Batteyr charging in an RV

panther3505 wrote:
Here's my rant for the day.

I have heard so much outright misinformation, misnomers, and just flat out uninformed individuals passing off their opinions as gospel regarding maintaining their batteries in their RV's. Hear are some cold hard facts from an electrical engineer.

1. RV’s do not have battery chargers; they have converters, which are nothing more than power supplies.

True, years of personnel experience has proved this.

2. An RV converter does not know what a battery is. The batteries; when installed in an RV’s electrical system are in parallel with the electrical system and, therefore, are nothing more than an additional load on the system.

True when the converter is on; when it's off they become a power source.

3. Regardless of current marketing ploys or manufacturer claims, no converter manufactured today by anyone can charge a battery separately from the 12v system, again the battery is in parallel.

True unless you isolate the converter from the RV loads, add voltage sense from the battery(s) and temperature compensation.

4. There are no components in a converter that isolate the charging function separate to supplying voltage and current to the entire 12v system.

5. Current converter “multi-stage” technology offers no real benefit over a single stage converter. When viewing the charge curve of a single-stage versus a multi-stage converter, the charging is nearly identical. The only thing that stands out is the fixed points in which the output voltages drop, however, time and current are constant regardless of single or multi-stage. Even with more popular 4 stage converters on the market, the misnomers that abound in the RV world are frightening. According to major battery manufacturers, the voltages that are required to desulfate or equalize a battery need to be a minimum of 15.4VDC. Due to the limitations of an RV’s electrical system that is 13-14.4vdc, the voltages required to desulfate a battery would be detrimental the sensitive low voltage systems now inside modern RV’s.

Partially true but.....single stage rarely will provide the ~14.8 required for a proper absorb charge. It will never provide equalize of ~15.4 and it will never drop to a proper float voltage; it keeps jamming what ever current the battery will take!
It may charge at a higher bulk current.