Leisure batteries discharge unreasonably quickly.

[Tor Johnsson]

I have a California Comfortline. I have two brand new AGM 70 Ah batteries, but they discharge to less than 50% in just 2-3 days even though I hardly use any electricity at all. (Only the refrigerator on level 3 and some lights and the control unit says -0,04A). The control unit says that the batteries are fully charged after driving for a about 1h.

If I turn on the engine with AC/car lights etc off the control unit says 14,2V 20Ah (Got about the same numbers with a multimeter.), but when I turn on the AC/ car lights etc it drops to 13,7V.

If I plug in the cable the leisure batteries gets 14,35V.

Is it possible that the leisure batteries are not fully charged due to too low Volt while driving even though the control unit says that they are 100% charged?

Or is there any other explanation?

 

[CaliforniaCylus]

Dependent on weather, we only get at most 2-4 days out of the batteries. Two days in very hot weather and 3 to 4 in cooler climates.

Installed solar panels and never looked back.

The fridge takes around 4a when the compressor is working away.

 

[WelshGas]

I have a California Comfortline. I have two brand new AGM 70 Ah batteries, but they discharge to less than 50% in just 2-3 days even though I hardly use any electricity at all. (Only the refrigerator on level 3 and some lights and the control unit says -0,04A). The control unit says that the batteries are fully charged after driving for a about 1h.

If I turn on the engine with AC/car lights etc off the control unit says 14,2V 20Ah (Got about the same numbers with a multimeter.), but when I turn on the AC/ car lights etc it drops to 13,7V.

If I plug in the cable the leisure batteries gets 14,35V.

Is it possible that the leisure batteries are not fully charged due to too low Volt while driving even though the control unit says that they are 100% charged?

Or is there any other explanation?

The battery % is a calculation based on the current being used at the time of the calculation and will vary a lot, BUT the voltage is accurate.

 

[pchmlk]

The battery % is a calculation based on the current being used at the time of the calculation and will vary a lot, BUT the voltage is accurate.

View attachment 139220

Doe the voltage reflect the health of the battery?

 

[WelshGas]

Doe the voltage reflect the health of the battery?

Overview


AGM (Absorbent Glass Mat) batteries, like other lead-acid batteries, experience a gradual voltage drop over time due to self-discharge. This self-discharge is a natural process where the battery loses its charge even when not connected to a load. The rate of discharge varies based on temperature, with higher temperatures leading to faster discharge. Typically, AGM batteries discharge at a rate of 1-3% per month at room temperature.

Here's a more detailed breakdown:

• Self-discharge:
  AGM batteries, like all lead-acid batteries, will naturally lose their charge over time even when not connected to a load.
  
  
• Rate of discharge:
  The self-discharge rate is generally 1-3% per month at room temperature (around 20°C or 68°F). This means a fully charged AGM battery will lose a small amount of its charge each month, even when not in use.
  
  
• Temperature dependence:
  The self-discharge rate is affected by temperature. Higher temperatures will increase the rate of discharge, while lower temperatures will decrease it. For example, at 8°C (46°F), the discharge rate is approximately 1-2% per month.
  
  
• Voltage drop:
  As the battery discharges, its voltage will gradually decrease. This voltage drop is a normal part of the discharge process.
  
  
• Factors affecting voltage:
  The specific voltage drop will depend on the battery's age, condition, and the load it's under.
  
  
• Monitoring voltage:
  Regularly monitoring the battery's voltage can help you assess its state of charge and identify potential issues.
  
  
• Signs of a failing battery:
  A battery that is losing voltage rapidly or dropping below a certain threshold (e.g., 11.5V under load) might be nearing the end of its lifespan or have other issues.