How do I pick a Battery Charger?

 Many battery chargers, including some sold on this site, put out continueous current and will charge your batteries in a short time. These can also overcharge your battery. Chargers like the BatteryMINDer will adjust the charge current and voltage to charge the battery and keep it charged without overcharging. A third process that the BatteryMINDer and other brands can do is condition the lead/acid battery. This conditioning will make the battery last longer.

Here are some simple steps to aide you in selecting the correct charger for your needs.

Step 1

Determine what type of battery or batteries you will be charging. Maintenance Free, Wet Cell (flooded), AGM (absorbed glass mat), Gel Cell or VRLA (valve regulated lead acid). In most cases one charger will work for all types except for Gel Cell. However, some of our Gel Cell chargers will work well with the other battery types.

Step 2

What size is your battery? What we mean is not physical size, but how many Amp hours does your battery store. As an example, a typical full size auto battery is about 50 amp hours, and it would take a 10 amp charger approximately 6 hours to recharge it if the battery were completely dead. Another example, a Marine Deep Cycle Battery may be rated at 100 amp hours, so it would take a 10 amp charger about 11 hours to recharge a dead battery to near 100% full charge, from a completely discharged condition. To calculate your total charge time, a good rule of thumb is to take the amp hour rating of the battery and divide by the charger rating (amps) and then add about 10% for the extra time to totally top off the battery.
Some folks need to size the charge for quick recharge, therefore requiring more amps from their charger. Others are not in a hurry and may select a smaller charger. The most important thing here is to make sure you have enough charger power to do the job you require in the time you allocate.

Step 3

Know your desired outcome. Some folks require a charger to keep their motorcycle, classic car, or aircraft battery charged during the off season. In such a case a simple low current charger will work fine. Others require a fast and powerful charger to quickly restore a trolling motor battery or a wheel chair battery set.

There are certainly other factors in selecting a battery charger, and it would be difficult to cover them all, but here a few. Input voltage, generally for use foreign countries. Exposure to elements, i.e. would you benefit from a waterproof charger? Perhaps you will need a charger that doubles as a power supply for a RV or some other application. Often people will need to charge multiple batteries simultaneously, so multiple bank chargers may be needed.

Following is a list of definitions of different types of batteries and their uses.

Choosing the right type / size battery:

Whether you have good or bad service from your battery will first and most importantly depend on choosing the right battery for the right job. Unfortunately most mass retail stores don't have the trained personnel to help you with this most important decision.  A store specializing in batteries is your best bet. Remember that it's not what you pay for the battery, but how long it will give you good performance that determines the real cost of the battery. Think long term when buying a battery. Each battery has its strengths and weaknesses. No battery is the perfect solution to any application.

Starter battery

When a car battery is connected to an external device, such as a starter, chemical energy is converted to electrical energy and direct current flows through the circuit. A good quality car battery will cost between $75 and $150 and, if properly maintained, it should last an average of five years. The primary purpose of a car (or SLI-Starting, Lighting and Ignition as it is known in the battery industry) battery is to start the engine. Its secondary function is to filter or stabilize the power. It also provides extra power for the lighting, two-way radios, audio system and other accessories when their combined load exceeds the capability of the charging system. Finally, a car battery provides a source of power to the electrical system when the charging system is not operating.

Starter Battery-Maintenance Type (filler caps)

•  Most commonly referred to as automobile/truck starter type. Least expensive (initial cost)
• Not to be used for non-starting type applications such as running lighting, deep cycling (trolling), fish finders, electronics.
• Must not be deeply discharged and should be re-charged immediately after being used.

Starter Battery - Maintenance Free Type (no filler caps w/ liquid electrolyte)

• Sold as never needing maintenance i.e. water.
• Satisfactory for most starter applications in frequently used equipment. Disadvantage: Can't determine health of battery without using an accurate digital volt meter or load tester.

Starter Battery - Sealed Gelled, AGM, or Dry (no filler caps -electrolyte is "non liquid")

• Much more expensive than non-sealed liquid type.
• Can be operated in any position without risk of spilling.
• Have a lower rate of self-discharge than non-sealed maintenance and/or maintenance-free (liquid) batteries.
•  Are considerably more sensitive to overcharging and self-discharge, which can cause serious damage and shortened battery life.
• Recommended for applications where little or no checking and/or maintenance can easily be performed.

Deep Cycle Battery - liquid - maintenance type with filler caps

• Designed to deliver maximum capacity through hundreds of full cycles of charge.
• Discharge without damage. Ideal for trolling motor, RV service (house) battery applications.
• Can be left in discharged state for extended periods without serious damage.
• Should not be used in starter type applications where heavy current draw is required over a short time period.

Deep Cycle (non-liquid) Sealed, Gelled and Absorbed Glass Mat (AGM) w/o filler caps

• Can operate in any position and confined areas.
• Have all attributes of maintenance type deep cycle batteries as described above.
• Rate of self-discharge is less than vented, free electrolyte (liquid) batteries, but serious recharge problems can develop if left uncharged for too long. Remember a battery can loose up to 1% of its capacity a day when left uncharged.