Marien Starting Battery =/= Deep cell battery

swimmer_spe wrote:

azrving wrote:

swimmer_spe wrote:

azrving wrote:
What voltages are you seeing as you use it? Have you checked the gravity?

I had it tested and it is good. But I kept killing it. Tells it is still a good battery, but not up for what I need it for.

Maybe you need more than one. Even a true deep cycle may not help you if you try to pull too many amp hours. I run six GC2 and use all they have. Do an energy audit.

Hoow do I do one? Only thing besides the lights is the furnace.

Suggest you Google "the 12 Volt Side of Life". Your battery is used for more than just lights.

Trusting the 3 light indicator may be unwise. For flooded jars the best way to check state of charge is to measure specific gravity by using a hydrometer.

What converter is in the RV?

I suggest changing to LED lights.

swimmer_spe wrote:
My trailer has a 3 light indicator. When it gets to red, I stop using power and recharge.

MEXICOWANDERER wrote:
Forklift batteries can be drained and destroyed

The succinct problem is like trying to manage a checking account without having the ability to read and write. I can't be overdrawn I have checks left.

The OP needs meters and the knowledge that enables him to use them effectively. A battery voltage cut out switch would work as a poor substitute.

My trailer has a 3 light indicator. When it gets to red, I stop using power and recharge.

Forklift batteries can be drained and destroyed

The succinct problem is like trying to manage a checking account without having the ability to read and write. I can't be overdrawn I have checks left.

The OP needs meters and the knowledge that enables him to use them effectively. A battery voltage cut out switch would work as a poor substitute.

The real bummer on deep cycle batteries is that a 12V deep cycle battery is hard to find and EXPENSIVE. You will likely only find them in a golf cart store and the cost of ONE 12V golf cart battery (size GC12) will likely be more than TWO 6V GC2 golf cart batteries from Costco or Sams Club.

wa8yxm wrote:
True DEEP CYCLE batteries like the GC-2 (six volt) or GC-12 (12 volt) The GC means Golf Car.. are designed to be run down as low as 50 percent (And quickly re-charbed I do not mean fast charge I mean don't let 'em sit discharged for long) over and over and over and over again.

MARINE/deep cycle are basically starting batteries. Like to be above 75-80% state of charge and INSTANTLY recharged when run down.. Not really the best choice for RV use.

Now I've had some folks say "Exact same chemistry so why is that" the answer is they are NOT exactly the same either chemically or physically.. Both the physical construction and the chemistry are a bit different. A few years ago there was a huge discussion thread on the chemical differences. and there have been several about the physical differences.. The plates are not pure lead they are an alloy and the alloy is different. also if I recall correctly fewer THICKER plates on the Deep Cycle.

Picking a couple of nits.

Regularly running "deep cycle" batteries down to 50% SOC or starting/dual purpose batteries down to 70-80% SOC will shorten the life of both. You should be more conservative in your maximum discharge,

The chemistry is (typically) close enough between the two to not quibble (although I know there are differences between various deep cycle batteries). The biggest differences are PHYSICAL. As mentioned, true deep cycle batteries have thicker plates (more lead) and weigh more. They also have more room in the bottom of the case for lead sulfate accumulation (a by product of discharging) that can eventually short out a battery.

Your battery is your bank account in amp hours.

Your useage in amp hours are your withdrawals.

Your charging abilities are your income plus you have to pay a penalty for system losses and battery internal resistance.

People are often surprised at what it takes to fully charge. It's sort of like you don't really notice how it's going out but you really notice what it takes to put it back in.

On top of all that you get into your charging equipment which could take DAYS to recharge depending on it's ability and other things like undersized materials or poor connections.

I've looked at peoples rigs with 13.3 volts getting to the battery while charging. The float voltage AFTER the battery is charged is 13.2!!!! It would take days to drive the specific gravity back up

We have zero info about what you are doing and your equipment so it's wide open.

If you are not getting up to full charge you will obviously see seemingly poor performance. You could have a NOT fully charged battery load tested and have it check ok. A load test is usually going to show you if the battery falls flat on it's face because of a bad cell but it doesn't mean it's fully charged.

Again, if you don't know what voltages you are working at you will kill any battery. You don't want to go by the monitor panel either

It's also best to know how to use a hydrometer when running wet batteries. A voltmeter is a must but a hydrometer tells the rest of the story

“The other three are deep cycle marine batteries to constantly run my trolling motor. Those batteries last several days before needing a charge”

They “need” full recharging daily whether or not they’ll “last” several days.