Originally Posted by WolfWhistle
p, I am not an expert, but rely on the battery manufacturers data when I make states like I do. If they are wrong, we certainly will not know better than they. 13.7v is too low for absorb and too high for float. So, this charger is junk.
And, is probably the reason your batteries aren't lasting like they should.
Absorb should be somewhere near 14.7v and depending on temperature; and as high as 15.1v it it is very cold outside, with temperature compensation in place.
I respectfully disagree with your statement that the best way to determine full is with a volt meter. Hydrometer is number one, because it isn't affected by the battery's temperature. If the battery under test was just under load or just being charged the battery is warm and needs to return to room temperature before being read. The difference in true voltage and the higher voltage is significant. Now, if the battery is sealed, a volt meter is the only way, but again the temperature needs to stabilize.
A hydrometer is a more accurate read than a voltmeter - but it's reading the battery, not the converter. The OP was asking if his battery was being overcharged by his converter. The voltmeter tells me what my converter is doing when it is on - a hydrometer does not.
As far as charge voltages, what the battery manufacturers say only matters to the designers of converters. RV converters have preset, non-adjustable voltage points - at least models that will fit in a 12ft box A-frame. Temperature compensation is a joke when my batteries are out on the tongue, and the converter is inside under the dinette, next to the water heater.
The "normal mode" for both Progressive and WFCO converters is preset at 13.6 volts (my voltmeter measured 13.7 on my WFCO - either meter or converter calibration could be off by 0.1 volts).
Storage (trickle) mode on WFCO is 13.1V; PD says 13.2V. The WFCO cutover from normal is 44 hours, PD uses 30 hours. My problem is that my WFCO would never drop from normal mode into storage mode. That's why I'm replacing my WFCO, and not because of 13.7V normal mode output.
Absorb ("boost") mode is advertised by both WFCO and PD as 14.4 volts. Can most batteries handle a higher absorb voltage at normal temps, and thereby charge a little faster? Yes, but the higher the voltage, the more monitoring that should be in place to prevent boiling.
Bottom line is that no readily available converters for small RVs come close to meeting your proposed specs. I trust converter manufacturers like PD to put out a good automatic product that does not inadvertently destroy batteries.
My battery bank is two 232AH 6V Interstate golf cart batteries because they will carry me for 4 nights (high 20s or warmer) in Colorado without recharging. That's as long as we will stay in any one place with our A-frame. We wanted to keep things simple for weekend camping, which is why we chose an A-frame in the 1st place. No generator and fuel to lug, no solar panels to position.
And if my batteries only last 5 years instead of 7, I'm OK with that. I didn't waste camping time checking them with a hydrometer, and I only paid $150 for the pair, including tax. I just want the converter to recharge them fully when I'm at home so they are ready to go for the next trip.
2014 Rockwood A122 A-Frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time