Best way for winter battery storage

[Sopper]

I am in the final stages of my first winterization of my Trailmanor 2720 and had some questions about the batteries. As you can see in the attachment, my TM has two batteries. My TM is also going to be stored when not in use, and during the winter, covered in one stall of my three stall garage. What would be the best way to store my batteries, long term, to encourage them to survive over the winter?

1) Unplug the batteries from the camper and let set in the garage.

2) Unplug the batteries from the camper, remove them from the camper frame and store them in my basement.

3) Unplug the batteries from the camper and install a trickle charger to both batteries (in series) powered in the garage

4) Unplug the batteries from the camper, remove them from the camper frame, store them in my basement and connect them, in series, to a trickle charger.

I want to do what is best for the batteries, and the camper, over the long Minnesota winter months. Your comments, suggestions and experiences are welcome and appreciated!

You do not say whether your garage is heated. If yes, store them there on a float charger, which is not the same as a trickle charger. If unheated, store them in the basement. Trickle chargers can dry out batteries over time. A float charger maintains a constant voltage after charging is complete.

[Sopper]

My garage is attached and insulated but not actively heated.

[Sopper]

Also...can you run two batteries in serial conenction on a float / trickle charger?

[Bill]

Sopper -

Assuming the two batteries are the same make/model/size/age, then yes, two in series will be just fine. If the two batteries were different, then they would charge at different rates, meaning that one would undercharge and the other would overcharge.

As for storing the batteries through the winter, there are at least a couple different answers. Mine is this.

A discharged battery will freeze and break at cold temps. But a low state of charge will hurt the battery regardless of anything else. So never store a discharged battery, regardless of temperature, and never let it become discharged during storage.

Is it that simple? Well, it is important to remember that if a battery is fully charged, and then disconnected from everything, it will still discharge via
self discharge. It is self-discharge that is your enemy.

A good source of information is www.batteryfaq.org (click on Car and Deep Cycle Battery FAQ, and scroll down to section 13.2). There you will find

"Batteries naturally self-discharge 1% to 60% per month (depending on the battery type and temperature) while not in use.... Cold will slow the process down and heat will increase it up....Store [the battery] in a cold dry place, but not so that it will freeze"

This site has a lot of other good information (such as the concrete floor myth), and is worth checking out. But at the bottom line, assuming that you start with a fully charged battery, then cold is your friend, not your enemy.

Incidentally, I can attest that this cold-storage approach works. When I leave Maine for the winter every year, I shut down all heat in the house, and leave my mini-pickup truck in the unheated garage. In this part of Maine, temperatures often dip to zero during the winter, though seldom lower. I don't have a charger because the power to the house is off. All I do in the fall is wash the top of the battery, charge it, then disconnect it and leave it in place. When I get back in the spring, I reconnect the battery, and it has never failed to start the truck's engine immediately. I've done this for 12 years with never a problem.

Bill

[rshenise]

I put my batteries in the (heated) basement...if you put them on a trickle charger check on them to be shure the water hasen't boiled off...
Most modern batteries, if stored properly should last 5-6 years.

I am a big fan of the Battery Tender (http://batterytender.com/). They monitor the battery voltage and charge as required. You can leave them attached to the TM and just connect the Battery Tender. as the parasitic loads of the TM draw it down, the BT will replace the charge. Cold is not an issue ( actually good) as long as the battery is fully charged. If both batteries are the same age and capacity, you can connect to one ( assuming it is two 12V Batteries in parallel) and be good to go. You can find the Battery tender at online retailers for less than the oem site.