What exactly is needed for solar trickle charge of lead acid battery??

[ArizonaAJ]

What is the best way to keep battery charged during storage between uses - 3 to 6 months?

[sande005]

What is the best way to keep battery charged during storage between uses - 3 to 6 months?

Depends. See the chart I posted a couple of replies ago. It is based on average temp. Be conservative - go by the daily average temp (high minus low), but guess less time if the low times are less than the high times, etc. Heat is bad. Cool/cold is good. If the time it will be uncharged is less than the time on the chart, no need to do anything. You can even take them inside during really hot weather, so they are comfy in air conditioning, if need be, to extend the time before charging is needed. Here in Minnesota, over the winter, all my batteries always come out of their outdoor winter nap (Nov-April) with 90-95% full charge. I've had some go a full year, summer and winter, and still be at 90%. But in Arizona summer, it will be far less. Ditto for other places with less "cool" winters.

Otherwise, it all depends on what power is available at your storage area. Many like a dedicated trickle charger, like a "Battery Minder" brand.
Some put them on time clocks, so they only get a "bump" for a few hours a day, or days per month (depends on the clock).
If you have multiple batteries it can get a bit more complicated. Even more complicated if there is no on site power.
You can just plug the RV in, and let the stock converter do its thing - but those are usually cheap and not the greatest for trickle, and therefore carry a slightly greater risk of failing and overcharging
The least fun thing is to uninstall and take them inside your house/garage. Usually no need, unless it is the only way to get power to them for trickle charging.

If on any charger, you MUST do a monthly check of the electrolyte levels, if not an AGM battery.

Lithium batteries never need trickle charging. If unused for longer periods, they should be partially discharged. See your manufactures instructions for that. The big one is to never charge when below 32F. Some have protection to prevent that.

Tell us more about your batteries and storage options, and you can then get more specific advice.