06/17/2026
🔋 Why Replacing Just a Couple Golf Cart Lead Acid Batteries Can Create Bigger Problems 🔋
This week’s case study involved a customer chasing an intermittent power loss complaint that simply didn’t make sense.
The cart would occasionally shudder, lose power, and even cause the battery gauge to go blank. To make matters more confusing, the two battery positions in question had already been replaced once before.
After performing a full charge, load testing, and internal resistance testing, we found the problem.
The two replacement batteries measured over 1.10 mΩ higher internal resistance than the rest of the pack and were only reaching about 8.07V after charging, while the other batteries were over 8.56V.
So why does this matter?
As battery internal resistance increases, the battery becomes less capable of accepting and storing charge. The charger only sees total pack voltage, so when the stronger batteries push the pack voltage high enough, the charger shuts off—even though the weaker batteries are still undercharged.
The result?
⚠️ Pack imbalance
⚠️ Reduced runtime
⚠️ Excessive voltage drop under load
⚠️ Controller power cutback
⚠️ Intermittent shuddering and performance complaints
This is one of the biggest reasons we caution against replacing only one or two batteries in an aging lead-acid pack. Newer batteries don’t always play nicely with older batteries, especially when their internal characteristics don’t match.
The lesson is simple:
📊 Voltage alone doesn’t tell the whole story.
Proper diagnostics, including internal resistance testing and O-Scope load testing, often reveal problems that can’t be seen with a voltmeter or handheld 100A Resistor Tester alone.
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PA Golf Cart World
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