Marien Starting Battery =/= Deep cell battery

[swimmer_spe]

I was given a Marine Starting battery. I keep killing it. I then learn that is because it is not a deep cell battery.

At least I now know.

[theoldwizard1]

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.

[theoldwizard1]

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.

[azrving]

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.

[azrving]

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.

[azrving]

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

[Lwiddis]

“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.

[red31]

swimmer_spe wrote:
I was given a Marine Starting battery. I keep killing it. I then learn that is because it is not a deep cell battery.

At least I now know.

I CAN kill a deep cell battery, I'm guessing you WILL.

[azrving]

Some people use devices such as a killawatt or measure amp draw x hours. You can measure amp draw with some multimeters or devices like a fuse buddy. One of the first things I bought was a trimetric battery monitor. If using incandescent bulbs and much furnace you deplete a group battery pretty fast.

The main basic tool is a digital volt meter. With a group battery I see a lot of comments about staying above 12.4 volts or so. Some will run down to 12.2. The important part is to bring the charge up fully. More batteries die of under charging vs over charging

[2112]

The furnace will kill a fully charged single group 24 battery in a few hours

[prichardson]

What size is it? Even with deep cycle capacity matters and that is related to group size. These range from a group 24 with only a 50-60 amp hour capacity to 8Ds and CG2s with capacities exceeding 200 amp hour.

[swimmer_spe]

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.

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

[azrving]

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.

[swimmer_spe]

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.

[azrving]

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

[swimmer_spe]

SoundGuy wrote:
Deep cycle, not deep cell 😉 ... and very few batteries really are truly deep cycle. It you'd paid for this battery and actually use it for dry camping then there may be reason for concern but since it was given to you you're ahead of the curve no matter how you look at it. 😄 If you normally camp on electric sites then this marine battery will work just fine for the purpose as long as you properly maintain it, it's only when you actually intend to rely on battery reserve to get you through a few days of dry camping that the type & number of batteries becomes an issue. Decide first what your need is then match the number and type of battery to this need ... in my case I've only had one, in fact on our first couple of popups I had none. 😉

I have been trying to use it to dry camp.... No I know why it did not end well.