Dead Batteries After Storage
You return to your RV storage location only to find your house and/or starter batteries are dead. How could this be since you charged your batteries and turned off your RV's electrical system prior to the storage season? What happened?
There are a number of possibilities and some certainties at play that cause this to occur each spring for campers getting ready to head out to their favourite campsite.
Most people are misinformed on the correct way to accurately determine their battery's level of charge.
Most RVs have a built-in battery charge readout and many have more than one. Unfortunately, almost all of the stock monitors fail to provide an accurate readout. This is due to their design and a lack of user knowledge on how to use the meter.
Battery voltage cannot be accurately read while or shortly after it has received a charge or power has been drawn from it. You can only get an accurate reading after it has been resting (no charge or draw) for a period of time. The battery industry says the rest period should be 24-hours but there is little change after about 4-hours. A fully charged flooded lead-acid or AGM battery will indicate a charge level of approximately 12.7 volts. These batteries can be used down to their 50% charge level of about 12.1 volts. Batteries drawn below 12.1 volts suffer damage that can reduce their life and efficiency.
To accurately determine your battery charge, let the battery rest for a minimum of 4-hours. then, check the voltage, at the battery, using a hydrometer, multimeter, or test light with a voltage indicator.
The power switch, or salesman switch, provided in most RVs does not disconnect the house/coach batteries. It merely disconnects a number of circuits, leaving others connected and able to place a small load on the batteries. Over time, this small load adds up and will eventually cause the batteries to be depleted.
The only way to eliminate all load from your RV batteries is to disconnect all leads from the negative battery terminal or install a battery disconnect switch to the negative battery terminal.
All flooded lead-acid and AGM batteries naturally self-discharge. Even totally disconnected, they will lose their charge over time, but at different rates.
Flooded lead-acid batteries self-discharge at a rate of about 4% per week. That means that a fully charged flooded battery will be deleted over 16 weeks. The self-discharge rate is significantly less for AGM batteries as they lose about 2% of their charge per month, making them ideal for long-term storage.
It should be noted that Flooded batteries also require their fluid levels to be maintained through the addition of distilled water. They should be checked at least every six weeks.
Basic Steps of Battery Care
1. Accurately determine your battery's state of charge prior to storage.
2. Disconnect all leads from the negative (—) battery terminal.
3. If using flooded lead-acid batteries, recharge and adjust fluid levels at least every 6 weeks.
4. Prior to returning your RV batteries to service, clean the negative and positive battery terminals and leads.
Follow these simple steps and you'll never return to dead batteries.
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