Is a full charge every single day too much of a good thing?

[WalkaboutTed]

We're not living inside the finished van yet as we are still working on getting the house for sale. We leave the refrigerator and the fantastic vent fan on low 24/7.  With that, we're pulling out about 75 amps a day, much of that while the sun is charging the panels (445 watts). We're not coming close to 80% usage. I also have a temperature probe connected to the batteries. 

Every day, we're down to less than 1.5 amps after absorption (on 300ah cheap Chinese group 27 AGMs ) in the afternoon (by 1300-1400) except for the vary rare day here in Tucson when we have a few clouds.  Often the van is driven in the morning. Am I correct that,  assuming my numbers of usage are correct,  I'm not letting the system too much of a charge? 

I read somewhere, though I can't find it, that not draining the batteries enough can be bad for them, that not getting enough of a workout by daily shallow discharges. . 

Until we move,  should we occasionally let the batteries rest by disconnecting of the solar panels for a couple of days? How often?
Tef

 

[frater secessus]

Lead-acid chemistry batteries (including AGM) thrive on staying fully charged as much as possible.

 

[John61CT]

All lead wants to be returned to 100% full as quickly as possible for longevity.

Only overcharging issue would be at too-high a voltage after full.

Cycling down to only 80% SoC will yield many more cycles than 50%.

A good controller on low float can stay hooked up all the time, especially since you do have loads running you will still need Absorb in the morning.

With that ideal pattern of usage you can plan to buy a superb bank when this one's dead, and you may well get a dozen or more years.

When **all** loads are off then OK to disconnect the charge, but then you need to hook it back up at least monthly to counter self-discharge

 

[user 37446]

I'm no battery guru but from the hundreds of Sternwakes posts and other that I've read, that's the idea, getting the batteries back to 100 percent daily...  
Are you sure you use 85 amps a day just with a 12v fridg and a f fan on low?  Seems awfully high usage... :huh:

 

[John61CT]

Nitpicky but must be AH per day, no such thing as amps per day.

That translates to ~3A average usage to get to 75AH over 24 hours, doesn't seem too high to me for Tucson.

 

[WalkaboutTed]

I just came in from checking the meter and cracking the windows for the night. I turned off the solar at sunset yesterday and reset the meter.  This morning, at 0930, the bank was at 12.6 volts. I then turned back on the solar.  Tonight, after  exactly 24 hours, the meter showed 62 amps into the bank .  

I thought it was amps, not amp hours. Oh. The meter doesn't differentiate and I don't know any better.

I thought I had read somewhat that consistent, shallow discharges would reduce the true capacity.  I guess I read incorrectly.  It's no big hassle to turn off the solar input every few days, but I'm better not to have to worry about it.

As always, thank you guys,
Ted