AGM batteries & solar battery tender

[garmp]

Thinking about switching over to AGM batteries & know nothing about what I should know & do. I tried to do online research but have a hard time distinguishing between a sales pitch & an honest review/opinion as I know nothing about the subject.
I did find that one important point is to keep the batteries charged while in storage. As I generally put it in storage from Nov to April. Cannot keep on our property due to our beloved HOA, so it is offsite with no electric available. Which brings me to a solar battery tender. These are effective??? Spending this kind of money on batteries, don't want them going south the first year. Since our coach is offsite can I use a solar tender discretely with no holes drilled, etc. I'd like to place the solar panel in the cab windshield & run the cables to the batteries. Does this even sound feasible?
And I guess solar battery tenders, like the batteries themselves, vary in price from one end of the spectrum to the other. And the higher the price isn't always the better.
Oh, where to start? Then there is always the consideration of total cost and what I can afford. But naturally I want the best for the least cost.
Any thoughts?

[pianotuna]

grit dog,

Similar in price li to agm but do require proper care. Not useful in the cold.

[Starchmill]

Just my experience, but I bought 2 AGMs for my Camper 10 years ago. They have always been outside in the Northeast winters. I pull the battery disconnect in late fall and dont touch it again until March or april and the Batteries have held up just fine. Totally worth the added expense considering the long life I have gotten out of them. I used to check on them once a month but never found them to need charging and then the past several years I havent checked at all and they are just fine over the winter without any additional charging. Maybe this isnt everyones experience, but it is mine and i have been extremely happy with the AGMs.

[Grit_dog]

pianotuna wrote:

garmp wrote:
My coach has a switch to disconnect the coach battery. Would that be sufficient enough rather than manually unbolting the batteries?

If you never cold weather camp, then LiFePo4 are a similar price to AGM. They can be stored for a long time with no charging--and in fact it is best to store them at 50% state of charge.

The other solution is a small solar charging system.

The disconnect switch may not eliminate all parasitic loads. Best to disconnect the negative post.

By similar, do you mean the cheapest Li are similar to the most expensive AGM batteries?
If apples to apples are similar, I’m very interested but haven’t seen that.

[bgum]

As stated by several people above disconnect a wire from the battery. An AGM will need charging after about 4 weeks or so even if you disconnect a wire. I suggest you disconnect a wire and put 10 watt maintainers on each battery. A disconnect switch is not adequate.
It may be simpler to bring the batteries home with you.

[pianotuna]

garmp wrote:
My coach has a switch to disconnect the coach battery. Would that be sufficient enough rather than manually unbolting the batteries?

If you never cold weather camp, then LiFePo4 are a similar price to AGM. They can be stored for a long time with no charging--and in fact it is best to store them at 50% state of charge.

The other solution is a small solar charging system.

The disconnect switch may not eliminate all parasitic loads. Best to disconnect the negative post.

[theoldwizard1]

Solar panels behind glass, especially if it is tinted, put out much less power.

[SJ-Chris]

garmp wrote:
My coach has a switch to disconnect the coach battery. Would that be sufficient enough rather than manually unbolting the batteries?

Maybe, maybe not. To be 100% sure you can disconnect the battery terminal wire at the battery.

I suggest, if possible, you should visit your RV at least once per month while in storage to check on it. You can bring a volt meter and check the battery voltage to make sure they are holding a charge and not being drained. It is also recommended to run the generator once a month for 30 minutes to an hour under some load to keep it happy.

Personally, I hate dead batteries so much I added solar to each of my RVs (which makes boondocking a breeze also). If you are a DIYer it is not terribly hard and doesn't cost too much. Message me if you'd like details on an inexpensive solar install.

Good luck!
Chris

[garmp]

My coach has a switch to disconnect the coach battery. Would that be sufficient enough rather than manually unbolting the batteries?

[bobndot]

As said disconnect them once fully charged. But stored for that long in colder temps, my AGM's always dropped down in voltage to the point of not cranking over. I would add a solar charger.

I use solar Battery Tenders on my stored snowmobiles off-grid as well as my elec start Generator. Works perfectly, all AGM batteries. It will keep two grp 27's topped off if fully charged from the start.

[KD4UPL]

Charge them up and unhook them. They'll be fine.
If you really want a maintainer that will work to but you will still need to unhook them or the LP detector, stereo, etc. Will still drain the battery with a litle panel. You could put in a real solar panel and have use of it for camping.

[2oldman]

You could charge them up and disconnect and they'd be fine. AGMs hold a charge a long time. And by disconnect I mean pulling a cable.

[Lwiddis]

When I had wet batteries I used a 30 watt solar panel and a weather resistant controller from WindyNation to maintain my batteries when not camping since my TT is covered. Worked very well. Are you considering Lithium batteries? If there is no draw their charge will last months. In fact many advise storing at less than full charge. The “buzz” is Lithium and not many are writing anything about other battery types.

[bgum]

We have one AGM battery being maintained by a Coleman 6 watt battery maintainer. You didn't state how many batteries you will be maintaining but Coleman also makes a 10 watt maintainer for $50. Most maintainers have a diode to keep the reverse flow of power during periods of darkness. If you totally disconnect your batteries the 10 watt may carry two. We bought ours at tractor supply. Notice a charger and maintainer are two different animals.