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Have you noticed your battery discharging faster than it’s supposed to be? One minute you have a fully topped-up battery bank and the next thing to fix battery draining fast. This could be a hassle especially when you’re off-grid, on the road, or during a power outage and are counting to use it as backup power.

Whether you’re using a car battery, AGM battery, lead-acid, or lithium battery, a decline in performance and faster discharge rate are usually caused by similar issues. These include battery age, over or undercharging, exposure to extreme temperatures, or sulfation. If your battery drains fast, it also most likely means that you need to replace it and nobody wants that, especially if you haven’t used it enough to get your money’s value.

In case you encounter this, don’t panic just yet. We have listed below some of the common reasons why your battery pack might not be lasting as long as it used to be so you know what to look out for the next time you buy your new battery bank:

You’re overloading it: You might be drawing too much power from your batteries. Try calculating your power requirements again before buying a new one to make sure your battery will be able to handle the load without declining in the long run.

BP12-60 agm battery

Partially charged battery

Another possibility would be your battery is not fully topped up, to begin with. This is likely to happen when you fast-charge it with a regulator that does not switch to float mode afterwards. If you’re using the battery for an RV, improper wiring can lead to power loss as well and can even cause a fire.

Incorrect charging:

Either you’re using the wrong kind of charger or there is something wrong with your charging procedure. If you’re using solar panels that are not compatible with your battery together with a PWM solar charge controller, it may not deliver the amount of power you’re expecting. Instead, you may even lose up to 100W as it passes through the regulator. You might not be charging your battery long enough too. It typically needs 8-10 hours to be completely topped up, and 12 hours if it’s fully discharged.

Infrequent usage or charging:

How long has it been since you last used and charged your battery? Keeping it stored for long periods of time is one culprit behind its decline. If you don’t recharge your batteries at least once a month, you could lose up to 10% of its total charge every month so don’t be surprised if it lasts you two hours the next time you take it out for camping. You can also prevent fast draining and a frozen battery as well by using a low power level from a trickle charger although this may not charge your battery bank fully.

Lack of maintenance:

A simple warm-up of your battery regularly or terminal cleaning can go a long way. If you’re using wet batteries, try to add water to them from time to time. While modern technology allows for maintenance-free batteries, a little extra care every now and then can still save your unit over time.


This is one of the most common reasons for battery failure. Aside from damaging batteries, it can also lead to an explosion which would lead to bigger problems especially if another person was harmed. Similarly, fast-charging them with a charging mode suitable for deep-cycle batteries can cause issues too. You could either go for a LiFEPO4 for this since it has a built-in BMS to prevent overcharge or buy a voltmeter so you can easily track your charge level.

3 FAQs

Do lead acid batteries develop a memory?

The quick and simple answer is, no. For those looking for extra credit, check out the below.

Lead acid batteries are not affected by the memory effect. The memory effect was limited to the nickel-cadmium batteries in the 70’s and 80’s. The memory effect was the occurrence when a nickel-cadmium battery would develop a cyclic memory that would allow the battery to “remember” how much energy was previously drawn.

During subsequent draws, the battery would not deliver more than it had before. Modern day nickel-cadmium batteries do not experience cyclic memory.

Do lead acid batteries discharge when not in use?

All batteries experience some amount of self-discharge, yes. But, the rate of discharge for lead acid batteries depends on a few key factors.

  • Temperature: The warmer the environment while a battery is in storage, the faster the rate of self-discharge. For example, a battery being stored at an average temperature of 80℉ will discharge at a rate of 4% per week. Whereas a lead acid battery being stored at 65℉ will only discharge at a rate of approximately 3% per month.
  • Length of Storage: The amount of time a battery spends in storage will also lead to self-discharge. A lead acid battery left in storage at moderate temperatures has an estimated self-discharge rate of 5% per month. This rate increases as temperatures rise and as the risk of sulfation goes up.
  • Sulfating: This is a buildup of lead sulfate crystals and it occurs when a lead acid battery is left sitting without a full charge. Even if you are giving your battery a small charge such as putting it in the car and letting it idle, this is still not enough to combat the self-discharge that can take place.
  • Dirt: Dust and dirt on a stored battery can also create a reaction that leads to self-discharge. You can easily prevent this by wiping down the top of the battery with a clean, dry, and soft cloth. The best way to reduce the amount of self-discharge while your batteries are in storage is with the three C’s. Keep them clean, cool and fully charged.

YTX9A-BS battery draining

Do I need to completely discharge my lead acid battery before recharging it?

This is a hard and fast NO. By fully discharging your lead acid battery, or even discharging it below 80% of its rated capacity, you could damage the battery.

The belief that a battery needed to be fully discharged before recharging goes back to the memory effect issue. (See question 1.) Since that is no longer an issue (and never was an issue with lead acid batteries) there is not a need to fully discharge.

By discharging a lead acid battery to below the manufacturer’s stated end of life discharge voltage you are allowing the polarity of some of the weaker cells to become reversed. This causes permanent damage to those cells and prevents the battery from ever being recharged.

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