Golf cart battery maintenance: the monthly routine

Golf cart battery maintenance for a flooded set is one short routine done once a month: charge, water, clean, check, equalize. Owners who do it report five to seven years from a Trojan set and four to five from a budget set. Owners who do not report two to three from either, which is why the routine is worth more than the brand.

Within the golf cart batteries guide, this is the upkeep page. If the set is already past four years and starting to fade, the battery calculator will tell you whether a new flooded set or a lithium pack is the cheaper next ten years, and the testing page finds a weak battery before you buy anything.

1. Charge first, then lift the seat

Water goes in after a full charge, not before, because electrolyte expands as the battery fills and a cell topped up flat will overflow onto the tray during the next charge. The one exception is a cell whose plates are showing: add just enough distilled water to cover them, charge, then fill to the line.

Charge, let the charger finish, unplug it, and leave the cart an hour. Then put on glasses and gloves, lift the seat, and set a Club Car or RXV to Tow before you touch anything.

2. Water every cell, distilled only

Pull the caps and look into each cell with a flashlight. The right level is about a quarter inch below the bottom of the fill well, the plastic tube that hangs down from the cap opening, and always above the top of the plates. A six-battery set has 18 to 24 cells; an eight-6V Yamaha set has 24. Fill each one with a long-spout funnel or a watering gun, which shuts off at the right level.

Distilled or deionized water only. The minerals in tap water, well water and bottled spring water settle on the plates and cost you capacity for the life of the set. In July a hard-used six-battery set drinks about a gallon a month; in January it may take almost nothing. A cell that takes far more than its neighbors is overcharging or cracked and wants a hydrometer check.

Do not overfill. A full cell pushes acid out of the vent during charging, which is where the mess on the tray and the crust on the terminals come from, and a battery that has lost acid cannot be fixed by adding water.

If you would rather not do this by hand, the watering kit in the picks links all the caps with tubing and fills the whole set from one point in two minutes. For most owners it is the one purchase that keeps the routine from being skipped.

3. Clean the terminals with baking soda

Mix a tablespoon of baking soda into a cup of water. With the caps on and tight, brush the solution over any crust on the posts and lugs. It fizzes as it neutralizes the acid; let it stop, then rinse with a little clean water and dry with a rag. Do not let the solution run into a cell.

Where a lug is heavily crusted, pull it, brush the post and the lug face with a brass brush until both are bright, refit and torque to about 8 foot-pounds, Trojan’s spec. Add a felt anti-corrosion washer under the lug if you have them. Then coat the finished connection with terminal protector spray.

Rinse the tops of the batteries too. A film of acid and dust across a battery top conducts a little current between the posts and drains the set slowly between drives.

4. Check every cable

Run a hand along each cable. It should be flexible its whole length; a stiff section near a lug means corrosion has crept up inside the insulation. Look for cracked insulation, green at the lug and any lug that turns on its post. Tighten what is loose. Replace what is green or stiff, in a set rather than singly; the battery cables page has gauge and lengths by make and the 48 volt diagram shows where each one goes.

After a drive with a hill in it, feel each lug. A warm one is a bad connection and will keep eating voltage until it is fixed.

5. Equalize once a month

Equalizing is a deliberate, gentle overcharge that stirs the electrolyte and strips the early sulfate that normal charging leaves behind. On a 48V flooded set it means holding the pack two to three volts above the normal finish voltage for a few hours. Trojan recommends it about monthly, or whenever a hydrometer shows more than 0.030 difference between cells in a battery.

Most modern chargers do it for you: the Lester Summit II runs an equalize cycle on a schedule, and many others have an equalize button or do a small one at the end of every charge. If yours does not, a shop can do it, or a charger with the mode is on the charger guide. Never equalize an AGM or lithium battery; both are damaged by the voltage.

Water the batteries after an equalize, not before, and expect them to drink more than usual.

6. Read the hydrometer

With the set charged and rested, draw acid from one cell into the hydrometer until the float lifts, and read where the acid meets the scale. A healthy charged cell reads 1.265 to 1.280. Do all the cells in one battery, then the rest. Write the numbers on a card and keep it in the glove box.

What the numbers tell you. All cells near 1.270 is a healthy set. One battery whose cells all read low is sulfated and may recover with an equalize. One cell reading more than 0.030 below the others in the same battery is shorted or badly sulfated and will not recover; that battery is on its way out and the testing page has the load test that settles it.

7. Before the cart sits: winter and long storage

Charge to full, water, clean the terminals and run an equalize if the charger has one. Then set the Tow/Run switch to Tow, or pull the main negative cable, so the controller and any accessories cannot drain the pack. Store the cart somewhere dry. A charged flooded battery is safe to well below zero; a discharged one freezes around 20°F and splits.

Recharge every 30 to 60 days, or leave it on a charger with a true float or maintenance mode. Do not leave an old timer-style charger connected for the winter; it will boil the set dry. In spring, water, charge, and check with the hydrometer before the first drive. The charging page has the times.

AGM sets skip the water and the equalize but want the same terminal check and the same storage charge. Lithium wants its terminals clean, a 50 to 60 percent charge for storage, and nothing else.

When to stop and call a shop

A battery with a bulged or cracked case, a cell that will not hold water, a post that moves in the case, or a smell of rotten eggs during charging is finished and may be dangerous. Set the switch to Tow, leave the seat up and have it removed. Acid on skin is a cold water rinse for 15 minutes; acid in an eye is the same rinse and a doctor. If the whole set is past four years and two or more batteries read low on the hydrometer, stop maintaining and start pricing; the cost page and the fitment pages for Club Car, EZGO and Yamaha are the next stops.