Can we talk about Lead Acid Battery maintenance?

[DXHum]

With lead-acid batteries, there is no "set it and forget it". It only took 4 or 5 lead-acid battery deaths for me to learn this simple lesson. These batteries are for the long-term storage of power.

I just invested in two brand new lead-acid batteries ($100.00 each) and I would like to get a few good years out of this new configuration.

So what should my maintenance practices be? How do I extend the life of my lead-acid batteries? Below is a picture of my two new batteries and how I will wire them in their permanent spot. Considering that I am using them for long term storage, should I take them off the NOCO and put them on "Battery Tenders" (12v 1.25A)?

 

[Hedges]

These batteries are for the long-term storage of power.

I just invested in two brand new lead-acid batteries ($100.00 each) and I would like to get a few good years out of this new configuration.

So what should my maintenance practices be?

View attachment 189858

Use them for starting (or surge) purposes only, and immediately recharge to float voltage.
Charge and float with temperature compensated voltage.

Do not use for energy storage. They were not designed for that.

 

[Mattb4]

Good resource to understand batteries is at: https://batteryuniversity.com/

 

[DXHum]

Use them for starting (or surge) purposes only, and immediately recharge to float voltage.
Charge and float with temperature compensated voltage.

Do not use for energy storage. They were not designed for that.

Well... I've already purchased them, and I can't bring them back. So while they may not be ideal for reasons I don't know/understand, I've made the commitment.

 

[Rednecktek]

Those are deep cycles so you're OK with them. As for maintenance, keep them topped up as much as possible, you'll want at least 2a going into each battery, so a 5a charger will be optimum for maintenance on 2 batteries. A smart charger that can do 25a will be a good investment.

How often do you deeply cycle your batteries? Your charge controller will probably want to do an equalization charge every month or so, for the first few times pop the caps and check the water levels. After a high charge some of yhe water may boil off and you'll want to top those up with distilled water. After a few cycles you'll get an idea of how much you'll have to add and how often. On my bank at camp I usually only have to add a couple cups a year, but they don't get cycled much.

 

[DXHum]

Those are deep cycles so you're OK with them. As for maintenance, keep them topped up as much as possible, you'll want at least 2a going into each battery, so a 5a charger will be optimum for maintenance on 2 batteries. A smart charger that can do 25a will be a good investment.

How often do you deeply cycle your batteries? Your charge controller will probably want to do an equalization charge every month or so, for the first few times pop the caps and check the water levels. After a high charge some of yhe water may boil off and you'll want to top those up with distilled water. After a few cycles you'll get an idea of how much you'll have to add and how often. On my bank at camp I usually only have to add a couple cups a year, but they don't get cycled much.

And by "cycled", you mean running them down and then recharging?

They currently sit as 13.4 volts. I'm thinking I'd like to hook up a load and run them down to about 12.5 volts and recharge. Is that a "cycle"?

 

[Rednecktek]

And by "cycled", you mean running them down and then recharging?

They currently sit as 13.4 volts. I'm thinking I'd like to hook up a load and run them down to about 12.5 volts and recharge. Is that a "cycle"?

Yup, exactly. Running from 13.4 to 13.2 isn't really a strain, but going from 13.4 to 12.4 is pretty much all it can do before you start damaging the cells. It's not going to die right away, but over time a little bit here and a little bit there really add up and since there's so little (relatively) capacity to lead acids, a little goes a long way.

 

[OzSolar]

Generically speaking batteries are built for one purpose.

-True starter batteries are good for starting your car thousands of times but will be damaged beyond use if you take more than 10% out of them even a few dozen times.

-Many true deep cycle FLA batteries are good for thousands of cycles to 50% or more. Not sure what would happen if you repeatedly tried to start your car with one but I bet it wouldn't be good.

-"Deep Cycle" marine batteries are much closer to starter batteries than deep cycle batteries. The fact that I just spent the last 5 minutes in a failed attempt at find a cycles vs. DOD chart for your battery or even a generic marine is pretty telling.

From what I've seen Leaving any battery severely discharged for very long is the #1 killer of batteries. Not charging them at all is a close 2nd.

If you keep those battery tenders on there in between cycles you can probably get 10 cycles to 50% DOD per year over the next 3 or 4 years. If you keep them charged up but only take 5% or less out of them 2x per year you going to get.... you guessed it.... no more than 3 or 4 years.


My *total* guess is that marine battery would look something like the green line I added to the below chart.

 

[Rednecktek]

Don't panic though, as I like to say "If you might break something on a learning system, break a CHEAP something."

 

[ArcFault]

Temperature is by far the single most critical parameter for battery life. The typical design temperature for lead-acid batteries is 25°C (77°F) and expected battery life is based on this number. A 10°C increase in temperature doubles of the speed of the chemical reactions. If a battery is in an unconditioned space that is typically at 35°C (95°F) you should expect only half of the rated battery life. I have designed DC systems in power plants using large flooded cells (2.2V per cell) of lead-calcium batteries in 58 to 60 cell banks and design standards required the space to be conditioned and we had alarms in the control room for both high and low room temperature. Low temperature was of concern as the calculations assumed a minimum temperature to assure adequate capacity. The qualified life for the batteries we used was 20 years.

 

[DXHum]

-"Deep Cycle" marine batteries are much closer to starter batteries than deep cycle batteries. The fact that I just spent the last 5 minutes in a failed attempt at find a cycles vs. DOD chart for your battery or even a generic marine is pretty telling.

Yes, finding information on these batteries, including on their website, is limited.

When I purchased them, I asked the sales person how many amp hours the battery was rated at. They couldn't tell me because it wasn't listed on their website.

I found them to be rated at 65 amp hours. So I have a rating of 130 amp hours.

 

[Hedges]

So my suggestion is to basically never cycle them, don't use for power through the night.

Set up a system which is PV direct, loads don't exceed what PV panel can power. But motor starting surge can come from the battery. Good for powering A/C or refrigerator or pump during the day. Trick is how you shut it off if PV can't keep up with the load, and avoid repeated start/stop cycles in that case.

One guy fed his EV HV battery to PV input of an inverter. It could power small tools but not big. With 4x automotive starting batteries it could start big tools.

Then usage is like starting a car engine, and batteries can last 3 to 10 years depending on quality, assuming fully recharged.

Or use these for automotive starting. (Although I prefer AGM, no corrosion of wires.) Or marine starting, where I think the deal is some motors lack an alternator, so battery continues to supply ignition.

I found them to be rated at 65 amp hours. So I have a rating of 130 amp hours.

https://www.autozone.com/batteries-starting-and-charging/rv-battery/p/duralast-24dc-dl-group-size-24-deep-cycle-battery-550-cca-685-mca/298374_0_0

65 Ah
140 RC, meaning 140 minutes at 25A, 35Ah cycling suggested for marine usage. About 50% DoD.

 

[DXHum]

So my suggestion is to basically never cycle them, don't use for power through the night.

Set up a system which is PV direct, loads don't exceed what PV panel can power. But motor starting surge can come from the battery. Good for powering A/C or refrigerator or pump during the day. Trick is how you shut it off if PV can't keep up with the load, and avoid repeated start/stop cycles in that case.

One guy fed his EV HV battery to PV input of an inverter. It could power small tools but not big. With 4x automotive starting batteries it could start big tools.

Then usage is like starting a car engine, and batteries can last 3 to 10 years depending on quality, assuming fully recharged.

Or use these for automotive starting. (Although I prefer AGM, no corrosion of wires.) Or marine starting, where I think the deal is some motors lack an alternator, so battery continues to supply ignition.

https://www.autozone.com/batteries-starting-and-charging/rv-battery/p/duralast-24dc-dl-group-size-24-deep-cycle-battery-550-cca-685-mca/298374_0_0

65 Ah
140 RC, meaning 140 minutes at 25A, 35Ah cycling suggested for marine usage. About 50% DoD.

So you are saying that I can use these batteries down to 6 volts? That would be 50% DoD, wouldn't it?

 

[Hedges]

Not 6 volts. The Reserve Capacity spec is 140 minutes x 25A = 35 Ah. A bit over 50% of 65 Ah.

Look up charts with voltage vs. SoC. Those might be accurate after the load was disconnected and battery sat for several hours.
Maybe a Peukert chart would give voltage vs. A draw and % SoC.

Just go by measured current X time. But controllers typically have low voltage disconnect so need a voltage.
Bigger fancier systems measure Ah. The equipment to do that costs more than your two batteries (but maybe there are some economical units.)

 

[wopachop]

Did you have to drill out the connectors to fit over the threads? Seems like nut is not sitting flat on the connector but instead hitting the area with wire.

Also by long term storage, are you saying these will only get used in an emergency maybe once a year?

Unfortunately for the price these batteries are not the best choice. Might be worth trying to sell them. It's more a battery used for starting motors.

I've got 2 of that style battery. They came on a trailer and used like a deep cycle. I've replaced them but keep them now to start my generator. For storage I fully charge using a battery tender and then take off the charger. Especially during hot summer months I don't leave the battery floating on the charger.

 

[HarryN]

With lead-acid batteries, there is no "set it and forget it". It only took 4 or 5 lead-acid battery deaths for me to learn this simple lesson. These batteries are for the long-term storage of power.

I just invested in two brand new lead-acid batteries ($100.00 each) and I would like to get a few good years out of this new configuration.

So what should my maintenance practices be? How do I extend the life of my lead-acid batteries? Below is a picture of my two new batteries and how I will wire them in their permanent spot. Considering that I am using them for long term storage, should I take them off the NOCO and put them on "Battery Tenders" (12v 1.25A)?

View attachment 189858

Those are "marine" batteries, not "deep cycle" nor "starter" batteries - but kind of a type in between, even though the label indicates other wise.

I use the same basic class of batteries (marine) as well, just usually the Lifeline version for cold weather applications.

I think the best thing that you can do is use a charger setup that is temperature compensated so that it is being charged at the right voltage profile for that particular temperature.

You want a charger that can really bang some power in them vs babying them.

For day to day standby power, I would use something simple like 200 - 300 watt of solar plus a bogart controller setup. The very small pulses will help to prevent buildup of small deposits on the plates.

Don't be afraid to use them, just make sure that your charging system has enough power to really bring them back up to full charge quickly. Something 20 - 50 amps like an iota charger or similar.

Running a cycle on those once in a while is fine - discharge down to roughly 12 volts and then really push in some power.

 

[Checkthisout]

FYI,

You could easily build a 304 Ah pack out of 4 lithium cells for about $600.00 and have 5 times the capacity those two batteries will provide.

 

[DXHum]

FYI,

You could easily build a 304 Ah pack out of 4 lithium cells for about $600.00 and have 5 times the capacity those two batteries will provide.

Yes, I have come to learn that these batteries aren't the best choice for the intended application (power storage for when the grid goes down).
But, they are purchased and installed, so, I'll work with whatever they can give.

I'll upgrade them to a battery better suited for power storage next time.

 

[time2roll]

With lead-acid batteries, there is no "set it and forget it". It only took 4 or 5 lead-acid battery deaths for me to learn this simple lesson. These batteries are for the long-term storage of power.

I just invested in two brand new lead-acid batteries ($100.00 each) and I would like to get a few good years out of this new configuration.

So what should my maintenance practices be? How do I extend the life of my lead-acid batteries? Below is a picture of my two new batteries and how I will wire them in their permanent spot. Considering that I am using them for long term storage, should I take them off the NOCO and put them on "Battery Tenders" (12v 1.25A)?

View attachment 189858

NOCO is fine same as Battery Tender brand chargers.

Although 2 amps is fine for float, the batteries will be better served if they are moderately cycled and charged robustly at 15 to 30 amps up to 14.6 volts and held for 30 to 60 minutes every 3 to 6 weeks. Hold at 14.6 until charge current drops below 2 amps. Otherwise if they sit for 6 - 12 months on float they may show good but they are low on charge when needed most.

To really verify the batteries are at 100% tip top charge a hydrometer with numbers should be use to check specific gravity of the electrolyte. If less than 100% they are sulfating and losing capacity. This assumes the caps are removable.

 

[Bluedog225]

Check in with this group before you buy batteries 7 and 8. They can help you get what you need.