Golf car owners sometimes complain that they didn’t get a full-year or more out of a set of batteries they recently purchased. While there are many factors that can determine the service life your golf car’s batteries can provide, poor longevity can ultimately start from choosing the wrong batteries. For example, if you’re shopping for the lowest cost batteries you can find, this may actually cost you more in the long run by having to purchase another set, simply because they didn’t last.
Of course there are other factors in making your golf car battery’s last, such as proper charging and maintenance and limiting the depth of discharge (DOD) to 50% or less on average. But starting with an optimized set of batteries for your particular application is the best way to save on their overall cost, by minimizing the life-cycle cost.
When it’s time to purchase a new set, compare amp-hour ratings. Amp-hour ratings are the average discharge current the battery can provide over a certain length of time (amps x time). It’s important to compare the ratings for the batteries you are considering with the same time rating. One industry standard that is used for comparison is a 20-hour rate or C20 (but there are others). For example, a 6-volt battery may list its amp-hour (Ah) rating as 200 Ah at the “20hr rate”. This means that the battery will provide 10 amps of current for 20 hours until the battery is fully discharged. Amp-hour ratings are independent of voltage so if eight 6-volt batteries are used in a 48 volt battery pack, the amp-hour rating at C20 is still 200 Ah. Other ratings commonly used for golf car batteries are the number of minutes the battery can be discharged at 56 or 75 amps. This gives the user a good indication of how long he can drive his golf car depending on driving conditions such as hilly vs flat and turf vs pavement.
Usually, a lower-priced battery with less capacity will have a lower amp-hour rating than one with higher capacity that costs more. The difference in cost is typically due to the amount of lead in the battery (battery weight) but is also determined by the battery design. More efficient battery designs utilize the total amount of lead more efficiently.
Battery design can affect how various batteries perform at low rates of discharge (C20) vs higher discharge rates (56 – 75 amps). This ratio is often referred to as the Peukert value and can be used to compare how efficiently different battery designs utilize the amount of lead in the battery. This can also affect overall battery life. Heavier batteries are not necessarily better than slightly lighter batteries. More efficient battery designs usually have a higher Peukert value. This information is not usually published at the point of sale, so consult the battery manufacturer for this information.
All of these numbers can vary between battery chemistries, so it’s important to compare apples-to-apples. There are three distinct battery chemistries used for golf car batteries that include flooded lead-acid (FLA), absorbed glass mat (AGM) and lithium-ion (Li) batteries. Each of these has its own advantages and disadvantages that you can consider each, to determine which one suits your application the best.
Flooded lead-acid batteries are still the most popular in most applications. They have the lowest initial cost and are 100% recyclable, so they are better for the environment. However, they do require regular maintenance in the form of watering and terminal cleaning. A single-point watering system can offset this inconvenience. They deliver longer life when the depth of discharge is kept below 50% DOD. AGM batteries are also lead batteries and are 100% recyclable. They do not require regular maintenance but are higher in initial cost. They are a good choice for applications in which regular maintenance may be an issue. Lithium batteries have higher energy density than FLA or AGM batteries and do not require regular maintenance.
They are much higher in initial cost vs lead batteries but will usually last longer even if discharged to greater DOD. It is important to recognize that lithium batteries require special chargers and battery management systems (BMS). This must be considered when replacing lead batteries with lithium batteries in a golf car because the BMS may or may not be built-in to a lithium battery or a lithium battery pack. While these batteries are becoming very popular, they are not yet being recycled and are therefore not as environmentally responsible as lead batteries. Disposal of lithium batteries at end of life should be considered in the total cost of ownership since there is currently a charge for disposal of lithium batteries. Lithium batteries cannot be recycled with lead batteries and should not be included in lead battery recycling streams.
No matter what capacity or chemistry battery you choose to replace your worn-out batteries, remember some key items when comparing them. 1) Cycle life comparisons should be made at the same depth-of-discharge (DOD). 2) Amp-hour ratings should be compared using the same discharge time and/or discharge current used in the application. 3) Run-time ratings are typically the most accurate way to compare batteries for any given application.
