Tuesday, July 1, 2008

Aircraft Batteries

Well, this past weekend I had some fun with cancelling a flight. Luckily, I have not had too many times of this. I had everybody in the plane including my son and his friend and the plane would not start. Whir, whir, stop. Whir, whir, stop. The propeller turned very slowly, but the engine would not catch. Then I grabbed the guy from the FBO and tried to jump the plane and got the identical whir, whir, stop.

First look

I suspected the battery, but why did the jump not work? So I went searching connections. Tugging on connections under the cowling and looking at the terminals on the battery in the back of the plane. This did not seem to help quickly. And was a little bit of a challenge with two 6-year olds running around. Luckily, the other dad helped out great with that. After a little investigation, I called it off for the afternoon and decided to check things more later. Luckily, we had only planned a short little hop in the plane for a BBQ and fire station visit.

Further investigation

Later in the day, I worked on the terminals and connections more and the plane did not react any differently. I made sure when working around the battery to disconnect the negative wire first then the positive before checking any other connections; this is indicated in the Cessna 182P Service Manual that I purchased on-line. If you bump the airframe with the wrench when taking off the negative wire it is then ok. If you bump the airframe with the wrench next on the positive wire, there should not be a connection since the negative wire is already disconnected. I still am careful to not touch the airframe just in case. Then I did cleaning with wire brush and then baking soda solution as well.

I did also notice a loose connection to the jump connector; maybe that explained the jump problem? There is an extra solenoid and diodes between the jump connection and where the battery hooks in. This is for protection of reverse hookups during jumping. So maybe there are other possibilities to check there with the A&P. Maybe I have two problems: battery problem and jump connection problem?

After looking further in my airplane logs, I noticed that the battery had been in use for 4 years and the previous battery had last 5 years. So... I started thinking more about a new battery.

Checking on a new battery

I took the battery out and had the FBO check it. One cell ended up looking bad with a hydrometer test, and they put the battery on a charger just in case. So time to start looking into new batteries.

I found a reprint of a recent Aviation Consumer battery article. It can also be found on the Aviation Consumer web site if you have a subscription. This is an excellent magazine for the plane owner. The article mentions a bit about both Gill and Concorde batteries and of both the flooded and sealed types. It mentions that sealed gill batteries had some problems, but should be ok now. Otherwise Concorde seemed to be a little better than Gill, but Gill was still ok. The article also talked about a number of other intersting things. Sealed batteries need to be new from the factory or kept good by charging periodically. The charger for the sealed battery is a special kind. The flooded battery should be charged before putting into use. It seems the sealed battery is not as important for this (maybe due to periodic recharging?), but still a good idea.

I also found some possible places to get batteries on-line: Aircraft Spruce batteries, Chief Aircraft Gill and Concorde batteries, and Air Power has some good deals on batteries.

In the End

On Monday, I checked in with the A&P and he indicated that battery was bad (one cell was bad) and they did have a Gill G-35 battery. So he got one ready for me. I really needed to either have my plane working that morning for an aerial photo mission, or I had to rent. So the Gill G-35 looked like the way to go. The previous battery in my plane was a Gill and lasted 5 years, so it must be ok.

It is interesting that the batteries are stored at the FBO without any liquid. Then the acid is added at the time the battery is put into service, and then it is charged. In my case, it was charged for maybe 1/2 hour with the filling caps off, then they waited for bubbling to stop, topped off the acid, and it was ready to go. There price was a little more than the on-line prices, but not too far off. $206 after base battery cost, acid, and tax. And not having to rent made the price even more worth while.

The time to put the battery back in the plane. First clean the battery box with baking soda and water solution, clean the terminals, coat the connections with petroleum jelly, and I was good to go. It fired right up like it used to, and I was off on my photo mission.

Another day and experience in owning my own airplane. I am sure it will be easier to recognize and diagnose next time.


1 comment:

Anonymous said...

I have had to put a new gill battery G35 on my Pa28201 every year for the last 3 years and it allways 1 sell gone down befor that it lasted 7 years I fly 100hrs year has any one had the same problem John UK