Battery drain

[parkmanaa]

2004 Club Car Carryall 2 Plus - Yamaha gas engine.

A fully charged battery will not run the cart a full day, under light duty.
Engine will not crank when voltage drops below 12 volts, (even at 11.8 or 11.9).
You may start the engine, leave it idling for a few minutes, engine dies and starter
won't turn engine over.
Had golf cart technician check it, he says starter/generator and voltage regulator
are fine. Technician also said he checked every wiring connection to
assure they were tight and no corrosion.
Told me to get a new battery, which I did, and immediately experienced the same
problem.

Love the cart and it runs great........when it will run.
Any ideas?

[golfcartg]

The starter/generator unit is a hybrid device that functions as a starter motor, using electrical energy from the battery to turn the engine over. Once the engine is running, the unit switches to its generator mode, converting mechanical energy back into electrical energy to recharge the battery.

Inside the starter/generator, the brushes are one of the most important components. These small carbon blocks conduct current between the rotating commutator and the stationary parts of the generator. Over time, these brushes can wear down, leading to poor contact and insufficient charging. Under heat and continuous operation, this wear can accelerate, causing intermittent issues like the ones you’re experiencing. The commutator, which the brushes contact, can also become worn or dirty, leading to similar symptoms. A worn commutator may have grooves or rough spots that prevent the brushes from maintaining a consistent electrical connection, especially as the unit heats up during use.

The voltage regulator, another vital part of the charging system, allows the generator to supply a steady voltage to the battery. The regulator controls the output voltage by adjusting the field current in the generator. Inside the voltage regulator, you’ll find components like diodes, transistors, and resistors that manage this current. Diodes allow current to flow in one direction only so the electrical charge moves correctly through the system. If these diodes become damaged due to heat or age, they can start to leak or fail entirely, leading to improper voltage regulation. This can cause the battery to either undercharge or overcharge, with undercharging being a likely culprit in your case, as it could explain why your battery voltage drops quickly under load.

In some cases, the resistor within the voltage regulator might degrade over time. A failing resistor could lead to inconsistent voltage regulation, causing fluctuations in charging that might not be apparent until the cart is under load for an extended period. This could explain why your cart runs fine initially but then quickly loses power as the battery drains faster than it can recharge.

Given the complexity and the specific demands of these components, using OEM (Original Equipment Manufacturer) parts is generally better than aftermarket. For example, the copper windings in an OEM generator are typically made to precise standards so that the generator can handle the specific load and temperature conditions. Aftermarket parts use lower quality materials, leading to less precise operation.

Given the symptoms you’re experiencing, where the cart struggles to maintain voltage and performance over time, making sure that all parts are up to the original manufacturer’s standards could be key to resolving the problem.

You can also check for a parasitic drain using a DVM. The first step is to disconnect the negative battery cable and place a multimeter in series between the negative battery post and the disconnected cable. Set the multimeter to measure current (amps). If you see a significant current draw with the cart turned off, it indicates a parasitic drain that is slowly depleting the battery even when the cart isn’t in use. To identify the specific source of the drain, use a wiring diagram and remove and replace each fuse or wire connection to open each circuit one at a time, carefully observing the multimeter for any drop in current. When the current draw decreases or disappears, you’ve located the circuit that is causing the drain.

If your cart has aftermarket accessories like alarms, stereos, or lights, these can often be sources of parasitic drains. Disconnect these accessories one by one to see if the drain stops. Poor installation or a faulty accessory is a common cause of unexpected drains. After driving around for a little, feel around for hot spots in the electrical system where current is flowing. This method is useful because components with higher than normal temperatures could indicate a draw on the system. This can be particularly effective in finding drains within complex wiring harnesses. If you have any specific questions feel free to ask!