Originally Posted by pbiJim
Thank you for that reference, but that still leaves me with contradictory information from two sources, each of which would seem to be trustworthy.
I'm still left wondering:
Does it vary by brand?
Is the information from Rolls a bunch of Hooey?
Is the generally-accepted standard-practice flawed?
Good questions, Jim.
The best answer I can give is that it depends. The two main factors, I believe, have to do with: (1) the very conservative nature of ratings and advice given by many battery
manufacturers. Often, these are conservative in order to avoid possible problems and liability in cases where (2) users abuse or ignore their battery
setups. I've heard also that sometimes recommendations are done more by marketing
people and lawyers than by engineers.
On the more technical side, in my experience more batteries are killed by undercharging rather than overcharging. Nigel Calder, MaineSail, and others who work with batteries every day tend to agree. Recommended charging
voltages are very conservative...too low...in many cases.
All lead-acid batteries have to be fully charged
and maintained at a substantial float voltage in order to retard plate sulfation. In addition, some need to be equalized periodically....just holding them at float voltage isn't enough to completely avoid the sulfation process.
I've had good experience charging
T-105s at 14.8 to 15.0 volts during the absorption phase, and floating them at 13.8 volts. Also, bumping back up to absorption voltage every day or two for 30-60 minutes seems to make a real difference in measured capacity. My Victron Multi-Plus is programmed to do just this.
But, if you're going to do this you need to properly care for your batteries, including using HydroCaps or WaterMiser caps, checking water
levels frequently, keeping them clean and filled only with distilled water
If you're the type of person who doesn't want to bother with battery maintenance
, then the manufacturers' more conservative charging/floating voltages are probably the best way to go.