Storing new marine batteries

[MikeCanuck]

Hi all, sorry if this dummy question has been answered before.

I'm thinking of buying 2 new group 27 marine batteries, charge them up to 100% with a grid smart charger, then connect them in parallel and simply want to store the batteries indefinitely until needed for emergencies.
Not connecting to any solar anything unless ever need to one day.

How would I get the longest storage life out of them and how long until I'd need to replace them if never used?

Should I keep them on the smart charger positive to one battery negative to other battery all the time?
Or would weekly or bi weekly top up be ok?

Just thinking about the next ice storm extended power outages here in the great white north and would like some backup power for low powered medical device that can run on 12v dc or pure sine inverter. Don't want or need a generator.

Thanks

[Sunking]

As long as they are fully charged up and kept cold, not much to do except top them up once in a while and keep the water level up. . Ultimately you can store them for their Calendar life by placing them on a Float Charge. Any good 3-stage smart charger has Float. Just hook it up and walk away. Only thing to do is check water level. As long as the batteries are not used, and place din a cool or cold location they wil not use water.

Only folks who need to go an extra step is folks in warm climates when they store their boats away for the short winter they have. Batteries are a double edge knife. Warm shortens cycle life but more capacity. Cold extends cycle life but lower capacity. For long term storage you want a cold fully charged battery. If the temps stay below 50 F can last 5 to 6 months if stored fully charged. Above 50 about a month or two before they need topped off.

You ar ein Ontario with two seasons. 4th of July and winter.

[MikeCanuck]

Great thanks, ok I'll just plan to keep it on float with a smart charger all the time then and check water levels once in a while.
How long would you guestimate the calendar life would be for cheapy walmart marine batteries here where, like you say, there are basically 2 seasons - above 0C and below 0C (30F)
thanks again..

[Sunking]

Great thanks, ok I'll just plan to keep it on float with a smart charger all the time then and check water levels once in a while.
How long would you guestimate the calendar life would be for cheapy walmart marine batteries here where, like you say, there are basically 2 seasons - above 0C and below 0C (30F)
thanks again..

Two days before the warranty period is up.

It is a good thing you have a charger with Float. Do this to get the most bang for your buck.

Top off batteries with water, then apply a standard full charge. Let them rest and hit them with an EQ charge. Then put them on float and walk away. Periodically check water level like once a month. In your climate, no use, and on Float Charge assuming you have the Float Voltage set correctly you should experience NO LOSS of electrolyte. If you see any, then you know the voltage is too high. Takeaway get the Float Voltage right and all is good. If you error, error on the low side if you plan on leaving them for months. Last thing you want to see this spring is exposed plates. If you see exposed plates game over, you loose.

Seriously don't let that alarm you. You would have to make a huge blunder on Float Voltage. You have a really good advantage in your cold climate. Where I am at is tropical which is bad news for any battery. Takes a lot of care in hot climates. In cold climates really slows down the aging process, you just sacrifice capacity which comes right back up with temps so no harm done.

Good thing you got Wally World batteries. If you got the receipt, take them back next spring and get a new one. Wally World rarely test them and just replaces them. If they do any test is just a quick load test with an automotive load tester. Very easy to pass or I should say fail the test. Just discharge them before taking them in and you pass, err fail and get new ones. They are not very bright, or else they would be working somewhere else.

You owe me a bottle of Crown Royal.

whiskey-smiley-emoticon.gif

[PNjunction]

I would take that just a small step further ... with regular exercise every 3-6 months.

Unless the battery is a telco-type battery intended for decades long float, you can run into the situation of where the battery isn't sulfated by being fully charged, but *stratification* can show up for flooded (or very tall agm's for that matter too).

Instead of buying a dinky "maintainer", get a charger that will do anywhere from 1/12th to 1/8th of the capacity current. (1/10th being the canonical value). This will stir the electrolyte with some activity upon charge. Keeps the chemicals active.

Discharge them to at least 10% or more - too shallow of a discharge isn't healthy either, and then followup with the charger that isn't just a wall-wart maintainer.

If you really want to get into it, do a proof-of-performance test at least yearly down to 60% DOD and recharge.

I've had countless friends do the same thing, and when it came time to perform 3 years down the road, the "fully charged" flooded battery that never received any exercise was a total wimp when it really counted.

[SunEagle]

I would take that just a small step further ... with regular exercise every 3-6 months.

Unless the battery is a telco-type battery intended for decades long float, you can run into the situation of where the battery isn't sulfated by being fully charged, but *stratification* can show up for flooded (or very tall agm's for that matter too).

Instead of buying a dinky "maintainer", get a charger that will do anywhere from 1/12th to 1/8th of the capacity current. (1/10th being the canonical value). This will stir the electrolyte with some activity upon charge. Keeps the chemicals active.

Discharge them to at least 10% or more - too shallow of a discharge isn't healthy either, and then followup with the charger that isn't just a wall-wart maintainer.

If you really want to get into it, do a proof-of-performance test at least yearly down to 60% DOD and recharge.

I've had countless friends do the same thing, and when it came time to perform 3 years down the road, the "fully charged" flooded battery that never received any exercise was a total wimp when it really counted.

I have heard of a number of people (companies) that installed emergency generators but did not properly "load test" them. They would just run them for a few minutes every 6 months and then shut them down. When time came to "do their duty" most couldn't handle the load and outright failed or provided less than 50% of their rated kw.

[PNjunction]

I've been through that at various places.

It isn't healthy for the generator to get no real exercise either!

Somewhat similar to buddies of mine who ran hot-rods and put Optima's in them in the auto store parking lot, drove it home, and just left it on a "tender" for a year or more at a time. They could start it up and shut it down every few months or so, but they failed early and of course blamed the battery. A little exercise is needed for batteries not specifically designed to just float!

You'll see that "able to float for 8 years" or so feature on some spec-sheets for batteries, but when you ask an engineer about it, they'll say "well, we're assuming you are going to use it ONCE in awhile!" - which means more than just start up and shut down.

[Raul]

I thought agm have a outstanding performance in standby aplications , up to 3% only self discharge and no need to water . Why would you chose floded if is not cycled reguraly?

[SunEagle]

I thought agm have a outstanding performance in standby aplications , up to 3% only self discharge and no need to water . Why would you chose floded if is not cycled reguraly?

2 reasons. Cost (FLA is about half the cost of AGM) and availability. There are more FLA distributors then AGM so you also have to pay a shipping charge for the AGM if you purchase over the internet.

[MikeCanuck]

Sunking re: You owe me a bottle of Crown Royal
You know we only drink beer up here, right? So next time you're in town, beer's on me, eh!

SunEagle/PNjunction: thanks for the battery exercise advice, very good to know as well.
Hopefully if I baby them based on everything you guys said they would be good for a long time and work when I really need them to one day...
...just in case my canadian "niceness" prevents me from executing on the crown royal longevity solution

Raul: yep, agms are crazy expensive here esp with our lowly dollar against the mighty american greenback. not cost effective for mr. poor man wanting a simple emergency standby. ie. group 27 marine fla battery here is a cheapy cad$112, best bang for buck, while the same size agm is ~$350. Plus 13% taxes then death since no more beer money!

[PNjunction]

Mike - all great advice above, but please resist the temptation to run down to Canadian Tire and pick up the cheapest little trickler around.

Many automotive chargers have a float mode, BUT that float is what is called "float monitoring". That is, they don't truly float, but merely allow the battery to self-discharge down to a certain level, and then recharge only when that low level is reached. This works to an extent for a battery that is soon meant for reinstallation in a vehicle, or one that has a large amount of parasitic discharge. Otherwise, while just monitoring, the battery is sulfating.

You live in a cold clime, so that may not be as big a problem as I present it, but still for those that do a TRUE float, you are in a clime that doesn't really need an endless float.

May I suggest the best of both worlds - the Tecmate-Optimate 6 charger. The float here is a 50% duty cycle of 30 mins on / 30 mins off. That actually helps put a *little* activity into your bank, rather than sitting at a steady-state, or no state much of the time like most others. Aside from that, your battery is tested every 12 hours. Plus, there is nothing to set, but plug in and walk away. If you want to know what all the blinkenlights mean, you can get into that too, but not totally necessary.

And obviously it will do a great job on more than just your marine batts. Even though your batteries may be inexpensive, don't cheap out on the gear used to maintain it. It helps even things out that way.

And you know what - get a little *practice* in for the big outage, which also serves as "exercise" time. You can do that simply enough with an inexpensive msw automotive dc/ac inverter, a screw-in led type bulb (40w if you want to go long periods), and a handy table-lamp. Don't let those agm's go below 12.2v at rest if you want to get the most out of them.

With a little 40 w led bulb, an inexpensive inverter, you could run that bulb from your 180ah battery for 166 hours straight before reaching the half-way point (50% DOD) that most advise not to go beyond for good cycle life. When the power is out, you'd be amazed at how valuable a simple 40w led bulb is. The 40w led actually only draws 6.5 watts!

There is a lot of information about calculating your power needs in other threads, but for now keep this in the notebook:

Your 180ah battery bank equates to storing about 2,160 watthours. Only half of that is usable if you don't want to exceed the halfway point - that's 1,080 wattHOURS. 1080 / 6.5 = 166 hours shown above. If you know the wattage of your other gear, you can start to calculate how much time you can run from that bank.

See how no exercise is boring when you own batteries?

[lkruper]

Sunking re: You owe me a bottle of Crown Royal
You know we only drink beer up here, right? So next time you're in town, beer's on me, eh!

SunEagle/PNjunction: thanks for the battery exercise advice, very good to know as well.
Hopefully if I baby them based on everything you guys said they would be good for a long time and work when I really need them to one day...
...just in case my canadian "niceness" prevents me from executing on the crown royal longevity solution

Raul: yep, agms are crazy expensive here esp with our lowly dollar against the mighty american greenback. not cost effective for mr. poor man wanting a simple emergency standby. ie. group 27 marine fla battery here is a cheapy cad$112, best bang for buck, while the same size agm is ~$350. Plus 13% taxes then death since no more beer money!

All the advice you have received is good, and it is not my intention to change your plans, however I wonder about what your cost would be to get two 6v golf cart batteries to make a 12v serial bank instead of two 12v marine batteries in parallel. Where I live, the Marine battery at Costco is more expensive per AH than their golf cart batteries.

There are also arguably advantages to charging two batteries in series compared to two in parallel.

[PNjunction]

Well yeah - 6v batteries have thicker plates and materials. You can make a more robust 12v battery out of two of them in series. Most 6v batteries are TRUE deep cycle batteries to start with - but always wise to check!

But look beyond just cost - would two Costco 6v GC batteries be as good as a singular 12v Trojan or Rolls or equal capacity? There is a tipping point in there somewhere and only you and your budget knows....

There is also the unknown about "bench racing" specs - quality of maintenance. If you treat your Costco batteries as IF they were Rolls, or just throw a Harbor Freight trickler on a Rolls, who wins in the end? Costco for sure.

The other question is: are you paying for a feature you'll never use with deep-cycle? Ie, deep cycle is considered a 60% or MORE discharge. Normally with solar we do no more than 50% daily - a heavy discharge for sure, but not really considered a deep-discharge.

In a backup-battery application, a lighter-duty hybrid or marine that only sees a few deep-discharges during it's lifetime, may be cheaper. Right now I'm abusing an SLI agm for testing and it has survived over 60 cycles down to about 50% DOD - something that would be ridiculous to do on purpose at the outset. But, it is cheaper than the deeper discharge version.

So now, you juggle cost, maintenance, AND application to the mix. Makes your head spin but provides great fodder for bench-racing.

[Sunking]

I thought agm have a outstanding performance in standby aplications , up to 3% only self discharge and no need to water . Why would you chose floded if is not cycled reguraly?

SunEagle pretty well answered that from a cost perspective. AGM cost roughly twice as much and last half as long as making them some 400% more expensive then FLA from cradle to grave. Same as Lithium, in the end much higher cost than FLA.

To expand a bit AGM does have niche applications neither FLA or Lithium can match. Depends on application.

One you named much lower Self Discharge Rates. When fully charged up and stored in cool temps about the same as Lithium at 1% per month. Charge an AGM up to 100%, store it at 30's F temps and you can easily store them a year.

High Charge Rates and Discharge Rates. Lithium can do that but not Deep Cycle FLA. When you hear the kooks with a 12 volt 100 AH battery with a 1000 watt Inverter, it had better be a high quality expensive AGM battery. Otherwise load that Inverter up more than 200 watts, and your Inverter is going to trip off-line from under voltage despite the battery is fully charged up. Live in an area with less than 3 Sun Hours in winter, you need AGM because you are looking at Charge rates exceeding C/6 unless you have 8 or more days reserve capacity.

Low Charge Rate of less than C/12. FLA needs at least C/12 to prevent stratification and to dissolve soft lead sulfate crystals from normal discharge depths.

Extreme cold environments.

Mobile applications or other Installations where spills and gassing are unacceptable like an Air Plane, Space Craft, Inverted or Side Mounted.

Where Deep Discharges are encountered frequently and/or routinely.

So AGM's and Lithium have their place, but cost needs to be justified when you are talking as much as 400% higher cost over FLA.

[lkruper]

Well yeah - 6v batteries have thicker plates and materials. You can make a more robust 12v battery out of two of them in series. Most 6v batteries are TRUE deep cycle batteries to start with - but always wise to check!

But look beyond just cost - would two Costco 6v GC batteries be as good as a singular 12v Trojan or Rolls or equal capacity? There is a tipping point in there somewhere and only you and your budget knows....

There is also the unknown about "bench racing" specs - quality of maintenance. If you treat your Costco batteries as IF they were Rolls, or just throw a Harbor Freight trickler on a Rolls, who wins in the end? Costco for sure.

The other question is: are you paying for a feature you'll never use with deep-cycle? Ie, deep cycle is considered a 60% or MORE discharge. Normally with solar we do no more than 50% daily - a heavy discharge for sure, but not really considered a deep-discharge.

In a backup-battery application, a lighter-duty hybrid or marine that only sees a few deep-discharges during it's lifetime, may be cheaper. Right now I'm abusing an SLI agm for testing and it has survived over 60 cycles down to about 50% DOD - something that would be ridiculous to do on purpose at the outset. But, it is cheaper than the deeper discharge version.

So now, you juggle cost, maintenance, AND application to the mix. Makes your head spin but provides great fodder for bench-racing.

At my Costco they sell 12v Interstate Marine batteries for about $79 that are 70AH. According to the Interstate representative they get about 200 cycles. The Interstate Costco 6v 207AH cost $84 each.

Marine 12v 140AH = $158 ($1.12 / AH @12v)
Golf 12v 207AH = $168 (0.81 / AH @12v)

But the advertised cycles for the Golf batteries is 1220.

Even if one does not need the cycles, the Golf batteries come out on top.

Of course, I don't know who makes the batteries for our OP at Sam's club and what his numbers would look like.