Deep cycle or RV battery choices

Scott91370 · 10-14-2017, 12:08 PM

It's time to replace my battery and I was wondering what people are using for long life.

I also have a couple of questions about charging because this battery only lasted about 2 years - which may be normal.
When your trailer is parked and unused for extended periods how do you keep the battery charged? Do you just plug in the shore line or do you use a trickle charger? I wasn't sure if the built in charger would turn itself on/off as to not over charge the battery.

oldmanAZ · 10-14-2017, 12:33 PM

IMO, long battery life depends most on your discharging and recharging practices:
* Doing the wrong things will kill a battery even if it is a long life battery.
* Doing the right things will help a mediocre battery last a long time.

My factory battery charger is designed to function as a trickle charger once the battery is fully charged. It does not switch on and off. I keep my trailer plugged in and my 2 batteries on the trailer's converter/charger. So far, going into year 3, that has worked for my two W*mart RV batteries.

RogerR · 10-14-2017, 12:35 PM

I fully charge my battery and bring it into the house for the winter. I try to give a charge one or twice over the winter.

Mine is a group 27 battery and I can lift it with some effort. If it gets to much I will buy a better smart trickle charger and leave it on the tongue. I have left my second car and gone to Florida twice with no problems so I would assume the same with an RV battery.

Isaacs · 10-14-2017, 01:28 PM

I have two mis-matched (group 24 and group 27) 12V "deep cycle" batteries that are about four years old. They are wired in parallel and constantly charged from my solar panel through a cheap charge regulator; never had any problems. I want to replace them with a pair of 6V golf cart batteries in the spring.

Siamese · 10-14-2017, 02:15 PM

I own a travel trailer and a sailboat. Because I own a sailboat, I spend a lot of time at a sailing forum where we have a member who is the gold standard for battery knowledge and advice. He's a guy who owns a marine service on the East coast, and shares his knowledge with us. He goes into such depth about batteries, I can't begin to comprehend the science and math he presents, but like many others, i can benefit from his conclusions.

Our "expert" is knowledgeable in FLA (conventional flooded lead acid batteries), AGM's, and LifePo systems. One of his conclusions is that for the vast majority of us, FLA is the best choice. AGM's have some desirable characteristics, but also have special requirements that not all of us can meet, and they cost considerably more.

So, my first choice is going to be FLA batteries. Not looking to initiate an argument with those who use AGM's and are happy. My guru designs and installs complex wiring systems and multiple, large bank battery systems in sailboats that are intended for prolonged offshore sailing. He sees a lot of AGM's that are toast in a short period of time because of bad installations and chargers that fail to provide proper voltage. And, he sees AGM's that are part of a proper system and give years of service.

Anyway, it's FLA batteries for me.

"Guru" has written extensively on FLA's that claim to be deep cycle, and has concluded based on testing, and sawing many batteries open, that many brand name deep cycle batteries are simply re-labeled starter batteries. There are a few that are heavier duty, some that fall somewhere in between, but pretty much all 12volt "deep cycle" batteries are not true deep cycling.

Popular on sailboats, are the larger 4D batteries. My previous boat came with a 4D from the factory for the house battery, and a group 27 for starting. Lifting a 4D battery will make your arms longer and your back shorter. They're not fun to lug around. Despite their popularity in the boating world, "guru" doesn't consider them to be true deep cycling either.

His preferred battery for most small to medium applications is FLA golf cart batteries. He reached that conclusion by testing them, installing them for years in yachts, and by sawing them open to look at the plates. The better golf cart batteries, like Trojan, offer true deep cycling and the greatest storage in the smallest footprint. Two 6v batteries wired in series yield 12 volts.

Why are golf cart batteries made better? Consider that it's an industry where every golf course in the country is a big consumer of batteries for golf carts. The golf carts leave the shed with a full charge, roll around the course, return to the shed, and go back on the charger over and over and over. Records are kept, so it's known when they were purchased, installed, and how many times they were used before they failed. A golf course manager can easily know which batteries offer the most discharges per dollar, and the battery maker who wants to sell them batteries will have to offer the right product. You can't fool the golf course managers.

Contrast that with travel trailer owners. Record keeping is minimal, chargers vary widely in quality (like the crappy WFCO chargers that fail to go into bulk charge mode), and maintenance is spotty. For the most part, batteries are bought based on anecdotal evidence from fellow campers, wind direction, price, etc.. If you're a battery manufacturer of "deep cycle" batteries for the RV industry, it probably makes sense to compete on price, or put your money into marketing, because your market, as a whole, just ain't that smart.

My recent TT purchase is on it's factory, 12v FLA "deep cycle" battery, which is okay with me for now. When it dies, I might replace it with a pair of 6v's. Of course, that would more than double the weight of my battery weight on the tongue, as each 6v weighs more than a single 12v (more lead). Or, I might just replace it with the best 12v "deep cycle" available to keep the weight down. We do a lot of boon docking, but we always have our 2200 watt generator with us and have upgraded our WFCO charger to a Progressive Dynamics unit, so we're always able to keep our battery topped off. We'll wait and see if we really need the additional storage.

With regard to my guru, I don't have a single link to every article he's written. Most of it is in three different sailing forums. Here's a link to his website, where, as of right now, he has an excellent article on battery storage right on the front page.

https://marinehowto.com

If you wanted to find more from this expert, try Sailnet.com where he is a regular contributor under the name MaineSail. He has some lengthy and impressive articles that make my head want to explode, but like I said, I'm content to just believe him and use his conclusions.

nunyadamn · 10-14-2017, 04:22 PM

My experience - bought 3 Optima big batteries for a boat I had for $230 each, trickle charger died over the winter in storage and killed all three batteries. I don't buy the expensive batteries anymore. I go with standard batteries that will handle what I need. If one dies I can buy for much less.

My travel trailer - I have 2 6v Costco batteries, been great for 3+ years so far.

Siamese · 10-14-2017, 05:04 PM

I'd be happy with a pair of Costco 6v's.

SmackIt · 10-14-2017, 05:36 PM

LiFePO4 if you can afford it. Light weight, charge very fast, can be drawn down below 10% without harm, will last for 3000 charge cycles or more.

**Mustang65** · 10-14-2017, 06:41 PM

Quote:

Originally Posted by SmackIt

LiFePO4 if you can afford it. Light weight, charge very fast, can be drawn down below 10% without harm, will last for 3000 charge cycles or more.

Down the road, I may reach deep into my pockets and flip for LiFePo4 technology, but due to the newness of the LifePo4 technology, the jury is still out on how long they will last (outside of the LAB). Granted they will continue to improve the technology, but my TT is no where near the pristine lab conditions that got the max numbers. Same holds true for FLA batteries. The temperature of the battery boxes (sitting in the hot sun in black boxes mounted on the front of the TT can exceed 160 degrees midday. Then drop to 60/70's at night, that will have an affect on the life of the batteries.

If you can figure out how to keep your storage compartment at a nice 68-70 degrees 24/7 and without going past 80%, you may see that 3000. My storage compartment is 80+ mid day, when all the SOLAR charging would be taking place, which would heat the area even more. The labs also spend a lot of $$$ on their BMS, most people I know are not going to dish out dollars for the best BMS, same as with FLA. If it works why change it.

So, if I a am still around in the distant future, I will check out what the independent testing shows and see if LiFeP04 is worth it.

At this time, with the LiFeP04 in my front storage compartment reaching those temperatures at PEAK charging time (BMS will not like that at all), I have a comparable number of cycles on my Trojan T145 batteries, which are in their 5th year now. Are they a little tired, yes they are and that is what is expected. Maybe another year or two. Will research again. Until then, I will just keep reading about them.

The old original Interstate 85Ah batteries that came with the TT are still working, they also charge perfectly, but only put out 40 Ah's each (tested). Not bad for 5 years. That is fine as I use them in my electronic projects now.

Don

My Registry

RVing with SOLAR

Scott91370 · 10-14-2017, 06:46 PM

Thanks for all the input. Siamese, that was actually way more deep than I could have expected but very appreciated!

I will check into the Costco 6v batteries, I never thought about going that route before.
I also found in my manual the the built in charger will full charge then go jnto a trickle mode. How well it does this of course is unknown. I wouldn't bet my check on it being as good as an aftermarket charger though.

Thanks again everybody, forums like this and people like you all make everything easier and in turn more fun.

GrumpyDad · 10-14-2017, 06:49 PM

Does anyone have opinions on running mismatched pairs of 6V batteries in a 4 battery setup?
Through some complicated circumstances it seems like I have a set of 2 older (but still good) Trojan T105's and I'll be coming into a pair of newer 6V unknown brand. Any downside to using mismatched?

For that matter, could a person run 2x6V in parallel with a single 1x12V Battery to have three total? Would the difference in amp-hour capacity mean the charging requirements would be different enough to cause problems?

sometimes I think too much, anyone else have that problem?

wabirch · 10-15-2017, 06:18 AM

Awesome info, the knowledge in this thread is hugely appreciated.

**Mustang65** · 10-15-2017, 06:22 AM

Your system is only as good as your weakest battery. It is like a chain, it is only as good as the weakest link. In a mismatched system, some of the batteries will be overcharged and some will be under charged. The life of the newer batteries (Ah output) will diminish at a faster rate.

If you really have the room and want to keep the older batteries, split your battery bank in to 2 battery banks, one for the new and one for the old. Get yourself a Marine battery selector/disconnect switch, capable for two batteries. Hook up the two battery banks to the switch. You can then select which bank you want to use independent of the other bank. Just NEVER use the selection that connects both banks together, especially during charging.

Get a couple of INEXPENSIVE Digital Voltage Displays, one for each bank and keep an eye on them. You can find them on Amazon, and we have a thread in the RVing with SOLAR social group, I believe the thread's title is Digital Battery Display. Many of the members have installed these and I believe they are happy, I know I am happy with mine.

The other thread is:
https://www.jaycoowners.com/forums/f...vel-32652.html

To charge them, you will need to charge each bank separately.

As for the 12VDC battery and 2 6VDC batteries, would you connect a "C" flash light battery with a "AAA" flash light battery, they both are 1.5VDC... I did not think so.

Don

My Registry

RVing with SOLAR

GrumpyDad · 10-15-2017, 03:17 PM

That's a good explanation Don, thanks.

Atlee · 10-15-2017, 08:35 PM

Currently I have a dealer installed Group 24 battery. By next spring, I hope to have a pair of 6V GC batteries in place. The golf cart batteries will either come from Costco or Sam's Club.

Quote:

Originally Posted by Scott91370

It's time to replace my battery and I was wondering what people are using for long life.

I also have a couple of questions about charging because this battery only lasted about 2 years - which may be normal.
When your trailer is parked and unused for extended periods how do you keep the battery charged? Do you just plug in the shore line or do you use a trickle charger? I wasn't sure if the built in charger would turn itself on/off as to not over charge the battery.

Scott91370 · 10-15-2017, 09:19 PM

Keep the info coming. I know a lot of people are learning here.

Unfortunately I don't have the resources at this time to go with the dual golf cart batteries so I will more than likely get another deep cycle style. This was very unexpected and the upcoming out of state hunting trip has taken a toll on my play money especially since I am plannng on a generator for this trip as well. I will however make sure I take better care of it than the current one so I will hopefully get more than just 2.5 yrs out of it.

Thanks again to everyone who has traveled this battery road before us for sharing!

**Mustang65** · 10-16-2017, 07:42 AM

Quote:

Originally Posted by Scott91370

I will however make sure I take better care of it than the current one so I will hopefully get more than just 2.5 yrs out of it.

Pick up one of these inexpensive Digital Voltage Displays before your hunting trip. Make sure that when the displayed voltage hits 12.0VDC you shut down your 12Volt system until you can recharge the batteries. Going lower than 12.0VDC will shorten your batteries life.

Don

My Registry

RVing with SOLAR

Isaacs · 10-17-2017, 08:01 AM

Has anyone tried using a battery desulfator? I had a conversation with an automotive engineer and he said they work.

Here's an interesting article: Battery Desulfators - Fact or Fiction - Import Tuner Magazine

Scott91370 · 10-17-2017, 08:37 AM

Quote:

Originally Posted by Mustang65

Pick up one of these inexpensive Digital Voltage Displays before your hunting trip.

I've been thinking about it even before your post. It will be here tomorrow.
Thanks!

Quote:

Originally Posted by Isaacs

Has anyone tried using a battery desulfator? I had a conversation with an automotive engineer and he said they work.

Here's an interesting article: Battery Desulfators - Fact or Fiction - Import Tuner Magazine

Interesting. For the price even if you get an extra year from a battery and go through 4 batteries you'll eventually save enough money to have paid for itself. And since it will maintain them over the winter it could just replace a regular battery charger.

**Mustang65** · 10-17-2017, 10:16 AM

Quote:

Originally Posted by Isaacs

Has anyone tried using a battery desulfator? I had a conversation with an automotive engineer and he said they work.

Here's an interesting article: Battery Desulfators - Fact or Fiction - Import Tuner Magazine

Not necessary on RV batteries as your battery charge controller accomplishes the same thing every 21 (or so) hours by stepping up the voltage to the battery to 14.1 volts when it is float mode. Once a battery doesn't stay at or above 12.6 Volts, it is pretty much toast. You can do what ever you think will help, but the damage is done. Some of these tips may raise the voltage back up a little, but the Ah's will not be there.

After time some the battery acid settles to the bottom of the battery this process mixes it up again toward the top of the battery.
Don

My Registry

RVing with SOLAR

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