How to care for a lead-acid battery in the off-season?

For example, if you are a motorcyclist, camper, fisherman or have a veteran, you probably think about what to do with the battery after the season at least once a year. We repeatedly come across a number of myths and half-truths on how to care for batteries in the off-season. In this article, we summarize important instructions based on years of experience and professional knowledge. Remember that a lead-acid battery (the so-called gel battery is also lead-acid) is best when it is fully charged.

The optimal procedure chronologically:
Disconnecting the battery
If you can, disconnect the battery before any extended downtime. If this is not possible (e.g. due to keeping the devices "alive"), nothing is lost. It will just be necessary to check the battery voltage more often, or recharge it as well. Any connected electrical circuit causes the battery to discharge faster. With running appliances (e.g. on-board clock) this is even more significant. When disconnecting the terminals from the battery, start with the negative terminal.

Battery fully charged
Charge the battery to full! A fully charged battery should have a resting voltage of approximately 12.8 V (at least 24 hours without discharging and charging and at the same time not connected). To choose the right charger, you can be inspired in our article dedicated to choosing a charger. If you have a maintenance type battery, check and top up the electrolyte before charging. We cover the charging process in more detail in the article below.

Battery storage, inspection and maintenance.
It is best to store the battery in areas where the temperature is constant between 5 - 15 °C, the sun does not shine on it and there is no abnormal humidity. Often people think that a battery is best at room temperature. In fact, a higher temperature will speed up the chemical processes in the battery and cause it to self-discharge faster. Also make sure that the contacts cannot be connected using a conductive object, e.g. falling of something metallic through the contacts. We will discuss charging itself later in the article.

Always fully charge each battery before first use at the beginning of the season.
When starting on a severely discharged battery, much larger currents must flow through the wires, which can result in blown fuses and, in extreme cases, damage to the electrical installation or devices.
Basically, it does not matter if it is a car battery, motorcycle battery or traction battery to power appliances. The above procedure is similar for all these types of lead-acid batteries. Are you surprised at how simple it is? It's not rocket science really, but we can forget about it after the season is over, and especially with an older battery, it can be the final nail in the coffin.
Off-season charging is possible in the following ways:
Regular charging (ideal)
For a battery in good condition, it is usually sufficient to charge it once every 2-3 months if it is stored properly. Almost any automatic charger (with the appropriate power and voltage) will do well for this type of charging. It is the best way to charge, not only in the off-season, but also when using the battery. This will maximize its lifespan.

Permanent connection (worry-free)
Permanently connecting the charger is somewhat carefree, but at the same time it can wear down the battery due to the constant effect of excessively high charging voltage. So that this charging procedure does not have a negative effect on the battery, the charger must have a mode for long-term maintenance or permanent connection. The Dutch Victron Energy chargers from our offer handle this discipline best.

Occasional start-up (not recommended)
If you recharge by starting occasionally, the engine should then idle for at least half an hour with all appliances switched off. However, watch out for poisonous fumes in closed spaces. In general, this is a rather inappropriate method of charging. A longer cold start, when the engine does not want to start, is very demanding on the battery. If the lead plates are already significantly weakened, this can cause the cell to collapse. In addition, a cold battery does not accept charging very well.

Battery regeneration / reconditioning
What do these terms mean? In every battery flooded with acid, the so-called electrolyte stratification. This means that acid with a higher concentration sinks to the bottom, causing an uneven load on the electrodes and accelerated degradation of the battery plates. In order to avoid this phenomenon, it is necessary to mix the electrolyte. Some modern automatic chargers have a battery regeneration (English Recondition) function. This consists in short-term charging with increased charging voltage and low current. This causes the electrolyte to "bubble" and mix. In the case of AGM and gel batteries, the aforementioned phenomenon is largely eliminated by the battery design, and performing this reconditioning function for them is not of great importance. It must not be used even with purely gel ones, in order not to damage them.

Battery desulfation

One of the phenomena that occurs during battery use is sulfation. That is, the deposition of lead sulfate on the electrodes. If the battery is sufficiently charged, the sulfate will dissolve again (desulphation) and the battery will remain in good condition. The above-mentioned battery reconditioning function can also have a positive effect here. However, if the battery is not charged sufficiently, the sulfate layer becomes stronger, and its properties gradually deteriorate. Eventually, it fails. When the sulfate crystals are already too large, we recommend leaving the desulfation to a professional battery service. We provide free service for batteries purchased from us.

From the two paragraphs above, you can see the importance of high-quality and complete recharging of lead-acid batteries.