Electric golf carts use deep cycle lead acid batteries as energy source for their motors. Selecting the right battery can be daunting task, especially with lithium batteries being more and more present in everyday life.
Deep cycle marine batteries used to power electric trolling motors, can be used as golf cart batteries and vice versa. Dual purpose marine batteries can be used, too, but deep cycle marine batteries are better suited for that role.
If you have issues with your golf cart batteries, the easiest thing to do is to replace old batteries with the exactly the same new batteries - especially if you were satisfied with performances of your old battery pack. This can be, however, very expensive and there are perhaps cheaper or better batteries on the market.
Note: First - whatever you do with your batteries, it is your own responsibility; second - don't go cheap on the golf cart batteries, because in the end, it can cost you more...
Most golf carts use battery banks with 48V total. This 48V is created by connecting in series:
- eight 6V batteries,
- six 8V batteries,
- four 12V batteries.
Strength of electric motors in golf carts vary and can go up to, or even more than 5 kW.
At 5 kW, batteries are drained at rate of ~104 A, but note that the starting current of electric motors can be higher, depending on the total weight of the vehicle, type of motor controller, driver's driving habits and similar.
GC2 (GC-2) and GC2H (GC-2H) Battery Group
Standard battery group size in golf carts is GC2 (or GC-2) battery, consisting of 3 cells and providing 6V. It's dimensions are 10 3/8" x 7 3/16" x 10 5/8" (264 x 183 x 270 mm) L x W x H. Note that there is very similar battery GC2H (or GC-2H), 10 3/8" x 7 3/16" x 11 5/8" (264 x 183 x 295 mm) L x W x H - GC2H is one inch (2.5 cm) higher than GC2 battery.
Standard capacity of the group size 6V GC2 batteries is around 225 Ah when drained for 20h and it rises to 240-250 Ah when drained for 100 of so hours. However, when drained faster, their capacity is reduced.
GC2 batteries come as flooded wet cells, as AGM and as gel cell batteries.
Sealed Valve Regulated Lead Acid batteries allow recombination of hydrogen and oxygen back into the water and require no maintenance and are IMHO, the best choice not only for golf cart batteries, but also as trolling and dual purpose general batteries.
Dual purpose and especially deep cycle batteries are NOT able to provide high burst of strong current as cranking (starter) batteries can do, but for golf cart applications, currents over 100 - 120 A are rare, except in larger golf carts which can achieve relatively high speeds. Such currents are not problem for deep cycle batteries, especially for 200Ah or larger batteries.
Size of the Battery Compartment
One of the reason for choosing the original size batteries is the size of the battery compartment.
Some battery compartments are 'close fit' compartments and leave little extra space for the batteries - this way batteries are firmly positioned and secured. If you go for different group batteries, be sure that they can fit into the battery compartment, or be ready to modify it.
Personally, I would go only for the same battery group as before, unless there are other strong reasons for different battery group.
Golf Cart Battery Watering System
In order to operate properly, flooded cells must be periodically checked and if electrolyte level is low, distilled water must be added.
It is not big job, if you have one battery. If you have battery bank, it takes some time - custom battery fill bottle with auto shut off valve can help speed things up. However, if you maintain golf carts for a large golf club, then you can simplify your life by implementing remote battery watering system.
There are several types of on-board battery watering systems, but they all work by replacing the battery's existing vent caps with new valves interconnected with tubing.
This allows the user to fill all battery cells from a single location. Depending on the system, filling can be done automatically or by remote command using smart phone or similar. When the proper electrolyte level is reached, each new valve independently shuts off water flow to the battery cells, allowing the batteries to be properly filled every time without having to look at the batteries. This can save enormous amount of time.
Even better solution - find good AGM deep cycle battery and stop worrying about water and electrolyte in your batteries. VRLA batteries have internal valves which that enables oxygen and hydrogen to form water again, without ever exiting the battery.
How Long Do Golf Cart Batteries Last - Battery Maintenance
How long will lead acid batteries last depend on many things, like:
- number and depth of regular discharges,
- battery and cables maintenance,
- battery temperature,
- battery construction, etc.
so it is impossible to give a fixed number of charge/discharge cycles.
To prolong the life of lead acid battery, never leave the battery fully or partly discharged - when golf cart returns, plug-in the charger, even on a daily basis. Avoid high temperatures during charging and discharging - batteries can tolerate high temperatures, but they shorten the battery life. Keep the golf carts in the shade, especially during summer and charge the batteries with intelligent charger which can recognize the condition of the battery and charge it properly in three phases:
- Bulk Charge - current is sent to battery at the maximum safe rate, until the voltage rises to near full charge level.
- Absorption Charge - voltage remains constant and current gradually tapers off as internal resistance of the battery increases during charging.
- Float, Maintenance or Trickle Charge - it's main purpose is to keep an already charged battery from discharging, to reduce or avoid gassing and to prolong battery life.
AGM batteries easily tolerate certain trickle charge, too, but don't overcharge your VRLA batteries.
During winter or off-season, be sure to trickle charge your batteries or charge them fully once a month - lead acid batteries discharge rate depends on the battery type and plate and electrolyte chemistry, but it ranges between 1 and 10% per month.
IMHO - during off-season, disconnect the batteries from the golf cart's electric system and charge them once a month.
Golf Cart Autonomy - Regenerative Breaking
Autonomy of a electric golf cart depends on many things, but mostly on:
- driving speed - driving golf cart at maximum speed discharges the batteries at maximum rate and decreases their capacity. Driving the golf cart at moderate speeds can prolong both the battery life and period between required charging.
- terrain - hilly terrain requires extra effort from motor and the batteries, thus leading to higher discharge rates and deeper discharges. Never allow discharging of deep cycle battery below 20-25% of fully charged battery. However, regenerative breaking recovers kinetic energy of the vehicle and store it back into the battery, thus prolonging the time between required charging. Regenerative breaking is not available in all electric golf cart models.
- vehicle mass - heavier vehicles require more power and thus more energy from the battery. It is not the same if the golf cart is used by one, two or more individuals, does it have to carry any extra equipment and similar. Few pounds/kilograms makes no difference, but couple of hundred pounds/kilograms will make the difference.
- tire pressure - lower tire pressure means less pressure on the grass and sand and easier terrain crossing, but lower tire pressure also means larger rolling resistance and decreased autonomy.
Golf Cart Lithium Batteries
Lithium batteries have numerous advantages over flooded or even VRLA AGM/Gel cell batteries:
- they are lighter for the same capacity,
- can withstand required discharging currents with ease,
- can be charged faster,
- no 'fade-away' effect - produce energy at almost constant levels, etc.
However, lithium batteries are very sensitive to charging and discharging conditions. To prevent any issues, 12V deep cycle lithium batteries are equipped with protective electronics, which monitors battery condition and protect the batteries against:
- overcharging the battery,
- too high charge or discharge currents, including various surges and spikes in the electric system,
- overheating the battery, etc.
With such protection, 12V lithium batteries can be used as one-to-one replacement for 12V flooded/AGM/Gel Cell lead acid batteries, but before you do that, check the manuals of the batteries you are interested in.
Personally, I have never used 12V lithium battery as replacement for the boat's main dual purpose battery, or as trolling motor battery, or for golf cart, or DPV or anything similar. I have used lithium batteries as kayak trolling motor battery pack, but those where high capacity lithium polymer batteries designed for use on the remote controlled airplane models, they where connected in parallel, protected by power diodes. Also, batteries where independently charged using lithium battery chargers and I was doing it on my own responsibility.
Note: author of this article has Master's degree in Electrical Engineering; thank you :)