do you need a battery but don’t want to spend more than the minimum necessary? If you have a very tight budget, but you need to have a certain degree of energy self-sufficiency, an flooded lead-acid battery may be your solution. Of course, do not miss our entry in which we will tell you some warnings and precautions that you should take into account to avoid putting your health at risk, shall we start?
Flooded lead-acid batteries and their most important characteristics
Flooded lead-acid batteries are made up of independent cells, which contain lead plates, positively and negatively polarized. The positive plates are coated with a layer of lead dioxide, while the negative plates are made of spongy lead. These cells, of just over 2V each, are immersed in a solution of sulfuric acid, closed by a plug that prevents the electrolyte from spilling, and are also connected in series, so that a 12V battery will consist of 6 cells.
The flooded lead batteries can be “normal”, like those installed for the starting of the car engine or deep cycle. That they are of deep cycle does not imply that they are sealed batteries, and much less hermetically sealed, keep it in mind at the time of buying it.
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Installing flooded lead-acid batteries
Flooded lead-acid batteries are batteries that use simple technology, which in turn makes them very simple to install. This does not mean that you should not follow a series of recommendations:
- As the cells are not sealed, the battery should always be placed in its natural position, with the terminals facing upwards, otherwise the electrolyte could spill out.
- It must be installed in a ventilated place, since the battery emits gases that are harmful to health.
- If you want to install several batteries do not connect them in parallel. Although in theory two equal batteries connected in parallel should work correctly, in practice you will shorten its useful life a lot.
Be very careful with the gases emitted by the battery. Try to install it in a ventilated place or build a watertight box with a ventilation grid towards the outside. Your health and the health of your family and friends is the most important thing.
Charging and discharging a lead-acid battery
During the discharge process of the battery, the lead plates become coated with lead sulfate, which is generated by the chemical reaction of lead dioxide from the positive plates with sulfuric acid. This chemical reaction will generate heavy water, sulfate crystals and lead sulfate. The sulfates will in turn react with the lead from the negative plates and generate more lead sultate.
PbO₂ + 2H₂SO₄ + 2e- ⟶ 2H₂O + PbSO₂ + SO₄²-
Pb + SO₄²- ⟶ PbSO₄ + 2e-
During battery charging, another chemical reaction takes place which will generate, again, lead dioxide and sulfuric acid. If the battery is not in good condition, because it has undergone many discharges below the recommended limit, because it has been discharged for a long time or because it has not been charged correctly, it is likely that the sulfate crystals cannot be dissolved and the battery cannot be recharged. In this case the battery is often referred to as sulfated.
Another factor that can give an indication of the state of charge of the battery is the electrolyte density. During discharge, the concentration of sulfuric acid decreases as it is transformed into sulfate and heavy water, whereas when the battery is being charged, the concentration increases. The density of the sulfuric acid increases with its concentration, so the higher the density of the electrolyte, the higher the battery charge level.
What is the performance and life of flooded lead-acid batteries?
Lead-acid batteries can deliver a lot of electricity quickly, which is why their most common application is as a starter battery. If a lead-acid battery is cared for, is not subjected to repeated deep discharge cycles and is properly maintained, it is possible to extend its life by up to 6 or 7 years, otherwise its life could be drastically reduced, even by half.
This type of batteries have a high rate of self-discharge, that is why it is recommended to periodically charge them when they are stored or left unused for long periods of time, to prevent them from sulfating.
Another way to extend the life of the battery is to keep it protected against extreme temperatures. Its optimum working temperature is 77°F, approximately. If the battery is frequently exposed to extreme temperatures, it may be affected as follows:
At temperatures above 77°F: Its durability may be compromised. To give you an idea, if the battery is frequently operated at 95°F, its useful life could be reduced to 50%.
At low temperatures: If the battery is under-charged, the acid concentration of the electrolyte is also low, so its freezing temperature could drop from around -58°F to around 14°F. Therefore, if a battery with a low charge is exposed to these temperatures, the electrolyte could freeze, increase in volume and cause damage to the cells or other battery components.
How to maintain an flooded lead-acid battery?
In these batteries, when not being sealed, during the process of load an evaporation of the water that composes the electrolyte takes place, reason why it is necessary to refill with distilled water every certain time. It is a simple process, but very important to maintain the battery in a good state of health. In addition, approximately every 20 cycles or 2 weeks of use the battery should be equalized.
Advantages of flooded lead-acid batteries
- They are the cheapest batteries.
- They have a great price-performance ratio.
- They have been on the market for a long time, so they are very reliable.
Disadvantages of flooded lead batteries
- They require periodic maintenance.
- Less durability with deep discharge cycles.
- They do not withstand extreme temperatures.
- They emit gases.
Opinions and final conclusions of the flooded lead-acid batteries and their price
In our opinion, the batteries that are installed inside a van should be of some type that is hermetically sealed, both for safety and comfort, since the problem of gas emission and maintenance is avoided. But as always, everyone’s budget is what it is and if you can’t afford a gel or AGM battery and you install the battery safely, making sure that gases do not enter the living qu arters we see no problem beyond performance and the advantages and disadvantages that each type of battery offers.
If you can afford to buy a hermetically sealed battery, or even if you can postpone the installation and save a little more to be able to do so, our recommendation is to do so. Either a gel battery or an AGM battery, whichever you prefer. They are safer, do not require maintenance and, given good use, are more durable, so you will be able to amortize it in the end.