Originally Posted by Malco
Herk What's a three stage converter,how does it work,and what other advantages does it have over a basic converter,if any?
I am sure your 2011 came with one also.
From the attached manual for my camper you can see that a newer converter and most good quality battery chargers "modulate" charging current based on battery voltage to avoid overcharging or "boiling the battery."
When you first charge a discharged battery, the voltage will be low and can accept a fairly stiff amount of amps under pressure (voltage) flowing into the battery.
uuummm, think of that battery as a very large "waffle" and each waffle "hole" will accept an electron. The charger has to be able to put an electron into each "hole." In the beginning this is easy since there are so many holes to choose from and no time is spent searching for an empty one. You can run the "electron hose" pretty much wide open without fear of "not finding a parking place" (charging current 25-35 amps - Stage 1 or BULK MODE).
As those holes fill (and the battery's charge and voltage increases) you can not keep that flow wide open. You have to dial back on the volume (amps) and decrease the pressure (voltage) to push those electrons around till they do find holes. If there are no holes to accept that charge readily available, heat builds up and the water in the battery will heat up and "boil."
So, the charger has to know the state of the charge and "step down" the charging current and decrease the voltage to maintain a safe charging level for the battery. Within a couple of hours of Full Out charging, the battery voltage and state of charge will trigger a decrease in amps and voltage (the next stage of charging also known as ABSORBTION MODE).
It will remain in ABSORBTION for several hours (up to 48) delivering about 4-6 amps (stage 2). If left there, like the older 2 stage converters, The battery will start to heat up as the capacity approaches 100% and boiling will start soon after. The newer converters have 3 stages and some new, higher end, ones (NOT OEM - LOL) have 4.
At about 90% of charge capacity, the converter will shift to stage 3 (or FLOAT MODE) and start trickle charging up to 100%. This current varies from about 1 amp initially down to 100 milliamps as the capacity goes from 90% to 100%. This process can take DAYS to fully charge a deep discharge battery, especially a high AH one (or bank).
the 4th stage of the higher end units have a "desulphation" stage which tracks charge/discharge cycles and "blasts" the "waffle" and knocks all the electrons loose and lets them resettle; basically re-newing the battery.
Folks who dry camp a lot quickly find out that there is not enough "not quiet time" at most campgrounds to full restore a heavily used battery (inverter running a Margarita Machine; TV surround system; half dozen computers; etc - JK) running the generator to charge the battery bank through the on board converter. So they use the generator to power a dedicated 2 stage battery charger connected directly to the battery - which is switched off while charging - and run the camper off the DC output of the power center. This DOES require monitoring as these chargers can overcharge the battery if you do not watch them; but since they do not go into "trickle charge" you can get 95% every day in the allocated run time..