If a lead-acid battery has voltage but no current, it indicates that the battery can hold a charge (showing potential difference) but cannot deliver power to a load.
- High Internal Resistance: The internal resistance of the battery may have increased due to sulfation, age, or damage, which prevents current from flowing even though the voltage appears normal.
- Corroded or Dirty Connections: Corroded or dirty terminals can create high resistance at the connection points, preventing current flow despite the presence of voltage.
- Broken Internal Connections: Internal damage, such as broken or disconnected plates, can disrupt the current path within the battery.
- Sulfuric Acid Stratification: If the electrolyte has stratified, with denser acid settling at the bottom and weaker acid at the top, it can affect the battery’s ability to deliver current.
- Severe Sulfation: While sulfation typically reduces capacity gradually, severe sulfation can sometimes lead to a situation where the battery has voltage but cannot supply current.
- Open Circuit: There could be an open circuit within the battery or the external circuit, which prevents current flow despite the voltage being present.
To address this issue, you can try the following steps:
- Clean the Terminals: Ensure that the battery terminals are clean and free of corrosion.
- Check Connections: Verify that all connections are secure and there are no broken wires or loose connections in the circuit.
- Test with a Load: Connect a known good load to the battery and measure the current flow. This can help identify if the problem is with the battery or the external circuit.
- Battery Maintenance: If sulfation is suspected, you might use a desulfator or an equalization charge (a controlled overcharge) to try to restore some of the battery’s capacity.
- Professional Testing: If simple checks do not resolve the issue, it might be necessary to have the battery tested by a professional using specialized equipment to diagnose internal problems.
