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  1. #13
    Junior Member dBC's Avatar
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    Quote Originally Posted by drivesafe View Post
    And you base this statement on your wealth of experience in this field,
    I don't think I've claimed any wealth of experience have I? Starfurry seems smart enough to work it out for himself. I'm not the one suggesting he change course.

    Quote Originally Posted by drivesafe View Post
    Oh thats right, you didn't know how to do something as simple as charge a battery with a battery charger, without destroying the battery.
    ??? I can't recall destroying any batteries. I'm almost 2 years and 40k in and both my camping and cranking battery behave like they're brand new. I also had great battery longevity in my old petrol 120 with a VSR.

    Quote Originally Posted by drivesafe View Post
    it does not require a constant voltage of above 13.65v to fully charge an Optima,
    Of course!

    Quote Originally Posted by drivesafe View Post
    it only requires that voltage level for the final stage of the charge and as DC/DC devices CAN NOT charge at a constant voltage as high as that, EXCEPT in the final stage of the charge, your theory would then mean a DC/DC device will also stuff batteries.
    That sentence is not even internally consistent.

    Quote Originally Posted by drivesafe View Post
    Your statements are not based on FACTS,
    They're based on the Optima datasheet, and what Optima told Jimmy when he complained that his battery didn't last two years.

  2. #14
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    Quote Originally Posted by dBC View Post
    ??? I can't recall destroying any batteries. I'm almost 2 years and 40k in and both my camping and cranking battery behave like they're brand new. I also had great battery longevity in my old petrol 120 with a VSR.
    You may not have destroyed your battery, but you were only too happy to instruct others on how, had they followed your misinformed advice, they would have destroyed their own batteries.

    This field is just like any other. You have to know how carrying out one operation might effect other devices/operations elsewhere in a system.

    You quite obviously have a very limited knowledge of this field but you are a self-proclaimed expert about a field you know nothing about.

    As above, without an understanding of how EVERYTHING in a system reacts with everything else in that system, you can not just make unsubstantiated claims and to hell with the consequences your unsubstantiated claims may have elsewhere in the system.

    As to the OP's opening post. Star asked a question, where he asked for options, I posted up some options.

  3. #15
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    Folks I am not against using DC/DC devices in situations where they offer a genuine advantage.

    For example, where an auxiliary battery is located in the engine bay of your new 150, and the cable lengths are short. Your alternator is easily going to do a far better job of charging the right sort of auxiliary battery.

    But if you are towing a camper trailer or caravan with your new 150, regardless of what type of house batteries you are using, because of the lower operating voltages, which are then exacerbated by the long cable run, then a DC/DC device is an advantage.

    It’s the old saying, horses for courses!

  4. #16
    Junior Member dBC's Avatar
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    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

  5. #17
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    This whole subject just gets so confusing sometimes, but im happy with what Im ending up with.

    Thanks
    Starfurry

  6. #18
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    aa

  7. #19
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    Quote 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.


    Quote 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.

    Quote 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.


    Quote 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.

    Quote 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.

  8. #20
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    Quote 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

  9. #21
    Junior Member dBC's Avatar
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    Quote Originally Posted by drivesafe View Post
    Iíll 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.


    Quote 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.

    Quote 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.


    Quote 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.

  10. #22
    Administrator Piggy's Avatar
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    Again this thread is being watched and the same culprits are at play.

  11. #23
    Junior Member dBC's Avatar
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    Yes, but I'm desperately hoping this time we can keep it civilised, technical and on-topic. That's certainly my intent.

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