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  • #16
    Anyhoooow, ignoring the personal abuse and getting back on topic....


    Starfurry, your "I'm going to stick with the DCDC charger" makes me think you've already decided that issue, wisely in my view but you can see it's always a topic that sparks great passion from some.

    If you are considering the VSR route instead, one variable worth considering/measuring is your alternator output voltage over an extended period and range of driving conditions. There does seem to be some variation from one 2.8L to another 2.8L and as far as I know, nobody has determined any pattern. The higher your voltage, the less likely you are to suffer from premature battery failure.

    The VSR mob are always looking around for some deep cycle battery technology that performs well under those operating conditions, but are starting to run out of options, particularly if you include longevity in the calculation. If you're tempted to think VSR vendors know more about Optima batteries than Optima do, you just need to remember Jimmy's experience. He rocked up to Optima with a premature battery failure and they simply told him "a charging voltage of less than 13.65 volts WILL damage them over time", and good luck getting a replacement camping battery out of Toyota or your VSR vendor. Drivesafe is correct when he says that voltage only matters during the Absorption stage and that's exactly what a charger (AC or DC/DC) does, and at least for most of us, what our 2.8L alternator does not do.

    Also be weary of anyone trying to flog you an under-bonnet VSR+LeadCrystal solution. mjrandom has reported excellent performance from lead crystal batteries, but down the back hanging off of a DC/DC charger. The South Africans are reporting premature bulging failures when used up front. They appear to be blaming the lead crystal bulging on a combination of high engine bay temperatures and the very high charging currents you get from Alternator+VSR solutions:

    http://www.4x4community.co.za/forum/...attery-problem

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    • #17
      This whole subject just gets so confusing sometimes, but im happy with what Im ending up with.

      Thanks
      Starfurry

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      • #18
        aa

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        • #19
          Originally posted by dBC View Post
          Anyhoooow, ignoring the personal abuse and getting back on topic....
          While you keep posting up ignorance based misinformation, I’ll keep correcting it, and if you call this “personal abuse”, well it’s self inflicted.


          Originally posted by dBC View Post
          The VSR mob are always looking around for some deep cycle battery technology that performs well under those operating conditions, but are starting to run out of options, particularly if you include longevity in the calculation.
          Again, just more deliberate misinformation. If using a specific battery technology, combined with direct alternator charging means you get the fastest recharge possible, then any logical thinking person would choose the best setup available, regardless of what it is.

          Originally posted by dBC View Post
          If you're tempted to think VSR vendors know more about Optima batteries than Optima do
          Quite the reverse. If you had the slightest bit of knowledge as to how batteries charge, you would then know that the alternators in new 150s meets and exceeds the battery manufacturer’s charging data.

          A battery does not have to be charged across the whole charge cycle at 13.65v, it only needs to achieve this voltage for the final stage of the charge, and every time you start a 150, the alternator voltage will be at or above the 13.65v, job done.

          And if you “think” this is not correct, then you better not use a DC/DC device, because this is EXACTLY how they work, only they take much longer to reach the final stage.


          Originally posted by dBC View Post
          Drivesafe is correct when he says that voltage only matters during the Absorption stage and that's exactly what a charger (AC or DC/DC) does, and at least for most of us, what our 2.8L alternator does not do.
          Once again, another absurd statement. If you had the slightest idea what you were talking about, you would know that while DC/DC devices try to mimic what a battery charger does, you would know that the use of a DC/DC device automatically means the charge cycle lacks the most fundamental factor that makes battery chargers superior to either DC/DC devices and alternators.


          The FUNDAMENTAL difference that both DC/DC devices and alternators lack, is time. Battery chargers do a better job at charging because their charge cycle is usually not time limited.

          So while driving, as there is a limited recharge time available, as an alternator will easily bring a battery to a higher state of charge during this limited recharge time, logic would be that an alternator is far better for any battery.

          dBC, one more bit of information for your limited knowledge of how batteries charge. It takes at least 8 to 10 hours to fully charge any type of lead acid battery to a 1005 SoC, and this includes Optima and Lead Crystal batteries.

          So in real life, neither a DC/DC device or an alternator can achieve a 100% charged state while driving, or are you going to claim you drive continuously for 8 to 10 hours.

          Originally posted by dBC View Post
          The South Africans are reporting premature bulging failures when used up front. They appear to be blaming the lead crystal bulging on a combination of high engine bay temperatures and the very high charging currents you get from Alternator+VSR solutions:

          http://www.4x4community.co.za/forum/...attery-problem
          Here we go, when you are incapable of putting up an honest reply, resort to good old scaremongering.

          dBC, you found one thread on a failed Optima and one thread on a failed Lead Crystal Battery. Now go and do a Google of all the batteries that have been destroyed because the DC.DC device charging them overcharged them.

          This is a common problem when using a DC/DC device, but try an find a single event where an alternator has overcharged a healthy battery.

          Alternators have been around now for about 70 to 80 years, and they do not overcharge batteries, unless there is something wrong.

          On the other hand, DC/DC device are renowned for over charging batteries, particularly when fridge is being powered from the battery being charge by a DC/DC device.

          Comment


          • #20
            Originally posted by Starfurry View Post
            This whole subject just gets so confusing sometimes, but im happy with what Im ending up with.

            Thanks
            Starfurry
            Hi Star, and you are not Robinson Crusoe when it comes to the confusion surrounding the use of DC/DC devices and my apologies for making it more confusing.

            It's not hard to see why it's so confusing when the sellers of these devices use grossly misleading advertising to do so, and then to make matters worse, you have just as misleading replies as dBC's posts up.

            Using a DC/DC device does not necessarily mean you will have problems, as long as you know their limitations.

            Just enjoy your RVing

            Comment


            • #21
              Originally posted by drivesafe View Post
              I’ll keep correcting it
              Well I think we've both assumed that role. The difference is you seem to like to talk about me a lot, I prefer to talk about batteries. I'll continue to ignore the personal attacks and focus on the issues.


              Originally posted by drivesafe View Post
              It takes at least 8 to 10 hours to fully charge any type of lead acid battery to a 1005 SoC
              8 to 10 hours? At the alternator voltages I see I suspect I'd have to measure it in months, not hours. After the initial big current burst that only an alternator can provide, it turns into little more than a glorified trickle charger. Drivesafe there is one thing you could do that would make this issue go away for good: publish some charging graphs of a low voltage alternator like mine. I bet you'll see it drops below 25A way sooner than you think it does.

              I'll concede my world view on this may be tainted by my camping/touring style. Once I've decamped and set off for the next location I always drive for at least 3-4 hours. Invariably my camping voltage has dropped to 13.2V well before I get to my next destination, which means the charger has gone into float mode. Now I know float mode doesn't mean fully charged but it's getting awfully close to it. For me, the important question is not "which system can get the battery up to 85% fastest?" (answer VSR) but rather "which system can get the battery more fully charged in a 3-4 hour drive?" (answer DC/DC). Battery longevity is all about how long the battery sits around at less than 100% charge, and how far below 100% charge it is. Pulling into camp each night knowing the battery is starting the night at 98% charge is reassuring.

              Originally posted by drivesafe View Post
              DC/DC device are renowned for over charging batteries, particularly when fridge is being powered from the battery being charge by a DC/DC device.
              We both know there's a trivial solution to that. After a long line of cars fitted with VSRs, when I moved to a DC/DC in the new 2.8L Prado I was convinced I was going to need a changeover relay for two reasons:

              1. when you've only got a 25A charging budget, losing 5A to running the fridge is a significant hit
              2. if the charger was about to switch from absorption (14.5V) to float (13.2V) just as the fridge came on, it would delay that switch and you'd risk overcharging

              In practice neither turned out to be an issue and the relay I bought for the job remains collecting dust in the parts bin. It wasn't that many years ago alternators held batteries at 14.4V all day long, so delaying the switch from 14.5V to 13.2V while the charger waits 5 minutes or so for the fridge to complete its cycle is not a huge deal. The reality is that once underway, with the aircon on, the fridge simply doesn't run long enough for either to be an issue. If ever that changes, I'll dig out the relay.


              Originally posted by drivesafe View Post
              Alternators have been around now for about 70 to 80 years, and they do not overcharge batteries
              Did you see the bulges in those Lead Crystal batteries in the South African thread? They were clearly getting way too many amps dumped into them for the temperature they were at.

              Comment


              • #22
                Again this thread is being watched and the same culprits are at play.

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                • #23
                  Yes, but I'm desperately hoping this time we can keep it civilised, technical and on-topic. That's certainly my intent.

                  Comment


                  • #24
                    I'll let a third party's post answer here.

                    Michael had a DC/DC device for some time, and then replaced it. The results speak for them selves!

                    Originally posted by 120D4D View Post
                    I made good use of the Traxide Isolator over the holidays and kept it busy due to the hot weather for that week, along with my need for very cold beer! We ended up driving the Prado most days, some days it was running for 1-2hrs and other days, just 45 mins.

                    Each morning I had between 12.29 – 12.38 volts at the terminals.

                    The Optima is certainly grabbing plenty of amps early on and sharing that with the cranking battery after its shut down for the day and the difference between the short and long drive was very little.

                    Our last day and night was stinking hot and due to an early departure the next day, we had to run both my Waeco CFX50 and a huge 85L EvaCool that was being used as fridge/freezer.

                    Not surprisingly in 40c heat, the power available was very low by the morning but the SC80 did exactly as it should - the AUX read 11.30v and the Cranking Battery had recovered from the 12v cut-out back up to 12.20v.

                    I have no doubt that with my DCDC, or any other standard type of isolator, that the 66ah Optima would have been well and truly dead flat by morning and the cut-out voltage would have been reached on both fridges. This type of usage is a rarity for us, but it was reassuring knowing I have that extra reserve capacity available should we need it.

                    Comment


                    • #25
                      120D4D, after you switched to a VSR you mentioned disappointment in your overnight resting voltage:

                      Originally posted by 120D4D View Post
                      Well it looks like my Yellow Top is on its last legs.
                      Haven't been happy with the overnight readings for a few weeks now, only seeing around 12.4V now with both batts in shared mode
                      Reading on, it seems that was just down to some corroded terminals. How did that resolve itself? After cleaning the terminals, what resting voltage are you seeing now?

                      Comment


                      • #26
                        It turned out that I'd cracked the case and it was spilling its juices.

                        Not sure if it was from overtightening the terminal (guilty of that I've now discovered) or from taking the battery in and out too many times but either way I broke it!
                        Cheers
                        Micheal.

                        2008 GXL D4D Auto. GOING... GOING... GONE
                        2015 GXL 1GD Auto. And it begins again...

                        Comment


                        • #27
                          Originally posted by 120D4D View Post
                          It turned out that I'd cracked the case and it was spilling its juices.
                          Doh! Bugger! So a new Yellow Top to replace it? What resting voltages are you seeing with that? I seem to recall you were seeing higher alternator voltages than many of us, and we were never able to work out why. So long as your resting voltage is nice and high, you hopefully won't experience what happened to Jimmy.

                          Comment


                          • #28
                            Originally posted by dBC View Post
                            Doh! Bugger! So a new Yellow Top to replace it? What resting voltages are you seeing with that? I seem to recall you were seeing higher alternator voltages than many of us, and we were never able to work out why. So long as your resting voltage is nice and high, you hopefully won't experience what happened to Jimmy.
                            Yep, another D27F is in.

                            I've only been looking at the voltages in the morning before I head to work on my SolidKit display.

                            I'm seeing around 12.8 - 12.9v at the Optima in the morning and when I'm sharing the charge across both batteries I see around 12.6 - 12.7v which i'm pretty happy about due to my short drives each day.
                            Cheers
                            Micheal.

                            2008 GXL D4D Auto. GOING... GOING... GONE
                            2015 GXL 1GD Auto. And it begins again...

                            Comment


                            • #29
                              Originally posted by 120D4D View Post
                              Y
                              I'm seeing around 12.8 - 12.9v at the Optima in the morning and when I'm sharing the charge across both batteries I see around 12.6 - 12.7v which i'm pretty happy about due to my short drives each day.
                              Yes, that sounds very healthy.

                              Comment


                              • #30
                                What do you mean by sharing charge? I have a yellowtop with a vsr and mine sits at 12.6 resting voltage. The optima spec for yellow top says it should be 13.1v - cannot recall ever seeing that

                                Originally posted by 120D4D View Post
                                Yep, another D27F is in.

                                I've only been looking at the voltages in the morning before I head to work on my SolidKit display.

                                I'm seeing around 12.8 - 12.9v at the Optima in the morning and when I'm sharing the charge across both batteries I see around 12.6 - 12.7v which i'm pretty happy about due to my short drives each day.
                                2010 Prado 150 GXL Diesel, Cooper AT3, ARB compressor, Catch Can, Redarc BCDC 1225, Projecta DBC150, Optima YellowTop and RedTop D34, Pioneer Backbone Platform

                                Comment

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