Possible weak battery, what to buy, 12 volt?

Not all batteries have removable cell caps for the hydrometer.
Agree with pianotuna, go with the largest capacity AGM you can fit into your battery tray, and research adding something to help top it up when you're not using it. If that means a new charger, or solar, or both, it might be worth it if you plan on keeping the trailer for a while longer. A portable 60W-100W solar panel and simple charge controller combo might help.

If you had an hydrometer you would know if the battery is weak or not. No "possibly". Next is what to do about it if it is weak. Does that mean it is shot and cannot be recharged, or is it just down in state of charge? Need a good charger to find that out. Check all that so the next battery has a better chance.

This is for Trojans, but applies to all:

https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

Spade Cooley,

I'd suggest using a modest solar charging system between and during trips. Since you don't boondock any 12 volt battery may meet your needs. In your shoes I'd go to AGM chemistry as then you eliminate almost all maintenance tasks.

I don't run a generator or boondock so the Marine battery should be sufficient.

if your just the avreage joe camper? all you need is two wal mart marine deep cycle batteries, been using them in boats and rv for twenty years never haqd one just up and die. BUT I do have a cut off switch at my battery where when I,m done for a couple weeks I flip the knife switch and my battery and rv/boat are completly dis connected from the unit .without this there is always a some juice being drawn from the battery.

Get yourself two golf cart batteries and call it a day. Don't even mess with 12 volt batteries, they are either not proper deep cycles or not cost effective compared to Sams Club golf cart batteries.

Spade Cooley wrote:
Should I get a marine battery or a deep cycle?

Regardless of what type you get, it will last longer if you keep it as near as possible to fully charged ALL the time.

It depends on your budget and your willingness to keep an eye on it.

I splurged and got AGM deep cycles. About twice the cost but I NEVER have to touch them. That's worth the cost difference......for me.

P.S. You should not be guessing about the battery.
Get an inexpensive digital voltmeter and test it.

Marine are generally not deep cycle.
If you use the unit enough to need more reliable 12 volt for times when not connected to shore power, look hard at running 2 six volt Deep cycle batteries such as are used in Golf carts.
More power available and better life expectancy.
As mentioned above the Duracells from Sam's or Batteries Plus are good reasonably priced choices.

Spade,

As you have a towable, you will have a hard time keeping the battery up as the TV can pretty much not be counted on to charge it because the wire length is too long.

As to what battery, you will have a hard time finding an inexpensive true deep cycle 12V jar. They are available, but they are rare. A marine battery is just a bad compromise.

But if you don't boondock often or long, don't worry about it.

So, is you want better answers:
How often do you drycamp?
How long do you drycamp?
Do you have a generator of any capacity?

Matt

When you decide what type you want, check Sam's Club, too. They sell Duracell brands which are made by East Penn Mfrg. I've had a couple of them, and they've worked well.