Battery Size (replacing)

[Campinfan]

I need to replace my RV battery. It is a 24DC model. I know that does not mean 24 volts DC. I see a 24DC battery I can get but there is also a 27DC that has more MCA (not sure what that means but I am used to CCA--cold cranking amps) So my question is, can I replace it with the bigger battery and if so, is it worth it to get the additional 60 MCA for $4 more? Just not sure if I HAVE to use the same size or is that just the minimum one the manufacturer uses to save a couple bucks.

[StirCrazy]

Veebyes wrote:
There are plenty of good reasons to go to an AGM. The double to triple the service life is only one of them. My first AGM gave me nine years.

In storage the AGM loses very little. My AGM sits, disconnected and untended, November to April and retains enough power to operate landing legs upon reconnection.

Zero maintenance other than annual terminals cleaning.

Yes they cost more. Much more. Given what they are over the 100 plus year old technology of the wet cell the AGM is worth it.

There's a reason why they are used in aviation and marine applications.

The reason they are used in marine, and aviation was they don't spill when the boat rocks or the planes bank. Also, before I retired from the Navy in 2009 we converted a lot of our stuff to Lithium batteries to improve reliability, capacity, and lifespan.

They do last longer compared to a normal starting battery but not when compared to a GC2 so let's throw out some context. The only reason to buy an AGM in an RV, in my opinion, is if you don't want to do maintenance on the batteries as they do protect themselves from low water levels better. To me it just doesn't make sense to get AGM for a RV application as here, the price is double for an equivalent battery.

[wa8yxm]

Campinfan wrote:
Thank you for all the great info. I did go get a 27 battery but next time I may upgrade to an AGM.
Not sure why my post does not make sense....it is the battery in my trailer that is listed. Maybe the manufacturer just went cheap.

I am not convinced of the advantages of AGM in most cases. IN SOME cases yes. AGM is better than a "Wet" battery but those are extreme.

IF you can expand the battery compartment go with a pair of GC-2

If not LiFePO4 is expensive but may well be worth it. And getting less expensive daily.

[valhalla360]

Veebyes wrote:
There are plenty of good reasons to go to an AGM. The double to triple the service life is only one of them. My first AGM gave me nine years.

In storage the AGM loses very little. My AGM sits, disconnected and untended, November to April and retains enough power to operate landing legs upon reconnection.

Zero maintenance other than annual terminals cleaning.

Yes they cost more. Much more. Given what they are over the 100 plus year old technology of the wet cell the AGM is worth it.

There's a reason why they are used in aviation and marine applications.

Other than checking water, nothing different than standard lead acid. I've not replaced a battery on an RV. Disconnect the cables, clean the terminals and water in the fall. In the spring reconnect and away you go.

The reason they are used in aviation and marine is you can flip them on their side or completely over without spillage. Usually, that's not an issue for most RVs.

So still waiting on a reason to pay soooo much more for AGM.

[Grit_dog]

valhalla360 wrote:

Campinfan wrote:
Thank you for all the great info. I did go get a 27 battery but next time I may upgrade to an AGM.
Not sure why my post does not make sense....it is the battery in my trailer that is listed. Maybe the manufacturer just went cheap.

Why would you bother paying for an AGM? The only advantage is you can flip the trailer and the liquid won't drain out...if you flip your trailer, the battery is the least of your concerns.

If you don't change your use pattern, a basic battery is going to be fine when you need one in 7-10yrs.
If you start boondocking, better to go with a couple 6v golf cart batteries as you get more amp-hr per $.

Except none of this matters. Since the little single battery on the big 5ver will either get overused and drained and cooked very easily or it is literally never used without being backed up by the converter.
There are more important considerations in this thread that are worthy of clarifying or debating than AGM or not.

[Grit_dog]

RLS7201 wrote:

Grit dog wrote:

RLS7201 wrote:
Marine/RV batteries are compromise batteries. They were developed for marine trolling and engine start. They do not excel at either.
For you application a standard lead cell starting battery is your bet choice.

Richard

You’re right about the first part, sort of. They’re actually just fine for starting and will take the short term high amp loads just fine but they’re a compromise for deep cycle/ house battery use like trolling motors and campers because they have more/thinner plates to accommodate the high amp loads.
Second part you’re completely off/backwards. A dedicated starting battery while it will do the same job as a deep cycle, it won’t do it near as long before it’s worn out. That’s why true deep cycles aren’t suitable for high amp starting loads. They have thicker plates that last longer under discharge conditions that a good operating starting / charging system keeps from happening.

It is my understanding that the OP was looking for a starting battery. Which makes my comments correct.

Richard

Your understanding was wholly incorrect as the OP has a camper trailer. As listed in his first post.
But regardless, dual purpose “marine” FLA batteries make fine starting batteries, just not great deep cycles in the long run.

[Veebyes]

There are plenty of good reasons to go to an AGM. The double to triple the service life is only one of them. My first AGM gave me nine years.

In storage the AGM loses very little. My AGM sits, disconnected and untended, November to April and retains enough power to operate landing legs upon reconnection.

Zero maintenance other than annual terminals cleaning.

Yes they cost more. Much more. Given what they are over the 100 plus year old technology of the wet cell the AGM is worth it.

There's a reason why they are used in aviation and marine applications.

[valhalla360]

Campinfan wrote:
Thank you for all the great info. I did go get a 27 battery but next time I may upgrade to an AGM.
Not sure why my post does not make sense....it is the battery in my trailer that is listed. Maybe the manufacturer just went cheap.

Why would you bother paying for an AGM? The only advantage is you can flip the trailer and the liquid won't drain out...if you flip your trailer, the battery is the least of your concerns.

If you don't change your use pattern, a basic battery is going to be fine when you need one in 7-10yrs.
If you start boondocking, better to go with a couple 6v golf cart batteries as you get more amp-hr per $.

[RLS7201]

Grit dog wrote:

RLS7201 wrote:
Marine/RV batteries are compromise batteries. They were developed for marine trolling and engine start. They do not excel at either.
For you application a standard lead cell starting battery is your bet choice.

Richard

You’re right about the first part, sort of. They’re actually just fine for starting and will take the short term high amp loads just fine but they’re a compromise for deep cycle/ house battery use like trolling motors and campers because they have more/thinner plates to accommodate the high amp loads.
Second part you’re completely off/backwards. A dedicated starting battery while it will do the same job as a deep cycle, it won’t do it near as long before it’s worn out. That’s why true deep cycles aren’t suitable for high amp starting loads. They have thicker plates that last longer under discharge conditions that a good operating starting / charging system keeps from happening.

It is my understanding that the OP was looking for a starting battery. Which makes my comments correct.

Richard

[Campinfan]

Thank you for all the great info. I did go get a 27 battery but next time I may upgrade to an AGM.
Not sure why my post does not make sense....it is the battery in my trailer that is listed. Maybe the manufacturer just went cheap.

[LouLawrence]

My last coach used 4 group 31 as the starting batteries (wired for 24V) and 4-8D as the hose batteries. My current coach has the same starting battery setup and 8-4D batteries. They certainly are used where the situation calls for it.

[Veebyes]

valhalla360 wrote:

Veebyes wrote:
Cram as many amps of battery bank in the space provided as possible.

That means doing some measurement of battery case size & seeing what will fit.

Typical case sizes are group 24, group 27, group 31, 4D and 8D. Each is larger than the next. An 8D is what you would see for starting large machines, or the marine version deep cycle onboard boast as 'house' batteries.

As pointed out a single group 24 is basically a waste of time. Good enough for a very small 'teardrop' sized trailer maybe.

Since the OP isn't boondocking, just get the cheapest battery. If it's $4 to upgrade to group 27,OK but don't spend a lot of money on something you won't utilize.

The truck umbilical cord will handle the fridge and other power draws while running down the road. The battery really only needs to run the trailer brakes in the event of an emergency where the trailer becomes disconnected from the truck or to run the jack to disconnect before plugging into shore power once at a campsite.

PS: 8D batteries are almost never used as house batteries in boats or RVs. They are simply too big and awkward for normal humans to move. If you want a big house bank and don't want to go with lithium, the standard is 6v golf cart batteries. But again, this is all massive overkill for the OP who isn't boondocking.

If all the OP has is what is needed to be plugged in all the time, no, he will not be doing any dry camping if the need or desire is ever to do so.

As far as 4D and 8D batteries go, I currently use a 4D AGM in the 5er.

Used to have a boat, single diesel engine, that had a single 8D for starting and house use, though it was not an overnighting boat. A friend had a 65' motor yacht that had six 8D AGM battery bank.

The beauty of the 4D and 8D is that you don't have all of those connections, potential problems, to maintain.

[Grit_dog]

^Very informative response!
I’ll add, I don’t think a couple GC2s is overkill at all.
If you look up the OPs trailer, she’s a bigun!
Alternatively, 1 little group 24 battery (like in the kids 6 banger commuter car), it’s amazing it carries enough juice to even setup and break down the trailer. There is certainly no tangible reserve capacity there for virtually anything. It must come straight off the umbilical cord after it’s hooked to the truck and right back on the cord as soon as the truck gets shifted into park at the rv site.

[valhalla360]

Veebyes wrote:
Cram as many amps of battery bank in the space provided as possible.

That means doing some measurement of battery case size & seeing what will fit.

Typical case sizes are group 24, group 27, group 31, 4D and 8D. Each is larger than the next. An 8D is what you would see for starting large machines, or the marine version deep cycle onboard boast as 'house' batteries.

As pointed out a single group 24 is basically a waste of time. Good enough for a very small 'teardrop' sized trailer maybe.

Since the OP isn't boondocking, just get the cheapest battery. If it's $4 to upgrade to group 27,OK but don't spend a lot of money on something you won't utilize.

The truck umbilical cord will handle the fridge and other power draws while running down the road. The battery really only needs to run the trailer brakes in the event of an emergency where the trailer becomes disconnected from the truck or to run the jack to disconnect before plugging into shore power once at a campsite.

PS: 8D batteries are almost never used as house batteries in boats or RVs. They are simply too big and awkward for normal humans to move. If you want a big house bank and don't want to go with lithium, the standard is 6v golf cart batteries. But again, this is all massive overkill for the OP who isn't boondocking.

[Veebyes]

Cram as many amps of battery bank in the space provided as possible.

That means doing some measurement of battery case size & seeing what will fit.

Typical case sizes are group 24, group 27, group 31, 4D and 8D. Each is larger than the next. An 8D is what you would see for starting large machines, or the marine version deep cycle onboard boast as 'house' batteries.

As pointed out a single group 24 is basically a waste of time. Good enough for a very small 'teardrop' sized trailer maybe.

[Grit_dog]

Bottom line, the OPs post makes no sense unless he’s not talking about the camper in his sig.
1 group 24 battery would barely put the 4 slides out and jacks down. If at all.