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  • What battery monitor do I chose?

    I have learnt it is essential to have a good quality battery monitor installed in order to give me real time information about SOC, amps in and out, power consumption and so on.

    I will need one with a 100A shunt, as my Inverter is a 3000W pure sine wave.

    My local supplier has two makes to chose from.

    1. A Bogart Trimetric TM2025-A, or
    2. A Votronic Battery Computer model LCD100S 48V

    The Bogart seems to be more comprehensive in the amount of information it gives. However, it is quite expensive - the basic item costs $359, 100A shunt $40, 48V adapter $39, Cable $69, a total of $507.
    The Votronic comes in a 48V form, and includes shunt and cable for $399.

    The dealer recommends the Votronic, as he said the Bogart has "a 20 page installation manual that is difficult to comprehend".

    Anyone out there with experience of using this equipment? What would you recommend?

    Thanks.

  • #2
    Wow!

    $500+ for SOC is rather pricey!
    If all you are looking for is State of charge a $6 LED panel mount volt meter will do the job. You can even add a second one for current and be at a whopping $25 with the shunt!

    Also have a look on eBay you can get what you just listed for $230~

    What do you want it to do?

    If you like making things you can build one with any of the micro controllers on the market today. Or just some LEDs and passive parts.

    Comment


    • #3
      Yes, imported goods are expensive here in NZ

      It does seem a bit over the top if all I want to know is SOC. Especially since I, and the previous owner of our place, managed adequately with the analogue voltage meter - I knew from experience that if the meter showed 54V when the sun went down that the batteries would be fully charge at 51.6V or thereabouts, or if after a couple of days of bad weather it was showing 50 - 52V, then it was time to put the genny on and bring the charge back up.
      However, I now have a new charge controller and a new battery bank. The batteries have a five year warranty, and one of the warranty conditions says - "A reliable battery monitor must be installed in the system that give accurate charge/discharge in amp hours, state of charge and history for the batteries."
      Bugs me a bit, because the controller has a monitoring function built in (& there is an optional extra available enabling me to connect the controller to my computer), with a small LED screen with selectable parameters, including SOC, battery voltage and current, days max and min, PV voltage & charge state, generated energy & Pv power, batt temp and device temp. But the supplier/dealer says that these readings are not accurate and cannot be relied upon to give real time information, except early in the morning when everything has been at rest overnight and the sun hasn't come out yet!
      So, if I want to keep the warranty looks like I need a monitoring device that meets the warranty conditions.

      Comment


      • #4
        Midnight Solar also has a battery monitor
        http://www.midnitesolar.com/productP...tOrder=3&act=p
        but I don't think it reports amps in vs out, just a LED gauge.

        I've heard lots of good reports about trimetrics, never heard of the other one.
        Powerfab top of pole PV mount (2) | 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

        Comment


        • #5
          History for the batteries
          For how long?

          I would contact the battery manufacture and inquire about the details. Also if they don't give you a spec. to meet it is hard to define and enforce a "quality" device...

          As far as DC power goes it is easy to get accurate number with simple equipment so it "not being accurate" sounds suspect to me, but know knowing what you are using it's hard to tell. AC power measurements can get a lot more complicated....

          Stick a FLUKE 43B on the wall, and let them argue with it's "accuracy"!
          (it also data logs...)

          Comment


          • #6
            Originally posted by Sub View Post
            I will need one with a 100A shunt, as my Inverter is a 3000W pure sine wave.
            <snip>
            Bogart Trimetric TM2025-A
            <snip>
            The Bogart seems to be more comprehensive in the amount of information it gives. However, it is quite expensive - the basic item costs $359, 100A shunt $40, 48V adapter $39, Cable $69, a total of $507.
            <snip>
            Anyone out there with experience of using this equipment? What would you recommend?
            I have (and like) the Trimetric 2025A. They are widely available for less than $160. Do NOT get a 100 amp shunt... you want a 500 amp shunt on a system the size of yours. Doesn't cost any more than a 100 amp shunt.

            Bogart makes a somewhat more advanced model with more communications capabilities for data logging... I have no experience with it. Another highly regarded monitor is the Victron battery monitor.

            --mapmaker
            ob 3524, FM60, ePanel, 4 L16, 4 x 235 watt panels

            Comment


            • #7
              Originally posted by Colt45 View Post
              For how long?

              I would contact the battery manufacture and inquire about the details. Also if they don't give you a spec. to meet it is hard to define and enforce a "quality" device...

              As far as DC power goes it is easy to get accurate number with simple equipment so it "not being accurate" sounds suspect to me, but know knowing what you are using it's hard to tell. AC power measurements can get a lot more complicated....

              Stick a FLUKE 43B on the wall, and let them argue with it's "accuracy"!
              (it also data logs...)
              The not being accurate comment came about when I rang the dealer to ask why does the controller monitor show batt voltage at 56V (when 51.6V is full charge) but SOC show as 60%? He explained that the SOC % being shown is the percentage of the programmed charge going in to he battery bank - e.g. Absorb is set at 58.8V, so SOC is showing 60% of that, and that if I wanted accurate SOC info I had to check the monitor early in the morning, before sun is up, and after the system had been at rest overnight! Which is why I need a device that will give me real time info as I don't relish getting up that early!

              Thanks for the heads up on the Fluke, will google that and check it out.

              Comment


              • #8
                Originally posted by mapmaker View Post
                I have (and like) the Trimetric 2025A. They are widely available for less than $160. Do NOT get a 100 amp shunt... you want a 500 amp shunt on a system the size of yours. Doesn't cost any more than a 100 amp shunt.

                Bogart makes a somewhat more advanced model with more communications capabilities for data logging... I have no experience with it. Another highly regarded monitor is the Victron battery monitor.

                --mapmaker
                Thanks Mapmaker. Makes me envious to see how much the Bogart costs in your country! I have read lots of good reviews about the Bogart. It seems the Votronic is not well known over there. It is made in Germany so should be well engineered, and here it is $100 or so cheaper than the Bogart. (Although our dollar is not worth quite as much as yours - I am quoting NZ $, which is presently worth around 85c US)

                Will look at options for buying overseas and importing privately - should not attract too much in import taxes, I hope!

                Thanks for putting me right about the size of the shunt needed.

                Comment


                • #9
                  Victron

                  Originally posted by mapmaker View Post

                  Another highly regarded monitor is the Victron battery monitor.

                  --mapmaker
                  Just checked, Victron products are sold here, the BMV600s costs $294.40 & the 602s is $385.25.
                  Presumably the 602s is the better model?

                  Comment


                  • #10
                    I faced just the same problem yesterday -- what battery monitor do I use? After thinking about it more, I realized that what I really wanted was a charge monitor. I wanted to see how much current was flowing in and out of the batteries throughout the day; collect historical data, monitor performance, and alert on trouble. The solutions that I saw all were proportionally expensive. After all, I only plan to have a 1.5 kW inverter and < 1 kW of panels.

                    After some research, I realized that I could pretty easily create a solution on my own. Texas Instruments makes an ina226 chip that does just what we need: reads shunt voltage and bus supply voltage. It even handles calibration and multiplication. It operates up to 36VDC, so it'll be good for 12v and 24v systems. It's fed via 5vdc. It will communicate via i2c with a raspberry pi. For less than $100, I'll have a programmable and network-capable charge monitor.

                    I'll release it all open source and make as post about it in a few nights.

                    Cheers!

                    Comment


                    • #11
                      [QUOTE=ryan.turner;118285]

                      After some research, I realized that I could pretty easily create a solution on my own. Texas Instruments makes an ina226 chip that does just what we need: reads shunt voltage and bus supply voltage. It even handles calibration and multiplication. It operates up to 36VDC, so it'll be good for 12v and 24v systems. It's fed via 5vdc. It will communicate via i2c with a raspberry pi. For less than $100, I'll have a programmable and network-capable charge monitor.



                      My system is 48V, so this will not work for me!

                      I have been doing a lot of research on line since first posting this. I have found some RV and live aboard boat forums who have very long discussions on this topic. The concensus seems to be that NO shunt based monitor will give accurate SOC reading! They claim that as the battery bank ages and capacity drops, the monitor "runs out of synchronisation" with the battery SOC.

                      For accurate SOC the device most often recommended is the SmartGauge. This device does not use a shunt. I have not been able to find local retail outlets for it, so would have to be ordered from the UK. However, further research shows that the SmartGauge can only be used on 12 & 24V systems!

                      The next most recommended monitor is the Bogart Trimetric. I can order on line from USA or other overseas dealers, but I worry that it would be difficult to get warranty/servicing issues sorted at a distance.
                      So it seems that I will need to pay around $500 NZ dollars (1 NZ dollar = 85c US), that price includes everything needed to install and partial programming by the NZ dealer. Looks like that is the way I will go.

                      Comment


                      • #12
                        Originally posted by Sub View Post
                        I have been doing a lot of research on line since first posting this. I have found some RV and live aboard boat forums who have very long discussions on this topic. The concensus seems to be that NO shunt based monitor will give accurate SOC reading! They claim that as the battery bank ages and capacity drops, the monitor "runs out of synchronisation" with the battery SOC.
                        Yes, the monitor runs out of synchronization, but it can be resynchronized. It is best to resynchronize it when the battery is fully charged... and the battery needs to be fully charged at least every week so it does not become stratified and sulfated.

                        A battery monitor is often compared to the gas gauge in your car, but that is not a good analogy.

                        The gas gauge in your car actually measures the level of gas in your tank. A battery monitor doesn't measure the level of anything. It is more like the odometer in your car. The odometer counts miles and the battery monitor counts ampHours.

                        Suppose you have a car that gets about 25 mpg and has a 15 gallon gas tank. Suppose also that your gas gauge does not work. What do you do? You use your odometer. For example: After a fill up you drive 150 miles and you expect that you have used 6 gallons and have 9 gallons remaining in your tank.

                        If you fill up the tank again you can, as above, use your odometer to estimate your gallons remaining.

                        But what if you do not completely fill your tank. For example, starting from a full tank you drive 150 miles and then you add 3 gallons to your tank and then drive 100 miles and then add 4 gallons to your tank and drive 150 miles and then add 5 gallons to your tank and drive 100 miles. At this point you estimate that you have 7 gallons remaining in your tank, but that estimate is not too accurate because your mileage is not ever exactly 25 mpg. The only time you know exactly how much gas is in your tank is when you have just filled it up (or when you run out of gas).

                        So it is with your battery monitor. The only time it is exactly accurate is when you fully charge your batteries and reset the battery monitor to read 100% full. It can be very accurate counting the amphours in and out of the battery, but it can only estimate the state of charge based on your assumptions of the battery capacity and of the battery efficiency. It can read 100% (by counting amphours into the battery) before the battery is fully charged.

                        Most shunt based battery monitors reset to 100% based on criteria that you set... usually end amps. For example, you may program the monitor to reset to 100% when the voltage is at least 58.8 volts and the current is below 20 amps for a minute. But is that really when your batteries are charged?

                        If you're going to train your monitor how to recognize a fully charged battery, then you yourself must know when the battery is fully charged. You may accomplish this by monitoring end amps during absorb charging and using an hydrometer or refractometer to know when your batteries are fully charged.

                        Bottom line: the longer its been since a complete charge, the less you can trust your battery monitor. And you can't trust it at all if its not set up correctly. That said, battery monitors are valuable tools in estimating your SOC, but you have to understand their limitations. You must have a hydrometer or refractometer, and and a way to monitor the current into the battery.

                        When you know the fully charged 'end amps' current and absorption voltage of your batteries, you can program your battery monitor to be more accurate.

                        Over time the battery capacity may decline. If you feel that your battery does not have the capacity that it once did, you can program the battery monitor to use a lower capacity in its calculations. I reduce the battery capacity setting of my Trimetric in the winter because my batteries are about 25° cooler in the winter than the summer.

                        --mapmaker
                        ob 3524, FM60, ePanel, 4 L16, 4 x 235 watt panels

                        Comment


                        • #13
                          Originally posted by Sub View Post
                          I have been doing a lot of research on line since first posting this. I have found some RV and live aboard boat forums who have very long discussions on this topic. The concensus seems to be that NO shunt based monitor will give accurate SOC reading! They claim that as the battery bank ages and capacity drops, the monitor "runs out of synchronisation" with the battery SOC.

                          For accurate SOC the device most often recommended is the SmartGauge.
                          I got news for you, no system is going to tell you accurately what the battery SOC is. There is only one-accurate way to determine a batteries true SOC, and that is to use a lab quality battery hydrometer and thermometer.

                          Also your boat friends are partially correct when they say SOC does not tell you anything about capacity, not even a hydrometer can tell you that. Only a controlled Load Discharge Capacity Test can tell you capacity which you cannot likely do without some very expensive test equipment and load boxes. You can have a 10 year old 100 AH battery sitting next to a new one and both will read 100% SOC. However the 10 year old battery if tested my only have 20% of its rated capacity, while the new one has rated capacity.
                          MSEE, PE

                          Comment


                          • #14
                            [QUOTE=Sub;118290]
                            Originally posted by ryan.turner View Post

                            After some research, I realized that I could pretty easily create a solution on my own. Texas Instruments makes an ina226 chip that does just what we need: reads shunt voltage and bus supply voltage. It even handles calibration and multiplication. It operates up to 36VDC, so it'll be good for 12v and 24v systems. It's fed via 5vdc. It will communicate via i2c with a raspberry pi. For less than $100, I'll have a programmable and network-capable charge monitor. My system is 48V, so this will not work for me!
                            I would just scale the input voltage sensing say, by 1/2 of the 48V. Of course you need to
                            multiply all its outputs by 2 for the right answer. Running at 48V, maybe you could afford
                            to double the loss in the shunt voltage drop, and be on target for watts or watt seconds.

                            Bruce Roe

                            Comment


                            • #15
                              Originally posted by Sunking View Post
                              I got news for you, no system is going to tell you accurately what the battery SOC is. There is only one-accurate way to determine a batteries true SOC, and that is to use a lab quality battery hydrometer and thermometer.
                              I have slowly reached the same conclusion from all my reading up on monitors. I have AGM batteries so cannot use hydrometer. I do not want to each day disconnect my battery bank from PV and inverter, let rest for about four hours, then use a voltage tester to check for SOC. I have been told that I can fairly accurately estimate SOC from the resting voltage. E.g. For AGM batteries 51.6V=100% SOC and 49.6V=50% SOC. (Information provided by the dealer who sold me the batteries).

                              I believe that battery voltage shown during charging or discharging is not accurate which is why the batteries need to "rest" . The information I have been reading about battery monitors seems to claim that they use some sort of algorithm to more accurately show battery voltage in real time without the need to rest the batteries.

                              Clearly, I need that sort of information to help me manage my system - i.e. can I watch TV tonight, do I need to start the generator, do I need to stop the generator from charging the batteries, and so on.
                              Another example, I seem to discharge my batteries between 15 and 20% each night, and from what I have been told I believe I then need to bring them up to full charge during the following day, except of course during times of bad weather, when I need to carefully watch to ensure I do not discharge by more than 50%, and when it gets close to that I start the generator and charge the batteries.

                              Am I correct in my understanding that a good battery monitor will provide me with that sort of information?

                              Presently I use an analogue voltage meter, and from experience I know that when the sun goes down and the voltage meter is showing 54V then my batteries are around a true reading of 51.6V. If showing 52V or less I fire up the generator until the meter reaches 56V, when I switch off, the meter tends to settle on 54V.

                              However, the analogue voltage meter is a left over from my original system when I had a 48V bank of Trojan T105s and a Xantrex PWM controller. I now have a 48V, 580ah @ c20 bank of AGM batteries and a eTracer 60A MPPT controller. I think I need something a bit more sophisticated to help me manage this and hopefully a good quality battery monitor will help me do that.

                              Comment

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