Battery Charging Issue

[5thWheelTerror]

I recently became tired of doing the daily "generator re-charge" on my trailer and the morass of wires connecting them, so I went out and bought two honkin' big AGM-L16 industrial 6V batteries. I have found that neither my on-board converter, nor my portable 12V Battery Charger will recharge these batteries higher than 67% (according to the charger and the little battery gauge in the unit). Do I need to have a 6V charger to fully charge these units? Or do I need a larger capacity charger??

[MM49]

Your problem is the AGM batteries are a few tenths of volt higher voltage. When hooked in series your charger will not get into boost mode. You need a higher charge voltage.
MM49

[5thWheelTerror]

Thanks for the input folks... I'll get it sorted...

[time2roll]

I would get a 90 amp IOTA converter with IQ controller.
Then think about 200+ watts of solar.

[avvidclif1]

You need to measure the actual battery voltage when fully charged (as high as it will charge)and nothing hooked up. The idiot lights in the trailer are just that, idiot lights. Mine shows full charged(4 lights) when the converter is on but when I unplug from 110v it shows 3 lights although the battery is fully charged. Your onboard charger will get them big honkers charged but the idiot lights won't tell you the true story.

[RoyB]

oops disregard...

[waltbennett]

The real issue is that I've not found any converter that will charge a 12v battery (6v in series or 12v) at 14.4v to 14.8v and that's what you must have to get 100% charge. Don't believe the little red LED thing, it's almost useless (how well does it read your tanks?). Go to your battery manufacturer's website and see what they say if you don't believe me. 13.6v is only a float charge level for after they've been fully charged. You must use either a solar system or an inverter that will provide these levels.

[RoyB]

I can recharge my one 12VDC wet cell deep cycle battery using 14.4VDC with around 20AMPs of available current capacity in around three hours time. Having two 12VDC wet cell deep ycle batteries in my bank it will want to draw around 40AMPs of DC current to charge the two of them in a quick three hour time frame.

You need to check your big battery specs to see how much current and at what DC Voltage you need to re-charge them. Then your on-board converter/charger has to be able to produce this required DC VOLTAGE and have enough DC CURRENT available according to your battery charging specs.

Roy Ken

[5thWheelTerror]

Keep in mind, these are 2 Batteries rated at 390 Amp Hrs (20 hour rate) or 255 minutes at 75 Amps and 915 minutes at 25 Amps (Each). Not sure how else to describe their size, except 20" tall and about 120 pounds apiece.

[5thWheelTerror]

It is a PPS 7300 Series Model 7355
55 Amp output at 13.6 VDC

The issue, though, is that either/both units will charge the 6V (in series) up to 66% and then they just "cut out".

[Old-Biscuit]

What voltage readings are you getting using a real meter at the batteries?

Those battery gauges in rig are pretty useless

What converter do you have?