Charging several diff size batteries together in storage

[Genr8rs]

Ok, need some good input. I have stored for winter on my shop shelves 4 automotive flooded cell batteries, 2 from cars, 1 from 5th wheel camper and a spare from a dump trailer, along with 2 lawn mower batteries. All are 12 volt.
In the past I have made jumpers to connect all of the positives together and all of the negatives jumping or connecting battery to battery together then connect them all to 1 charger that is on a time clock. The charger is good for all but lithium battery. It seems to work fine. Before I do connect them together I charge each one individually. What are the issues I may have overlooked?

[Grumpy]

If you charge them all first you are just keeping a maintenance charge on them, that usually works vs trying to put a full charge on different size/amp hr. batteries.

[GHen]

I think if you connect them together they will only maintain them to the level of the weakest battery. If they are all charged, I would connect them separately and once a week connect to a different battery.
I have an jet ski battery, a hot Rod battery and a big deep cycle in the garage. I just switch those every few weeks. They are always fully charged.
Make sure you keep them off the concrete, at least put them on some wood if you need to have them on the floor.

[Jagiven]

My understanding connecting all these different batteries together is a bad thing! They all have different internal resistances and if one battery is bad it can have bad side affects on the rest.

I somewhat follow Ghen method. I have 4 batteries I store. When they are put away, I check the fluid levels, and voltage. Pending on the battery, I will put it on the battery maintainer for a few days to a week. Swap out batteries as needed, unit they are topped off.

After they are fully charge, I let them sit for 3+ months without a being connected to anything. Maybe sometime around February, I check the voltage. If they are all still good, Ignore them until maybe March. Then they all go back on the trickle charge one at a time. My experience only very old batteries loose a charge over the winter. Those batteries in my experience don't make it through the following season.

I have to admit. If it looks like we will be having a nasty winter storm coming, I might check the voltage and toss the deep cycle batteries on the maintainer. I primary do this as I have my SB furnace setup to be powered by an inverter when needed. Those deep cycle batteries will be brought in if needed.