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Old 12-23-2014, 10:47 PM   #11
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I hate batteries. Just saying......

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Old 12-24-2014, 11:09 AM   #12
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I'm just saying that 4 trojan house batteries with upwards of 300-400 AH of capacity will take awhile on bulk charge which, by definition, will stop when the batts are at 14.4 or so volts and shift to the absorption cycle at that point. The OP has a 70 amp charger (which would probably not actually keep the 70 rate vary long as it heats up). Most chargers DO NOT deliver their rated power very long, and drop off to less than that. I too have used a Victron and other real time monitors and bulk charge should ALWAYS take several hour from 50% discharge. Wet cell batts should never be charged at more than 25% of their capacity, they can't take more amps than that without damage. A 70 amp charger sounds about right for that battery bank and should take several hours to reach the 14.4 point,

My only concern is if the OP is expecting to see 14.4 volts right away when charging, they arn't gonna see that for several hours and that indeed is normal.

Sulfation is also not as big a problem as most people think, unless you keep you batteries plugged in all the time. MFG's of these "sulfation" chargers have a vested interest in making this issue bigger than it is.

Best thing to do is to disconnect your batteries whenever possible, charge them occasionally when they drop 10% or so to keep them up, AND cycle them down to 50% or less and back up, a couple times a year to exercise the plates and electrolyte. Battery tenders are not necessary, but man do the MFG love to sell them to you.

Just my Opinion, after more than 40 years with Boats and RV's and lots and lots of batteries.

Thanks for all the great discussions.

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Old 12-24-2014, 11:23 AM   #13
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We're in about total agreement! I'd add pulse chargers to the list of gimmicks too.
Have a great Christmas.
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Old 12-24-2014, 12:29 PM   #14
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The solar guy is completely correct.........10 years ago.

Back in the day, a charger put XX power to the battery, even the automatic ones put XX amp rate until the battery quit absorbing power, the voltage would go up, the charger would quit.

Now, most any charger/converter is a smart or multi stage through the advent of processor technology. A 70 amp rate might start out at 70 amps, but progresses through 40, then 20, then 10, then float which is a very slow rate. The numbers are arbitrary, but show the example.

That means that the batteries don't endure as much as they charge, they don't get as hot, meaning they don't boil off water like they used to.

So, we lose very little water. I've had four 6V batteries in mine for four months now, cycled them from 12.3V to fully charged for over two weeks straight during that time, they're still full.

If you're charging rate meets your needs, then don't worry about it. If you're losing very little water I'd consider that a good thing, means you're not working them too hard.
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Old 12-25-2014, 11:10 AM   #15
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Originally Posted by SKnight View Post
The solar guy is completely correct.........10 years ago.
Now that's another point, and a good one.

For further info from the OP (me), I'm plugged into shore power about 99% of the time (being a full-timer) and rely on my Magnum interter/charger to manage the charging chore for me.

I've looked at configs I can change and one of them is Absorb Done Time which is currently set at two hours.

Other items are

VAC dropout = 80
Max Charge Rate = 100%
Battery Type = flooded
AC Input Amps = 10


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