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  • #46
    I have to add to this debate and point out that deep cycle chart on page 14 of the battery spec. The graph shows charge cycles from a very deep 10.02 volts. I know it is very unwise, even with a deep cycle battery, to constantly let a battery get down to 10.02v. To me, it looks like the long term damage is being done because the voltage is allowed to get too low not because of the voltage that charges it. The higher voltage charge, after a very deep cycle, only reduces the long term damage from letting your battery run down too low. If you do "accidentally" let the voltage get extremely low, you can recondition the battery using a proper charger that has a high charge voltage recondition program.

    I also have to point out the temperature compensation graph on page 15. If the battery is under the bonnet then its temperature is going to rise. The under bonnet heat is the reason why car manufactures make the alternator run at a reduced voltage as temperatures rise. To quote the battery spec, "the voltage MUST be reduced as the temperature rises". Looking at the chart, at 25 degrees the theoretical ideal cycle voltage is 14.7v. At 40 degrees it is 14.4v and reduces to 14.1v and flat lines when temps go above 60. Therefore, the magical 14.7v cyclic charge voltage, and float voltage, should be compensated when temperatures change from 25 degrees.

    Yes, a charge voltage of 13.6v is not ideal if the battery is at or below 25 degrees. If the battery is located under bonnet and subject to heat from the engine and radiator, the voltage from the alternator fine and is doing what it should! Therefore, a DC/DC charger only should be used if the battery is not under the bonnet or if the charger has the ability to lower the voltage if it senses the battery temperature is rising.
    Last edited by Mr ok; 24-05-2017, 10:25 PM. Reason: typo

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    • #47
      The bottom line is if you can't correctly charge the Optima's and the Odyssey batteries from the vehicles alternator then both manufactures are marketing a product that is not fit for purpose. They are targeting these batteries for use in vehicles and boats as combo starter and deep cycle batteries stating provides cranking power and deep cycle ability to run accessories etc knowing that standard vehicle alternators can not properly maintain the battery when used as such?

      DBC,

      Regarding your statement:

      "It's a shame more deep cycle manufacturers aren't so open with their testing data."

      I would not say that is a fair comment, most manufactures specify their recommended charging regime, again most manufactures (Optima being an exception) readily provide information regarding life cycles versus depth of discharge. Most deep cycle AGM batteries, especially starved electrolyte batteries would not take kindly to being charged at 14.7V -15V for 16 hours as per the odyssey requirement.

      Personally I find the data questionable, they indicate it is important to charge at 14.4V - 15V, only data supplied for 14.2 and 14.7V. Then in small print:

      Samples 1 & 2: Given a 24hr CC charge @ 650mA prior to cycle 55, then resumed cycling
      Sample 3: Given a 24-hr CC charge @ 650mA at cycle 359, then resumed cycling
      Sample 4: Given a 24-hr CC charge @ 650mA at cycle 254, then resumed

      What affect did the constant current charge have on the results, it appears it was an attempt to resurrect the battery, interestingly the Ah was higher for a short period after the CC charge than the other two. What would another CC charge at 100 cycles would have done?


      Why also the rather large difference in cycles between the two at the higher charge voltage?

      It would seem rather than other manufactures come clean it is more a case of deceptive advertising practices of Odyssey and possibly Optima as it would appear these batteries are not suitable for use as deep cycle batteries when charged from common vehicle alternators.
      LeighW
      Avid PP Poster!
      Last edited by LeighW; 25-05-2017, 11:00 AM.
      HKB Electronics, manufacturer of the Alternator Voltage Booster, Silver 2008 D4D,Lifted,Underbody protection, Alternator Voltage Booster, Tiger Z winch, Lightforce DL, Air Horns, Tanami Drawers, Drop down fridge slide, Outback cargo barriers, Rotronics dual Battery system, Polaris GPS, HF/UHF/VHF, Radio speaker combiner, Long ranger water tank, Diff breathers, Inverter, Snorkel and others

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      • #48
        Originally posted by LeighW View Post
        The bottom line is if you can't correctly charge the Optima's and the Odyssey batteries from the vehicles alternator then both manufactures are marketing a product that is not fit for purpose.
        I think that's what Jimmy has been saying all along.

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        • #49
          Sooooo.... back to the original question. What's the consensus on the best bang for buck aux battery and why?

          Comment


          • #50
            http://www.rpc.com.au/pdf/REDARC_iso...e_vehicles.pdf
            That explains my point overall regarding the use of a VSR and a variable output alternator.
            However, as I have said earlier, Drivesafe has his opinion and I have mine.
            JimmyC
            Advanced Member
            Last edited by JimmyC; 27-05-2017, 11:43 PM.

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            • #51
              Hi Jimmy and why is it when I post up info based on real world facts, that this is nothing more than my opinion, but you read some advertising and it answers all your questions.

              Jimmy, based on the info you have posted up in your various replies, your problem has nothing to do with what type of system you are charging your battery with, it is the SHORT driving times you do.

              Here is a link to high current DC/DC devices. These start at 80 amps and go up to 300 amps.

              https://sterling-power-australasia.c...rs-up-to-130a/

              This is REAL DC/DC charging power, but if you were to fit the 130 amp unit ( your alternators maximum is the limiting factor for using anything bigger than a 130 amp unit ), you still WOULD NOT resolve your specific situation.

              If you ( or anybody else ) do not drive long enough, no setup is going to charge your batteries, and again, Jimmy this is based on facts, not my opinion.

              Comment


              • #52
                Re-reading our back and forth, I believe I moved off track and began to generalise regarding the Prado charging system as a whole and I think that caused a little confusion between you and I.
                So, yes, if my aux battery were to be discharged my normal short commutes would cause my aux battery to take a while to charge so I know that my short drive times do not contribute well to a fully charged battery. However the only times my battery was discharged below 12.5v or so would be when camping, which would be followed by a 90 minute+ drive back home, therefore charging the battery so I still cannot reason what made a battery, that is supposed to be one of the best you can buy, last less than 2 years other than the low charging voltage of the toyota?
                Do you believe that the low charging voltage of the Prado (13.3-13.4 volts) shortens the life of a battery?

                Comment


                • #53
                  Hi Jimmy and you keep changing your replies.

                  If your Toyota’s alternator voltage NEVER got above 13.4v, then your I would imagine, long term, this would be detrimental to any type lead acid battery, not just an Optima.

                  But Jimmy, you have posted so many different alternator voltages, so what is the voltage you are concerned about and why? Because in an earlier post, you stated your were getting up to 14.5v for the first 20 minutes.

                  If you are getting just 14.0v for short periods of time, then there is no reason why your Optima can not reach a fully charged state, and under normal use, your battery should have had a longer life span.

                  Is there more to your battery use than you have posted up?
                  drivesafe
                  Senior Member
                  Last edited by drivesafe; 28-05-2017, 08:10 PM.

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                  • #54
                    You are right in saying that if it never gets above 13.4 it would damage a battery.
                    If you read my post regarding the alternator voltages it states that the 14.5 is achieved with a boosting diode (AOC), and on a 5 or so degree night at cold start. Once warmed (approx 20 mins give or take depending on driving) the output drops to the 13.9 - 14.0 mark. The AOC achieves on average a 0.5 volt increase in charge voltage so do the maths there. Otherwise I am more than happy to whip out the multimeter and post some photos of readings.
                    I only bought the AOC after I had replaced the Optima so all the Optima charging voltages were less. Way less if you consider that for 6 months of the year here the temperature is over 30 during the day where I saw pre-AOC installation numbers of 13.1-13.2V charging according to the display in my car on a 30 degree day within 2-5 minutes of engine start.
                    If the battery is discharged to 50% SOC and it's a 30 degree day when you drive home from camping then the low voltage is surely damaging the battery right?
                    I don't believe my battery usage is the issue, Century start battery, SBI12 isolator, Optima d34m (prior to replacement), 4 gauge cable connecting. Never deep discharged the battery below 12.0v. But as stated I camped multiple times where the morning temperature was already 30 so the battery was not going to get it's full charge voltage.

                    Comment


                    • #55
                      So from what I see the low charging voltage (after its warmup period) from a variable output alternator is what causes damage and loss of lifespan to a battery, couple this with a VSR without the use of a voltage booster then you have the recipe for a damaged battery.
                      As I have said the solution to this for the average user is the fitment of a DC/DC charger and/or the fitment of a voltage booster.

                      Comment


                      • #56
                        Hi again Jimmy and sorry mate, but you just do not understand what is meant by low voltages damaging a battery.

                        Again as posted above, if the voltage never gets over 13.4v, then yes, long term, the prognosis for any lead acid battery would not be good.

                        This is not the case with your situation, but this is where you misunderstand the voltage levels.

                        If the voltage goes up to say 14.0v and then drops to 13.2v, you think that the lower voltage will now damage the battery.

                        Providing the voltage goes over 13.85v each time you start to drive your vehicle, eventually, your Optima will reach a fully charged state.

                        If after the initial higher voltage, your alternator voltage then drops down again, your battery will not be effected in any way, while the voltage remains above 12.7v.

                        If the voltage did drop below 12.7v, the battery, if it had reached a fully charged state, it would start to be discharged by the vehicles own electrical needs.

                        NOTE, even this would not damage the battery short term or long term. It would only damage the battery if is was kept at this low voltage all the time.

                        In the real world, and not having a go at you, just using real world situation to give you an example of what is happening millions of times everyday.

                        Vehicles with STOP/START operations, the alternator is turned off every time the motor stops, when the vehicle stops, say at traffic lights and the vehicles electrics run off the battery ( or batteries in some dual battery setups ). When the driver presses the accelerator peddle, the vehicle starts it’s motor again, the alternator then replaces the battery energy used while the motor was off.

                        STOP/START vehicle’s batteries last around the same length of time as the starting battery in any other vehicle.

                        So having the voltages go high and low all the time does not damage a battery, but if the voltage never went high at any time, then the battery could be damaged.

                        Again Jimmy, I don’t think you understand how batteries are charged, but rather than keep repeating myself and you not believing what I post up, try googling IUoU battery charging.

                        IUoU is the basic method most multi stage battery charges use to charge lead acid batteries. If you google this, you may better understand how you can successfully charge a battery and not damage it just because the voltage drops.

                        Comment


                        • #57
                          Originally posted by JimmyC View Post
                          I saw pre-AOC installation numbers of 13.1-13.2V charging according to the display in my car on a 30 degree day within 2-5 minutes of engine start.
                          If the battery is discharged to 50% SOC and it's a 30 degree day when you drive home from camping then the low voltage is surely damaging the battery right?.
                          Yep. If it's dropping to those voltages 5 minutes in and never rising again, it's not because the alternator has hit its power limit and is flat out; rather, the alternator has backed right off. It would be interesting to have put an ammeter on your battery under those conditions and see how much current was going in, but at 50% SOC, my guess would be not much (significantly less than the 25A say you'd get from a DC/DC pumping it in at higher voltages). I've attached a graph of how much current my camping battery will take at voltages slightly higher than that (13.4V) and it's pretty disappointing. The cause for my low voltage (still higher than yours) was a combination of the low alternator voltage (13.6 - 13.7) and the ~0.3V drop across the inadequate temporary wiring I used for the experiment, but either way, it shows the effect of low voltage on charging rate. For the purpose of charging your camping battery, I think even your long pre-AOC drives were effectively being turned into short drives courtesy of the alternator voltage dropping to 13.2V just 5 minutes in.

                          What I'm unsure about is what Optima really mean when they warn of shortened battery life from charging voltages lower than 13.65V. It's possible they just mean you'll never get the battery fully charged, and then suffer from the usual sulfation problems of leaving a battery under-charged. But it almost sounds like they're saying even if you do drive long enough to get it fully charged at those low voltages, you'll shorten its life (as in the Odyssey test results). VRLAs are curious beasts. Early in their lives they behave more like flooded lead acids, but as they age, they become more like NiCd batteries because of the need for an oxygen recombination cycle. NiCds actually benefit from high finishing currents to achieve that.
                          Attached Files

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                          • #58
                            What is the SOC of the battery at the start of charging?

                            That's a low charge rate, a Marine pro discharged to 60% SOC pulls [email protected] initially is still pulling 29.5A 30 minutes later with a terminal voltage of 12.8V. With a terminal voltage of 13.6V its still pulling 28A.

                            Would be worth keeping in mind if its hot enough for the alternator compensation to back off the charging a DCDC charger mounted under bonnet will do the same thing, a common complaint of those travelling north is the DCDC chargers stop charging when the temperatures go up.

                            You can mount the charger in front of the radiator but then your defeating the purpose of the temperature compensation.

                            Optimas aren't hard to charge if you get a good one, I've had two die prematurely, the third is fine so far and is being charged using the same system, as far as I'm concerned there just c%^p batteries to start with.

                            Who exactly at Optima indicated their batteries weren't suitable for charging of alternators when being used as a deep cycle battery?
                            LeighW
                            Avid PP Poster!
                            Last edited by LeighW; 29-05-2017, 02:57 PM.
                            HKB Electronics, manufacturer of the Alternator Voltage Booster, Silver 2008 D4D,Lifted,Underbody protection, Alternator Voltage Booster, Tiger Z winch, Lightforce DL, Air Horns, Tanami Drawers, Drop down fridge slide, Outback cargo barriers, Rotronics dual Battery system, Polaris GPS, HF/UHF/VHF, Radio speaker combiner, Long ranger water tank, Diff breathers, Inverter, Snorkel and others

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