Battery Problems.

[jralcala]

Have 2 regular 12 volt marine batteries in my Cougar 367FLS. They dont seem to last very long. Hear 2- 6volt golf batteries is the way to go. Gonna check the wires and all the connections but wanna see if there are any opinions out there.

[chuckster57]

Welcome to the forum!!

When you say they don’t last very long, it depends on what your operating on 12V when not plugged into shore power. You need to know how many Amp hours each battery is rated for. Then start figuring out how many amps each item your using is drawing. It takes a bit of math, but you can calculate it.

[jralcala]

Only info I could find on the battery and I have 2 of them. I go the night before and turn the fridge and gas on. But I know there are little small things that are on on like clock the smoke and Co detector and etc. But when ai go back the next morning and hook up. I have to put a jump box on the batteries tonget the landing gear up. Also I moticed before wven touching any of that the batteries are almost dead just from the fridge.

[JRTJH]

You probably have multiple issues going on.

First, there is a battery cutoff switch installed by Keystone in most trailers. It DOES NOT cut off all battery power. All of the "safety features" (CO detector, LPG detector, etc) and the "memory circuits" in the radio remain energized. Those will drain your batteries to "completely dead" in a couple of weeks, maybe sooner.

Second, if your batteries have been "drained to nearly dead" multiple times, then they may not be capable of accepting a full charge, so they may be "the problem with not lasting one night"...

Third, if you're turning on the refrigerator and nothing else, and the batteries are dead (require jumpering) the next day, then those batteries were not fully charged when you turned on the refrigerator. So, the question would be, "Why were they not fully charged?" Answer: One above, two above or a combination of both ???

The above doesn't answer your question of whether your batteries (when in serviceable condition) would work with your trailer. I'd guess there are probably 50% of RV'ers with similar batteries and they "get along just fine" for a night or two of dry camping. So, if your batteries are OK, then you should be able to camp a couple of days without problems (assuming reasonable DC power use), but with your statement about dead batteries with only the refrigerator in operation for 8-12 hours.... You've got some damaged batteries, I do believe.....

ADDED: The above is based on your trailer having a gas/electric "RV" refrigerator. If you have a "residential refrigerator" then trying to get it from "room temperature" to "operational temperature" would "suck the life out of two small batteries in an "overnight marathon of cooling a hot reefer".....

[flybouy]

What kind of fridge? Is it a residential running on an inverter? Some lp fridges have door heaters that can take a lot of watts.

The batteries you have are meant to start an outboard boat motor. They are not deep cycle and are virtually useless for the application.

[chuckster57]

If you have a pair of the batteries you show in that picture, you don’t have deep cycle batteries. The link clearly states marine “starting” battery. Starting batteries are a different type than the deep cycle needed to power an RV for any length of time.

What you need to do is find two true deep cycle batteries, denoted by an AmpHour rating not a cold cranking amps rating. If your going to be doing any dry camping (not plugged in) I would look into a pair of golf cart 6V batteries wired in series.

[LewisB]

To the responses, I would add that you need to consider

• how all the connections are made to your battery bank and
• the size of the paralleling cables.

It is very common for users with 2 or more batteries to sort of make indiscriminate connections to more than one battery - any place they can get 12VDC. If your parallelling cables between the batteries are small gauge, this can lead to variable resistance between various loads (or sources) and the individual batteries in your battery bank. So, for each of your load connections (main cabin, auxiliary connections like front jacks, inverter, etc.) and for each of your source connections (shore power, generator, solar, etc.) you need to do one of the following:

• make all of the [+] connections to one battery in the bank and all the [-] connections to the other paralleled battery in the bank, or
• use heavy gauge cable to make your parallelling connections.

Why? The circuit resistance between each load and the batteries and each source and the batteries must be identical - if not, the weaker of the two batteries will determine the performance (both discharge and charge) of the total battery bank. With undersized parallelling cables, you will only see the life of the weakest battery and you very well may not be charging both batteries uniformly.

Lastly, like a chain, the performance of the battery bank will only be as good as the electrical performance of the weakest battery. So batteries in a bank should alway be uniform size/age/condition and should always be replaced as a set. If one battery fails a load test and you replace only that bad battery, you likely have just switched the location of the weak link and the other non-replaced battery will fail quickly. (I learned all this the hard way!]

[jralcala]

Any opinions on 2 6 volt golf cart batteries over 2 12 volt deep cycle batteries? The fridge is gas/ electric and is a Dometic but will have to double check. Will be running some test and checking to see if there is a converter problem.

[chuckster57]

If your dry camping 2 GC 6V batteries are better, if you camping with hookups then they aren’t worth the extra cost.

[Old Mustanger]

Originally Posted by chuckster57

If your dry camping 2 GC 6V batteries are better, if you camping with hookups then they aren’t worth the extra cost.

That's the most sensible/informative statement I have read on the 12V vs 6V discussion.

[bbells]

You are right. No matter what the issue is in the above statements (if there is one), marine deep cycle batteries are not deep cycle batteries. A true 12v deep cycle battery weighs at least 100 pounds and never say ccr. If you actually use the batteries you will be lucky if they last 6 months to a year. Plus, they are all low amp hour. This means you cannot use them very long before going dead. 2 6v golf cart batteries are a great way to go. For less than $100 each at Batteries Plus you can get 200ah batteries. They also carry 12v 200ah golf cart deep cycle batteries for about $280. FYI: TV 4 ah, LED lights .5ah, furnace 4ah while running, AC don't use on batteries. (Battery ah/2)/(used ah*hours used) = How long your battery will last. This is a rough calculation. It would be better to only use 30-40% of your batteries power.

[Comptech]

I added two 6 volt batteries last year so i could run my CPAP while stopped for the night. The best thing you can do for extended run time.

[thefulminator]

I used to work in a battery shop. There are some very important questions that haven't been asked yet.

How old are these batteries?
You can check the age by looking for a stamp in the post or case or a sticker on the case with a letter and number combination. The number is the last digits of the year and the letter is the month, A through M excluding I. A is January, B is February, etc. when the battery was made.

Have the cells been checked to be sure they have adequate water in them?
If needed add water then charge. Never test after adding water without charging first.

Have the batteries been left discharged and allowed to freeze?
Look to see if the case side have bulges in them. This is a indication that the battery was discharged with most of the acid is in lead leaving the cell full of water. The battery froze, the water expanded into ice and the case bulged.

Is there any water and grime on top of the batteries?
I know from experience that a battery can discharge on its own through the gunk between the battery posts acting as a conductor and allowing current to pass between them. The current flow is low so you don't get arcing.

Are the posts/connections clean?

When you charge them how are you doing it?
A battery won't charge when it is really cold. If you are charging on your trailer be sure to give adequate time for the charge if it is cold outside. If charging in your garage, never let the battery sit directly on the concrete floor. The concrete acts as a heat sink and will pull the heat out of the battery faster than you can put it in during charging. Isolate batteries from concrete with wood or foam blocks.

[Hamops]

I don't think that you have failing batteries. There are parasitic loads in the trailer that are hooked directly the battery at all times. Key loads can be the LP Gas detector and the CO2 monitor. If the trailer is not connected to shore power or a battery charger, then those parasitic loads will drain the battery in one or two days.

The easiest way to resolve that problem is to install a disconnect switch on the positive cable from the battery. This will totally isolate all the DC loads in the trailer.

I had the same issue, years ago and installing a disconnect at the battery resolved my problem of the battery discharging.

[Bullet1928]

This a little off base from the original thread but I was wondering what others do with their batteries when they take their units into the shop for work. There is sometimes a lengthy wait for them to get a unit in once you drop it off. Do you take the battery(s) out and take it with you? I lost a set of batteries because my fifth wheel sat a few weeks on their lot before making it into the shop. I had the disconnect switch enabled but forgot to disconnect the batteries completely to eliminate draws from sensors and other power drains.

[moparmad]

my opinion would be 6vlt deep cycle. knowing exactly how batteries are made and designed it would also be an agm. cost more yes. life cycles, durability and depth of discharge and ability to handle high amperage recharge, and then go back and look at cost vs life to me there is no other option. take into consideration plate size/thickness, plate lengths, the susceptibility to stratification and sulfation. Agm is the way to go. You can get up to 400ah out of two. Lithium ion cost way too much and then you have to worry about temps and charge rate. As mentioned before, check your draw, make sure its reasonable. As for electron flow, again mention before, hook battery up closest and farthest posts. Flow must go through entire battery bank, if you have a lot of wiring, suggest a bus bar. And for disconnects, I like the "forklift" style quick disconnect battery connectors. they make different sizes up to 4/0 awg that can handle up to 1000amps surge 400amp constant. They are inexpensive, marine grade and don't corrode. I have ran into trouble using the more expensive "switch" style ones where the contacts get pitted and cause high resistance giving inverters headaches.. id put in a pic but haven't figure out how to do that yet. its a basic quick disconnect and both neg and positive are disconnected. You can go cheap, but that's what your going to get in return. Just my opinion