible increased chance of failure for some more cheaply made batteries.

    Isn't the lower end of the charge rate set at something that will vigorously bubble the battery to sir the electrolyte? Or is it to prevent the cells sitting too low, for too long and sulphating ? I haven't done the math.
    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 ,

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Emergency power

    "Isn't the lower end of the charge rate set at something that will vigorously bubble the battery to sir the electrolyte? Or is it to prevent the cells sitting too low, for too long and sulphating ?"

    stirring of the electrolyte is a result of charging and those rates weren't derived just to stir it.
    your last question describes a float charge and not the normal bulk charge rates.
  • rohanjcprohanjcp Solar Expert Posts: 30 ✭✭
    Update and grounding

    Hello thank you for all your helpful feedback in this forum. I would like to update you about my solar system:

    *My crimper tool, cutting tool, and stripping tool have arrived.
    *I looked at the manual of my Samlex inverter and noticed that the positive and negative input to the inverter required a tiny pin-type terminal connector for my 8AWG wire. I searched and couldn't find it online. I asked SAMLEX where I could get it and they said it can only be ordered from Taiwan. They reassured me that i can use any copper terminal and fit it by smashing or pushing any kinds of connectors etc.

    My question today is based on my conversation with the Samlex rep. He sounded like it was important to ground the inverter. The concept of grounding has been mentioned in this forum many times but I'm still confused. here is where I think it means:

    Image10.gif
    Based on the info from this website.

    It seems that all I need is 1 piece of bar that has many screws on it and that would do. Like this one.

    Is it something as easy as this?

    Thanks

    rohan
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Emergency power

    not quite right. it is considered a common point, but...........
    the inverter needs a heavy gauge copper wire from the inverter to an 8ft copper ground rod outside and your utility also has such a ground wire and rod for your home if you are on the grid.
  • rohanjcprohanjcp Solar Expert Posts: 30 ✭✭
    Battery monitoring

    Hello friends,

    I would like to thank you all for all your help and support. 2 days ago, I was finally able to charge my 12v battery under the sun with the new setup. As most of you know, I started totally from scratch and relied on your feedback and support to get this far. Many thanks to you all.

    My next step is to use the 12v battery on an inverter. I have everything i need except a battery monitoring device. Bill suggested the watts up meter / doc watson meter. However, upon research, I learned that it tells me the amount of energy passing through. I don't know of this is the conventional way to keep track of battery power, but I got spoiled with those little aa/aaa battery tester that tells you straight off how much percent of energy is left. I know that it is better to measure the amps in the 12v battery than the voltage of the 12v battery. I just don't know which product can do that other than the products in the $180 range.

    Is there a better product that would be more helpful in understanding how much energy is left on the battery that is almost like a wattsup meter? I will use the battery and the inverter without the panels and would like to know when I am at 50% energy left.

    Here are 2 products I was looking at:
    *A blue sea dc analog voltmeter (here)
    *An Equus 3320 Auto-Ranging Digital Multimeter (here)

    What do you think of these or do you have any other product that you like?

    rohan
  • BB.BB. Super Moderators, Administrators Posts: 29,697 admin
    Re: Emergency power

    The Wattsup and such list Watt*Hours--and you just need to do the division by battery capacity with a calculator.

    However, the best is to use a true Battery Monitor designed exactly for the task. They include xx% of battery capacity. But they are not cheap.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rohanjcprohanjcp Solar Expert Posts: 30 ✭✭
    Wattsup meter
    BB. wrote: »
    The Wattsup and such list Watt*Hours--and you just need to do the division by battery capacity with a calculator.
    -Bill

    Thanks Bill. That's probably just what I needed.

    The wattsup gives the following 8 measurements A, V, W, Ah, Wh, Ap, Vm, Wp.

    The A, V, and W are always displayed on device while the Ah (charge), Wh (energy), Ap (peak amps), Vm (minimum volts), Wp (peak watts) take turns to show up. Are you meaning to say that I wait for the Wh (energy) to show up and do the math?

    Also, would you be able give me the formula you are referring to?
    I am thinking:
    Amps left in the battery= battery capacity / Wh in the meter (battery's energy indicated)
    Amps left in the battery= 40AH AGM battery (24 hours period) / Wh in the meter (battery's energy indicated)


    Also, this device uses 14awg wires. Do you think it would work on my system that uses 10 awg and 8 awg?

    Thank you so much.
    rohan
  • BB.BB. Super Moderators, Administrators Posts: 29,697 admin
    Re: Emergency power

    Well... You can get the Amp*Hours of the battery from its Ratings table (20 Hour Rating is how much current the battery can provide from 100% to 0% state of charge over a 20 hour period (good number to start with).

    So, a 100 AH battery can supply:

    100AH/20Hours = 5 amps (over a 20 hour period)

    And you can use the AH portion of the meter to measure that directly.

    And, for the most part, reading AH from the battery is more accurate. The battery is some 98% efficient (+/-) regarding Charge in and out (Amp*Hours).

    For Watt*Hours, just take the Amp*Hours times the battery's average voltage:

    100 AH * 12 volts = 1,200 Watt*Hours or 1.2 kWh

    Batteries because the voltage depresses on discharge (approx. 12 volts) and is elevated on charge (aprox 14.2-15.x volts)--Watt*Hours is less accurate of measurement of battery capacity (very roughly, 80-90% accurate).

    The Battery Monitor takes into account that a battery's "capacity" changes based on current flow (higher current, lower effective capacity). And some of the higher end units even have a remote battery temperature sensor to even better judge battery state.

    Lastly, a battery monitor will also reset to 100% capacity when the bank is equalized (and lots of other features that log battery performance). The Watts up and similar do not have that ability.

    The Watts up and Doc Watson devices are good bench top systems for performing experiments (and, I guess they are even small enough that people put them in their electric power RC planes).

    Certainly, if you are going to draw lots of power (over 20 amps or so) to run your inverter/charger/etc.--they are probably too small for your needs (Although, I think you can add an external shunt to them). It all depends on how much you want to experiment vs just getting some that works.

    The Trimetric (from a couple other people's comments here--I have never used one) is a good low cost unit and performs the task well. However, it probably costs 2-3x the Wattsup unit... Only you can decide if it is worth the price or not to you.

    I probably would stay away from the analog panel meter. They are not really accurate enough for your needs (you need at least 0.x volt accuracy) and you would probably need to install a press to test switch to read the voltage (may discharge your battery if left on for long periods of time if no charging current available).

    DVM wise--get whatever you like. I have used Flukes over the years at work--but my home DVM is still a cheap no-name unit I bought for college some 30 years ago (gosh--am I cheap :roll: ).

    For my 2 cents--I would go with a real battery monitor. Anything else is either guessing (if using a DVM and amp meter) or a pain (measuring specific gravity of the electrolyte), or impossible to do directly (sealed batteries). If you save your battery bank from an early death--the battery monitor may have paid for itself (depending on the size of your battery bank).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rohanjcprohanjcp Solar Expert Posts: 30 ✭✭
    Trimetric

    Hello Bill,
    Thank you very much for your wise advice. I will read up about the trimteric and their shunts.

    rohan
  • mike95490mike95490 Solar Expert Posts: 8,463 ✭✭✭✭✭
    Re: Emergency power

    OK, I finally got a public pictorial up about my Monolith construction.
    http://tinyurl.com/SolarMonolithConst

    My links at the AEZ site keep getting broken as they move stuff around.
    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 ,

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Emergency power

    very interesting mike, but looks very heavy. any chance of that rim casting a small shadow?
  • mike95490mike95490 Solar Expert Posts: 8,463 ✭✭✭✭✭
    Re: Emergency power
    niel wrote: »
    very interesting mike, but looks very heavy. any chance of that rim casting a small shadow?

    Sure there is a chance, but re-aiming 3 or 4 times a day solves most of that. And 1 or 2x day bath in the desert to keep the dust off. Many folks without a water allotment for panel washing, get very low power by the end of the 2nd week.

    And, heavy is the idea, when I pull the dolly off, it's much more resistant to walking away. Two people can carry it a short distance, but not far. Also resists wind gusts pretty well. (2 batteries make great ballast, they are in marine battery cases, with the straps lashed on)
    OK, I finally got a public pictorial up about my Monolith construction.
    http://tinyurl.com/SolarMonolithConst
    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 ,

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Emergency power

    my comments bolded and this to satisfy 18 characters or more.:p
    mike90045 wrote: »
    Sure there is a chance, but re-aiming 3 or 4 times a day solves most of that. And 1 or 2x day bath in the desert to keep the dust off. Many folks without a water allotment for panel washing, get very low power by the end of the 2nd week.

    maybe hand wash as best as you can and then use a 12v portable sweeper for finer stubborn particles.

    And, heavy is the idea, when I pull the dolly off, it's much more resistant to walking away. Two people can carry it a short distance, but not far. Also resists wind gusts pretty well. (2 batteries make great ballast, they are in marine battery cases, with the straps lashed on)

    good points.
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