What's killing my Eclipse Batteries?

One of the most common areas of concern for Eclipse operators is battery life. While common sense tells us that all batteries will eventually need to be replaced, the service life of Eclipse 500/550 batteries has failed to meet operators expectations.

So what causes your battery to fail prematurely? In the studies we conducted, the primary cause of battery failure was high battery internal resistance traced to sulfation of the negative plates within the battery and internal grid corrosion.

Sulfation within the battery builds during prolonged periods of charge deprivation. These periods of charge deprivation can be caused by small amounts of battery current drain over extended periods. This current drain is known as parasitic drain.

How does this affect the batteries in my Eclipse Jet?

We know that the Eclipse 500/550 has a small constant current drain acting on the System Battery. We also know that the performance of the battery is directly impacted by the battery's internal resistance. As the internal resistance increases, performance decreases.

RAS has determined that the cause of the parasitic drain is current demands within the System Battery Bus Contactor (BBC). Using specialized test equipment, and an Eclipse battery and BBC, we can demonstrate the destructive impact of the parasitic drain.

For our test, a BBC was connected straight to the battery. No other electrical connections were present.

Every other day for 18 days, the battery's internal resistance was measured and recorded. The reading from the test are shown below:

Each day as the internal resistance is increased, the battery's capacity is decreased. This test was performed on other batteries as well, each producing similar results.

While these tests were conducted in a controlled environment, the increase in resistance would be much higher as the ambient temperature increases.

While some of this increased resistance would be reduced by charging the batteries, the longer the parasitic drain is present without battery charging, the higher the chances are that the increased resistance will become permanent and irreversible.