Q for deep cycle battery experts

theoldwizard1 wrote:
Off season/extend storage : Do you use a battery maintainer (like Battery Tender) or do you just use a "good" (higher power) charger and restore the charge every X weeks ?

I have 80 watt solar panel charging continuosly,,w solar controler obviously..
I also keep another car battery from my car project hooked up to this to keep charged up,,works perfect..just need to clean the snow off the panel in winter..

The best is battery maintainer with floating circuit.
It is 13.5V for starting batteries and don't know if it is different for deep cycle.
Still any maintainer is subject to failure, so monthly monitoring is recommended.
Since I had no power in the storage, I just disconnect the cables and DC batteries would hold good charge for 10 months.
Have them at 13 years of age and still giving decent voltage, although showing on weak side under the load.

For extended storage like over the winter I just fully charge then disconnect for 3-4 mos and fully charge when I return home. For shorter storage between camping trips (1-3 weeks) I leave it disconnected and fully charge with my 40 Amp B&D 40 amp charger until full then float charge at 13.2v for a few days before I go camping. Equalize several times a year and desulfate for 24 hrs once a year. I know many on here stay plugged in all year, but maybe someone knows just how much plate loss occurs when plugged in all the time. Said another way which causes a less plate loss a drop of 5% SOC then charge or a constant float charger of 13-13.6 volts?

Get AGM batteries. Always disconnect completely, when not in use.

Recharge fully, every time you come back from a trip and before end of camping season. Store in Garage, especially if you live in a cold climate. Cold Climates are very easy in the off season if the battery is fully charged and stored inside.

AGM batteries have very low off season discharge rates. Recharge fully every 3 to 4 months, maybe once or twice in the off season.

I have used a battery tender on mine and had good results. since there are systems in the TT that drain the battery in a few weeks it makes sense to me to keep up with the drain. many TT converters do not have the charge wizard to maintain the charge on the battery, if left plugged in it will kill your battery

In order of reliability:

Solar with a MPPT charge controller or at least a quality multi-stage PWM CC like the ZAMP ZS-30A. Multi-stage is key, so the batteries are not boiled. The advantage of solar is the ability to get it set, and then forget about it.

Second to solar, if you have power nearby, I would go with a Battery Minder because of its desulfate ability (it charges in pulses so it won't cause the liquid to boil, but does enough to keep stratification from happening.) Better a relatively low amp charge keeping the batteries at/near 100% SoC than to charge/discharge it repeatedly.

Charging it up every month or so does work, but make sure to water the batteries.

Solar

"Yes"

I also am not an expert but did stay at a Holiday Inn once. I keep a marine charger hooked to mine.
bumpy

fully charge
disconnect
repeat in 30 days

Or

Add a modest solar system which often doubles the lifespan of the battery bank.