RV Battery Swap Question

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Apr 6, 2025 | 11:21 AM

kshoop1958

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Laughing Gas

Joined: Apr 2021

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From: Middle TN

RV Battery Swap Question

I'm looking to swap out my flooded cell fifth wheel batteries with a pair of AGMs, have a question about sizing. Currently have two Interstate deep cycle flooded, size 27 that are rated for 88 amp hours and 750 marine cranking amps. I see Walmart carries an Everstart deep cycle AGM, size 24 that just fits in my boxes, rated for 70 amp hours and 875 marine cranking amps. So they have more cranking amps, but less amp hours. What do you guys think for someone who virtually never boondocks, and basically just wants less maintenance?

Apr 6, 2025 | 11:33 AM

OBS460

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Consider that the FLA batteries are only able to utilize 50% of their rated capacity the AGMs actually have more usable AH than the FLA with 88AH. AGMs are a much better choice for an RV.

Apr 6, 2025 | 12:04 PM

kshoop1958

Thread Starter

Laughing Gas

Joined: Apr 2021

Posts: 998

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From: Middle TN

Quote:

Originally Posted by OBS460

Consider that the FLA batteries are only able to utilize 50% of their rated capacity the AGMs actually have more usable AH than the FLA with 88AH. AGMs are a much better choice for an RV.

Thank you, much appreciated from a guy who's not very knowledgeable about battery technology, or electrics in general for that matter.

Apr 6, 2025 | 04:19 PM

PROSTOCK

Cargo Master

Joined: Feb 2004

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From: Central Texas

For $104 out the door I put that #24 Everstart deep cycle battery in my camper two weeks ago. The last one went 4+ years. I have a generator for boondocking if I ever. I need a battery to run the jack and little else. AGM is overkill for my needs.

Apr 6, 2025 | 05:43 PM

CR172

Fleet Mechanic

Joined: Feb 2017

Posts: 1,597

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From: N. Texas

Lithium. I went from a single LA battery to two LiPo batteries. These are fed from 1K watt of solar panels.

Apr 7, 2025 | 07:36 AM

SpencerPJ

Fleet Mechanic

Joined: Jan 2020

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Your 2021 TT should have a converter that will charge an agm battery, and that battery from walmart should work just fine for your needs.

Apr 7, 2025 | 09:25 AM

kshoop1958

Thread Starter

Laughing Gas

Joined: Apr 2021

Posts: 998

Likes: 608

From: Middle TN

Quote:

Originally Posted by SpencerPJ

Your 2021 TT should have a converter that will charge an agm battery, and that battery from walmart should work just fine for your needs.

It does have an AGM profile, went ahead and pulled the trigger. Thank you all for confirming!

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Apr 7, 2025 | 10:08 AM

powerboatr

Cargo Master

Joined: Apr 2021

Posts: 2,024

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From: Texas

And look at weight penalty
most travel trailers are already in the sub 1800 lbs of stuff range

Lithium are nice, but unless your converter is set up to manage them, thrn your buying another charger to manage them
If your not boon docking or dont have a generator or then a big bank of batteries is good
I had 4 flooded 6 volts
Swapped them for 2 large 12v with more amp hrs
6 years ago..still performing as specified
But..we don't boondock and if shore power is disconnected..the genny. Is running
I like having lots of ac to cool the coach
I have 6 slides snd they are battery zappers
but my set up runs them in just fine..without genny or shore power

Apr 7, 2025 | 10:19 AM

#10

1Butcher

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Quote:

Originally Posted by robert sloane

Lithium are nice, but unless your converter is set up to manage them, thrn your buying another charger to manage them

I have read this more often than not. So often that I did my own test. Using my stock converter [not lithium rated], I was able to charge my 304aH Lifepo4 battery to 95%. I know for a fact, you do not need to swap out the stock converter. It might take some time to fully charge the battery, but if you are not boon docking, then it really does not matter. I suspect that those that say the converter must be swapped out is because people are just saying what they have read. I don't trust anyone since there are only a few that really know what they are talking about. That is why I proved it to myself that a stock converter will charge a LifePo4 battery just fine. Don't trust me, I am just another clown on the internet. Prove it yourself.

One small 100aH LifePo4 battery is as good [probably better] than two 100aH LA/AGM batteries and maintained right, it could be the last battery you will ever buy.

Many newer RV's may have a lithium ready converter.

Apr 7, 2025 | 01:59 PM

#11

CR172

Fleet Mechanic

Joined: Feb 2017

Posts: 1,597

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From: N. Texas

Yes, our controllers have Li settings. We aren't boondockers .... yet. We are going up to MI to help clean out my MIL's old farm house. We are going to try not to connect to anything and see how it goes. We will have access to power if needed but I don't anticipate needing to run the AC's. If so, we also have an onboard 5.5K propane generator. This trailer was made for the boonies...

Apr 7, 2025 | 03:24 PM

#12

drew999999

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Joined: Feb 2019

Posts: 278

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Quote:

Originally Posted by robert sloane

Lithium are nice, but unless your converter is set up to manage them, thrn your buying another charger to manage them

I really wanted to move to Lithium, but would have had to swap converters. In the end, I couldn't justify the costs. (Was really just needing more juice to keep the 120v fridge going on drive days since we never boondock). Ended up swapping the 12v battery out for 2 Costco golf cart batteries. They work great, but the downside is they're fairly heavy.

Apr 15, 2025 | 10:18 PM

#13

HRTKD

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Joined: Oct 2015

Posts: 19,727

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From: Wyoming

Quote:

Originally Posted by 1Butcher

An RV converter with a lead acid profile isn't ideal but it will work. An AGM profile is better. The biggest concern with an RV converter with a lead acid charge profile is if it has four stages. The equalization stage uses a voltage that is higher than a LiFePO₄ battery wants. Sure, the BMS should stop the charge if the voltage is too high, but I don't recommend taking that chance.

The other issue with most RV converters is that they just suck. The charge using a canned profile tends to take much longer than if you could use a LiFePO₄-aware charger that is programmable. This is important if you have to charge from a generator. If you're on shore power for a day, no big deal.

Apr 16, 2025 | 08:33 AM

#14

1Butcher

Cargo Master

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Quote:

Originally Posted by HRTKD

An RV converter with a lead acid profile isn't ideal but it will work.

Yes, I would agree with that. All too often, I read that the stock converter won't work. If you are on a budget, buy your LifePo4 batteries and next year, get the converter. You will be fine. Another benefit is you can spend a year to find out what will work for you. My requirement was to charge as fast as I could, when I plug in. That is why I got a 125A converter. I did have to swap breakers to a 20A to prevent it from tripping.