What kind of Battery to buy. . . Marine Deep Cycle okay? - Page 2 - Fiberglass RV

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Old 04-15-2008, 09:34 AM   #15
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We have an Optima "Yellow Top" AGM gel-cell on our Scamp for three reasons . . . well four, if you count draining the one the trailer came with down to nothing so it wouldn't hold a charge ever again . . .

The first reason we went with an AGM battery is, if you do drain the battery down to nothing, you don't kill the poor thing. It'll survive multiple rounds of charging and complete discharge before loosing its ability to store power. Given how we killed the first one, this sounded wise. If, on the other hand, you buy a 24-month Walmart battery and kill it, you can take it back to them within that two-year period and they'll give you a full replacement at no charge.

The second reason is all batteries loose some energy as they store electricity, 10-15% for most deep cycle batteries. AGM batteries are 95+% efficient, which is very important if you depend on solar panels for your power.

The last reason is weight: they are slightly lighter than a regular lead-acid battery of the same capacity.

Two other reasons you might want an AGM battery:

First, AGM batteries don't out-gas explosive hydrogen as they charge, so you can install them inside your trailer for better towing balance or to prevent theft. (Regular lead-acid cells have to be installed outside.) Ours is installed outside anyway, so not a factor for us.

Second, AGM batteries are essentially made up of separate 2v gell-cells wired together. Connect three cells together and you have a 6V battery. Connect 6 togther and you get 12V. There is functionally no difference between two 6V AGM batteries and one 12V other than the two 6V have a wire that connects the two of them together and the two 6V cells take up a little more space than the one 12V.

If we didn't have the solar setup I'd probably go with the Walmart deep cycle marine battery. They're about $60; the Optima was $160.


how come you didn't go with the blue-top optima?*


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Old 04-15-2008, 10:14 AM   #16
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Trailer: 1990 16 ft Scamp Deluxe
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What is Wally? Is it Wal-mart?

Thanks for the coding -- it seems we got a hybrid.
The Optima battery sounds like a good ($) battery esp if we want to put in solar later on. The website says the blue top is for RV's, so wondering about the yellow top usage for trailer? Is the yellow top better for the solar usage?
Glad this posting has helped some other battery shoppers.
I don't feel quite so confused, or alone in my confussion, now!



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Old 04-15-2008, 12:15 PM   #17
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Just a note on AGM (page way down). AGM (absorbed glass mat) and gel-cell are not the same battery chemistry.

Optima's starting batteries are gel-cel; they call them SPIRALCELL because of the way they are constructed.
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Old 04-15-2008, 02:04 PM   #18
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Indeed, Wally is WalMart. Deals on batteries can be found at big box auto stores, Costco, Sam's, KMart, etc. If one intends to travel out of local region, then nation-wide sources of tires, batteries, etc. should be considered.

Here are some thoughts to consider before spending extra $$ on AGM. It's your money and your choice:

1. AGMs are effectively just a lead-acid battery with the acid in a sponge instead of a puddle.

2. Most (all?) batteries are composed of smaller cells, but the cells may have different construction, like designed for starting or deep cycle or something between. That's why it's not good to mix battery types in a string. AGMs seem to be dual purpose because starting is mentioned on specs and description, but that may be less of a drawback than with a flooded dual purpose battery.

3. Although they outgas H2 less than the flooded batteries, they still outgas. Post from another RV group:

"The NEC made no exceptions for the battery venting requirements in RV's.

The AGM battery manufacturers are careful to state the batteries must be vented.

If you can find an AGM battey manufacturer that has an exemption for venting, please post a link. You'll be the first - no one in the past has found a manufacturer with an exemption."

That said, I know of many folks who have mounted AGMs inside van campers, etc., even on their sides (but not upside down). I also know of folks who have mounted flooded batteries inside, as they used to do in some vehicles like VW. I would do the former, but not the latter.

4. AGM's come in smaller Amp-Hour capacities than typical flooded battery of same nominal size. OP was looking for more power, not less.

5. AGM's reportedly last longer than flooded, but not as long as they used to. They were having troubles with improper charging systems damaging them; reportedly they were redesigned to tolerate a greater voltage range but in the process, they lost some expected life. I believe they also fixed the thermal runaway problem that was happening with the early AGMS.

6. AGM's will tolerate a lot faster recharge rate than flooded batteries.

7. As to economics, I don't believe an AGM compared to a series of flooded batteries is going to prove in. It would be more convenient, however, not having to replace battery for longer number of years. Add to the equation that the warranty on the AGM will expire much sooner than a series of warranties on flooded batteries.

8. Having had a battery stolen from the tongue of my Scamp, I was darned glad it wasn't an AGM -- That would really affect the life-cycle economics... If one's battery is mounted inside, it would be safer and of less concern on this score.

When the AGMs start dropping in price and start replacing the flooded cells, then I will consider them again, but for now I will continue to use flooded cells. YMMV!
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Old 04-15-2008, 03:27 PM   #19
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Trailer: 1990 16 ft Scamp Deluxe
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Thanks for all the input . . . now I know what I really want is a "true" Marine Deep Cycle Battery as I can discharge that down 80%. . . that Wal-mart, and other big boxes, sell those inexpensively with a warranty. (I know now that this kind of battery says DC on the Wally label & will look for that). The battery dosen't have to be purchased from a RV speciality shop.

I also know now to look on the label of a Marine Battery to make sure it doesn’t say CA or MCAA as then it is not a true Deep Cell, but a hybrid, and it should not be discharged more than 50%. Although, it still could be used for this purpose.

Considering expense, the $50 - $70 "true" Marine Deep Cycle Battery sounds like it will do the job, without breaking the bank. We mostly go out for just weekends, so this should be enough power.

Thanks again,
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Old 04-15-2008, 06:45 PM   #20
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Pete, you were right. I did purchase an AGM battery. Obviously not an informed purchase, but it's done now and it sounds like this battery will work fine.
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Old 04-15-2008, 06:59 PM   #21
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how come you didn't go with the blue-top optima?
The blue-top battery can deliver more cranking amps (more power over a shorter period of time) than the yellow top. I may be quite wrong about his, but my understanding is that the more amps a battery can deliver under duress, the less efficient it is in absorbing and storing new power.

Just a note on AGM (page way down). AGM (absorbed glass mat) and gel-cell are not the same battery chemistry.

Optima's starting batteries are gel-cel; they call them SPIRALCELL because of the way they are constructed.
I believe they are AGM batteries assembled in a spiral pattern. See their diagram.

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Old 04-15-2008, 08:45 PM   #22
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Other folks have different experience, but.. I will give you mine as well.

I have a group 24 Wally World RV Deep cycle battery. It has performed just as well as any of my Interstate batteries, and I have "OOPSED" and discharged it pretty deeply a couple of times.

I run around 60 watts of solar and find it charges the battery for "my" needs nicely every day, even overcast ones. With my furnace, 45 watts was not enough to get me through an evening with anything more than "get the chill off" heat" and lights. Now I can run the furnace more and watch a DVD or something too. (I have 30 more watts to add and I should be really stylin then)

Anyway, I trust when Peter says that AGMs can withstand a bigger discharge than a regular battery, but I find that I rarely, if ever, run my battery into the ground enough to worry about battery life being shortened.

I have quit paying the 120 bones for an Interstate, and even if I replace the Wally Battery every 3-4 years, I still come out ahead a few bucks. The Wally World one cost 49 bones.. but I am sure the price has gone up since last summer when I bought it.
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Old 04-15-2008, 08:48 PM   #23
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Pete, you were right. I did purchase an AGM battery. Obviously not an informed purchase, but it's done now and it sounds like this battery will work fine.
If you got an AGM, then you will be alright; treat it well and it will last a long time. Many informed people have chosen to go with AGM because they feel the benefits are justified, esp the one about no maintenance.

In this case, we are sort of picking hairs. Just don't let it get stolen...

The Optima batteries are quite popular with the 4x4 rock-climbing crowd because they can take a beating, even be turned upside down, and not be harmed.

I forgot to mention, I would expect that the lack of acid on the outside top would lead to less corrosion at the battery terminals, thereby making the system more reliable.
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Old 04-24-2008, 04:52 PM   #24
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Thanks for all your expert advice.

I ended up getting the Costco group 24 Marine Deep Cycle battery for about $58. It has a 36 month warranty.


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Old 04-25-2008, 12:33 PM   #25
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Here is another good reference about the 12 volt electrical system in your trailer; it contains a lot of information about batteries as well.


-- Dan Meyer
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Old 05-04-2008, 12:52 AM   #26
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I added two 6-volt deep-cycle golf cart batteries to my setup.

I plan to do a lot of camping without shore power and this is the way to go.

Presently, with my trailer parked in my yard, I just use the old battery that came with the trailer and connect a regular battery charger to it to power my lights, stereo etc.

This battery on its own will only last about an hour because it is worn out. However since I am plugged all the time this is not a concern to me. My good batteries are presently in warm storage hooked up to a smart charger and will be transferred to the trailer once I start camping.

Check out my post in modifications. Kevin61 1976 Boler restoration

Most of the photos are on Facebook and you may have to join to view them. I am in the process of transferring the photos to a site that is easier to access.

Hope this helps
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Old 10-10-2010, 11:24 AM   #27
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Anyone thinking of buying an Optima Blue top battery should note that there are 2 different blue tops, so make sure you get the right one! This is from Optima's website;

"BlueTop: The BlueTop starting battery (dark gray case) is to be used when a dedicated starting battery is required and it should never be used for cycling duty. The dual purpose BlueTop (light gray case) can be used for both starting and deep cycling; it is a true deep cycle battery with extremely high cranking power.

Trolling motors, marine applications with heavy electrical accessories and RVs should use a dual purpose BlueTop (which is both a starting and deep cycle battery)
Use a BlueTop starting battery for marine applications and RVs when the battery’s only function is engine starting
Note: The difference between BlueTop and YellowTop deep cycle batteries is that BlueTop batteries have both automotive (SAE) posts and threaded posts, while YellowTops (other than D31T) only have SAE posts.

If you ever get confused on the color tops just remember: if it has a dark gray case then it is a starting battery; if it has a light gray case then it is a deep cycle (dual purpose) battery."

They also confirm the battery needs to be vented if placed inside a passenger compartment, and that their batteries have ports for connecting a vent hose.

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Old 01-30-2011, 08:30 PM   #28
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Originally Posted by Booker B. View Post
I have also found this 2 part article quite informative:

The 12 Volt Side of Life
I just read your post. WOW! You are good!!! Excellant information on 12 volt and things to do that make boondocking easier.

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