'Float' voltage under varying DC loads
This post is an observation, and observation which bucks the 'this wors like this, and that works like that' mentality which pervades online forums. Empiracle data trumping theory. I can spin a di...
Forum Discussion
landyacht318 wrote:
I think many converters, doing their float or storage modes, while the owners are above using as much DC electricity as they want, are blissfully unaware that their batteries are likely discharging at a very slight rate, instead of being kept chock full by the converter as its mareting will loudly proclaim.
I have never spent the additional money to replace our Class C's stock Parallax 45 amp fixed voltage converter. I wanted dry acid batteries instead of liquid acid for a variety of reasons, so alternatively I spent the money for a retrofit to 230 AH of 12V AGM deep cycle coach batteries that get along well with the converter.
I have a +/- 0.1 amp resolution ammeter mounted on the cab dash (with it's shunt installed in the negative lead of the 230 AH AGM coach battery bank).
My batteries are specified to be floated in the 13.5-13.8 volt range - a perfect match for the stock converter. Since AGM batteries have such a low internal intrinsic resistance, when they're around 50% discharged they also charge good enough - at a 10 to 15 amp rate - from this same 13.5-13.8 volt fixed voltage converter. If I need to charge the AGMs quicker than through the converter, I first just idle the V10 with it's 130 amp alternator for awhile so as to temporarily pump current at up to a 70 amp rate into them (per the dash ammeter I installed -> the E450's stock alternator is capable of this at engine idle speed).
Whenever a converter - or other charger - is attached to your RV battery bank and current is being drawn from that 12 volt converter/battery system ... what you may be seeing is the current being primarily drawn from the source with the lowest internal resistance. This is usually going to be the batteries themselves instead of the converter or charger. As soon as the load is removed, the higher resistance (and voltage) source - usually the converter or charger - will resume providing current into the now somewhat depleted battery bank.
Source voltage setting, source amperage capacity, and cable size are not the only parameters to be concerned with .. internal resistance of sources and loads can often be just as important in a system.
However, some of the above is just my opinionated guess as to what may be happening in your situation. ;)
