pnichols wrote:
For years, now, NO ONE has explained the technical reason(s) as to why RV deep cycle dry (AGM) lead acid batteries require voltages greater than 14 volts to charge them fully if one has plenty of time to do less-than-14-volts charging. Is there some electro-chemistry reason - maybe related to activation energies, for instance?
In other words - for us non-full-time RV'ers who have plenty of time when at home to keep our RVs hooked up so that our stock single voltage converters can be left on continuously - why should we need to spend the money and effort to replace our single-voltage converters? What's the reason(s) that we might slowly be ruining (either by shortening their service life or reducing their capacity) our AGM batteries over time if we make and keep them "fully charged" this way when not on RV trips? What does "use 14.XX volts for cycle service charging" mean? Is this talking about faster charging back to original full capacity - or not ever getting fully charged back to original full capacity unless 14.XX volts are applied?
I guess I don't believe battery degradation happens from using lower charging voltages for long periods if someone can't explain it technically. Maybe there's a lot of battery hoopla out there?
https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/
This is an blog that goes into great(and long)detail about charging requirements that RV batteries require to be successful. There is a lot of stuff in here and you kinda have to "chew up the fish and spit out the bones" to digest the right and necessary info. The two things that made sense to me is the idea that charging a battery is like filling a tire with your home compressor. You'll never get to 80psig in your tires by using 80psig from the compressor. It'll take a long time to get to 80psig using 90psig from the compressor. But if you're at a 100-120 psig in the compressor 80psig is no big deal. Same with volts, you need to force volts in with more on the upstream side. The other thing that makes sense is how none of the ratings on chargers really mean much as far as output volts and amps. They're rated on a bench in a clinic, not installed in an RV with too small a wire going to far and not putting out enough volts in the first place. This though on chargers applies to solar and controllers too if not installed with heavy enough conductors and set up with the dip-switches to charge at a high enough output.
