Most Common Lead Acid Battery Mistakes

Anytime you make a purchase, it’s best to understand the ins and outs of your new product. But, let’s be honest – sitting and reading through a manual or doing research isn’t always the top item on your to-do list. So, we narrowed down what you need to know here. If you’re new to lead acid batteries or just looking for better ways to maintain their performance, keep these four easy things in mind.

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1. Undercharging

Undercharging occurs when the battery is not allowed to return to a full charge after it has been used. Easy enough, right? But if you do this continuously, or even just store the battery with a partial charge, it can cause sulfating. (Spoiler alert: sulfation is not good.)

Sulfation is the formation of lead sulfate on the battery plates, which diminishes the performance of the battery. Sulfation can also lead to early battery failure.

Pro tips:

• The best way to prevent this from happening is to fully recharge the battery after use and before storing.
• You should also top off the charge every few weeks if the battery will be stored for a long period of time.

2. Overcharging

While you certainly don’t want to keep your battery in an undercharged state, overcharging is just as bad. Continuous charging can:

• cause corrosion of the positive battery plates
• cause increased water consumption
• even allow for excessive temperatures causing damage inside the battery.

This continuous heating from overcharging can destroy a battery in just a few short hours.

Pro tip: a good rule of thumb to help avoid the trap of overcharging is to make sure you charge your battery after each discharge of 50% of its total capacity.

If the battery will be stored for a month or more you should charge to full capacity before storing and then charge throughout the storage time. Every few weeks should be fine. You can also consider using a trickle charger.

A trickle charger is designed to charge your battery slowly over a period of time and not overcharge it. Some trickle chargers can be safely connected to the battery for a few days while others are designed to stay connected for a few months.

3. Underwatering

Because water is lost during the charging process, damage can occur if that water is not replenished.

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If the electrolyte level drops below the tops of the plates, the damage can be irreparable. You should check your batteries’ water level frequently, and refill the cells with distilled water as needed. Under watering, the battery can cause sulfation that is irreversible.

Pro tip: the best way to avoid this is to refrain from overcharging and check your water levels. The more the battery is used and recharged, the more often you will need to check for electrolyte depletion.

Keep in mind, a hotter climate will also increase water depletion. Make sure the battery is fully charged before adding more water to the cells.

4. Overwatering

Not only can your battery have too little water to function properly, but it can also have too much. Overwatering can cause the electrolytes to become diluted, which results in diminished battery performance levels.

Pro tip: a normal fluid level is around ½ inch above the top of the plates or just below the bottom of the vent. If you check your fluid levels and the water level is sufficient, do not top it off.

Let’s do a quick myth buster: there is a common belief that lowering the charge voltage to 13 volts or lower will decrease the need to check the water levels as often.

While this is true, it can also lead to battery stratification – which causes the battery acid to separate from the electrolytes and collect at the bottom of the battery. This leads to sulfation which, as mentioned earlier, leads to decreased battery performance and a shortened life cycle.

So, what does this all mean?

The issues surrounding over and under charging as well as over and under watering can be a fine line to walk. It’s really just about finding the sweet spot.

Most battery manufacturers provide a list of guidelines that will make it easier to care for and maintain your lead acid battery. We know better than anyone that a ton of factors can go into maintaining the proper charge and the proper electrolyte levels. If you can only remember one, remember temperature — it’s one of the biggest factors.

• The warmer the environment, the more often a stored battery needs a top off charge, as well as have its water levels checked.
• The cooler the environment, the more time you can let pass between charges and water refills.

Checking out the manufacturer’s recommendations will go a long way in helping you prolong the life of your battery. If you need clarification or have any questions, give the NEB experts a call; we’re here to help, after all.

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)?

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.

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"?

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. 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.

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.

-"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. 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.

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

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.




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? 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.

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)?

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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.