Technical tips

Why are batteries broken after the winter?


Are you ready to use the boat or motorhome again after winter? Or is it still on shore or in storage or is the boat still in the water?
Then the batteries in your vehicle or boat need extra attention. To ensure that the batteries can now be used again, proper maintenance of the battery is essential.

Battery maintenance

Sometimes the name maintenance free battery gives a different idea to the owner of what is actually meant. Yes maintenance free in the sense that the batteries do not need to be topped up with water. The batteries do need to stay charged for sure. Often this is not the case.

Batteries don't last a lifetime

Most batteries do not reach the expected service life. This is sometimes because the batteries are of inferior quality, but mostly because the batteries have been abused.

You can find the most common cause of not achieving the service life here.

If the battery is empty, the electrolyte (the liquid substance or gel) can freeze already by a few degrees below zero, which can cause damage to the battery. Fully charged batteries can withstand very extreme freezing, where 20 degrees below zero is not a problem at all!

By the way, the naturally always present self-discharge is faster at higher temperatures than at low temperatures. Nevertheless, it is necessary to keep the batteries always in a charged state. Of course you can discharge them up to a certain percentage which depends on the type of battery. Depending on the applied technology such as open or closed wet batteries, but also Gel or AGM and Lithium batteries, these versions all have different values. This value is also called DoD which stands for Depth of Discharge. This means to what extent may I discharge the batteries without damaging them excessively. Usually this is between 50 and 80% of the capacity. So pay close attention to what is applicable to your battery, if you do not do this it may lead to a shorter life span.

The use of a proper battery charger ensures a fast and safe but above all a full charge of your battery up to 100%. These chargers are also called intelligent or smart chargers.  Such a battery charger can be connected to the battery using the correct diameter cable and a fuse near the battery. Once switched on, this system ensures an optimal and safe charging Voltage, which only benefits the life of the battery.

If you already have a smart battery charger, you only need to make sure that the charger is switched on. Of course it is recommended to disconnect the other 12V or 24V network. This has the advantage that the neighbour who just borrows the power and forgot to put the plug back in can’t damage the battery set because small consumers will completely drain the battery. We regularly see that a small consumer stays on and takes all energy from the battery until it is completely empty. It also happens that the battery charger/inverter combination switches to inverter mode in the event of a mains failure and thus drains your batteries completely until it is completely empty. The WhisperPower combi’s are standard equipped with the Charger only switch. This function ensures that only the battery charger part runs on shore power. If the shore connection fails the inverter will not switch on. So it is important to activate this function during longer periods of absence.

What happens to the battery when it is completely drained?

If the battery is completely or largely empty, the battery will sulphate due to the deep discharge. When the battery is discharged, lead sulphate is formed which develops a very hard crystalline structure and deposits on the battery plates. As a result, the crystals and the part on the battery plate where this is attached can no longer participate in the conversion process when charging and discharging the battery. In other words, there is loss of capacity.

This is always the result of too deep a discharge and we know that it often happens unconsciously. Yet you must prevent this at all times. Discharge is allowed, albeit not lower than the DoD, but then immediately charge properly and up to 100% full. If charing is only done after a longer period of idle time, we notice the consequences of this. Because the crystal structure is on the plates and it protects parts of the plates, there is less active surface available on the plates and there is active material in the crystal which reduces the battery capacity. This will cause the charging current to flow on a limited surface of the plates. As a result, the current will be higher than normal in those places and the battery plate will heat up on that area. The battery acid will also become warmer and react more violently. Usually lead falls out of the plates and this in turn results in a shortened cell . When this is done, the battery life is over. Another consequence can be that the battery gets so hot and gasses if the charger is not equipped with a temperature sensor near the batteries. In that case, the charging Voltage will be too high, causing the battery to gas with all the nasty consequences (the battery tears open or can even explode). It is also possible that the battery capacity has become so low that the battery is no longer usable. Which means end of life.

Over-discharging the battery and leaving it discharged for a few days results in sulphating. This happens both with old and certainly also with new batteries. As a direct result of this, capacity is lost and in the event of prolonged discharge this can lead to the battery breaking down. This can usually be seen when the battery Voltage is low (due to cell closure, or when the battery is at rest, or the battery gets warm during charging. You may also notice that there is no more capacity available.

This has nothing to do with the quality of the battery! But it does have to do with how the battery is treated. Or rather not correctly (well) treated.

Bart van den Bosch

Advice for the winter or do not use for a longer period of time

For those who want to avoid that risk completely, there is little else to do than fully charge the batteries and then disconnect them completely from the installation. We recommend that you turn on the charger at least once in the winter after about 2 to 3 months in order to recharge the self-discharged batteries. It is not recommended to take the battery home and put it away warm. Increased temperature shortens the life of the battery pack outside the risk of damage during carrying.

If you have a good battery charger, it is equipped with a so-called maintenance or multi-stage maintenance charge mode. This is of course fine to use in the winter even if the charger is on for a long time. The choice depends on the type of battery and the capacity of the battery.

We at Whisper Power will be happy to advise you on the right batteries in combination with the right battery charger.

TIPS: End of the season

  • Fully charge the battery. And keep it charged during the winter. Take precautions so that the battery cannot be discharged.
  • Avoid overcharging by using incorrect charging equipment, as this will damage the battery set.
  • Disconnect the battery set. Clean the terminals and clamps thoroughly if necessary.
  • Excessive crystallisation may indicate electrolyte leakage due to cracks at the terminals, overcharging or galvanic corrosion.
  • Check the cable connections and rectify any faults immediately.
  • When checking and disconnecting the battery terminals and/or cabling, protect the tool from touching both battery terminals.
  • For traditional 'wet' batteries, check the electrolyte level and top up the cells with demineralised water if necessary.
  • Closed batteries are maintenance free as far as the electrolyte is concerned. However, they must be correctly and fully charged and remain in a charged state.
  • Use a proper battery charger with a maintenance charge, refer to the battery documentation for the required power and the correct settings.
  • Charge wet batteries preferably every month and for gel and AGM this can be once every 3 months. We recommend the same for lithium batteries.
  • Lithium-Ion batteries can be stored with a 60-70% charge for half a year without looking back. In a next tip I will give more information about the treatment of a lithium battery.

TIPS: Beginning of the season

  • Check that the battery is securely in place and fixed.
  • Connect the battery terminals, use a type with covers.
  • Tighten the terminals properly for optimum electrical connection.
  • Tightening the terminals too tightly may damage battery terminals or detach from the housing, resulting in electrolyte leakage.
  • Consult the battery documentation for the correct moment (expressed in N.m = newtonmeter).
  • Coat the terminals and poles with a thin layer of acid-free Vaseline and close the caps.
  • Charge the battery set and check the charging voltage and current and check if the battery charger has a temperature sensor and is mounted on or near the battery.
  • Check the settings of any connected battery monitor.