Community Forums

bro61021 · 05-03-2023, 03:44 PM

My travel trailer battery needs to be replaced. The battery currently in it is a 675 CA deep cell starting battery. TT's obviously don't have a motor. The battery is used for appliances, lights, emergency brakes etc, when the trailer is not connected to a campground pedestal. Why do I need CCA starting Amps. Can I just get a deep cell battery? If so what specifications should I be looking for in a deep cell battery and how much?

twinboat · 05-03-2023, 03:52 PM

Most 12 volt batteries built for RV deep cycle use are a hybrid battery with a CCA rating.

True deep cycle 12 volt batteries are expensive, so most folks go with 2-6 volt, GC2 , golf cart batteries, wired in series for 12 volts.
Can be found for around $100 but you need 2.

For overnight dry camping on the way to a campground with power, the RV/Marine battery will do the job.

If you want to do more then 1 night at a time, go for deep cycle.

The more AH ( amp hour ) your batteries have, the longer they will last between charges.

LETMGROW · 05-03-2023, 04:09 PM

Quote:

Originally Posted by bro61021

My travel trailer battery needs to be replaced. The battery currently in it is a 675 CA deep cell starting battery. TT's obviously don't have a motor. The battery is used for appliances, lights, emergency brakes etc, when the trailer is not connected to a campground pedestal. Why do I need CCA starting Amps. Can I just get a deep cell battery? If so what specifications should I be looking for in a deep cell battery and how much?

CCA is "Cold cranking Amps" The higher the better. I would buy the largest battery you can fit in your battery box. Opt for a Deep cycle battery such as a marine battery unless you do have room for two 6 volt Golf Cart batteries as "Twinboat" suggested. These would need some additional wiring to wire them into series to provide 12 Volts.

ArtJoyce · 05-03-2023, 04:18 PM

I would get a group-31 deep cycle battery. If you can not find a 31. Get a group -29.

tuffr2 · 05-03-2023, 04:21 PM

I would advise getting the biggest group size you can. Most RV's come with a cheaper group 24 battery. I had a group 27 battery and it severed me well. But look at a group 31 battery as being the best battery for an RV. That is is you do not want two 6v golf cart batteries that would be better yet.

A lithium ion battery is the best now but might need some modifications to your trailers converter.

Dave Pelletier · 05-03-2023, 04:27 PM

I'd swap that battery out for two 6V GC batteries. You'll get about 225 Amp Hours capacity and about half that is usable.

Dave

Winemaker2 · 05-03-2023, 05:10 PM

This may help explain some of the mystery but marine /RV battys are not the best / or equivalent to true deep cycle.
Gold cart battys are a great alternative as they are deep cycle, high volume, competitive cost and will likely outlive any marine/RV batty.

https://marinehowto.com/what-is-a-deep-cycle-battery/

The key is AH rating and it is usually stated as the 20A rate (it will vary with the A draw rate so important to compare the same discharge rate)
Above is true for flooded lead acid and if/when you switch to AGM (sealed) battys much of the above no longer holds true.

Bigfin · 05-04-2023, 07:10 AM

I have been very happy with the price and performance of shoe horning in two Costco group 27 DC wet cells to replace the group 24’s my trailer came with. I also upgraded the converter and increased solar panels. A genny used for - 2 hours a day takes care of cloudy days. Cheers!…

**hamm2018** · 05-04-2023, 07:27 AM

Quote:

Originally Posted by bro61021

My travel trailer battery needs to be replaced. The battery currently in it is a 675 CA deep cell starting battery. TT's obviously don't have a motor. The battery is used for appliances, lights, emergency brakes etc, when the trailer is not connected to a campground pedestal. Why do I need CCA starting Amps. Can I just get a deep cell battery? If so what specifications should I be looking for in a deep cell battery and how much?

Here is some nighttime reading material for you:
https://batteryglobe.com/group-27-vs...%2075%20pounds.

Persistent · 05-04-2023, 08:06 AM

Quote:

Originally Posted by bro61021

My travel trailer battery needs to be replaced. The battery currently in it is a 675 CA deep cell starting battery. TT's obviously don't have a motor. The battery is used for appliances, lights, emergency brakes etc, when the trailer is not connected to a campground pedestal. Why do I need CCA starting Amps. Can I just get a deep cell battery? If so what specifications should I be looking for in a deep cell battery and how much?

As you reasoned, you do not need 675 CA performance in your travel trailer.

Engine start batteries are designed to provide extreme high starting current (675 amps) for very short times (10 seconds). The battery installed in your TT will do that in freezing weather.

Nothing in your TT comes anywhere close to that high current. A 12 volt furnace may draw 8 amps. However, it will run for long periods and repeatedly. "Deep Draw" batteries are designed to deliver low currents for long periods. The standard test for amp hour capacity, is to use a discharge that last for 20 hours, not 10 seconds.

If the battery does not have an "Amp Hour" rating, it is probably an engine start battery and will perform poorly in your TT. Ignore "Cold Cranking Amps". Look for an "Amp Hour" rating.

Flooded cell lead acid batteries are the traditional deep cycle battery designs. Gulf cart flooded cell batteries are often cheap and do a good job in travel trailer applications. Gulf cart batteries are typically 6 volts, so you need a minimum of two wired in "series" for your TT.

A battery design that performs better for a TT is an "AGM" type. They work better for both deep draw and small engine starting and so often have both a CCA rating and an Amp Hour rating. AGM batteries often cost more then similar Amp Hour flooded cell batteries. Shop around for price you may find a bargain AGM for little more than a flooded cell battery.

AGM batteries charge and discharge faster than similar flooded cell batteries.

AGM batteries resist damage better when drawn down flat better than flooded cell batteries.

AGM batteries do not require monitoring of water level in the batteries.

Fully charged AGM batteries that are disconnected can be stored for 12 months without damage. Fully charged flooded cell batteries that are disconnected can be stored 6 months without damage.

Unfortunately most AGM batteries don't tolerate high voltage charging as well as flooded cell batteries. 13.6 volts is the maximum most AGM's can tolerate without capacity loss. Some charger use 14.4 volts for long periods and some use 15.0 volts for "conditioning" or "equalizing". These high voltages should not be used on AGM batteries.

14.4 volts for 4 hours on deeply discharged AGM batteries is usually the maximum allowed. See battery manufactures specifications for your battery.

All lead acid battery designs must be stored fully charged for long life. Fully charge for 14 to 18 hours before disconnecting and putting into storage.

Do not let lead acid batteries sit in discharged state for any longer than necessary. A week at 50% SoC is probably OK. Three months at 50% will probably kill the battery altogether. Fully charge 14 to 18 hours as soon as possible.

bro61021 · 05-04-2023, 08:18 AM

Quote:

Originally Posted by Dave Pelletier

I'd swap that battery out for two 6V GC batteries. You'll get about 225 Amp Hours capacity and about half that is usable.

Dave

If I go from a group 24 acid battery to 2-6 volt batteries does the trailer wiring
or battery cutoff switch need to change. Any impact on my inverter.

bro61021 · 05-04-2023, 08:22 AM

Quote:

Originally Posted by tuffr2

I would advise getting the biggest group size you can. Most RV's come with a cheaper group 24 battery. I had a group 27 battery and it severed me well. But look at a group 31 battery as being the best battery for an RV. That is is you do not want two 6v golf cart batteries that would be better yet.

A lithium ion battery is the best now but might need some modifications to your trailers converter.

If I upgrade to a higher group is there any impact to my inverter or electric system

Mark_K5LXP · 05-04-2023, 09:48 AM

The only impact is greater run time, maybe longer operational life. Generally there's no downside past cost, weight and size.

Mark B.
Albuquerque, NM

Marine359 · 05-04-2023, 10:04 AM

It’s not true that you must upgrade your converter/charger in order to switch to LiFePo4. Takes the same space as a group 27 deep Marine deep cycle, so , it will fit in your existing battery box. You can buy a 100ah one now for around $300. And, you don’t have to change your converter/charger. Your stock converter/charger WILL charge the LFP. You just won’t be able to charge it to 100% of its capacity, because the stock charger is 3 stages, and LFP only has 2 stages. Therefore when the stock charger gets to 80%, it will stop charging a LFP, because it needs 14.4v, and the charger will switch to float at a lower voltage. But the 80% you get will be fully useable down to zero. Think: is it more cost effective to get 80 useable amphrs for $300, or better to get about 150 useable amphrs from 2x 6v GCA flooded batteries for about the same price. You’ll never have to replace the LFP, and don’t have to maintain it. If you need more than 100ah useable, AND you can handle the extra tongue weight of 2x GCA, and you are fine with maintaining them, then 2x GCA is the right choice for you. If you spend the bucks to get 200ah of LiFePo4, then it makes sense to spend the extra bucks to upgrade your charger so you can use 100% of their capacity. Along with that, you gain the advantage of fully charging your batteries in about 25% of the time it takes to charge FLA.