Choosing the right charger

This used to be the easy bit, get the biggest and heaviest you can find! That was fine when automotive batteries had to be checked every week and topped up, and they lasted about a year, two if you were really lucky.

Today’s batteries are a different animal, they are smaller, lighter, more powerful and you don’t need to top them up, and with luck they will last for up to five years. This change in technology has meant that the charger has had to develop too.

Different battery types require different charging routines to ensure that the battery is correctly and fully charged, with the sophisticated electronics now on all vehicles a fault with the battery can cause all sorts of problems.

There are two main types of battery technology fitted to vehicles:

Calcium/Calcium or Calcium/Silver type is used as a starter battery, and on single battery vehicles this is the type fitted. AGM or Absorbed Glass Matt, on vehicles fitted with two batteries (and there are more than you think) this is the battery that powers the systems other than the engine related systems.

Both these battery types require different charging methods if they are to be correctly charged, putting high current into a Calcium battery can damage it and be potentially dangerous, where an AGM type is more able to accept a higher charge.

So to sum up the ‘one type fits all’ and ‘the bigger the better’ approach to battery charging is no longer acceptable as delicate electronics and humans can suffer unless the correct procedure is followed.

Each one of our charger models carries a description of the battery types it is suitable for.

What is sulphation?

Batteries have a finite life and cannot be expected to last forever, however it is possible to increase the life expectancy of the battery by following a few simple rules.

During the normal discharge process, the sulphuric acid in the electrolyte reacts with the lead plate material to produce soft lead sulphate crystals in the pores, and on the surfaces of the positive and negative plates inside a lead-acid battery. When a battery is left in a discharged condition, continually undercharged, or the electrolyte level is below the top of the plates, some of the soft lead sulphate re-crystallizes into hard lead sulphate. The hard lead sulphate cannot be reconverted during subsequent recharging process. This creation of hard crystals is commonly called permanent "sulphation". It accounts for approximately 85% of the lead-acid battery failures that are not used weekly. The longer period over which sulphation occurs, the larger and harder the lead sulphate crystals become. The positive plates will be light brown and the negative plates will be dull, off white colour. These crystals lessen a battery's power capacity and ability to be recharged. How the battery is used is important; this is because deep cycle and some starting batteries are typically used for short periods, vacations, weekend trips, etc., and are then stored the rest of the year to slowly self-discharge causing sulphation. Car batteries are normally used several times a month, so sulphation rarely becomes a problem provided the car is in regular use.

How Can I Tell If my Battery is Sulphated?

Chances are that your battery has some permanent sulphation, if it exhibits one or more of the following conditions:

If your wet Standard (Sb/Sb)* or wet Low Maintenance (Sb/Ca) battery has been not been echarged for over three months, especially if the storage area was warm or hot. (Six months for wet Maintenance Free (Ca/Ca) or one year for VRLA AGM or Gel Cell.) If the temperature compensated absorption charging voltage is correct and the battery is gassing excessively. Poor performance, or it will not hold a charge

Typical Battery Construction

How do I Prevent Sulphation?

Batteries naturally self-discharge 1% to 60% per month (depending on the battery type and temperature) while not in use and sulphation will begin occurring when the State-of-Charge (SoC) drops below 100%. Cold will slow the process down and heat will speed it up. Storing batteries under 250 AH on concrete floors will not cause them to naturally self-discharge faster than normal.

Physically inspect for leakage or damaged cases, remove any corrosion, clean and dry the tops of the batteries to remove possible discharge paths from dried battery electrolyte, and clean the terminals.

If the battery is in a vehicle, remove the negative connection from the battery to eliminate the additional parasitic (key off) discharge. Use a suitable tool such as the Gunson vehicle memory saver (4148) to prevent loss of security and or radio codes.

If the battery has filler caps, check the electrolyte (battery acid) level in each cell. If required, add only distilled, deionized or demineralized water to the recommended level, but do not overfill.

Fully charge and equalize levels in wet (flooded) batteries, if required, and recheck the electrolyte levels when the battery cools.

Store a battery in a cold dry place, but not so that it will freeze, and where it can be easily recharged. The freezing point of a battery is determined by the SoC and the higher it is, the lower the freezing temperature.

Do not use a cheap, unregulated "trickle" charger or a manual two stage charger which was not designed for "float" charging or you will overcharge your battery. A less desirable alternative to float charging would be to periodically test the State-of-Charge. When it is 80% or below, recharge. The frequency of testing and recharging will depend on the ambient storage temperature.

How Do I Remove Existing Sulphation?

The MPL charger from Traction Charger is designed to recover Sulphated batteries and restore as much of the capacity as possible. At initial connection any charger must 'see' a battery is present before starting its charging cycle, this prevents damage due to reverse connection and sparking between charger clips and battery terminals. Most chargers need ‘see’ more than 8volts in the battery when connected to recognize that a battery is present and to start the charging process but the MPL will recognize a battery with only 1 volt. This means that the MPL charger will attempt to recover and charge a battery that is 'completely flat' whereas other chargers would not be able to start charging at all. At the start of each charge the MPL charger tests the battery to determine if it is deeply discharged or if sulphation has occurred, and the correct recovery algorithm is automatically applied.

After the deep discharge test, the constant current charge provides the fastest possible return of energy to the battery. Even deeply discharged batteries can be recovered, in this way.

Partially discharged batteries are automatically limited to 50% maximum current in order to minimize plate surface charging and heating. When the battery reaches the preset gassing voltage, the charger switches to constant voltage mode. The calculated proportional timing ensures sufficient gassing to prevent stratification, mix the electrolyte thoroughly, and give a green hydrometer indication, but minimizes electrolyte loss and gas emission.

After the completion of charging, the MPL charger switches to the standby or float mode, which compensates for self-discharge and holds the battery at peak charge ready for use.

Using the MPL can dramatically improve the performance of batteries that have been stored and reduce warranty costs along with improving customer satisfaction. *Note: Ca = Calcium, Sb = Antimony