What about those pesky batteries?

03-23-2012, 06:59 PM

MIke | What about those pesky batteries?

After an unusually long inactivity of N20W I went to the airport and found that the "keep alive circuit" drained the number one battery down to four volts. Normally this would be an issue however; I have two batteries in the plane. Both batteries are the B&C 100-1, 12volt, 25 amp hour batteries also known as the Odyssey (925) battery(s).

A few years ago I had to replace the number one battery because it wouldn't hold a charge. I decided to call B&C to discuss the lack of longevity of these batteries. I was told if the batteries are charged with more than 14.4 volts the batteries will degrade and have a life of less than two years. Also, incorrectly charging would also degrade the battery. So this means that a normal car charger is not able to be used if you turn up the charging amps past 10 amps since the voltage usually increases to over 15 vdc (volts direct current). After carefully charging the battery with a low current car charger I started the plane and checked the alternator charging voltage. Since the charging voltage was a little high, I adjusted the voltage regulator so the alternator would charge at a maximum of 14.4 charging volts.

So now what?

If the plane is left for a long period of time a trickle charger is recommended.

Which charger should be used?

To start off the charger needs to be waterproof and compatible with salt water.

You need to pick a gel cell charger that has a charging voltage of not more than 14.4 volts dc @ 4 amps (assuming the battery only needs to be topped off) and a charging profile that ends in a trickle charge as needed. The closest one I could find was from dualpro. This battery charger will be able to charge both batteries at the same time with a maximum of 10 amps per battery at a maximum of 14.4 vdc. If you decide to add one of these chargers http://www.dualpro.com/products/sportsman/ to your plane, make sure you order one with a gel cell charging profile. This profile is important since it charges the battery in stages (different current levels) so it won't cook the battery therefore reducing its longevity.

What about the weight of the charger?

I decided to install the charger in the nose storage compartment close to the batteries. Some seawinds have extra weight in the nose to offset the weight in the tail and mine is no exception. Since the battery charger weighs 11 lbs, it was easy to remove the equal amount of ballast therefore keeping the CG where it belongs.

Now all I need is an extension cord that will reach from NY to FL......