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Battery Cycles - When to Charge your Golf Cart Batteries

Underneath the seat of your trusty electric golf cart lies the lifeblood of its propulsion system – a bank of deep-cycle batteries.  Though often ignored, proper maintenance and usage of these batteries is essential if you wish to get the maximum life and value from them.  One commonly overlooked and understandably misunderstood topic is the quandary of when and how often your batteries should be charged.  In order to accurately address this topic we must first look at the batteries themselves and what makes them tick.

Though they vary in voltage and amp-hour capacity, practically all major golf car brands take advantage of lead-acid deep-cycle batteries as they offer the best power to price ratio.  The lead-acid part refers to the mixture (electrolyte) contained within the case of the battery and the lead material (plate) that reacts with this mixture.  The deep-cycle term means that these batteries are built for just that – being deeply cycled.  A cycle simply refers to a battery being discharged and then recharged again.  These batteries differ from your standard automotive type battery in that they are designed to provide power over longer periods of time rather than a massive amount of current all at once, which is perfect for golf cars and all the accessories we love to add to them.

To reiterate, a cycle is one complete discharge and recharge of the bank of batteries.  Manufacturers typically recommend that you do not drain their batteries down beyond 20-30% of their overall capacity.  In other words, they suggest that you only consume 70-80% of their rated capacity – so a 1200 amp-hour battery suddenly becomes a 840-960 amp-hour battery.  For those of you who feel slightly ripped off and want to push their batteries further, keep in mind that today’s smart chargers require a nominal voltage of around 20-30% before they’ll kick on.  In addition, going beyond the 20-30% threshold can be damaging to your batteries so do your best to avoid this whenever possible.

Among several other factors (temperature, load, rate of charge being the others), the way you cycle your batteries directly effects whether your batteries will last 2 years or 6 years.  For instance, if a battery is discharged to 50% DOD (depth of discharge) every day it will last approximately twice as long as if it is cycled to 80% of its capacity.  If you were somehow able to cycle your batteries at 10% DOD they would last about five times as long as compared to 50% DOD.  Obviously there are variables and limitations involved in the DOD you apply to your batteries, but 50% DOD is typically considered to be the happy medium when it comes to prolonging the life of your batteries.

On the opposite side of the spectrum are those who throw their batteries on charge no matter how much (or little they use them).  For example, if a bank of batteries is cycled to only 5% DOD it will actually do more harm than good as compared to cycling the batteries down to 10% DOD.  This primarily happens because at very shallow cycles Lead Dioxide can build up on the positive plates in clumps rather than in an even film.  Again, if you stick with the recommended 50% DOD you’ll avoid over-charging, short cycling, and causing low-voltage damage.  With that said, hitting the 30% DOD mark on occasion, or charging when you’ve only cycled 10% because you need the capacity for tomorrow isn’t necessarily a big deal, but try to avoid it if you can.

Of course, all of this battery monitoring is pretty hard to do if you don’t have a state-of-charge meter.  Of all accessories available for your batteries this is by far the most important if you plan to responsibly charge and maintain your batteries.  They are relatively easy to install and easily pay for themselves in the long run – take a look in our online store for a complete line of golf cart battery meters.


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