Generator vs Battery/Inverter/Solar
We have just purchased our first truck camper - a used 2007 Lance 845 and have a couple questions that I hope you can help us out with. The camper is still at the dealer and we're considering having a...
Forum Discussion
HMS Beagle wrote:
Higher voltage will not harm flooded lead acids, though they will go through water a little quicker. But it will eventually harm AGM batteries, and pretty quickly ruin gel batteries. For longest life you want a proper 3 stage charge, with set points for the battery chemistry being charged.
To be sure, we agree completely. No one is proposing using a voltage higher than that specified by the battery manufacturer. The key point is that the charging voltages for modern batteries, of all types, are higher than many would expect and those voltages go higher still as the temperature drops to freezing or below. The classic "charge an AGM at 14.2v or 14.4v is only true at 20C/70F. The proper charge voltage will be lower for a battery under the hood in Death Valley and much higher camped up at Leadville in the winter. Thus temperature compensation is especially disable for your shore and solar chargers.
Another peculiarity of AGM batteries is their life will be shortened by chronic undercharging - which is actually more likely in a camper. They need to be fully charged periodically to maintain capacity.
Again, you are exactly right. This is the point drilled into my head by the folks at Lifeline. Most (camper) batteries die from never being fully charged. A quick boost charge from the engine or the genset won't do it. You need the long absorb stage that almost only ever comes from solar or shore chargers.
One problem with many of the "converters" installed in many RV's, even a few touted as being "multistage" or "intelligent," is that they drop the voltage too much during the absorb stage. This isn't a huge problem for a camper plugged in overnight, every night, but those of us whose camper may go for more than a year without ever plugging in, a charger that did not complete the absorb stage would be a major problem.
